Isotope and Nuclear Chemistry Division

Home , Isotopes of nitrogen, Major actinide

/Isotope anci"Rviclear Chemistry Divlsibn The high-pressure diamond anvil cell technique is being applied to a variety of simple solids by Basil I. Swanson, Stephen F. Agnew, and Llewellyn H. Jones of the Isotope and Structural Chemistry Group (INC-4) in conjunction with David Schiferl in the Shock Wave Physics Group (M-6) and Robert L. Mills in the Condensed Matter And Thermal Physics Group (P-10). This technique allows the spectroscopic study of chemistry at high pressure and is directly applicable to understanding the chemistry involved in detonation. Agnew and Swanson are shown adjusting the position of the diamond anvil cell (arrow) in the optical path of the laser Raman spectrometer. The spectrometer is used for spectroscopic analyses of the contents of the high-pressure diamond anvil cell in backscattering geometries. The disassembled diamond anvil cell is shown at left.

On the cover, we see two closeup views of the contents of the high-pressure diamond anvil cell. The upper left picture shows solid molecular oxygen at 100 000 atm; the red vs the clear portions of the sample represent two different crystalline orientations of the usual e— or "red" phase of oxygen. The lower right picture shows the product of a pressure-induced reaction of nitric oxide; the colors are due to various nitrogen oxides. Reports on the application of this technique can be found in Section 3 of this report.

Cover photography by Henry W. Johnson and Stephen F. Agnew LA—10130-PR

DEC4 017073

DISCLAIMER

This report was prepared as an account of work sponsored by an agency of the U ;'.ed States Government Neither the United States Government nor any agency thereof, nor any of their employees, makes any *arranty, express or implied, or assumes any legal liability or responsibility Tor the accuracy, completeness, or usefulness of any information, apparatus, product, or process disclosed, or represents that its use would not infringe privately owned rights. Refer- ence herein to an> specific commercial product, process, or service by trade name, trademark, manufacturer, or otherwise does not necessarily conslitute or imply its endorsement, recommendation, or favoring by the United States Government or any agency thereof. The views and opinions of authors r -iressed herein do not necessarily state or reflect those of the United States Government i,.- any agency thereof.

* i •*; r % *<

>4*

UC-4

•SMHOTIW of m mmn is ACKNOWLEDGMENTS

This report was prepared with the assistance of a number of talented people. The staff members who served as technical editors were David C. Moody (Group INC-3), Eiichi Fukushima (Group INC-4), Merle E. Bunker (Group INC-5), Allen S. Mason (Group INC-7), Kimberly W. Thomas (Group INC-11), and Bruce R. Erdal (INC Division Office). Word processors who prepared the original drafts were Karen E. Peterson, Marielle S. Fenstermacher, Cathy Schuch, Lia M. Mitchell, C. Elaine Roybal, Carla E. Gallegos, and Joann W. Brown. The report was designed by Gail Flower (Group IS-3), typeset by Joyce A. Martinez (Group IS-6), and pasted up with the assistance of Janey Howard of the INC Division Office staff. GLOSSARY

AAP atom-atom potential method AP ammonium picrate cm. center of mass DMPE bis- l,2(dimethylphosphino)ethane DOE Department of Energy EOB end of bombardment EPRI Electric Power Research Institute FOOF diflourine dioxide FTIR Fourier transform infrared FWHM full width half maximum GSI Gesellschaft fur Schwerionenforschung HENP High-Energy Nuclear Physics FIILAC heavy ion linear accelerator at LBL HPLC high-pressure liquid chromotography IAEA International Atomic Energy Association ICONs program named for the Isotopes of Carbon, Oxygen, and Nitrogen INS Intense Neutron Source KP potassium picrate LAMPF Los Alamos Meson Facility LATA Los Alamos Technical Associates LBL Lawrence Berkeley Laboratory LLNL Lawrence Livermore National Laboratory NAA neutron activation analysis NADPH reduced triphosphopyridine nucleotide NBS National Bureau of Standards NCX nucleon charge exchange NIH National Institutes of Health NMR Nuclear Magnetic Resonance NNWSI Nevada Nuclear Waste Storage Investigations NTS Nevada Test Site NWPA Nuclear Waste Policy Act MIT Massachusetts Institute of Technology MLIS Molecular Laser Isotope Separation program ONC octanitrocubane ORNL Oak Ridge National Laboratory OWR Omega West Reactor PBX plastic bonded explosive PIXE proton-induced x-ray emission RNM radionuclide migration SIR Stable Isotopes Resource SISAK short-lived isotope separated by the AKUVE technique SNL Sandia National Laboratory SPECT single-photon emission computed tomography TATB triaminotrinitrobenzene TBHC tertiary butylhypochlorite TBP tetrahydrofuran TOFI Time-of-Flight Isochronous spectrometer TRIUMF Meson facility in Vancouver, BC, Canada tRNA transfer ribonucleic acid UNILAC Universal Linear Accelerator, GSI USGS United States Geological Survey 0 ^'S'ftHY1 f'/^'lr-r

Overview 1 Radiochemicol Diagnostics'of !, 1. Weapons Tests 13 Weapons RadioChemical Diagnostics 2; Researph and Development 17 3. Other Unclassified Wecrpons Research 27 Stable and Radioactive Isotope Pro- 4. ductlon> Separation and Applications Element and Isotope Tremsp7 n o Actinide and Transition Metal Chemistry ; , \ 133 6. 3 Stmcfearal Chemistry, ^^ecftoscop 7, and Applications \ :s<. „ .- 145 Nuclear Structure ahd Reactions 1S7

Iiiadicftio n facilitie: s i 9. y 1 : " A4vca>ced Develdfpment and 11. anspott i •--•• 12. Earfe^dbd Plan

V. !l

I! , ii. s .= on -o- !,. DIVISIONAL OVERVIEW 3

ABSTRACT

This report describes progress in the major research and development programs carried out in FY 1983 by the Isotope and Nuclear Chemistry Division. It covers radiochemical diagnostics of weapons tests; weapons radiochemical diagnostics research and development; other unclassified weapons research; stable and radioactive isotope production, separation, and applications (including biomedical applications); element and isotope transport and fixation; actinide and transition metal chemistry; structural chemistry, spectroscopy, and applications; nuclear structure and reactions; irradiation facilities; advanced analytical techniques; development and applications; atmospheric chemistry and transport; and earth and planetary processes.

DIVISIONAL OVERVIEW

During fiscal year 1983, several division personnel were honored for their efforts. Llewellyn H. Jones of INC-4 and Carl J. Orth of INC-11 were named Laboratory Fellows for "application of infra-red and Raman spectroscopy to structural problems" and "pioneering investigations of the indium anomaly at the Cretaceous-Tertiary boundary in the Raton and San Juan Basins," respectively. Gordon M. Knobeloch of INC-11 was honored with one of the Weapons Complex Recognition Awards for his "development of radiochemical techniques." In October 1982 the Division Office moved to new quarters at TA-48; the new building houses an unclassified conference room, which has been used extensively for colloquia and meetings. The Fifth Annual Division Information meeting was held in September 1983, and Division-wide seminars of general scientific interest were held on a monthly basis. Monthly and special division seminar topics and speakers are listed in the Appendix. Twenty undergraduate and graduate students participated in our successful summer student program. During the year we hosted eight postdoctoral appointees and 64 visiting scientists, of whom 38 gave lectures and colloquia. We continued our numerous interactions with other laboratories, and about 32 research visitors participated in our LAMPF nuclear chemistry program. We were also pleased to have Dr. Shuheng Yan from the Institute of Atomic Energy, Beijing, China, as a research visitor at LAMPF for the year. Visiting committees of eminent scientists reviewed our Nuclear and Radiochemistry, Medical Radioisotopes, and Stable Isotopes Resource programs, helping us evaluate them and set priorities. At the end of FY 1983, we had 188 people in the Division, including 109 scientists, 86 with Ph.D. degrees. A profile of the division's funding for FY 1983 is shown here. 4 DIVISIONAL OVERVIEW

ISOTOPE AND NUCLEAR CHEMISTRY (INC) DIVISION FY 1983 FUNDING PROFILE

NUCLEAR WEAPONS DIAGNOSTICS AND RAD

ENERGY RESEARCH

INSTITUTIONAL •SUPPORTING RESEARCH

OPERATING 120-8 M

CAPITAL M M OTHER AGENCIES $21.9 M OTHER DOE

MAJOR PROGRAM FUNDING FOR FY 1983 Program Strategic Funds Area Total $K $K

1-3. RADIOCHEMICAL WEAPONS DIAGOSTICS AND R & D 7964 (DOE/OMA) 7747 Test Analyses (DOD) 217 4. STABLE AND RADIOACTIVE ISOTOPE PRO- DUCTION, SEPARATION, AND APPLICATIONS 2866 "C-NMR and Metabolism (DOE/OHER) 584 Stable Isotopes Inventory (DOE/OHER) 680 National Stable Isotopes Resource (NIH) 402 Medical Radioisotopes (DOE/OHER) 1200 DIVISIONAL OVERVIEW 5

5. ELEMENT AND ISOTOPE TRANSPORT AND FIXATION 3778 Nevada Nuclear Waste Storage Investigations (DOE/NV) 2878 Geochemistry (DOE/OBES) 605 Defense Radionuclide Migration (DOE/NV) 295 6. ACTINIDE AND TRANSITION METAL 1664 CHEMISTRY

Actinide and SO2 chemistry (DOE/OBES) 445 Actinide and Fluorine Chemistry (ISR) 369 Plutonium Separation (ISRD) 100 Laser Isotope Separation of Plutonium (DOE/ONMP) 750 7. STRUCTURAL CHEMISTRY, SPECTROSCOPY, AND APPLICATIONS 1174 Crystal Density of Explosives (NSWC) 60 Vibrational Spectroscopy; X-Ray Diffraction Studies (ISR) 668 NMR Studies of Solids (ISR) 246 Inelastic Neutron Scattering Studies (ISR, OBES) 200 8. NUCLEAR STRUCTURE AND REACTIONS 972 Nuclear Chemistry Research at LAMPF (DOE/OHENP) 622 TOFI-LAMPF (ISR) 75 Fission Studies (ISR & OHENP) 275 9. IRRADIATION FACILITIES 1061 Weapons Support (DOE/OMA) 715 Health and Environmental Support (LANL) 220 Irradiation Services (other institutions) 126 10. ADVANCED ANALYTICAL TECHNIQUES 1050 Accelerator-Based Mass Spectrometry Techniques (DOE/OHER) 75 Ultrasensitive Analysis Using Ion Accelerators (ISR) 75 Mass Spectrometer Development (DOE) 900 11. ATMOSPHERIC CHEMISTRY AND TRANSPORT (DOE/OHER, NSF) 437 12. EARTH AND PLANETARY PROCESSES 214 Search for Anomalous Iridium Concentrations 56 Lunar Geochemical Map (NASA) 67 Solar Neutrino Flux (DOE/OHENP) 80 IGPP 11 6 DIVISIONAL OVERVIEW

INC DIVISION ORGANIZATION

DIVISION LEADER IL-JLilQEFMAN DEPUTY DIVISION LEADER N. A. MAIWJVOFi* ASSOCIATE OIVISION LEAOERS RAOtOCHEMKAL DIAGNOSTICS.D. W. lAM ADVANCED RESEARCH CONCEPTSUL ERDAl ASST. DIVISION LEADER FOR FINANCE •maiKBmi

1 I

INC-3 INC-4 IMC-» MEDICAL RADIOISOTOPI ISOTOPE AND RESEARCH RESEARCH STRUCTURAL CHEMISTRY „ REACTOR GROUP LEADER H. A. D'MlfN GROUP LEAOERJL A. PEWNtMAN 6ROUP LEADER M, L UMHEl DEPUTY GROUP LEADER. DEPUTY GROUP LEADER «, 1, (YAK DEFUTV SROUP LEADER-M. M. KWIM ASSOCIATE SROUP LEADERS ASSOC. SROUP LEADER.H. T. WILLIAMS

STAILE ISOTOPES-l. 1. McMTEER

INC-7 IMC-11 ISOTOPE OEOCHEMISTRY NUCLEAR AND RADIOCHEMISTRV GROUP LEADER L /LMlAKT GROUP LEADER J E. SATTIZAHW + DEPUTY GROUP LEADER.A. J. GANCARZ DEPUTY GROUP LEADER.W. R. DANKLS ASSOCIATE CROUP LEADERS ASSOCIATE CROUP LEADERS CEDCHEMISTHr R. J. VHALE DATA ACQUISITION J P. IALA8WA ISOTOPE ANALYSIS- LAMPF-«, J, BROPlSJJt RADWCHEMISTRY-K. WOLFSJfM RADIOCHENKTRV- ASSISTANT CROUP LEADER FOR ASSISTANT CROUP LEADER FOR ATMOSPHERIC PROJECTS P. R. CUTHALS ADMINISTRATION C C. LONCMMI

•Effective January 1, 1984, Nicholas A. Matwiyoff became Director of the newly estabiished University of New Mexico—Los Alamos NMR Center for Non-Invasive Diagnosis to be located at the UNM Medical School. He will hold joint appointment as Professor in the Department of Cell Biology at UNM and as Coordinator for Nuclear Medicine in INC Division. "Effective December 1, 1983, Robert A. Penneman retired and was replaced as INC-4 Group Leader by Basil I. Swanson. -(•Effective February i, 1984, James E. Sattizabn became Deputy Division Leader of INC Division and was replaced as INC-11 Group Leader by William R. Daniels. DIVISIONAL OVERVIEW 7

This report covers contributions during FY 1983 (October 1, 1982—September 30, 1983) to unclassified projects and to unclassified work related to the nuclear weapons program. The reports are grouped according to the division's strategic areas of work. Other division quarterly and annual reports are also published for certain specific programs. In the Appendix, publications and presentations for FY 1983 are given for each group. Highlights from our work in FY 1983, arranged by strategic area, are given below. The approximate funding for each strategic area follows.

1. RADIOCHEMICAL DIAGNOSTICS OF WEAPONS TESTS

A significant fraction of INC-Division's funding and resources is devoted to the Radiochemical Test Diagnostics Program. We must determine the yield of all Los Alamos nuclear tests at the NTS as well as provide many details of the physics and chemistry of nuclear explosives. The program is funded 76% in test diagnostics and 24% in research and development. This ensures continued progress by giving a healthy blend of direct programmatic obligations backed by appropriate research in support of the program. Results are now reported at two internal classified forums, both of which meet monthly—Experimental Review Group (ERG) and Weapons Working Group (WWG). Addi- tionally, twice a year we hold an InterLaboratory WOrking Group (ILWOG) meeting with Lawrence Livermore Laboratory to review current procedures and new techniques in radiochemical test diagnostics for efficient use of our joint resources. The classified summaries of these activities can be made available to properly cleared individuals by contacting Donald W. Barr of the Division Office.

2. WEAPONS RADIOCHEMICAL DIAGNOSTICS RESEARCH AND DEVELOPMENT

• The nuclear microprobe shows promise as an analytical tool for preshot determination of concentrations and homogenity of tracer, detector, and impurity elements in test device components.

• (p,xn) measurements have been made on strontium isotopes. Advanced nuclear model analysis of these data should result in increased confidence in the calculated neutron cross sections used for the nuclear diagnostic effort.

3. OTHER UNCLASSIFIED WEAPONS RESEARCH

• Complex exothermic disproportionation was discovered in nitric oxide at high static pressures, thus demonstrating the effect of pressure in accelerating these reactions, which are important in the chemistry of detonation.

• Two new crystalline forms of N2O4 were created at high static pressures.

• A laser-induced phase transition was discovered in e-O2 at ambient temperature and at 20 GPa pressure. 8 DIVISIONAL OVERVIEW

• X-ray and Raman experiments showed that intermolecular interactions of nitromethane are enhanced at high pressure.

• A high-pressure structure of solid N2 at 2.94 GPa and ambient temperature was determined to be the same as that of hexagonal close-packed |3-N2, which exists at ambient pressure immediately below freezing.

• Static high pressure Raman studies showed that TATB is completely stable as a function of pressure up to 16 GPa.

• The atom-atom potential method was used to obtain a very large predicted density for octanitrocubane (ONC), thus confirming the result from the group additivity method that this compound would be an extremely powerful explosive.

• Carbon-13 solid state NMR was used to characterize commercial block copolymers for small differences that alter their effectiveness as binders in plastic-bonded explosives.

4. STABLE AND RADIOACTIVE ISOTOPE PRODUCTION, SEPARATION, AND AP- PLICATIONS, INCLUDING BIOMEDICAL APPLICATIONS

• The nitric oxide plant was extensively modified to increase production capacity.

• Kilogram quantities of all stable isotopes of carbon and nitrogen isotopes as well as 16O and 18O were produced by distiiiation.

• Labeled L-tyrosine was made successfully from phenol by biosynthesis.

• Chemically 'modified and labeled dihydrofolate reductase was studied by 13C NMR as part of a continuing se!ries of studies of the structure and dynamics of enzymes that are the target of cancer chemotherkpeutic agents.

• Real-time metabolic information in living tissues was obtained for microorganisms and perfused organs of Small animals by use of 13C NMR.

• An improved procedure for the separation of 52Fe has been developed and involves anodic oxidative dissolution in HC1 followed by separation on a tributylphosphate-coated silica gel column.

• The procedure for recovery of 82Sr from molybdenum targets has been standardized, and a method of recovering pure "Zn from the waste products has been developed. \ \ • The maximum production capability of 123I from a CsCl target using the batch process at^ LAMPF has been evaluated, and an on-line system for the continuous collection of 123Xe, the parent of 123I, is being developed. ,

• A novel electrochemical separation technique has been developed to separate 67Cu from the bulk zinc oxide target. Typically, 1500 to 3000 mCi of 67Cu that have been recovered.

• DIVISIONAL OVERVIEW 9

• Aryltrimethylsilane intermediates have been examined as a means of regiospecificaily introducing radiobromine and radioiodine into amines that are useful in brain studies.

5. ELEMENT AND ISOTOPE TRANSPORT AND FIXATION

• The geochemistry program in support of the Nevada Nuclear Waste Storage Investigations has been changed to better implement the Nuclear Waste Policy Act of Congress.

• The chemistry of the groundwaters in the tuffs surrounding the repository site at Yucca

Mountain has been determined to be a dilute NaHCO3 type of water.

• A thermodynamic model of analcime has been developed as a step toward estimating future stability of the sorbing zeolites in Nevada tuff.

• After a seven-year delay resulting from engineering difficulties, water samples were collected from the Cheshire cavity at the NTS. Analysis of these samples will provide information on the concentrations of mobile radioactive species produced in the test that could possibly migrate off the NTS. This Radionuclide Migration Program study in a rhyolitic medium complements that in the Cambric cavity region in alluvium, which has provided reassuring data indicating essentially no potential for offsite water contamination.

• Particle-induced x-ray emission has been shown to provide quantitive analyses of the major rare-earth elements in complex geologic materials.

• Experimental data as well as geochemical calculations indicate that addition of silica to a geothermal well will be detrimental to its operation.

6. ACTINIDE AND TRANSITION METAL CHEMISTRY

• FOOF was shown to be unsurpassed .in fluorination power at room temperature or below by any known agent.

• Attempts to convert PuO2-nH2O to a basic carbonate, Pu(OH)«2CO3, as reported in the literature, were unsuccessful.

• The rates of polymerization and disproportionation of Pu(IV) have been studied using low concentrations («10~6 M Pu, 10~4 M HC1, and 0.01 M ionic strength). The results indicate that disproportionation of Pu(IV) to give Pu(III) and Pu(V) at pH values greater than about 3 occurs much more rapidly than expected. At pH values greater than about 4, polymerization of Pu(IV) is even more rapid.

• Several trivalent uranium phosphine complexes, of which only two cases were known before this work, were synthesized.

• A homogeneous catalytic conversion of SO2 and H2 to sulfur and water was carried out with molybdenum and tungsten complexes as catalysts. 10 DIVISIONAL OVERVIEW

7. STRUCTURAL CHEMISTRY, SPECTROSCOPY, AND APPLICATIONS

• The first example of an isolable molecular hydrogen side-on bonded to a transition metal was discovered. These are intermediates "frozen out" in the oxidative addition process and aid the understanding cf such processes.

• A far-infrared spectroscopy system was developed to study low-energy motions of matrix- isolated molecules in rare-gas solids.

• The degree of orientational ordering of SF6 in solid methane was determined by polarized light FTIR studies.

• Nitrogen-IS NMR was shown to be sensitive to ammonia molecules adsorbed on different sites in zeolites and to the presence of water near the ammonia.

• Improved NMR coils were developed for use at high frequencies or for large samples.

8. NUCLEAR STRUCTURE AND REACTIONS

• Studies of the fission of polonium, osmium, and erbium composite systems demonstrate that the Sierk model gives a good description of both the mass and angular momentum dependence of fission barriers in this region.

• Results of measurements of excitation functions for the production of heavy actinides from reactions of 48Ca with 248Cm tend to support the concept of a binary transfer mechanism that results in actinide nuclei having low excitation energy, that is, "cold" nuclei that are not immediately destroyed by prompt fission or particle emission.

• Reexamination of ratios of measured (n~, rcN) to (n+, TIN) cross sections shows that nuclear reaction models based on classical concepts are inadequate to explain the experimental data. To obtain meaningful results, account must be taken of quantum mechanical aspects of the reactions.

• The spectrometer optical design phase for the TOFI spectrometer has been completed, and significant process has been made in the engineering and construction phases of the project.

• Results of He-jet gas-transport experiments carried out on a side beam at LAMPF indicate that a He-jet system should operate satisfactorily in the intense (>800 A) Line-A proton beam. Plans are proceeding for construction of a He-jet coupled isotope-separator facility af LAMPF that will be used to study nuclei far from stability produced through high-energy fission and spallation reactions.

9. IRRADIATION FACILITIES

• Over 12 500 samples were irradiated in the OWR, and other use of the reactor totaled 1200 experiment hours. Twenty-six Los Alamos groups and seven outside laboratories made use of the reactor. \

DIVISIONAL OVERVIEW 11

• Neutron activation analysis was used to measure the fissile material content of 5820 samples and the trace-element content of 3000 other samples.

• A dynamic neutron radiography setup has been constructed at the OWR that allows video observation and recording of fluid or component motion inside a sealed assembly.

• Based on an in-depth study of possible failure modes of the OWR, it appears likely that the reactor can be operated many more years before serious problems are encountered.

10. ADVANCED ANALYTICAL TECHNIQUES: DEVELOPMENT AND APPLICA- TIONS \ • Accelerator-based mass spectroscopy of beryllium is being developed for application to weapons diagnostics. • A small solid-angle, gas ionization detector having an energy resolution of 0.44%, a Z resolution of 3.1%, and a vertical position resolution of 2.0 mm has been developed for making direct mass measurements at LAMPF.

1!. ATMOSPHERIC CHEMISTRY AND TRANSPORT

• The first long-range meterological tracer experiment in Antarctica is being assembled. Five nations will sample for heavy methane at eight locations, and additional samples will be taken by aircraft.

12. EARTH AND PLANETARY PROCESSES

• Trace element patterns in samples of the Cretaceous-Tertiary boundary clay collected in Montana and in New Mexico are essentially identical.

• Calculations show that the production of cosmogenic nuclides can vary considerably both with the size of the extraterrestrial object bombarded and with the amount of the solar modulation of primary galactic cosmic-ray particles.

RADIOCHEMICAL DIAGNOSTICS OF WEAPONS TESTS IS

RADIOCHEMICAL DIAGNOSTICS OF WEAPONS TESTS

The Radiochemical Test Diagnostics Program requires a significant fraction of INC-Division funding and resource commitments. We must determine the yield of all Los Alamos Nevada tests as well as provide many details of the physics and chemistry of nuclear explosives. The program is funded 76% in test diagnostics and 24% in research and development. This ensures continued progress by giving a healthy blend of direct programmatic obligations backed by appropriate research in support of the program. Results are presently reported at two internal classified forums, both of which meet monthly—Experimental Review Group (ERG) and Weapons Working Group (WWG). Addi- tionally, twice a year vfe hold an InterLaboratory WOrking Group (ILWOG) meeting with Lawrence Livermore National Laboratory to review current procedures and new techniques in radiochemical test diagnostics for efficient use of our joint resources. The classified summaries of these acitivities can be made available to properly cleared individuals by contacting Donald W. Barr, INC-DO. Ra<$Qchemical • O^[GS Research

>-:•*.•*• -:i.

•^^'.!

i;:.';># •. *••,

k%^H

' •.. X WEAPONS RADIOCHEMICAL DIAGNOSTICS RESEARCH AND DEVELOPMENT 19

APPLICATION OF THE LOS ALAMOS NUCLEAR MICROPROBE TO NATIONAL SECURITY PROGRAMS

Timothy M. Benjamin, Clarence J. Duffy, Carl J. Maggiore, Pamela S. Z. Rogers, and Joseph R. Tesmer

Materials assay is an important application of the Los Alamos Nuclear Microprobe under National Security Programs. The quantitative determination of the concentration and homogeneity of alloyed or impurity elements in nuclear explosive components is vital for accurate performance analysis. Two techniques have particular relevance. The RBS method and results were detailed in last year's report.1 The PIXE technique was only briefly mentioned. We have applied PIXE to samples of uranium and a light-element matrix.* For a uranium matrix, the PIXE technique is ideal for elements that have x-ray lines between 4.2 and 11 keV. However, many important elements have x-ray lines only outside this region, and they are near numerous intense uranium x-ray lines. Molybdenum is such an element. Conventional chemical analysis had indicated that a molybdenum contaminant was present in a uranium component. We addressed this problem using PIXE. The PIXE spectrum is shown in Fig. 2.1 as a plot of the square root of counts vs channel number (20 eV/ch). The unlabeled peaks are all the result of uranium. The tantalum and iridium peaks are intentional additions; the other

165.5 U235 Ta Ir Mo?. Rh Filter C5124. Run No. 110 1 1 1 1 1 1 1 • • • ••

••

132.4 _ ••

•• i •• t • § 99.3 _ o O o o *. "MI1 1 1 £ • *• 66.2 _ a « • • • • «• 1 • CO $ • • t • • • 1 1 33.1 to/U 0.0 I I I I I I I i i 50.0 224.0 39B.0 572.0 746.0 920.0 Channel Number (20eV/Ch)

Fig. 2.1. A square root of counts vs channel number (20 eV/ch) plot of a tantalum-plus-iridium-loaded uranium sample. The data were optimized in alpha energy and taken with a rhodium x-ray filter to maximize the molybdenum- to-uranium count ratio. The molybdenum remains hidden beneath uranium peaks. 20 WEAPONS RADIOCHEMICAL DIAGNOSTICS RESEARCH AND DEVELOPMENT

labeled peaks are all contaminants. The molybdenum peaks underlie the shoulders of uranium peaks at both high (K lines) and low (L lines) energies. Two optimization means were applied when generating this spectrum in an effort to enhance the molybdenum counts relative to uranium counts. By using pure metal standards, we varied the beam energy to maximize the molybdenum- to-uranium count ratio. Maximization occurred at 9 MeV when using alpha particles. Next, we used a rhodium filter (3 mg/cm2), which absorbs the low-energy interfering uranium line to a much greater extent than the molybdenum L lines. This filtering technique cannot be profitably applied to the higher energy molybdenum K lines. The resultant, optimized spectrum (Fig. 2.1) still does not show a resolved peak as an indication of molybdenum. The next step was to record a spectrum of pure uranium under identical conditions and subtract it from the Ta-Ir-Mo? spectrum. The subtracted spectrum (Fig. 2.2) shows very little except an average enhancement of counts in the Al-Si-Mo region relative to the channel 190 to 400 region. The tantalum and iridium peaks are pronounced. The structures just below channel 190 and above 610 are uranium residual counts caused by the inexact matching of the uranium peaks, probably because exactly identical geometry for the two samples is difficult to obtain. The barium, chromium, and iron contaminants observed in Fig. 2.1 are absent, which suggests that these are components of even "pure" uranium. The data in the Al-Si-Mo region are expanded and given in Fig. 2.3.

U No. 215 - DU No. 213; Q-.86542, Scaling Channels: 138-148

190.0 330.0 470.0 610.0 750.0 Channel Number (20eV/Ch)

Fig. 2.2. The difference spectrum derived by subtracting a pure uranium spectrum from the tantalum-plus-iridium- loaded spectrum in Fig. 2.1. WEAPONS RADIOCHEMICAL DIAGNOSTICS RESEARCH AND DEVELOPMENT 21

The three-peak curve plotted on Fig. 2.3 is the result of a linear least square fit to the data. The peak positions are known and the FWHM as a function of energy is calibrated with well-resolved singlet peaks in the spectrum. Only the intensities of each of the three peaks need to be fit. More aluminum and silicon are clearly present in the Ta-Ir-Mo? sample than in "pure" uranium. The molybdenum is less convincing. Using the tantalum concentration (4130 ± 200 ppm) determined by wet chemistry as an internal standard, the molybdenum peak area yields less than 300 ppm molybdenum. In support of the validity of this value and the method, we artificially added 100 counts in a random fashion to the molybdenum peak region. This represents a 50% increase in the peak area. On deconvolution, the resultant molybdenum peak area had recovered 90 counts. The method is clearly sensitive, even with statistically poor data, to concentrations on the 100-ppm level. Based on these results, the uranium component was accepted. As the first step in undertaking routine trace-element analyses of light element matrices,* we analyzed a sample (using 3-MeV alphas) that had scandium and arsenic as intentional additions.

U No. 215 - DU No. 213, Q-.86542; Scaling Channels: 138-148 12.9

-10.0 74.0 88.0 102.0 116.0 130.0 Channel Number (20eV/Ch)

Fig. 2.3. A three-parameter linear least square fit of aluminum, silicon, and molybdenum to the low-energy part of the difference spectrum in Fig. 2.2. The molybdenum concentration is less than 300 ppm.

*Any element of combination of elements with x-ray lines less than Z = 13 (aluminum). 22 WEAPONS RADIOCHEMICAL DIAGNOSTICS RESEARCH AND DEVELOPMENT

LEM 3699-10-9965 45.3

210.0 370.0 530.0 830.0 350.0 Channel Number (ZOeV/Ch)

Fig. 2.4. A square root of counts vs channel number (20 eV/ch) plot of an arsenic-plus-scandium-loaded light- element matrix sample. An excess of chlorine was detected as well as several unexpected impurities.

The spectrum (Fig. 2.4) revealed several interesting points. As expected, the background is minimal as a result of the low mean atomic number of the matrix. The characteristic x-ray lines from the matrix are too low in energy to be detected, which gives excellent trace-element sensitivity throughout the spectrum. The arsenic and scandium peaks are prominent and weD resolved. Peaks corresponding to the element chlorine are in excess of specifications. This is not surface contamination (such as a fingerprint) because the alphas penetrate and produce x rays to ..approximately 10 urn in depth. Minor and relatively unimportant impurities of silicon, sulfur, calcium, and iron are observed. A number of unexpected elements were also detected. These elements, yttrium, thulium, lutetium, and thallium, are probably the result of cross contamination that indicates poor quality control in the preparation of this specimen. These results provide a strong argument for the necessity of developing our PIXE technique for nondestructive, in situ analysis of test components. WEAPONS RADIOCHEMICAL DIAGNOSTICS RESEARCH AND DEVELOPMENT 23

(p,xn) MEASUREMENTS ON STRONTIUM ISOTOPES

Donald W. Barr, Silvia A. Beatty, Kari Eskola,* Malcolm M. Fowler, James S. Gilmore, Rene J. Prestwood, Elizabeth N. Treher,** and Jerry B. Wilhelmy

For neutron-deficient isotopes near the N = 50 neutron shell, the proton binding energy becomes substantially smaller than that of the neutron. Under these conditions, there can be a high probability for proton emission from the excited nuclei. We must rely on nuclear-model calculations of the (n,p) and (n,pn) cross sections to interpret weapons performance because these important destructive reactions in the yttrium detector system are difficult to measure. As an aid to the modeling effort, we have undertaken an experimental program to measure the inverse (p,xn) processes in strontium isotopes. These data help us select suitable values for the yttrium- level density parameters, gamma strength functions, and sub-Coulomb barrier behavior of the proton transmission coefficients. Approximately 100-ug/cm2 targets of the enriched isotopes 86Sr, 87Sr, and 88Sr were vapor- deposited on thin carbon foils and irradiated in a scattering chamber at the Los Alamos Tandem Van de Graaff Accelerator. After irradiation, the target foils were counted using high-resolution Ge(Li) detectors and associated pulse-height analyzers. The yields of the yttrium isomers and isotopes have been determined from the decay or growth-and-decay of characteristic gamma rays. For proton energies below 10 MeV, we measured elastically scattered protons at known forward angles and geometries during the irradiation and directly determined the (p, n) cross sections relative to the Rutherford scattering cross section. Above 10-MeV proton energy, the accuracy was improved when the target thickness was determined from Rutherford scattering during a separate bombardment at 4.0 MeV, which is below the (p,n) thresholds for 8M8Sr. After waiting until any 87Y had decayed to a minor level, we irradiated the foil again at the desi.ed proton energy and gamma counted in the usual manner. In this case, it was necessary to measure the number of protons in both runs with a Faraday Cup and current integrator. Chief sources of error in the data are resolution of the decay data for the ground states of 85 8S 87 85.86,87.8SY (2%) and metastable states of - - Y (1%); integration of the fluence of scattered protons (3%); scattering cross sections (2%); and current integration (1%). Uncertainties in the gamma branching intensities per disintegration are as follows: 88Y (0.7%), 87Ym (1.3%), 87Yg (l.l%),86Ym(3.1%),86Y*(0.7%),85Ym(17%),and85Y11 (10%). Above the (p,2n) thresholds, 86Ym'g and 87Ym'8 were produced from two isotopes in the targets. In the most severe case this amounted to a 25% correction, but the uncertainty in this procedure resulted in only an additional 2% error in the cross section. Figures 2.5-2.7 present the analyzed measurements on 86Sr, 87Sr, and 88Sr, respectively. Advanced nuclear-model analysis of these data (by Group T-2) should result in increased confidence in the calculated neutron-induced cross sections for the neutron-deficient yttrium isotopes.

•Visiting Staff Member from the University of Helsenki, Finland **Squibb Institute for Medical Research 24 WEAPONS RADIOCHEMICAL DIAGNOSTICS RESEARCH AND DEVELOPMENT

t 10 12 14 16 It PROTON ENERGY (MeV)

Fig. 2.5. Thresholds and experimental excitation functions for (p,xn) reactions on *6Sr.

E.feW I III I 3 5 7 S II 13 IS 1? PROTON ENERGY WeV)

Fig. 2.6. Thresholds and experimental excitation functions for (p,xn) reactions on "ST. WEAPONS RADIOCHEMICAL DIAGNOSTICS RESEARCH AND DEVELOPMENT 25

1000

O «Si

A Msrfpjn)*?¥"> D

MM) 0.) I i i i I i |i i a ,''.t n 16 II PRDTON ENERGY (MlV)

Fig. 2.7, Thresholds and experimental excitation functions for (p,xn) reactions on 88Sr ; OJher Unciasslfl^ Weapons Resedrch '•'>

*'.*- >'# OTHER UNCLASSIFIED WEAPONS RESEARCH 29

SPECTROSCOPIC STUDIES OF MOLECULES AT HIGH PRESSURE

Basil I. Swanson, Stephen F. Agnew, Llewellyn H. Jones, Robert L. Mills (P-10), and David Schiferl (M-6)

The principal motivation for studying small molecules at high static pressures is to obtain a data base of vibrational and electronic structure changes that can be used to help interpret results of real-time studies of shock propagation in these systems. We have focused our FY 1983 research in this area on the oxides of nitrogen, in particular, nitric oxide. Although most molecular systems are chemically stable to high static pressures, we have observed pressure- induced chemistry for nitric oxide and complex photochemistry and chemical equilibria for the products formed. We believe that the results obtained have important implications for the chemical mechanism of shock-initiated detonation of nitric oxide and will also provide

information concerning the likely intermediates of N2O2 detonation, which could be probed using time-resolved studies.

Nitric Oxide Early attempts to study nitric oxide at high static pressures were compromised both by the use of low-purity NO and by the absence of adequate spectroscopic characterization. We have subsequently been successful in loading high-purity NO in diamond anvil cells and in using Raman, ir, and uv-visible absorption spectroscopies to characterize the cell contents. Although the original intent of this endeavor was to study nitric oxide itself as a function of pressure, we discovered that nitric oxide rapidly disproportionates under static high pressure. This disproportionation proceeds spontaneously above 2 GPa (minimum undetermined) and above 150 K to

produce N2O, N2O3, and N2O4. It has indeed been possible to grow single crystals of N2O4 from the solution containing all three product species by carefully controlling temperature and

pressure. The Raman peaks we observed for the solid N2O4 (Fig. 3.1) agree with values observed earlier (Ref. 2) for low-temperature, low-pressure solid N2O4. Figure 3. l(a) shows the liquid N2O4 spectrum, and Fig. 3.1(c) shows that of the high-pressure solid; both are consistent with molecular N2O4 in these environments. We observed vibrational modes associated with N2O in the Raman and in the ir (Fig. 3.2). The presence of N2O3 is indicated by its characteristic visible absorption spectrum.

It is interesting to note that the complete disproportionation reaction to form 2N2O + N2O4 releases approximately two-thirds of the enthalpy of the net reaction 3N2O2 = 3N2 + 3O2. The experimental results we obtained at static high pressure provide evidence for a pressure-induced, highly exothermic disproportionation reaction of NO, which we believe is a very important process in any detonation mechanism of nitric oxide. Moreover, the presence of this reaction in high-density nitric oxide illustrates a more general principle, that is, the importance of pressure- accelerated reactions in shock-initiated detonations. Chemical reactions that are accelerated by pressure are characterized by negative volumes of activation and are expected to play an important role in detonation chemistry. Previous work on the disproportionation of gaseous nitric oxide3 suggested that the reaction is third order in NO concentration and is accelerated by pressure. This study was restricted to pressures of 400 atm and lower, but it does illustrate that the disproportionation, which normally takes weeks at low pressure, proceeds much more quickly at high pressure. We believe that the mechanism for disproportionation in the condensed phase is concerted and involves neighboring (NO)2 dimers. 30 OTHER UNCLASSIFIED WEAPONS RESEARCH

500 1000 -1 CM

Fig. 3.1. Raman spectra of fluid N2O4 and a-N2O4: (a) fluid at 0.23 GPa, (b) solid at 1.6 GPa, and (c) solid at 7.6 GPa.

We have been hindered in our understanding of this high-pressure NO reaction by the variously colored products: clear, yellow, brown, red, and blue. This apparent complexity was

largely resolved when we realized that the clear, yellow, and brown colors were all N2O4 in various forms. In addition, the blue color was caused by the N2O3 that originated from an incomplete disproportionation of NO. Unfortunately, the source of the red color remains somewhat obscure. However, this color is known to occur when Lewis acids are co-condensed with NO at 115 K (Ref. 4); because the nitrosonium ion NO+ can act as a Lewis acid, the red + + color also could be caused by an interaction between NO and N2O2. The NO does often form in reacted NO from the N2O« product, depending on the pressure of the cell. Moreover, a red + color is produced when nitric oxide is condensed onto NO PF6~; presumably, it is the result of + the same interaction between NO and N2O2. We note that diamond anvil cells loaded with either N2O2 or N2O4 at high pressure (>5.0 GPa) have shown evidence for ionic species. OTHER UNCLASSIFIED WEAPONS RESEARCH 31

Thus, we have identified a variety of product species in reacted nitric oxide at high static + pressure, including N2O4, N2O3, NO , NO3~, N2O--, but strangely enough, no NO itself has ever been observed! We think that this information will contribute to an eventual understanding of the detonation chemistry of nitric oxide. Toward this end, we have started to study N2O4, one of the product species, and will examine its properties in the absence of the other product species.

(0 •cH D m _O L 0 2500 2800 3100 3400 3700 X I/CM -p 0) c w

4 00 600 800 1000 1200 I/CM

Fig. 3.2. The ir spectra of N2O/N2O4 solution. Labeled peaks correspond to N2O. 32 OTHER UNCLASSIFIED WEAPONS RESEARCH

Dinitrogen Tetroxide In the studies of this molecule at high pressure, we have observed two new crystalline

modifications. Two molecular N2O4 crystals are stable above approximately 0.4 GPa and are named a- and |3-N2O4. The

.£1 L 0

1500 2000 z LU

•i 500 1000 CM

+ Fig. 3.3. Low-frequency and high-frequency spectra of NO NO3" at 3.1 GPa. Peaks caused by residual N2O4 are labeled. Diamond first-order peak is at 1333 cm"1 and divides the low- and high-frequency regions. OTHER UNCLASSIFIED WEAPONS RESEARCH 33

transformation and illustrates a much more general characteristic of high-density molecular systems: the decrease in volume that results in formation of an ionic solid from a molecular solid can make such transformations thermodynamically favorable.

The p-N2O4 is formed by laser annealing the cubic a-N2O4 solid at 1.08 GPa. Initial irradiation of a-N2O4 produces local melting and a blue color, presumably N2O3, that fades in time. When we use more laser power, P-N2O4, the new crystalline form of N2O4, appears and will not melt under further irradiation. This |3-N2O4 shows a highly polarized Raman spectrum, which indicates a strong alignment of the N-N bond (Fig. 3.4). Unlike the a-N2O4, P-N2O4 is not cubic because it is not optically isotropic, as we determined under crossed polarizers. We believe

the a-N2O4 is identical with the low-temperature cubic Im3 solid. The particular orientation of the N2O4 molecules in p-N2O4 could be a clue as to why the P~N2O4 transforms so readily to the ionic form, whereas a-N2O4 is apparently stable against this transformation.

Cb)

(a)

500 1000 -1 CM

Fig. 3.4. Raman spectra of p"-N2O4 at 1.16 GPa (no analyzer was used): (a) electric vector of laser perpendicular to crystal long axis, (b) electric vector of laser parallel to crystal long axis. 34 OTHER UNCLASSIFIED WEAPONS RESEARCH

The very different stabilities of a- and P~N2O4 with respect to a pressure-induced transforma- + tion to the more stable NO NO3~ is an example of topochemical transformation. That is, although the molecular form of N2O4 in the two covalent phases is identical, their different packing arrangements result in distinctly dissimilar chemical behavior under high pressure. The clear implication is that the molecular-to-ionic transformation involves a concerted mechanism where short-range structure significantly affects the activation barrier for the transformation. This principle may have more general significance; it is possible that variations in the short-range structures of high explosives are important factors in the early chemical transformations that accompany shock-initiated detonation.

The blue species formed upon laser irradiation of a-N2O4 is apparently N2O3. The mechanism for the photolytic generation of N2O3 is not yet clear. However, it is possible that the N2O3 is formed by a simple photolytic cleavage of a N-0 bond in a-N2O4. Several new bands (620, 778, 1290 cm"1) appear during the laser annealing process (Fig. 3.5) and agree reasonably well with

500 1000 -1 CM

Fig. 3.5. Spectra (obtained at 1.03 GPa) of N2O4 that is undergoing photolysis at the indicated approximate power levels. OTHER UNCLASSIFIED WEAPONS RESEARCH 35

the published values for N2O3 in CH2C12 at -40° C (Ref. 5). We observed this same photolytic production of N2O3 in single a-N2O4 crystals grown from the N2O/N2O4 solutions that are produced by reacted nitric oxide.

Oxygen We have extended the work on molecular oxygen and have reached several important 6 conclusions. Isotopic mixtures of O2 have provided several surprises. Certain isotopic bands 18>18 exhibit anomalous behaviors in the red, high-pressure, e phase of oxygen. In particular, an O2 1M8 18 I8 with a 6% O2 impurity shows two Raman bands in the O- O stretch region for pressures greater than 10 GPa (Fig. 3.6 and Table 3.1). This result is in contrast to the single Raman band 1M6 observed in O2.

TABLE 3.1. Vibrational Frequencies (cm"1) for

€-O2at 13.5 GPa 16/"\ Ho Observed Observed

Ir 0-0 stretch 1513 1433 (1426)1 Combination band 3059 2884 (2884)* Combination band 2964 2791 (2794)1 Raman O-O stretch 1578 1498 (1488)* Libron 133 126 (125)'

'Values of "O2 peak positions (in parentheses) are scaled 1 2 from those of "O2, according to (16/18) ' .

1M6 I8il8 16lI8 To explore this effect further, we doped a O2 sample with 10% O2 and 0.6% O2. We believed that the degree of interaction between the vibrations of isotopically distinct neighbors would be related to the difference in the frequency of the vibrations. Indeed, the difference 16>I6 18>18 between the O2 and O2 vibration frequencies is sufficient so that we observed only a single Raman band for this sample in the e phase. However, isotopic shift irregularities are present in the ir absorption spectra and are illustrated in Fig. 3.7. Here, the peaks of the ir absorptions are 16>16 plotted as a function of pressure. Whereas the O2 peak is shifted correctly with respect to the 1M8 1M8 O2 peak, the 0.6% O2 impurity peak is significantly different than that calculated (dotted line). 36 OTHER UNCLASSIFIED WEAPONS RESEARCH

I6Q

03 "E =5

L±J H

120 1450 1500 1550 1600 FREQUENCY (cm'1)

1M6 I6l Fig. 3.6. Raman spectra of O2 (upper) and "'"02 (lower) at 1.35 GPa in a sample containing 6% "O, OTHER UNCLASSIFIED WEAPONS RESEARCH 37

1500 -

u 1450 -

1400 10.0 12.5 15.0

Pressure (GPa)

Fig. 3.7. Pressure dependence of the ir absorption for the various samples shown.

From these observations, it is apparent that the oxygen molecules in the e phase are strongly interacting. This evidence provides several clues to the crystal structure of €-O2 as well, a structure that has not yet been determined. The fact that there is a strong ir absorption indicates that there must be more than one molecule of oxygen per primitive unit cell. Otherwise, the strong coupling that is necessary to induce a dipole moment could not exist. However, it is impossible to 18a8 16 18 explain the presence of the second O peak in the presence of 6% - O2 or the observation of two ir overtone bands for all of the oxygen samples with fewer than three molecules of oxygen per primitive unit. Because the mutual exclusion of the ir and Raman peaks indicates centricity, a four-molecule primitive cell is proposed. An interesting sidelight in the oxygen story is the observation of a laser-induced phase transition produced by laser heating a sample of e-O2 near the 10-GPa phase boundary. We hope that studying the relaxation of this laser-induced process will give an indication of the rate of the phase transition. The dynamics of phase transitions become important because we need to understand the shock-induced behavior of a material. Thus, although diamond anvil cells are normally associated with only static measurements, this is not a rigid limitation, and we hope that using a fast-pulsed laser will help us study the dynamics of this phase relaxation in diamond anvil cells. 38 OTHER UNCLASSIFIED WEAPONS RESEARCH

HIGH RESOLUTION INFRARED SPECTRAL STUDIES OF GUEST-HOST INTERAC- TIONS AND DYNAMICS IN LOW-TEMPERATURE IMPURITY-DOPED SOLIDS

Llewellyn H. Jones, Basil I. Swanson, Herbert A. Fry, and Scott A. Ekberg

Quantification of Orientational Ordering of SF6 in Solid Xenon Matrices Earlier we showed that one of the dominant sites of SF6 in xenon matrices shows site symmetry splitting and orientational ordering.7 From our further work, we can estimate the degree of orientation as a function of deposition temperature. We evaluated the polarization by recording the spectrum with the substrate window at 45° (about the vertical axis) to the beam of a Nicolet 7199 FTIR spectrometer, with a polarizer in the light path. We recorded separately the absorption of vertically and horizontally polarized light (see Fig. 3.8).

in P. CD

in Hi

in en

930.0 931.0 932.0 933.0 93«t.O I/CM

Fig. 3.8. Absorbance for v3 mode of matrix of Xe/SF6 = 7000. Deposited at 10 K; annealed at 60 K. Spectrum recorded at 10 K. Window at 45° for incident beam. Lower curve (H): horizontal polarization. Upper curve (V): vertical polarization. Absorbance scale of curve V displaced upward for clarity. OTHER UNCLASSIFIED WEAPONS RESEARCH 39

The host matrix grows with the (111) plane parallel to the substrate surface.8 There are other (111) planes in the lattice at tetrahedral angles (70.53°) to the substrate surface and to each other. We assume that a fraction XP of molecules on a given type of site maintains registry of a three- fold axis with the < 111 > growth direction. The remaining molecules 1-XP distribute themselves equally along the other three < 111 > directions. If we designate by B and C the doubly and singly degenerate modes, respectively, we calculate that

A£/A£ = (1 - a) + a(0.25 + 2XP)/(1 - XP) , (1)

= (SJ|/SS) [(1 - aX5 + 4XP) + 8a(l - XP)]/

[(1 - aX4 - 4XP) + a( 1 + 8XP)], (2)

= (SJ|/SS) [(1.25 + XP)/(1 - XP)] , and (3)

a = 0.5/n^ , (4) where nm = refractive index of matrix host at the appropriate frequency and temperature; S£ is the oscillator strength of mode C, and A£ is the absorbance of mode C for horizontal polarization. The important quantities are the relative intensities of peaks B and C polarized horizontally and vertically with the matrix plane rotated 45° about the vertical axis from the direction of the incident beam. The quantity a [Eq. (4)] is known from refractive indices.9 Then, from our observed polarized spectra, Eq. (1) yields a value for XP. Knowing XP, we can then calculate (S£/S£) from Eq. (2) and independently from Eq. (3). Table 3.2 presents the results from a series of experiments at several deposition temperatures and the intensity ratio of site A to that of site (B,C). A pulse deposition of about 1 torr-liter per pulse was used. From these studies, we see no evidence of site symmetry splitting (and thus no orientational ordering) for site A (Fig. 3.8). However, for site (B,C), it is apparent that increased deposition temperature results in decreased orientational ordering and an increase in the per cent of molecules that are stabilized in site A. The decrease in orientational ordering is in line with the idea that increased deposition temperature makes it more difficult to relieve the excess energy that can destroy registry with the growth plane. The increase in population of site A as deposition temperature is raised indicates that A is a more stable site than (B,C) and probably would be the lone site observed for dilute SF6-doped xenon crystals formed near the melting point of xenon. In accord with this conclusion, we have observed that high-temperature annealing (74 K with a chlorine overcoat) leads to loss of site (B,C) without diminishing the population of site A.

Orientational Ordering and Site Structure for CC14 in a Krypton Matrix To investigate further the potential forces leading to registry and orientational ordering, we have studied the ir absorption spectra of matrices of CC14 in rare gas solids. The tetrahedral CC14 molecule should fit rather easily in a tetrahedral substitutional site of argon, krypton, or xenon. From the C-Cl bond length10 of 1.77 A and a Van der Waals radius11 for clorine of 1.8 A, we estimated that the ratio of the size of a CC14 molecule to the size of four rare gas atoms in 40 OTHER UNCLASSIFIED WEAPONS RESEARCH

TABLE 3.2. Temperature Dependence of Orienta- tional Ordering, Relative Absorption Coefficients for the Symmetry Split Site, and Ratio of Site Absorption Intensities

for SF6 in Xenon Matrices Deposit Temperature XP* A /A s5/s^b A (B+C) (K)

10 0.89 1.0 1.9 20 0.82 0.95 1.9 30 0.77 1.0 2.1 40 0.75 1.1 2,4 50 0.74 0.95 3.8 *XP is the per cent of site (B,C) molecules that are oriented with their unique axis perpendicular to the substrate surface. "S* and So represent oscillator strengths for modes B and C. Whether there is truly a difference is not clear at this time.

tetrahedral symmetry in the cubic close-packed solid is about 0.92, 0.87, and 0.80 for argon, krypton, and xenon, respectively. A three-atom substitutional site, even in the case of xenon,

would be too small to accommodate a CC14 molecule without severe distortion. Thus, we expect four-atom substitutional sites with guest-host interactions dominated by Van der Waals attractive forces.

Figure 3.9 shows a spectrum of the v3 and the vl + v4 modes of CC14 in a krypton matrix. Because of the several isotopic species, we observe a multitude of peaks. The isotopic abundances 35 35 37 3i 37 35 37 37 are C C14 (0.323), C C13 C1 (0.421), C Cl2 C12 (0.206), C C1 C13 (0.045), and C C14 (0.004), neglecting the 13C species that will have about 1% of the 12C abundances. Only the first four species above contribute significantly to the absorption observed; the large number of peaks results from the lower symmetry of the mixed isotopic species, the presence of two dominant sites, and site symmetry splitting. 3i Fortunately, the spectral features for v3 and vx + v4 of C Cl4 are well separated from those of the other isotopic species (Fig. 3.10). There are three peaks for each mode, and they are labeled in order of increasing frequency: A, B, and C for vl + v4 and A', B', and C for v3. The ratio of intensities l{y1 + v4)/I(v3) is about 0.57, which indicates rather strong Fermi resonance because Vj + i>4 would otherwise be quite weak compared to v3. These spectra were observed with the window rotated about the vertical axis 45° to the incident beam and with a polarizer in the beam. We recorded spectra for incident light with the electric vector vertical (parallel to the matrix surface) and horizontal (at 45° to the matrix surface) (shown in Fig. 3.10). As discussed in Ref. 12, this can give a quantitative estimate of the degree of orientational ordering. OTHER UNCLASSIFIED WEAPONS RESEARCH 41

Figure 3.10 shows that C and C are much more intense for horizontal polarization, whereas A and A' are more intense for vertical polarization. As discussed in Ref. 8, this indicates that C and C are vibrations oriented primarily perpendicular to the substrate plane whereas A and A' are oriented parallel to this plane. This shows that A,C and A',C arise from one site for which the symmetry is split into doubly degenerate (A,A') and singly degenerate (C,C) modes. Peaks B and B' show no significant orientation and represent a second site for CCi4 in krypton for which the triple degeneracy is maintained (Td or T symmetry). Annealing at higher and higher temperatures leads to some sharpening of the absorption peaks as well as conversion of several per cent of site (A,C) to site B. In line with this observation is the fact that deposition temperatures above 35 K lead to less of site (A,C) and more of site B; also higher deposition temperatures lead to less orientational ordering, as can be quantitatively estimated from the equations in Ref. 12. Table 3.3 gives the results of these deposition temperature measurements. It should be noted that annealing does not affect the degree of orientational ordering for site (A,C), and the conversion of site (A,C) to site B on annealing is small compared to the range of this effect when it is caused by deposition temperature.

780.0 783.0 786.0 783.0 79fe-.O

KR/CCLt 10000 T-10K

CO UJ • CJ a:

V) s ain -JUUll 75 .0 751i.O 757.0 760.0 763.0 766.0 I/CM

Fig. 3.9. Absorbance of v3 and i>, + vt modes of CC14 in krypton matrix (1/10000). Deposited at 10 K, spectrum at 10 K. 42 OTHER UNCLASSIFIED WEAPONS RESEARCH

764. 0 764.5 765.0 765.5 766.0 I/CM

a in

u u o Z CD

o en 786.0 78B.5 787.0 787.5 738.0 I/CM

12 35 Fig. 3.10. Absorbance of v3 and vx + v4 for C C14 in krypton matrix (CCl4/Kr = 1/10000) at 10 K. Window rotated about vertical axis 45° to incident beam. Polarized horizontal, ; polarized vertical, .

A surprising fact is that the site symmetry split components straddle the frequency for the more symmetric site. Thus, both sites have rather similar interaction potentials with the surrounding host atoms. One wonders then what factors give rise to these two distinct sites. A possible explanation is that one site is in a cubic close-packed (CCP) environment, whereas the other is in a hexagonal close-packed (HCP) environment of nearest neighbors. The cubic lattice has a four-

atom substitutional cage of Td symmetry that can accommodate a CC14 molecule. Such a cage may collapse slightly around the tetrahedral CC14 molecule in an isotropic manner, thus preserving the Td symmetry. The hexagonal lattice does not contain a Td site but does have a four-atom trapping cage of C3v symmetry that can accommodate a CC14 molecule. In this case, the cage may collapse slightly about the CC14 molecule while maintaining the C3v site symmetry and thus split the triply degenerate v3 mode into a singly and doubly degenerate mode. The guest- host potentials are about the same for each case, so the matrix shift will be similar. OTHER UNCLASSIFIED WEAPONS RESEARCH 43

TABLE 3.3. Orientational Ordering and Site

Distribution for CC14 in Krypton Matrices: Dependence on Deposition Temperature Temperature (K) XP" B/Lb

10 0.8 0.49 20 0.8 0.49 30 0.8 0.47 35 0.66 0.45 40 0.5 0.53 44 0.5 0.62 48 0.3, 0.35 0.64 52 0.35 0.69 "XP is fraction of molecules on site (A,C) oriented with C perpendicular to substrate. bB/E is the ratio of intensity for site B to sum of intensities of both sites.

For the above explanation to be tenable at low-temperature depositions, we must either have a 50-50 mixture of CCP and HCP crystals or the crystals that are nominally CCP must have a large number of stacking faults leading to about 50% HCP and 50% CCP sites. We favor the latter explanation; however, detailed x-ray diffraction studies will be necessary to resolve this problem.

One notes from Fig. 3.10 that the peaks for v3 are considerably broader than the corresponding peaks for vx + v4. This is surprising because these levels must have similar character as they a;re highly mixed because of Fermi resonance. It suggests that the upper level of v3 relaxes rather 1 quickly to the upper level of v, + v4 plus a bulk phonon of about 22 cm" (well within the density 13 of states for solid krypton ). From the increase in width for v3 over that of vt + v4 and the expression x = (2nc8v)~, with 8v = FWHM, a relaxation time x can be estimated as 100 to 200 picoseconds.

Orientational Ordering and Site-Selective Fhotolysis for UF6 in Solid Argon Matrices

High resolution infrared studies of UF6 in argon matrices show two dominant monomer sites. The lower spectrum of Fig. 3.11 shows four peaks. The change in intensities on rotating the window show that C and D are oriented primarily perpendicular to the substrate and A and B are parallel to the substrate.8 Photolysis of this matrix with a broad-bapd mercury arc for a uv source

leads to dissociation of up to 50% of the UF6 to UF5. The upper spectrum of Fig. 3.11 shows a spectrum of the remaining UF6 peaks on the original site. We note that B and C have diminished substantially more than A and D. This tells us that A and D are site symmetry split components on one site, and B and C arise from a second site. We also note that UF6 on site (B,C) is dissociated more readily than that on site (A,D); thus, we are observing site-selective photolysis. With further studies, we hope to relate this site selectivity to differences in site structure. 44 OTHER UNCLASSIFIED WEAPONS RESEARCH

in p- 1 .5 0 J 11 A B A- D » L I i c 8 it * 1 • L * I 61 3.0 61b.5 6)9.0 61S.5 62' i.o 6ie.S Blb.O DlS.S ft? I/CM I/CM

Fig. 3.11. (a) Absorbance for v3 of Ar/UFS = 2000. Deposit at 20 K, annealed at 30 K, spectrum at 10 K. (b) Absorbance for same matrix as (a) after uv photolysis with mercury arc at 10 K.

It is quite remarkable that two sites show such similar average frequencies and high orientational ordering. Because they both show registry with the (111) growth plane, they are each expected to have a C3 axis. One possible explanation is that one trapping cage has local CCP symmetry whereas the other is HCP (see the discussion in the previous section on CC14 in krypton). Further study and thought are required to elaborate on the implications of these results.

In Fig. 3.12, we show the effects of photolysis followed by annealing. The v7 mode of UF3 formed by photolysis is shown at the far left. We note that photolysis leads not only to the formation of UF5 but also to substantial alteration of a good portion of the normal UF6 sites to give rise to new absorption peaks, primarily the three in the 622 to 624 cm"1 region. These sites are stable only at low temperature; annealing at 30 K. leads to conversion to a new set of sites, as seen in curve C. Finally, if the matrix is overcoated with xenon and annealed at 40 K, the spectrum indicates the UF5 has all been converted back to UF6 and the UF6 sites are converted primarily back to the original two [(A,D) and (B,C) of Fig. 3.12]. A remarkable phenomenon is that orientational ordering is preserved for these sites after the 40 K annealing. Thus, UF6 molecules originally highly oriented on sites (A,D) and (B,C) are converted by photolysis in part to UFj and in part to sites of quite different structure; however, high-temperature annealing leads to recombination of UF5 and fluorine to form UF6 and to reversion of most of the sites to the initial structure. The orientational ordering is maintained after this cycle of rather drastic changes. We conclude that the forces leading to orientational ordering are quite strong because the registry is maintained for the fragmented species and for the grossly altered sites. UNCLASSIFIED WEAPONS RESEARCH 45

*0K flNNEflL

30K ANNEfiL

220 MIN HG ARC 10K NO ANNEAL

Id AR/UF6 2000 I 30K ANNEAL 20K DEPOSIT

58 585 618 620 622 62

Fig. 3.12. Absorbance for v} of UF6 and v1 of UF5 in matrix Ar/UF6 = 2000 deposited at 20 K. All spectra recorded at 10 K. A = original deposit, B after photolysis, C after 30 K anneal following B, D after 40 K anneal following C.

Far-ir Matrix Isolation Spectroscopy of Isotope Species of Ammonia and Water In our laboratory and others, research in mid-ir matrix isolation spectroscopy has indicated that low-energy motions of molecules isolated in rare gas solids are important in vibrational energy dynamics. Therefore, we have recently developed a far-ir system to st tdy low energy motions of molecules isolated in rare gas solids. This apparatus uses a Digilab FTS-20C F ourier- transform spectrometer with several modifications:

1. A liquid-helium-cooled germanium bolometer has been added as a detector;

2. To reduce the 1/f noise, the mirror velocity has been increased by a factor of 4; and

3. The sample chamber has been modified with reflectance optics and a liquid-helium transfer cryostat. 46 OTHER UNCLASSIFIED WEAPONS RESEARCH

Figure 3.13 shows a sample spectrum obtained with the apparatus. The spectrum is of a mixture of deuterated ammonia molecules in an argon matrix. The observed transitions are the J 1 = 0 -*• 1 pure rotational transitions of NH3, NH2D, ND2H, and ND3. The peak at 10 cm" for ND3 represents the lower end of our frequency capability. These results on ammonia provide evidence for an inversion splitting of the J = 1 •*— 0 rotational transition of NH2D and an isotope I5 14 dependence of the gas matrix shift of the J = 1 •*- 0 transitions of NH3 and NH3. Water has yielded results that are particularly interesting. Figure 3.14 shows a sample I8 16 1 spectrum obtained for a mixture of H2 O and D2 O in argon at 0.1 cm" resolution. This 16 18 spectrum shows clearly resolved 1(1,1) •*— 0(0,0) pure rotational transitions of H2 O, H2 O, 16 18 16 18 HD 0, HD O, D2 O, and D2 O. The linewidths for these transitions are considerably narrower than those previously reported.14"17 We believe this to be a result of lower concentration and lower temperatures. In Ref. 17, the authors attribute a peak around 32 cm"1 to "pure" argon phonon modes allowed by the noncrystal nature of the solid. We have found that if the vacuum 1 system is conditioned with D2O the peak at 32 cm" becomes smaller and eventually will 18 disappear as the conditioning is more thorough. If H2 O is added to the system, an extra peak

12 14 16 IB 19 WAVENUMBERS

Fig. 3.13. Far-ir spectrum of the rotational transitions of a mixture of deuterated ammonia molecules. OTHER UNCLASSIFIED WEAPONS RESEARCH 47

15 WAVENL»«ER3

Fig. 3.14. Far-ir spectrum of the rotational transitions of an isotopic mixture of water molecules.

appears at 31 cm . We believe these experiments demonstrate that the peak at 32 cm Ms in reality a water peak. We see no discrete absorptions attributable to pure argon in the 10 to 60 cm"*1 region. In Table 3.4, the transition freqencies in the gas phase, in an argon matrix, and in a krypton matrix are listed along with the linewidths in the argon matrix. The uncertainty in the matrix values is estimated to be 0.03 cm"1. In both argon and krypton, the relative gas-matrix shifts and the linewidth among the isotopimers correlates with the degree of rotation-translation coupling (RTC). The RTC occuis because in the matrix the molecule is restricted to rotate around its center of action rather than its center of mass where the rotational and translational kinetic energies are separable. The center of action is the point in the molecule that minimizes the anisotropy of its interaction with the matrix cage.18"20 For water, the center of mass will be between the oxygen atom and the center of action. Thus RTC is increased in this molecule if the center of mass is moved closer to the oxygen. In the 18 series of isotopimers of water, H2 O, which has the center of mass closest to oxygen, has the 1 16 largest gas-matrix shift (-5.6 cm"" ) and largest linewidth (0.5). D2 O, which has the center of mass furthest from the oxygen atom and closest to the predicted center of action, has the smallest matrix shift (-0.6) and linewidth (< 0.1). As expected, the other isotopimers lie in between these two extremes. 48 OTHER UNCLASSIFIED WEAPONS RESEARCH

TABLE 3.4. Line positions, Hnewidths, and gas -• matrix shifts of the 1(1,1) «- 0(0,0) ^_ transitions of water* " ^"

; ': • . " ' "'' " .. • ' ' •• Av (Gas—»• Matrix) isotopimer Gas" Argon Krypton Linewidth" Ar Kr

14 H2 O 37.14 32.42 31.22 0.31 4.7 5.9 Hj^O 36.77 31.15 30.48 0.50 5.6 | 6.3 HD"0 29.82 27.36 27^06 0.22 2.5 1 2.8 HD"O 29.47 26.51 26.20 0.30 3.0 ! 3.3 T)fO> 20.26 19.63 19.47 0.10 0.6 ] 0.8 1> D2 O 19.88 19.07 18.92 0.12 0.8 1.0 •All values in cm"1. "Calculated from rotational constants in works cited in Ref. 22. CFWHM in argon matrix.

The correlation between RTC and linewidths is hard to assess because we are uncertain if the observed linewidths are dominated by inhomogenous or homogeneous broadening mechanisms. If they are homogeneous, it is reasonable that the linewidths would increase with RTC because the rotation levels would have more translational character and most likely be more strongly coupled to the lattice. This stronger coupling would result in faster relaxation and dephasing times. If the broadening mechanism is inhomogeneous, it is hard to explain why the linewidths are correlated with RTC. However, we believe that homogeneous broadening is most likely the dominant mechanism because the linewidths increase with temperature. The matrix shifts for all isotopimers are greater in krypton than in argon. This is expected because krypton is more polarizable and would exert a greater perturbing potential. The magnitude of the difference between the shifts in argon and krypton appears to be dependent on the isotopimer. In general, the shift from an argon to krypton matrix is larger if the gas-matrix shift is larger. However, the ratio of these two shifts has a complicated isotope dependence that we do not understand. Because in previous papers there have been questions about the relative intensities of pure rotational lines of water,21 we have investigated the temperature dependence of their intensities. Unfortunately, we have not been able to observe transitions other than the 1(1,1) •*— 0(0,0) transition and make relative intensity measurements. However, we made integrated intensity measurements of the 1(1,1) •*— 0(0,0) transition of HDO as a function of temperature and compared them to intensities calculated from the gas phase rotation constants and appropriate Boltzman distribution (see Fig. 3.15). HDO was used because it doesn't have the spin relaxation problem of H2O. The estimated uncertainties in temperature are ±0.5 K and in intensity 5% for the lowest temperature and 15% for the highest temperature. It appears that the intensities have the temperature dependence expected from a Boltzman distribution, within experimental error. We have demonstrated that low concentration and temperature have allowed us to obtain much improved spectra of the pure rotational transitions of water. Successful modeling of the isotope dependence of the matrix shifts and linewidths measured here should further the understanding of the rotational and translational modes of matrix-isolated molecules. OTHER UNCLASSIFIED WEAPONS RESEARCH 49

•z. Ul •z.

8 12 TEMPERATURE

Fig. 3.15. Calculated D and measured A integrated intensity of the 1(1,1) -«- 0(0,0) transition of HDO in an argon matrix. The intensities are normalized so at 4 K the intensity is 10.

HIGH-PRESSURE DIFFRACTION STUDIES IN DIAMOND ANVIL CELLS

Structure of N2 at 2.94 GPa and 300 K

Don T. Cromer, Allen C. Larson, Robert R. Ryan, Richard A. LeSar (P-10), Robert L. Mills (P-10), and David Schiferl (M-6)

We are continuing to study small molecules contained at high pressure in diamond anvil cells. We determined the structure of N2 at 2.94(6) GPa and found it to be the same as the P-N2 structure at low temperature and 1 atmosphere. The structure is a hexagonal close-packed array of N2 molecules with the N-N vector tilted 54° from the c axis but randomly oriented about this axis. Calculations using a Gordon-Kim electron-gas model show that this structure has a minimum energy when the N2 molecules are tilted at an angle of 51°.

High-Pressure Studies of Nitromethane

Don T. Cromer, Robert R. Ryan, and David Schiferl (M-6)

Nitromethane is the simplest hydrogen, carbon, nitrogen, oxygen explosive and has therefore been the subject of numerous experimental and theoretical studies. In addition, it is the most complex molecule that we have studied in a diamond anvil cell. We have completed studies at 0.3, 0.6,1.0,2.0,4.0, and 6.0 GPa. The structure is the same as at low temperature and 1 atmosphere, 50 OTHER UNCLASSIFIED WEAPONS RESEARCH that is, space group Yl-?.fLx (Ref. 23) At the two highest pressures, we could determine only the unit cell size because the crystals were too strained for us to measure diffraction intensities. At the two lower pressures, we could find no evidence of fixed hydrogen atoms, which indicates free rotation of the methyl group around the C-N bond. At 1.0 and 2.0 GPa, there is some evidence for fixed hydrogen atoms, although they are not accurately located. The results do indicate enhanced intermolecular interactions as pressure is increased. The structural results should affect the many theoretical studies on nitromethane that are currently under way.24"26 Figure 3.16 shows the volume compressibility of nitromethane. Table 3.5 gives the bond lengths as a function of pressure. There is no significant variation in the N-O distances. The C-N distances are not significantly different for adjacent pressures, but a systematic apparent shortening of the bond is evident. We have made Raman measurements at several pressures in a diamond anvil cell. Figure 3.17 gives the assignments and pressure dependence. The most remarkable aspect of the v(P) 1 1 dependence is that vc.N (915 cm" , P = 0) changes only about 15 cm" between 0 and 2.0 GPa, whereas application of Badger's rule for the bond length difference measured by x-ray diffraction indicates that Av should be on the order of 100 cm"1. The obvious explanation is that a significant increase in intermolecular coupling exists at elevated pressure and affects the increased C-N bond strength. The results indicate that vibrational studies at high pressure will not necessarily signal important structural changes. Recent time-resolved spontaneous Raman results in the shock front of nitromethane shocked to 2.0 GPa and 300 to 400 °C show the same vc.N frequency shift that we observe in the hydrostatic experiments in spite of the large difference in temperature.27

Cell Volume, A*

Fig. 3.16. Volume compressibility of solid nitromethane. OTHER UNCLASSIFIED WEAPONS RESEARCH 51

TABLE 3.5. Variation of Bond Distances With Pressure in Nitromethane

C-N NO, N-O2 GPa (A) (A) (A)

0.3 1.524(26) 1.193(15) 1.195(19) 0.6 1.487(16) 1.201(9) 1.205(11) 1.0 1.461(11) 1.199(8) 1.240(9) 2.0 1.452(14) 1.207(13) 1.218(11)

1600

1500

1400 . II t

1300

1200

1100

1000

900

700 it t I 600 t-

500

400

300

200 - 100 - •i: i 0 12 3 4 5 6 7 9 10 11 12 13 14 GPa

Fig. 3.17. Frequency response of solid nitromethane to hydrostatic pressure. 52 OTHER UNCLASSIFIED WEAPONS RESEARCH

INS AND OPTICAL SPECTROSCOPIC STUDIES OF ORGANIC EXPLOSIVES

Basil I. Swanson and Sushil K. Satija*

We have carried out a detailed Raman scattering study of both TATB and fully deuterated D'-TATB at high pressure to understand the shock insensitivity of these materials. Using an ethanol-methanol (1:4) mixture as the pressure medium in a diamond anvil cell, we generated pressures up to 16 GPa. At these pressures, we have not seen any indication of pressure-induced chemistry or a phase transition in TATB, which proves that TATB is a very stable compound under extreme conditions of pressure. The behavior of TATB should be contrasted with that of NO which undergoes spontaneous disproportionation at elevated pressures. Raman scattering data from normal TATB at higher pressures suggest a strong interaction between C-NO2(vCN) and C-NO2(vNO,sym), which is also coupled to NH2(5). In TATB, 1 linewidths of the C-NO2(vNO,sym) mode (1169 cm" at room pressure) increase as a function of pressure; this indicates that the above coupling increases as the pressure is increased. From the linewidths of various other modes of TATB, we have checked that the line broadening of the 1169 cm"1 mode is not caused by an inhomogeneous pressure profile in the diamond cell. Beyond 6.5 GPa, the linewidth of vN becomes narrow again. This is probably because of the decrease of anharmonicity in the potential as the pressure is increased. Increase in linewidth of 6 2^yNO,sym) mode is also observed up to 6 GPa in D TATB. The coupling between various vibrationaHnodes suggests that TATB is able to dissipate the shock energy very effectively amongst variousfnodes, thereby making this compound rather insensitive to shock. We have also observecha^jositive activation volume for photolysis in TATB. At room pressure it is easy to photolyze TATB by using a relatively modest amount of laser power (2 to 3 mW) in the visible region. In fact, it is not possible toiget atmospheric pressure Raman spectra of TATB without some photolysis. At high pressurgj/iowever, we were not able to photolyze the TATB sample even with 100 to 200 mW of laserypower incident on the sample. These experiments were performed using 5145, 4880, and 4579 A radiation, which led to increasingly rapid photolysis at atmospheric pressure. Using a diamond anvil cell oven capable of 750 K, we are now measuring the thermal degradation rate of TATB as a function of pressure and temperature. At room pressure, TATB decomposes at 550 K. Because the pressure vs volume data for TATB are known from shock studies, we have also calculated the mode Griineissen parameters for various vibrational modes in TATB.

High-Pressure Studies of Ammonium and Potassium Picrate We have also obtained preliminary data on the pressure dependence of the Raman spectra for both ammonium and potassium picrates. Potassium picrate has been studied up to 5.5 GPa and ammonium picrate to 2.5 GPa. We see no evidence for pressure-induced chemistry or structural phase transformation. We will continue this work up to «20 GPa pressure.

*Brookhaven National Laboratory OTHER UNCLASSIFIED WEAPONS RESEARCH 53

DENSITY PREDICTION FOR OCTANITROCUBANE

Don T. Cromer, Allen C. Larson, Elizabeth M. Overmeyer* and Robert R. Ryan

Octanitrocubane (ONC) has been proposed as a novel explosive compound because its density, predicted by the group additivity method,28 is over 2.1 g/cm3, a value that is near the extrapolated maximum for carbon, nitrogen, oxygen compounds. Although the predicted density (2.1 g/cm3) seems to be only slightly higher than that of other dense organic explosives (TATB, 1.94 g/cm3), the difference becomes highly significant because the Chapman-Jouquet detonation pressure is proportional to the square of the solid state density.2' The group additivity method involves assigning volumes to common molecular fragments by least squares averaging the volumes over classes of organic compounds of known density. The density of similar compounds can be predicted accurately by this method (2 to 3%), and it has proven to be a useful tool for guiding new chemical synthesis. However, the method is less useful when applied to compounds with unusual structural characteristics. For example, the most comprehensive treatment of the group additivity method28 predicts a density of 1.80 g/cm3 for TATB, a value that would have discouraged synthesis had it been predicted in advance. We have made density predictions by using the computer program WMIN,30 which employs 6 atom-atom potential functions of the form V(ry) = -Auru + Bu exp(-allri,) + e,e|/r,,, where A, B, and a are determined empirically,31 and the atomic charges are taken from theoretical calculations or from x-ray diffraction measurements. The atom-atom potential method (AAP) has reproduced densities for known structures that agree with the known density to an accuracy comparable to that of the group additivity method. However, the most challenging aspect of the AAP method is the derivation of a correct starting structure for materials of unknown structure. Although this problem is intractable at the present time, surveys of the known crystal structure of organic compounds indicate that, depending on the molecular symmetry, certain space groups and coordination numbers occur with a high probability. Nevertheless, many polymorphs are possible with packing efficiencies only slightly less than the true structure. Therefore, reasonable but incorrect structures will provide a lower bound for the true density. Using the methods outlined above, we have computed unit cell volumes, and hence, densities, for several models of the crystal structure of ONC (Table 3.6).

TABLE 3.6. Predicted Crystal Energy and Density of Octanitrocubane Model. Energy Density fkcal/mole) (g/cm3} 1 -22.88 L938 2 -28,34 2.127

'-• 3 -33.62 1.987 4 ^0.45 2.222

'Graduate Research Assistant from Arizona State University 54 OTHER UNCLASSIFIED WEAPONS RESEARCH

We obtained molecular coordinates of ONC and Mullikan charges on the atoms from a MINDO-3 molecular orbital calculation. Model 1 has one molecule centered at the origin of a triclinic unit cell, space group PI (Fig. 3.18). Model 2 is triclinic, space group Pi with two molecules related by a center of symmetry in the cell. Model 3 is similar to Model 1 but with Mullikan charges of-0.0845, 1.1035, and -0.5095 on carbon, nitrogen, and oxygen, respectively. Model 4 is similar to Model 2 but with the Mullikan charges added.

Fig. 3.18. Projection of the PI structure of ONC.

The density increase when charges are added to the model is perhaps surprising. The molecule, to a first approximation, is a sphere with negative oxygen atoms on the surface. We had surmised that there would be a repulsion between molecules and, hence, a lower density. However, the Coulomb attraction between nitrogen and oxygen on neighboring molecules is slightly greater than the oxygen-oxygen repulsive terms. The magnitudes of the charges from the MINDO-3 calculation are larger than we derive from analysis of experimental x-ray diffraction experiments in organic compounds, and the predicted density of 2.222 g/cm3 is probably too high. Nevertheless, this method does predict a rather high density in agreement with the group additivity approach to de isity prediction. Refinements of the method should provide a reasonable tool for searching for organic compounds with unusually high densities. OTHER UNCLASSIFIED WEAPONS RESEARCH 55

CHARACTERIZATION OF KRATON POLYMERS BY NMR

William L. Earl

Kraton is a trademark for a series of commercially useful polymers. The particular Kraton polymers used in this study were Kraton-G 1650 and 6500. These polymers are used as "binders" in an experimental plastic bonded explosive (PBX) X-0298. The original tests were performed with Kraton-G 6500, but later tests with Kraton-G 1650 resulted in a PBX that was not well bound. The manufacturer of the polymer claimed that the two formulations were identical. The question posed is: Can nuclear magnetic resonance (NMR) characterize the two samples and detect any differences between them? These two polymers are triblock copolymers with two blocks of polystyrene and one block of a random copolymer of ethylene and 1-butylene. A schematic structure of the polymer is

(SSSSSS)n(EEBEBBBEEBEBE)m(SSSSSS)n,

where the ethylene-butylene block is randomly polymerized; n represents an average molecular weight of 9450, and m represents an average molecular weight of 51 000. A high resolution, 13C NMR spectrum of one of the polymers is shown in Fig. 3.19. The peaks caused by the solvent (deuterochloroform) and the internal refe^.-nce (tetramethylsilane) are marked. It is clear that this spectrum is rich in peaks and it can be separated into three regions. The aromatic region contains the ring carbons of the styrene. There are methyl resonances caused by the sidechain of the 1-butylene and a wealth of methine and methylene resonances caused by the backbone carbons of all three constituents. The reasons for the many peaks are the tacticity (stereochemistry) of the styrene blocks, which are atactic, and the randomness in the ethylene/butylene block. Methylene carbons will have different chemical shifts, depending upon whether the adjacent carbons are methylenes or methines. The complexity of the aliphatic region of the spectrum can be seen in Fig. 3.20.

Methyleneand Methine Carbons

TMS J Aromtic Cirbons Methyl Carbons

100 50 (THS)

13 Fig. 3.19. The C NMR spectrum of Kraton-G 1650. The solvent (CBC13) and reference peaks are marked. The spectrum is divided into three regions of different kinds of carbons in this polymer. 56 OTHER UNCLASSIFIED WEAPONS RESEARCH

-CH-

45 40 35 30 25 ppm(TMS)

Fig. 3.20. An expansion of the tnethylene and methine region of Fig. 3.19. Two peaks are marked to demonstrate the chemical shifts of representative types of carbons in the polymer backbone.

It is possible to assign all of the peaks in this spectrum to various kinds of carbons in the polymer. Because the NMR data were taken under careful quantitative conditions, it is possible to integrate the peaks and thus "count" the number of each kind of carbon. This count can then be related to the relative amounts of styrene, ethylene, and 1-butylene that were polymerized. After performing this analysis, we conclude that the relative percentages ar?, as follows:

6500 1650

Ethylene 64 65 Butylene 23 21 Styrene 13 14

Under most conditions, these small differences would probably not be significant, but in its use as a binder the Kraton composes only about 2.5 wt% of the total PBX. Under these conditions, it is entirely possible that the small chemical changes could make major differences in the physical properties of the PBX. These chemical changes were substantially verified by researchers in Group M-l by proton NMR, which showed differences in the relative areas of the aliphatic and aromatic protons that agree with the above I3C data. In fact, the 13C NMR also shows that the styrene blocks are atactic and were probably polymerized using a free radical catalyst and that the degree of randomness of the ethylene/butylene blocks is essentially the same in the two samples. OTHER UNCLASSIFIED WEAPONS RESEARCH 57

In conclusion, 13C NMR can be used to characterize Kraton polymers; it is used to determine relative concentration of each monomer, the tacticity, and randomness of the blocks. It is possible that the small chemical differences observed are responsible for the different behavior of these polymers as binders, but at this time we do not understand the details of the polymer-explosive interaction well enough to make a definitive statement.

HIGH RESOLUTION NMR STUDIES OF NITROMETHANE

William L. Earl and Ray Engeike (M-3)

Nitromethane is a common organic solvent that is also a very insensitive explosive. Studies at Los Alamos have shown that the sensitivity of nitromethane can be significantly increased by introducing physical discontinuities in the material (suspended grains of sand).32 These discontinuities are presumed to be the source of "hot spots" in a shock wave and thus cause iocal heating, which increases the sensitivity of the material to shock. This type of behavior is well known in hydrodynamic studies of explosives. It is also known that the sensitivity of nitromethane can be increased by adding organic amines to the solution. This chemical increase in sensitivity may be many orders of magnitude for just a few weight per cent of the amine. The solution remains homogeneous and so the "hot spot'" concept does not apply. We have postulated that the increased sensitivity is the result of a chemical effect and that the compound responsible is the nitromethane aci-ion generated in basic nitromethane solutions:

H O-

CH,NO2 + OH" <± H2O + C=N . (1) ti 6 We believe that we have found the NMR signal for the aci-ion in a solution of ethylenediamine in nitromethane. We are now comparing the spectrum obtained with several other model compounds to make an unambiguous assignment of the peak. We have also discovered that basic solutions of nitromethane decompose to a brown tar-like material. This decomposition complicated our search for the aci-ion, but it is indicative of either a lowering of the energy of activation for decomposition of nitromethane or an alternate path for decomposition. We have also noted that the decomposition proceeds to different products in the presence or absence of oxygen. We have not, to date, characterized the decomposition reactions.

ISOTOPE PRODUCTION, SEPARA TION, AND APPLICA TIONS 61 STABLE ISOTOPE PRODUCTION AND APPLICATIONS

THE NATIONAL STABLE ISOTOPES RESOURCE

Robert E. London and Nicholas A. Matwiyoff

The national stable isotopes resource (SIR) is operated as part of the ICONs program named for the isotopes of carbon (12C, 13C), oxygen (16O, 17O, 18O), and nitrogen (14N, I5N). The program encompasses

1. Production of large quantities of the separated isotopes by low-temperature distillation of CO and NO;

2. Development of efficient synthetic methods to incorporate the isotopes into complex molecules;

3. Improvement of techniques, especially NMR and mass spectroscopy, for the analysis of isotopically labeled compounds; and

4. Participation with extramural investigators in cooperative research and development programs to develop the use of stable isotopes in the biosciences and in environmental studies.

The focus of the SIR is on developing uses of stable isotopes in the biosciences by

• producing and providing enough separated 13C, 15N, and oxygen to support the program;

• synthesizing labeled compounds for accredited investigators when those compounds are not readily available from commercial or other sources at acceptable costs;

• developing an active program of research collaboration with investigators in the biosciences community and providing, as necessary, isotope-labeled compounds and analysis and data interpretation with NMR and mass spectrometry;

• advising and assisting investigators who use isotopes of carbon, oxygen, and nitrogen;

• hosting visiting scientists for training in the use of stable isotopes and encouraging exchanges of talks, short courses, and extended research opportunities;

• collaborating with other resources in synthesis and mass spectrometric and NMR analyses to speed development of isotope methodology; and

• performing core research designed to keep the resource at a state-of-the-art level.

Several projects supported by the SIR during the past year are highlighted here. 62 ISOTOPE PRODUCTION, SEPARA TION, AND APPLICA TIONS

Stereochemical Aspects of Propranolol Metabolism Propranolol (3-isopropylamino-l-naphthoxy-2-propranolol) is the most widely used P-adrenergic antagonist in the US, and it is used worldwide to treat angina pectoris and hypertension. The drug is used as a racemic mixture and is highly metabolized by glucuronidation, aromatic hydroxylation, and oxidative N-dealkylation. Stereoselectivity of its metabolism may be important to the P-adrenergic antagonist activity. The antihypertensive action of the agent probably arises from effects of a single enantiomer and may involve one or more pharmacologically active metabolites. To obtain better understanding of the metabolism of this drug in humans, Wendell L. Nelson of the Department of Medicinal Chemistry, University of Washington, has designed a series of mass spectrometric studies in which enantiomerically pure propranolol-18O is prepared from [l-18O]naphthol, and the 18O-Sabeled chiral forms of the drug at steady state are fed to adult male human volunteers. The stable isotope label will provide a marker that allows determination of the stereochemical origin of all of the known metabolites of propranolol. Use of the stable isotope label in human subjects provides information concerning the metabolism of propranolol without resorting to radioisotope labeling, which is a much more difficult procedure to carry out in human volunteers. Incorporation of 18O labels into compounds of interest has most typically been effected by a 18 chemical exchange procedure in which the initially unlabeled metabolite is dissolved in H2 O. Typically, rather extreme conditions are required to achieve a significant exchange rate, there is frequently much degradation of the precursors, and often the yields are low and the products are impure. The SIR staff has developed an alternative approach for l8O labeling that makes use of what is generally considered an undesirable property of Grignard reagents—sensitivity to the presence of oxygen. Thus, the Grignard will form a peroxide adduct with oxygen, and the reaction of this peroxide with a second Grignard reagent leads to the formation of two molecules of the corresponding alcohol. For the synthesis of [l-18O]naphthol, the appropriate Grignard reagent, naphthyl magnesium bromide, is prepared, and then allowed to react with oxygen in a closed vessel. Using this approach, we prepared 10 g of naphthol labeled to the 94% level with 18O for Dr. Nelson to use in the proposed metabolic studies.

Regulation of Insulin Receptor Level in Animal Cells The broad utility of radioisotopes in biochemistry reflects the use of radiolabeled tracers to study the fate of labeled precursors. However, despite the ability to detect the radiolabel in a complex mixture of products, it is never possible to physically separate labeled and unlabeled materials on the basis of the label alone. Such a capability is of obvious use for determining turnover rates of various cellular components because it is needed to separate newly synthesized molecules from older molecules of the same type. The use of stable isotope labels provides a basis for carrying out such separations by using the density difference that can be exploited by density gradient centrifugation. Thus, the experimental approach involves using a pulse of material that is "heavy"; that is, it contains 13C as well as 2H and 15N. For example, protein synthesized from such heavy amino acids has a molecular weight that is 10% greater than protein synthesized from the corresponding unlabeled amino acids. Separation by density gradient centrifugation allows us to quantify the relative amounts of protein synthesized from the heavy and the normal density amino acids. This, in turn, provides a basis for assessing turnover rates of various cellular components. ISOTOPE PRODUCTION, SEPARA TION, AND APPLICA TIONS 63

Among the various potential applications of this technology, the study of the turnover rates of hormone receptors is of intense current interest. Dr. M. Daniel Lane of the Department of Physiological Chemistry, Johns Hopkins University School of Medicine, has recently used this approach to study regulation of insulin receptor levels in animal cells. In particular, his group has carried out studies of 3T3-L1 preadipocvtes, a subline of mouse fibroblasts. Treating these cells with insulin as well as other agents results in an accumulation of triglyceride and increased sensitivity to certain hormones. Using the density labeling approach, Dr. Lane's group has studied accompanying changes in insulin receptor number and turnover. In carrying out these studies, Dr. Lane's group has used "heavy" amino acids that were separated from heavy algae I3 produced by the resource staff. Such algae are grown on a medium containing CO2, 15 ( NH4)2SO4, and D2O as sources of the heavy labels.

Synthesis and Structure of 15N-Labeled tRNAs by Using NMR The tRNAs present an interesting structural paradox. Twenty different amino acids are associated with 20 different aminoacyl-tRNA synthetases, which aminoacylate the tRNAs with a high degree of fidelity. Thus, each group of amino-acid-specific tRNAs must have important elements of uniqueness that distinguish them. Although in protein synthesis each aminoacyl- tRNA must be bound to an elongation factor and eventually pass through the ribosomal machinery during biosynthesis of proteins with virtually no constraints other than those dictated by the mRNA template, the process also requires that the structures of the various tRNAs must have many elements in common. NMR provides a special approach for studying this delicate balance of unique and common structural features that permit tRNAs to fulfill their important biological roles. Proton NMR studies of the downfield region between 9 and 16 ppm, where the NH protons of the bases resonate, have been of particular value from the standpoint of structural analysis because these protons participate in the hydrogen bonds that are essential for stabilizing a particular topology. Such JH NMR studies are ultimately limited by the difficulty inherent in assigning particular resonances to particular bases. Dr. C. D. Poulter of the Department of Chemistry, University of Utah, has recently developed a methodology involving 15N labeling. In particular, culture of microorganisms on a medium containing [15N]-labeied bases such as [3-lsN]uracil provides a means of introducing the 15N label. As a consequence of the scalar coupling interaction between the 15N and the directly bonded proton, all protons bonded to uracil N-3 can be identified, and this facilitates assignments. In addition to labeling the uridine, the uracil precursor labels other bases including pseudouridine, thymidine, and thiouridine. Because of the relatively small number of these modified bases present in the tRNA molecules and the unique chemical shifts associated with the modifications, studies of the corresponding protons should be particularly facilitated. Some of the tertiary hydrogen bonds involving pseudouridine are of particular interest because they may stabilize important conformations. These studies are of great value for determining the structural and dynamical characteristics of these critically important nucleic acid molecules. 64 ISOTOPE PRODUCTION, SEPARATION, AND APPLICATIONS

SEPARATION OF STABLE ISOTOPES — PRODUCTION

Thomas R. Mills and Raymond C. Vandervoort

The objectives of the stable isotope production program are to provide separated isotopes of carbon, oxygen, and nitrogen (ICONs) for research purposes and also to develop new or improved techniques for incorporating the separated isotopes into commonly desired chemical forms. Isotopic materials are sold at cost to Los Alamos investigators or to the general research community through the Mound Facility. During FY 1983, the value of isotopic products produced for Mound sales was $680,000. The isotopes are separated by cryogenic distillation of CO for carbon isotopes and of NO for nitrogen and oxygen isotopes. Table 4.1 shows the quantities of isotopes separated during FY 1983.

TABLE 4.1. Quantities of Isotopes Produced in FY 1983 Isotope Quantity Enrichment (kg) (%)

12C 1.0 99.95 13C 1.5 99 + "N 4.0 10 + "N 1.3 60 + "N 1.7 98 + "O 50 99.98 "O 0.2 50 + »o 1.5 10 + "0 2.5 95 +

To meet the greatly increased demand for isotopes of nitrogen and oxygen, many modifications were made to the NO isotope plant:

1. A smaller diameter exchange column was built to provide more efficient isotopic exchange o? 15 the N depleted NO and the HN03 feed under increased flow rates.

2. A larger diameter SiO2 drying bed was built to permit higher NO feed flows with longer time between bed regeneration.

3. The control valves and the waste-acid liquid seal have been changed to provide more reliable operation and greater throughput of the isotopic feed system. ISOTOPE PRODUCTION, SEPARA TION, AND APPLICA TIONS 65

4. A new platinum catalyst reactor was built to eliminate cross-degradation of 17O and 18O isotopic water that had been found while using a common reactor.

5. A totally new conversion train was built to make the new product of 10% 1JN directly from the bottom drawoff of the first-stage NO column. This system is necessarily 10 times as large as the conversion system for high-enrichment 15N.

Production of I3C was significantly reduced in FY 1983 because there was a large inventory on hand. There was also the possibility that a private US company would succeed in separating 13C product. The 13C plant is now in a standby mode that will continue through FY 1984. Most of the isotopically enriched CO or NO is converted to other labeled compounds for use by researchers. The reactions used were summarized in an earlier report.33 Table 4.2 lists the forms ai.d amounts of labeled compounds prepared in FY 1983.

TABLE 4.2. Isotopically Labebd Compounds Made in FY 1983 Quantity Quantify Product 100% Basis Product 100% Basis (Mol) r (Mbl)

12 CO2 40 "NH, 221 12 CD4 63 ("NH^SO, 118 "CO2 72 K"NO, 37 I3 CD4 56 H"NO, 67 Hj!6O 3125 :5N, 10 H2"O 12 \y- ...... I H2"O 234.

THE CHEMICAL SYNTHESIS AND BIOSYNTHESIS OF COMPOUNDS ENRICHED WITH STABLE ISOTOPES

Thomas E. Walker

The staff of the SIR has developed many of the synthetic methods for incorporating stable isotopes into natural products, drugs, and other compounds of interest in tracer and structural studies. Compounds have been made for the program's internal use, extramural investigators, and collaborators. The approach taken for the synthesis of natural products has changed recently from an emphasis on chemical synthesis to an emphasis on biosynthesis or a combination of simple chemical synthesis and biosynthesis, particularly for chiral compounds. In some cases, biosynthesis is clearly impractical and chemical synthesis remains as a vital link in the synthesis of natural products. 66 ISOTOPE PRODUCTION, SEPARA TION, AND APPLICA TIONS

Synthesis of 18O-Enriched Phenol and Naphthol A request by Dr. Wendel Nelson of the University of Washington to the SIR for l-[18O]naphthol prompted us to develop a synthesis for 18O-enriched phenols. The l-[18O]naphthol supplied to Dr. Nelson was used to synthesize [18O]propranolol, which is an important (3-adrenergic antagonist used extensively in the treatment of many cardiovascular diseases, including hypertension and angina pectoris, as well as in other disorders. It is extensively metabolized in man and other species by several metabolic pathways, including oxidative N-dealkylation, aromatic hydroxylation, and glucuronidation. Many previous studies on stereochemical aspects of propranolol metabolism have used pseudoracemic propranolol, in which one of the enantiomers is labeled with deuterium in the naphthalene ring or in the isopropylamine side chain, and the other enantiomer is not labeled. These methods have limitations because the deuterium labels are not retained in certain metabolites. Incorporation of a stable isotope label(s) at metabolically inert positions is needed to obviate the use of multiple pseudoracemic propranolols.34 We considered several possible synthetic routes to l-[18O]naphthol and rejected them for various reasons. An exchange reaction in aqueous acid has been described;35 however, because the naphthol was to be used for mass spectral analysis, the enrichment had to be greater than 90% I8O and preferably above 95%. The conditions of the exchange reaction are harsh—180° 18 for 24 hours in 10 N HCl. The amount of H2 O required to obtain the high enrichment and the I8 effort involved in recovering pure H2 O from the ION HCl made the exchange reaction an unattractive alternative. We also considered several other reaction schemes including catalytic reactions, but none were deemed suitable for use with 18O for a variety of reasons. The best synthetic approach appeared to be the oxidation of a Grignard reagent.

The reaction of Grignard reagents with O2 is generally considered an undesired side reaction with no synthetic value, which requires that one work in an inert environment. However, Kharash and Reynolds36 have described a synthesis for phenols that uses oxygen gas and the appropriate aryl halide. They use an excess of oxygen gas, whereas for our purposes we must use a minimum of gas in a leak-tight system. Normally, if one conducts an experiment in an inert environment and a little oxygen leaks in, the yield decreases slightly with the formation of a minor impurity. With the use of isotopic oxygen, any leaks will result in an intolerable decrease in the final enrichment Kharash and Reynolds36 describe a mechanism whereby the yield of phenol can be increased by adding an aliphatic Grignard to the reaction mixture. Although this approach clearly improves 18 the yield of phenol from aryl halide, it is not clear what happens to the yield from O2. Table 4.3 describes a series of experiments designed to find the conditions for the highest yield of

TABLE 4.3. The Yield of l-fajNaphthol from 1-Bromonaphthalenc and "O2 _ Yield from Equivalents Yield from 1-Bromonaphthdene »O (%) (%) Recovery ArBr RBr ArOH ROH ArBr RBr (%) : 1 e 0 .; -23 | - \'\ • '15 •' is J i as 20 |2(5 " 23 61 46 1 1.0 17 |3'7 28 61 54 ISOTOPE PRODUCTION, SEPARA TION, AND APPLICA TIONS 67

l-[18O]naphthol. Although by adding an alkyl Grignard it was possible to increase the yield of naphthol from aryl halide and to increase the 18O recovered, it was not possible to increase the 18 yield of naphthol from O2. The 18O-enrichment in l-[I8O]naphthol was very high, as is shown in Table 4.4. Mass spectral analysis of the naphthol was done using an Extranuclear Spectrel Quadrapole mass spectrometer's direct insertion probe. Two sources of 1BO in the reaction proved to be significant: leaks of air into the system and oxygen in the nitrogen used as an inert gas. An oxygen scavenger was used on the nitrogen line to eliminate that problem, and careful design of the vacuum system and reaction flask eliminated the other. This work has been accepted for publication.37

lf TABLE 4.4. Isotopic Analysis of O2 and l-[lgO]NaphthoI

Compound 16O "0 "O

"O2gas 2.42 2.93 94.64 l-[l8O]Naphthol 2.8 2.9 94.3

Biosynthesis of Labeled L-Tyrosine and L-Tyrosine Analogues One major thrust of our synthesis effort is the application of biosynthesis to the preparation of isotopically enriched natural products. Biosynthesis has several advantages over chemical synthesis.

1. Biosynthesis is stereospecific; only the biologically important isomer is produced.

2. Biosynthesis allows us to produce labeled compounds from readily available and inexpensive enriched precursors, for example, acetate, D-glucose, etc.

3. Biosynthesis in general requires fewer steps than chemical synthesis.

4. Biosynthetic reactions can be readily scaled up to produce large quantities of labeled compounds.

5. Biosynthesis allows products with distinct labeling patterns to be produced using identical biosynthetic conditions with a different labeling pattern in the precursor.

6. Biosynthetic processes are generally not very labor intensive; that is, the microorganism does most of the work.

There are two major practical problems that must be addressed before biosynthesis is successful:

1. How to maximize the incorporation of label from precursor into product, and

2. How to minimize the degree to which the label becomes distributed to undesired sites in the product. 68 ISOTOPE PRODUCTION, SEPARA TION, AND APPLICA TIONS

The major goal of our development of biosynthetic techniques is to derive the benefits of biosynthesis and yet avoid the potential pitfalls. One of the most successful biosynthetic projects we have undertaken is on the biosynthesis of labeled L-tyrosine from phenol by using the bacterium E. herbicola. The reaction to form L-tyrosine is catalyzed by the enzyme p-tyrosinase that accumulates to high levels (about 10% of total protein) when the bacteria are grown on media containing tyrosine. In the biosynthetic direction, p-tyrosinase will catalyze the reaction of phenol with serine to produce L-tyrosine in high yield. We have used this approach to produce L-tyrosine with the following labeling patterns 2 I3 and amounts synthesized to date: L-[2',3',5',6'- H4]tyrosine (20 g), L-[4'- C]tyrosine (10 g), 13 18 L-[3',5'-"C2]tyrosine (10 g), L-[ N]tyrosine (3 g), and L-[4'- O]tyrosine (5 g). The deuterated product is prepared from perdeuterated phenol and unlabeled serine. The two 13C-labeled 13 13 L-tyrosine isotopomers were prepared from [l- C]phenol and [2,6- C2]phenol, respectively. The labeled phenols were chemically synthesized from 13C acetone by Dr. Carl Storm and his associates at Howard University. The L-[13N]tyrosine was made from unlabeled phenol and a 15 mixture of sodium pyruvate and ( NH4)2SO4 that the enzyme can use as substrates in place of serine. The [I8O]tyrosine was prepared from [18O]phenol that was chemically synthesized from 18 l8 18 bromobenzene and O2, a reaction developed for the synthesis of [ O]naphthol from O2 described earlier. The enzyme p-tyrosinase is also useful as a catalyst for the preparation of L-tyrosine analogues from phenol derivatives. If we could use aniline as a substrate, we could synthesize p-aminophenylalanine, and this amino acid would be a better precursor for L-phenylalanine than L-tyrosine. Unfortunately, the yield of p-aminophenylalanine from aniline is less than 0.1%. A second attractive possibility is the conversion of phenylpyruvate to L-t^Njphenylalanine from 15 ( NH4)2SO4. Although the enzyme accepts P-hydroxyphenylpyruvate as a substrate, no phenylalanine could be detected from phenylpyruvate. We tried a third phenol analogue, thiophenol, for the synthesis of L-thiotyrosine. This amino acid is not available commercially and is potentially very useful for the synthesis of peptide analogs that might exhibit pharmacologic activity. Our results suggest that L-thiotyrosine is not formed by the enzyme; however, work is continuing on the problem. A fourth substrate we have successfully used is 2-fiuorophenol for the synthesis of L-3'-fluorotyrosine. Although this product has been used as an NMR probe of proteins, it is currently available only as a D,L-mixture.35 The 2-fluorophenol is accepted as a substrate, although unlike L-tyrosine, the product does not precipitate from solution. The yield of L-3'-fluorotyrosine from 2-fluorophenol is about 75%, and no impurities are observed by gas chromatographic analysis or by I3C NMR. Figure 4.1 shows a 13C NMR spectrum of D,L-3'- fluorotyrosine from Sigma Chemical Company and L-3'-fluorotyrosine from E. herbicola. We also analyzed the L-tyrosine and L-3'-fluorotyrosine samples on a chiral capillary GC column (Chiralsil-Val from Alltech Associates) and could detect no D-isomer in either sample.

Biosynthesis of L-[I3C]Glutamate The preparation of labeled L-tyrosine by E. herbicola is a procedure in which the incorporation of label from precursor to product is high and there is no label scrambling. In contrast, the biosynthesis of labeled glutamate from D-glucose by the bacterium Brevibacteriumjlavum leads to lower yields, a dilution of the label, and some label scrambling. Nevertheless, we have 13 13 13 synthesized L-[2,4- C2]glutamate from D-[l- C]glucose and L-[3,5- C2]glutamate from ISOTOPE PRODUCTION, SEPARA TION, AND APPLICA TIONS 69

(a)

>A«'i-•'»,. i >,i«,in. i»li*-

^^ 200 150 100 50 ppm

I3 Fig. 4.1. Proton decoupled C NMR spectra of 3'-fluorotyrosine in approximately 1 N NH40H. The spectrum in (a) was from a sample of D,L-3'-fluorotyrosine purchased from Sigma Chemical Company; we obtained the sample of L-3'-fluorotyrosine in (b) by biosynthesis from 22-fluorophenol and L-serine using E. herbicola. The only difference in the spectra is the impurity in the commercial sample (a).

I3 D-[2- C2]glucose, although the enrichments and label specificity are lower than desired. This reflects two problems: (1) the splitting of the 6-carbon glucose skeleton into two identical 3- carbon fragments, which dilutes the label by 2, and (2) alternate pathways that lead to label scrambling. A solution to the first problem is to use labeled pyruvate, a 3-carbon keto acid. Our initial attempt to produce L-glutamate from pyruvate suggested that L-glutamate accumulated only in the presence of excess biotin. Subsequent experiments have shown that several products are produced from pyruvate and that the composition of the mixture is dependent on several factors, including nitrogen source, pH, and biotin levels. The overall yield of total products from labeled pyruvate is low and the mixture would have to be separated chromatographically. If we can develop a convenient technique for the synthesis of labeled pyruvate', this may become an attractive method of preparing not only glutamate but also L-alanine, L-valine, and a-ketoglutarate. The problem of label scrambling, which is caused by alternate pathways, should be easy to solve by simply inhibiting one step in the offending pathway. Three pathways have been shown to lead to label scrambling:

(1) residual Krebs cycle activity,

(2) the glyoxylate shunt, and

(3) the equilibrium back reaction of oxaloacetate to fumarate. 70 ISOTOPE PRODUCTION, SEP ABA TION, AND APPLICA TIONS

In each case, fumarate is a symmetric intermediate that leads to the equilibration of the label between two sites as for oxaloacetate:

COO" COO" "COO- I I C=O CH CH

CH2 < > CH + CH 13COO~ 13COO~ Oxalacetate Fumarate Fumarate

All attempts have failed to reduce label scrambling by inhibiting these pathways. The Krebs cycle contributes only about 6% to the overall L-glutamate and therefore is not very significant.38 The glyoxylate shunt was not affected in glucose-grown cells in the presence of oxalate or itaconate at concentrations shown to inhibit the production of glutamate from acetate. The result suggests that the glyoxylate shunt is not significant in glucose-grown cells and that the fumarase back reaction is responsible for the observed label scrambling. Unfortunately, none of the inhibitors we tried have reduced the label scrambling. What is needed is either an effective inhibitor of fumarase or a genetic modification that reduces the fumarase activity.

NMR STUDIES OF CHEMICALLY MODIFIED DIHYDROFOLATE REDUCTASE

Robert E. London, William E. Wageman, Raymond L. Blakley,* and Lennie Cocco*

NMR is the only spectroscopic technique capable of probing individual nuclei of complex molecules or mixtures of molecules in solution. As part of a continuing series of studies to develop and evaluate specific 13C labeling in combination with NMR detection for analysis of protein structure and dynamics,39 we recently studied chemically modified [methyl-13C] methionine-labeled dihydrofolate reductase. Interest in this enzyme, which catalyzes the NADPH-dependent reduction of dihydrofolate to yield tetrahydrofolate, the active form of folic acid, is based in part on its role as a target of the particular class of Pharmaceuticals known as antifolates. These drugs, particularly methotrexate and aminopterin, are used to treat neoplastic disease. Reaction of proteins with various chemical reagents represents one of the oldest approaches to the analysis of proteins, and this approach combined with NMR can provide unique insight into the nature of the solution structure. In the particular series of studies recently completed,40 we used iodoacetate as the chemical reagent and [methyl-13C]methionine to label the enzyme. As in

•St. Jude Children's Research Hospital ISOTOPE PRODUCTION, SEPARATION, AND APPLICATIONS 71

previous studies, we introduced the label into the protein by growth of the microorganism Streptococcus faecium, which synthesizes large quantities of this enzyme on a medium containing the labeled amino acid [methyl-13C]methionine. Gleaner and Blakley have shown41'*2 that the reaction of the uncomplexed enzyme with iodoacetate results in carboxymethylation of several methionine residues of the enzyme. In particular, we obtained the following degree of modification: Met-28 (92%), Met-36 (46%), Met-50 (48%), and Met-163 (19%). Three other methionine residues Met-1, Met-5, and Met-42 are not significantly modified. Alternatively, we found that if the fodoacetate reagent is added to a solution containing the enzyme as well as a saturating level of the antifolate drug aminopterin, Met-28 and Met-50 are protected from the reagent and are not modified. This result presumably reflects binding of the drug near these residues and leads to inaccessibility of these methionines to the chemical reagent. Figure 4.2(a) shows the 13C NMR spectrum of the uncomplexed [methyl-I3C] methionine-labeled enzyme. Figure 4.2(b) shows the same spectrum after the labeled enzyme reacts with the iodoacetate in the presence of aminopterin. As is apparent from the spectrum, the changes are minimal. Alternately, Fig. 4.2(c) shows the spectrum of the enzyme after reaction with the iodoacetate but without the prior addition of the drug. In this case, the spectrum shows substantial modification. Resonances lose intensity near 15.0 ppm, and additional resonance intensity appears near 25.0 ppm. The latter, chemically shifted resonances correspond to methionine residues of the enzyme that have been carboxymethylated by the reagent. Using the studies of Gleisner and Blakley, we believe these resonances correspond primarily to Met-28 and Met-50.

250 23D1 UO 150 13.0 ppm

Fig. 4.2. Proton decoupled "C NMR spectra of [methyl13C]methionine dihydrofolate reductase derived from S. faecium: (a) uncomplexed enzyme; (b) uncomplexed enzyme exposed to iodoacetate in the presence of aminopterin; (c) uncomplexed enzyme exposed to iodoacetate in the absence of aminopterin. 72 ISOTOPE PRODUCTION, SEP/A. \TION, AND APPLICATIONS

We obtained further insight into the NMR data by subtracting spectrum lb from spectrum lc (Fig. 4.3). In this case, we observed two relatively sharp resonances that correspond to Met-28 and Met-50. The intensity ratio of these resonances should be approximately 2:1 (92%:48%). In this way, the protein chemistry data can be used to provide assignments for the 13C NMR resonances that are critical to the interpretation of the NMR study. We performed other studies in the presence of additional inhibitors and cofactors and used the results to provide a more detailed analysis of the structure of the enzyme in solution.40

-Met-28 b.c \ (15.42)

Met-50 (14.73)

17 16 15 14 13

Fig. 4.3. Carbon-13 difference spectrum: Fig. 4.2(b)-(c).

IN SITU AND IN VIVO METABOLIC STUDIES BY NMR SPECTROSCOPY

Robert E. London, James R. Brainard, Judith Y. Hutson, Clifford J. Unkefer

The combination of stable isotope labeling and NMR detection provides a unique opportunity to study metabolism in living tissue in real time. We have performed studies in a variety of microorganisms, perfused organs, and (in a few instances) intact experimental animals and humans.43 This approach is clearly optimal for the study of metabolic regulation; data obtained through traditional biochemical separation and isolation techniques have little relevance to the regulatory processes occurring in the intact system. Consequently, such studies are generally limited to metabolic pathways that have already been established and where the primary aim is to quantify flux through competing pathways and the response of this flux to various physical and hormonal perturbations. Although the pathwaysare, in general, well established, we evaluate and plan the particular labeling strategy to be employed^produce maximum information. During the past year, we have focused one of our principal efforts on the cellular pyridine nucleotides. These nucleotides participate as cofactors in most of the oxidation/reduction reactions within the cell and, in particular, are involved in the transfer of hydride ions to substrates. For example, the reactions are generally of the form

+ CnZyme + H + NAD(P)H + R > NAD(P) + RH2 . (1) ISOTOPE PRODUCTION, SEPARATION, AND APPLICATIONS 73

Subsequent transfer of a proton derived from water leads to the net production of RH2, the reduced substrate. In these studies, we used the chemical synthesis of 13C-enriched niacin—the vitamin precursor of the pyridine nucleotide coenzymes. In microbial studies, we added the labeled niacin to the growth medium; subsequently, it was incorporated into the pyridine nucleotide pools and provided sufficient sensitivity for us to observe the intracellular pools. We have previously described the results of preliminary studies to evaluate the intracellular redox state of E. coli.4* The principal conclusions of these studies were that

1. chemical exchange between oxidized and reduced nucleotides is sufficiently slow on the NMR time scale so that we observed resonances corresponding to each form;

2. we did not readily observe reduced resonances corresponding to the reduced triphosphopyridine nucleotide NADPH, which suggests specific broadening of these resonances as a consequence of association with cellular enzymes; and

3. the diphosphopyridine nucleotide pool remains highly oxidized even under anaerobic conditions.

Subsequent studies on the yeast Saccharomyces cerevisiae, similarly cultured in a medium containing the labeled niacin, have revealed some interesting differences. As with the E. coli, resonances corresponding to NADPH are not readily observed; however, the imposition of a variety of reducing conditions (including removal of the oxygen supply and addition of ethanol) results in a highly reduced diphosphopyridine nucleotide pool. We found that the pool reoxidizes rapidly upon reversal of the reducing environment. Figure 4.4 summarizes the effects of cycling

A) ANAEROBIC Cl N, BUBBLED

B] O, 8UB8LED D) O, BUBBLED

Fig. 4.4. Cycling of the pyridine nucleotide reduction charge in the yeast S. cerevisiae in response to alternate 1 bubbling with O2 and N2. The NADH/NAD" " ratio increases under anaerobic conditions and decreases upon resumption of the oxygen supply. 74 ISOTOPE PRODUCTION, SEPARA TION, AND APPLICA TIONS

with O2 and N2. These differences between the prokaryotic bacteria and the eukaryotic yeast cells presumably reflect the compartmentation of the cellular coenzymes into the cytosolic and mitochondrial pools in the latter. Preliminary data suggest that the yeast spectra are dominated by the nucleotides in the cytoplasm. These data in turn suggest very different regulatory roles for the pyridine nucleotide reduction charges in the two systems. In addition to these studies on microorganisms, we have continued our studies on perfused organs. The viability of the organ is maintained for periods of sever:.! hours by the perfusion of oxygen-rich fluids through the arterial system. We created an "artificial" hamster with pumps to keep the fluid flowing, an artificial iung to oxygenate the fluid (perfusate), and artificial kidneys (filters) to remove bubbled and particulate matter. Two approaches have been evaluated for labeling the pyridine nucleotide pools of the perfused Syrian hamster liver. In the first, we inject the animal with a large dose of the labeled niacin precursor several hours before sacrifice. In the second, we add the labeled precursor to the perfusate after initiating the organ perfusion study. In Fig. 4.5 we see a series of spectra showing the gradual labeling of the pyridine nucleotide pools that results from the second approach. In this study, we readily observe resonances corresponding to nicotinate (niacin), NAD(P)+, and nicotinamide. The observation of a significant resonance corresponding to nicotinate reflects the continuous addition of this precursor, and this resonance disappears shortly after the niacin additions to the perfusate stop. Based on the established pathways for pyridine nucleotide metabolism, these data can be interpreted to reflect the synthesis of NAD+ from niacin by means of the enzymes of the Preiss-Handler pathway,45 and the subsequent formation of free nicotinamide via the glycohydrolase. We use the nicotinamide as a precursor for the synthesis of pyridine nucleotides by other organs and by the mitochondria.

C-Z C-Z NICOTINAMIDE NICOTINAMIDE / C-Z C-2 C-2 NICOTINATE ^NAO* 17°-197 306-323

'«->» 272-289

STOPPED - NICOTINATE ADDITION

238-255 mln

160 ISO 140 130 160 150 140 130 ppm ppm

Fig:. 4.5. Labeling of the pyridine nucleotide metabolites in a perfused hamster liver from a [2-13C]nicotinaie precursor. We added the labeled nicotinate to the perfusate at a constant rate of 2.7 mg/hour. Resonances from the labeled nicotinate, as well as from nicotinamide and NAD+ are readily observed. ISOTOPE PRODUCTION, SEPARA TION, AND APPLICA TIONS 75

In addition to these experiments, we have initiated studies involving the effects of various perturbations on the pyridine nucleotide levels analogous to those carried out in the yeast. Initial data suggest that pyridine nucleotide pools in the perfused Syrian hamster liver behave much like the pools in the yeast; the diphosphopyridine nucleotide pool is highly reduced in response to the addition of ethanol. More detailed quantitative studies are currently in progress. In addition to the studies on pyridine nucleotide metabolism, initial 13C NMR studies of perfused guinea pig heart havs been carried out in collaboration with Dr. David Hoekenga, a cardiologist at the University of New Mexico. We designed these studies to provide baseline data on the metabolic behavior of perfused heart under standard perfusion conditions. Preliminary experiments dealt with the metabolism of [lI3C]glucose and [3-I3C]pyruvate and we obtained the following results.

1. Glycogen synthesis from [l-13C]glucose is readily observed.

2. Stimulation of glycogen synthesis by insulin has been readily observed.

3. Under the conditions of the study, simultaneous production of lactate and glycogen is observed.

4. Glycogen synthesis was observed after addition of 7 mM [l-13C]glucose even during periods of hypoxia and ischemia.

5. Addition of the [3-13C]pyruvate precursor resulted in the accumulation of significant levels of both [3-13C]lactate and [3-I3C]alanine. We have also begun to study the addition of pharmaceutical [3-I3C]-L-carnitine.

RADIOACTIVE ISOTOPE PRODUCTION AND APPLICATION

THE PRODUCTION OF RADIOISOTOPES OF TUNGSTEN AND OSMIUM USING LEAD TARGETS

Kenneth E. Thomas

Both 17iSTa and I9IIrm have decay characteristics that are suitable for use in generator systems for diagnostic nuclear medicine. The osmium-iridium generator system is currently used for angiocardiography.46"47 The tungsten-tantalum generator has been used with the multiwire proportional camera and may be useful in assessing ventricular function.48"49 Tungsten-178 (21.7- day half-life) is the parent of l78Ta (9.3-minute half-life), and 191Os (15.3-day half-life) is the parent of 191Irm (4.9-second half-life). Currently, 178W is produced by means of the (p,4n) reaction on 181Ta by using «40-MeV protons. Thin targets («8 MeV thick) are used and yield a 1.5 mCi/uA- hour. Osmium-191 for the l91Os —• 19Ilrm generator is produced by neutron-irradiating the separated isotope 190Os. Large quantities of 19IOs may be produced in this manner; however, the radionuclide is not carrier free. 76 ISOTOPE PRODUCTION, SEPARA TION, AND APPLICA TIONS

Proton-induced spallation of large lead metal targets may be a means of producing larger quantities of 17*W and higher specific activity 191Os. The predominant osmium isotope present in aged osmium samples would be 183Os. Although this isotope presents generator shielding problems, it would allow assessment of a carrier-free generator system before using the mOs. The only other tungsten isotope that would be present in aged tungsten samples v/ould be 181W, which should present no problems for generator usage but may be of interest to physicists. The experiment described in this report is an attempt to measure the production of mOs, 18SOs, 178W, and other heavy-element isotopes that result from irradiating lead metal with «800-MeV protons. Chemical separation processes are also tested in this work. One irradiated target has been processed. The irradiation took place at LAMPF with the target in beam for 27 days. Beam current entering the beam stop irradiation facility during this period averaged 390 uA and resulted in an integrated beam of 2.56 x 10s uA-hours. Target handling at the beam stop has been described earlier.50 The lead target was irradiated in position 9 (stringer 9). The beam traversed at least five targets before striking the lead target. The target was composed of 154 g of lead metal melted into a copper tube that was then welded closed. The details of target construction and handling have been described previously.51 Following irradiation, the target was returned to the INC-3 hot cells, and short-lived radionuclides were allowed to decay. Chemistry was performed 38 days after irradiation. A flow scheme of the separations chemistry used for this target is shown in Fig. 4.6. The end of the welded copper tube was machined off, the opened tube was held above a flask containing 300 mi of H2O, and heat was applied to the tube with a heat lamp. The molten lead dripped into the water and a fresh shiny surface resulted.

Pb TARGET

OISSOLVE IN HNO. AND HEAT -IOUID

EXTRACTION WITH CHLOROFORM a-BENZOINOXIME I 1 2M NoOH EXTRACTION W FRACTION 1 Ot FRACTION

Fig. 4.6. Flow scheme of separations chemistry for removal of osmium and tungsten from an irradiated lead target.

After all the lead had been melted from the tube, the flask was attached to a system with a condenser and a dropping funnel containing concentrated HN03. The condenser was attached by tubing to a vessel containing 100 mi of chloroform and 100 mi of H2O. The outlet of this container was connected to a second vessel containing 200 mi of 2M NaOH (see Fig. 4.7). These vessels served as traps for the osmium tetraoxide gas evolved during the dissolution process. Measurements were made later to determine the effectiveness of each trap liquid. ISOTOPE PRODUCTION, SEPARA TION, AND APPLICA TIONS 77

0.SSOLVWG TRAP I TRAP II

TO AIR IN EXHAUST t Fig. 4.7. Schematic of dissolving and distillation system. 4IU HNO3 1 HgO 2M Pb CHCIj NaOH

As HNO3 was added to the lead in the dissolving flask, the flask was heated on a hot plate. After enough HNO3 was added to make the solution AM, air was passed through the system to remove osmium. When all the metal was dissolved, the solution was allowed to cool. Enough water was then added to keep lead nitrate in solution. The next day an extraction was performed en the lead nitrate solution to remove tungsten. The extraction was similar to one used by Meyers and Nagle,52 which employed a-benzoinoxime in CHCI3. Tungsten was removed from the dissolved target in the organic phase. Nuclides were identified by their gamma rays observed in spectra obtained from a Ge(Li)-pulse height analysis system. The system had been calibrated for counting 5-mi solution samples. Appropriate volume dilutions were made to obtain samples whose counter dead-time was less than 15%. Nuclides identified in the lead target and the amount present at the EOB are listed in Table 4.5. Results of the osmium distillation step of the separation are given in Table 4.6. Only 20% of the total 185Os transferred into the trap solutions. No 191Os was observed in the osmium fractions.

TABLE 4.5. Nuclides Observed in Lead

Target . "'• ••.•- •' Amount Present Nuclide Half-Life at EOB (day) •(QV.

206Bi 6.2 3.1 ; 205Bi 15.3 5.4 »*ri 12.2, 7.3 >3Hg 46,6 0.3 i I9SAu 184.0 0.3 0 1MPt 10.2 2.9 ll9Ir 13.3 0.5 | ll5Os 94.0 1.5 lf3 Re • ,• .:: • 70.0 \ • 2.1 I7iW 21.5 % 2.0 ! I7S Hf f •••' 70.0 Ih * 1.1 "2Hf 1.87 (yeir) 0.07 "?Yb . .;•'*>• 32.0 }.. 0.6 78 ISOTOPE PRODUCTION, SEPARA TION, AND APPLICA TIONS

TABLE 4.6. Results of Osmium Distillation . Fraction of Distilled Trap Solution Osmium Impurities

CHC13 0.9 None observed 293 H2O 0.1 Hg IM NaOH trace 203Hg and 103Ru

Greater than 90% of the 178W present in the target solution was extracted into the a- benzoinoxime/CHClj. However, the tungsten fraction was not pure; contaminants included silver and niobium isotopes with smaller amounts of 183Os, 203Hg, and 93Zr. Osmium chemical yield as measured in the trap solutions can probably be increased substantially over the 20% measured in this work. This increase can be accomplished by three additions to the current procedure:

(1) bubble air through the solution in the dissolving flask, (2) boil the solution to lower volume after all lead is dissolved, and (3) add more HNO3.

Chloroform appears to be the best liquid for trapping the osmium because it seems to stop osmium preferentially to mercury and ruthenium. Greater retention of osmium in chloroform can probably be obtained by placing a small glass frit in the gas transfer tube to break up the bubbles and by passing the bubbles through a column of chloroform rather than in a wide-bottom flask as is done in this experiment. Following its distillation and entrapment in chloroform, osmium can be extracted into 2MNaOH. Various clean-up steps of the tungsten, including washes of the organic phase with H2O2, HNO3, and H2O proved unsuccessful. Tungsten is easily back-extracted into NH4OH, but so are the contaminants. Further work is necessary to obtain pure tungsten samples. Although mOs was not observed, an estimate of the upper limit of its production can be made. The 125-keV gamma ray of 185Os was observed as a low-intensity peak in the gamma spectrum of the osmium fraction, but the 129-keV gamma ray of 19IOs was not observed. If the assumption is made that the count rate of the 129-keV gamma ray is equal to that of the 125-keV gamma ray, the maximum amount of I9IOs produced in the 27-day irradiation described in this paper would be 5% of the 185Os activity, or 75 mCi, at EOB. By using ratios of saturation factors, the maximum amount of mOs that could be produced is calculated to be about 90 mCi for an irradiation length of at least 60 days. Variation of the total 191Os and the activity ratio 191:185 with irradiation time is illustrated in Fig. 4.8. It may be possible to increase 191Os production by using larger targets and by placing the target in an irradiation position with fewer targets in front of it. Even these steps would at best gain only a factor of 5 to 10 in production. Platinum or gold targets may yield higher amounts of 191Os, but these targets are very expensive. ISOTOPE PRODUCTION, SEPARA TION, AND APPLICA TIONS 79

'9l0S PRODUCTION 10* p- (a)

S IO1 10 20 30 40 50 CO 70

I0"1 k (b) Iff* 10 20 30 40 SO 60 LENGTH OF IRRADIATION DAYS

Fig. 4.8. Variation of (a) total '"Os production and (b) activity ratio 191:185 as a function of the irradiation time.

PRODUCTION AND RECOVERY OF "Fe FROM AN IRRADIATED NICKEL TARGET

Fred J. Steinkruger and Glenn E. Bentley

Iron-52, as the parent isotope in the 52Fe —•• "Mnm generator, is in demand in the medical community for use in myocardial studies. The principal problem with supplying 52Fe to extramural users is that its 8.28-hour half-life requires production and recovery of a substantial quantity of the isotope to allow for decay during processing and shipping. A procedure developed during FY 1982 involved dissolving a nickel target in hot HN03, evaporating to dryness, redissolving in HC1, and separating isotopes on an anion column. This procedure proved excessively time consuming.53 A new procedure was developed involving anodic oxidative dissolution in HC1 followed by isotope separation on a silica gel column coated with tributyl phosphate (TBP). Five nickel disks, 2.54-cm diameter by 0.16-cm thick, were irradiated at the beam stop of LAMPF. These disks were suspended from a platinum rod anode of an electrochemical cell. A 2.54-cm-diam copper rod served as the cathode. The electrodes were immersed in 800 mi of 6Af HC1 in a jacketed li beaker. The electrodes were connected to a 2O-Vdc-135-A power supply. The nickel disks were essentially dissolved in 30 minutes by using the current control mode of the power supply set at 60 A. Higher current was not used because it caused the solution to boil. Redesign of the electrodes and the cooling system will permit higher current, hence, faster dissolution. Silica gel was rendered hydrophobic and coated with TBP by using the procedure of Bhosale and Khophar.54 A column of 25-mi bed volume was poured using distilled water. The column was rinsed with 4M HC1 (previously equilibrated with TBP). The nickel target solution was applied onto this column and rinsed through at a rate exceeding 10 mi/minute. The column was rinsed with 2.5M HC1 until all radioisotopic impurities were removed. Iron-52 was quantatively recovered using 0.25M HC1. 80 ISOTOPE PRODUCTION, SEPARATION, AND APPLICATIONS

This procedure results in the recovery of iron isotopes in approximately 4 hours. The increased speed of this process will ensure the capability to meet deadlines for shipping i2Fe to extramural users. Assay of the nickel solution revealed the presence of several hundred millicuries of 48V. Because some extramural investigators have requested a supply of this isotope, a procedure was developed to recover the 48V. In the process described above, 48V is eluted with the target and other undesired radioisotopes in the 2.5M HC1 rinse. Vanadium can be recovered using the following modifications:

1. Adjust the molarity of the eluted target solution to 6Mby evaporation or addition of 12M HC1;

2. Add 1% V/V of 0.1 AfKMnO4 to the solution to bring vanadium to the +5 valence state;

3. Pass the adjusted solution through a TBP-coated silica gel column as rapidly as possible;

4. Rinse the column, again rapidly, with AM HC1 until 48V appears;

5. Recover the 48V in 2.5M HC1;

6. Evaporate the solution to dryness and redissolve in 0.1 M HN03;

55 7. Apply the HNO3 solution to a cation column; and

8. 48V is recovered in the solvent front.

This modified procedure provides a source for another isotope desired by extramural investigators. If 52Fe is not required, this modification can be applied after target dissolution.

PROGRESS WITH ISOTOPE PRODUCTION FROM MOLYBDENUM TARGETS

Kenneth E. Thomas and Wayne A. Taylor

Strontium-82 The chemical separation procedure described in last year's annual report56 has been standardized. The strontium clean-up from the molybdenum target is usually performed from HNO3-H3PO4 dissolving solution. This employs 50 m£ AG50W-X8 cation exchange resin; 250 mi 50% dioxane in H2O as a column wash; 500 mi! 0.5M NH4C1 to remove rubidium; 500 mi 0.5Af a-HIB to remove yttrium; 250 mi 0.5M HC1 to remove NH+; and 250 mi 6Af HC1 to elute strontium. During FY 1983, five targets were processed for strontium. The results are tabulated in Table 4.7. The strontium isotope ratios (of activities at EOB) listed in this table have been corrected for 85Sr, as was discussed last year.57 Table 4.8 contains a listing of specifications we have placed on the strontium product. The 83/82 ratio is important because of growth of 83Rb into the 82Sr-82Rb generator eluent, and the 82/85 ratio is of concern because of the need to shield 85Sr. ISOTOPE PRODUCTION, SEPARA TION, AND APPLICA TIONS 81

TABLE 4.7. Production Data forMSr Hours in Target Total Ci Ratios at EOB Run No. uA-hour Beam Mass •'Sr at EOB 82/85 83/82

9 3.16 x 105 677 64 12.0 1.13 — s

13 1.60 x 10 403 450 —.. :" • 1.06 .. — 14 5.18 x 10* 142 64 1.7 1.38 7.2 18 4.92 x 104 125 167 5.1 1.43 6.5 21 4.08 x 105 695 289 20.0 1.05 3.0

TABLE 4.8. g2Sr Product Specifications

Specific activity No carrier added Concentration of MSr >50mCi/mJ Chemical form Dilute Radiochemical purity* iJSr <5 mCi/mCi MSr "Sr <0.04 raCi/mCi "Sr "Rb <0.15mCi/mCil2Sr All other <0.01 mCi/mCi KSr *At time of shipment

Zinc-65 A method for recovery of 65Zn from strontium production wastes was also discussed in last year's annual re^ rt.i6 The zinc recovered in this manner was impure. A purification method has been developed in which 65Zn is recovered with 99.9% radiochemical purity. The purification is performed as follows: the impure zinc solution is made 2Af in HCl by addition of concentrated HCl. Next, this solution is passed through 5 mi of AG1X8 anion exchange resin. The column is then washed with 20 mi of 2M UCl, and zinc is eluted with 40 mi 0.005M HCl. Recovery of "Zn exceeds 90%, and the only observed radioactive contaminant was *°Co at 5 x 10"5 mCi per mCi of 65Zn (April 20,1983). Stable contaminants determined by emission spectrometry included sodium (2.6 ug/mCi 65Zn), calcium (0.8 ug/mCi 65Zn), and iron (9.7 ug/mCi 65Zn). 82 ISOTOPE PRODUCTION, SEPARA TION, AND APPLICA TIONS

INC-3 ISOTOPE PRODUCTION ACTIVITIES IN FY 1983

Karen E. Peterson, Martin A. Ott, Franklin H. Seurer, and Kenneth E. Thomas

A major portion of the efforts of INC-3 is tied to production and supply of radioisotopes to the medical research community. These radioisotopes are generally unavailable commerically or can only be made in high yields at Los Alamos. Group INC-3 makes available these and other radioisotopes to any interested researchers. During FY 1983, 58 targets were packaged and irradiated at LAMPF to produce 15 different radioisotopes; a summary of these targets is given in Table 4.9. A total of 35 Ci of 15 radioisotopes were shipped to 44 organizations from around the world. The shipments are summarized in Table 4.10.

TABLE 4.9. Number of Targets Clad And Irradiated at LAMPF For Certain Isotopes Target Targets Material Isotopes Irradiated

CsCl »3I 7 Csl 1 CsCl 127Xe (I18Te) 10 Csl 127Xe (118Te) 4 Mo 77Br, 82Sr 3 Mo 82Sr 4 ZnO 67Cu 13 NaCl 7Be 3 Si 26A1, 22Na 1 Pb 178W, mOs 2 In i<»Cd 2 RbBr •:4tV,,<*fe 4 Ni 48V, 52Fe 4 ISOTOPE PRODUCTION, SEPARA TION, AND APPLICA TIONS 83

TABLE 4.10. Medical Radioisotope Shipments - FY 1983 No. Amount Isotope Institution Shipments (mCi)

Al-26 Oak Ridge Natl. Lab/EPRI 1 0.004 Total 1 0.004 Br-77 George Washington U. 4 624 Johns Hopkins 4 955 Los Alamos Natl. Lab/INC-3 8 963 Los Alamos Natl. Lab/INC-7 1 1 TRIUMF, Vancouver, Canada 1 ro U. New Mexico 6 511 Washington U. 2 339 Total 26 3443 Br-77 U. Mass. 2 52.6 Estradiol Northeastern U. 1 3 U. New Mexico 1 1.36 Total 4 56.96 Cu-67 Cal. State, Fullerton 4 2030 Columbia U. 1 5 Hospital for Sick Children, Toronto 4 493 Johns Hopkins Med. Inst. 2 148.4 Los Alamos Natl. Lab/INC-3 1 2.4 Los Alamos Natl. Lab/LS-3 3 30 Mayo Clinic 1 . 15 U. Cal., Davis 5 1083 Total 21 3806.8 Fe-59 Los Alamos Natl. Lab/INC-11 • 2 0.0042 Total 2 0.0042 Gd-148 Lawrence Livermore Natl. Lab 2 10.8 Total 2 10.8 Ge-68 Brookhaven Natl. Lab 1 10.12 MRC/Hammersmith, London 2 11 Mt. Sinai Med. Ctr. Florida 1 3 Oak Ridge Assoc. Univ. 2 11 Ofc. Des Rayonnement, France 1 20 ORNL/DOE 1 253 U. Hospital, Netherlands 1 5 U. Chicago 2 4 U. Liege, Belgium 1 25.4 Washington U. 2 15.06 Total 14 357.58 84 ISOTOPE PRODUCTION, SEPARATION, AND APPUCATIONS

TABLE 4.10. Medical Radioisotope Shipments - FY 1983 (cont) No. Amount Isotope Institution Shipments (mCi)

1-123 Benedict Nuclear 1 248 Medi-Physics 1 31 Total 2 279 Lu-172 VA Hospital, San Diego 2 17.6 Total 2 17.6 Lu-173 Los Alamos Natl. Lab/INC-11 1 0.8 Los Alamos Natl. Lab/INC-7 1 0.16 Total 2 0.96 Rb-86 U. South Carolina 3 0.316 Total 3 0.316 Sr-82 MRC/Hammersmith, London 4 550 Squibb 5 3392 Mt. Sinai 1 170 U. of Texas 1 170 NIH 1 125 Sloan Kettering 2 310 U. CaL, Donner Lab 4 1031 U. Liege, Belgium 4 432 Total 21 6180 Tb-158 Los Alamos Natl. Lab/INC-11 1 0.010 Total 1 0.010 Ti-44 Los Alamos Natl. Lab/INC-DO 1 0.013 Total 1 0.013 V-48 Cal. State, Northridee 4 24.7 Los Alamos Natl. Lab/HSE-8 1 0.067 Los Alamos Natl. Lab/INC-11 1 0.15 Total 6 24.92 Xe-127 Brookhaven Natl. Lab 5 20,820 Total 5 20,820 Y-88 Hybritech, Inc. 1 10 New England Nuclear 2 16 VA Hospital, San Diego 1 10 Total 4 36 Total Shipments: 118 Total Curies Distributed: 35.03 Ci , ."> ISOTOPE PRODUCTION, SEPARATION, AND APPLICATIONS 85

IODINE-123

John W. Barnes, Martin A. Ott, Kenneth E. Thomas, and Philip M. Wanek

The isotope 123I is useful in nuclear medicine and is produced at LAMPF through the decay of 123Xe that is formed by spallation of cesium in CsCl. The batch process currently in use involves the transfer of 123Xe after irradiation to a generator where it is held for an appropriate decay period for the formation of 123I. A proposed on-line process uses the same generator system, but the xenon is continuously transferred to the generator during irradiation. The development of a reliable target container and a trouble-free vacuum system for 123I production was reported in the 1982 annual report.58 Additional experiments were performed to demonstrate the maximum production capability of the batch process at LAMPF. A target containing 175 g of CsCl was irradiated for 4 hours and subjected to a 4-hour growth period. The quantity of 123I recovered, corrected to the end-of-growth period, was 850 mCi with 0.4% 125I contaminant. The surface of the void above the salt was washed with dilute NaOH to extract 123I that resulted from decay of 123Xe during irradiation. The resultant solution contained 900 mCi of 123I, corrected to the end-of-growth period, with 0.5% contamination by 125I. The 123I in this last solution represents a proof of principle for the on-line process. It is not considered a usable product from the batch method because it contains undesirable spallogenic iodine species that were extracted from the surface of the solid CsCl block. However, the sum of the two solutions, 1750 mCi of 123I, does represent a conservative approximation of the 8-hour production from on- line operation. There is a continuing effort toward the realization of an on-line process for 123I. A new stringer is being designed and constructed in our own shop. We have made an acrylic model of the target carrier system to show the feasibility of adding the helium gas lines for continuous removal of 123Xe from the molten target. Gas flow experiments established the criteria for a final system at LAMPF. A site visit to TRIUMF and the University of California, Davis, assisted in the choice of control systems. A more powerful milling machine that is now on order will speed the manufacture of hardware for this project.

CHARACTERIZATION OF LAMPF-PRODUCED RADIOHALOGENS

Glenn E. Bentley and Phil M. Wanek

Bromine-77 and 123I are radiohalogens that are produced at LAMPF by irradiation of molybdenum metal and cesium chloride, respectively. The bromine is separated from the target material by codistillation with nitrosyl chloride during dissolution of the target material with a mixture of nitric and phosphoric acids containing a few milligrams of chloride carrier.59 The product solution resulting from the chemical process contains "Br contaminated with chloride, nitrate, and nitrite. Much of the chemistry that is used to attach 77Br to organic molecules as a radioactive label requires that the bromine be available in high specific activity and minimized impurity levels. 86 ISOTOPE PRODUCTION, SEPARA TION, AND APPLICA TIONS

Iodine-123 is recovered from the irradiated cesium chloride target material by removing the 123Xe parent of the iodine from the target under vacuum and allowing the iodine to grow in from the xenon in a cryogenically cooled trap. The iodine is recovered from the trap by rinsing it with a dilute NaOH solution.60 The iodine's primary gamma-ray emission of 159 keV and its versatile organic chemistry make it potentially very useful for medical imaging studies. The use of ml as an imaging agent for human diagnostic studies requires that it be well characterized in respect to impurities. Ion chromatpgraphy is a technique that allows the separation and quantitation of many ionic species, both inorganic and organic.61 We have used the technique to assess the purity of both the "Br and l23I products from our process chemistry and to separate the bromine product from chloride, nitrate, and nitrite. Table 4.11 shows typical analyses of "Br product solutions as well as measured specific activities for two of the samples. Table 4.12 shows the ion chromatography results for a typical 123I product. The presence of significant quantities of species other than iodine is somewhat of a mystery because the iodine is recovered by allowing its parent xenon to decay. This indicates that the impurities that are observed are transferred to the xenon decay trap as gaseous materials. We have speculated that the source of the contaminants is reaction during irradiation of the components of residual air that is left in the container after it is sealed. This could lead to the formation of nitrogen oxides and other gaseous products, which could be transferred into the trap with the xenon and then converted to acid anion salts after NaOH is added to remove the iodine.

Table 4.11. Ion Chromatographic Analysis of 77Br Product Solutions Chloride Nitrite Nitrate Bromide Sample (fig/mi) (ug/mi) 1 442 982 3790 18.6 2 380 560 13 400 4.3« 3 225 270 3880 12.9b 4 m 271 5385 1.6 5 194 202 915 14 'Specific activity = 14 700 Ci/mmole. "Specific activity = 8800 Ci/mmole. ISOTOPE PRODUCTION, SEPARA TION, AND APPLICA TIONS 87

Table 4.12. Species Observed by Ion Chromatography in a Typical 123I Product Retention Retention Time Time (Standard) (Sample) Concentration Species (minutes) (minutes)* (ug/mi) cr 2.39 2.42 3.5 NO2 3.00 3.03 1.7 NO7 6.36 6.66 3.6 SQ*~ 7.78 7.78 4.3 'Four unidentified peaks were also observed in the chromatogram.

RECOVERY OF 44Ti FROM A PROTON-IRRADIATED VANADIUM TARGET AND 44 44 DEVELOPMENT OF A Tir-+ Sc GENERATOR

Shuheng Yan, Harold A. O'Brijen'rFred J. Steinkruger, and Wayne A. Taylor

Recovery of 44Ti Scandium-44, a positron emitter with a 3.9-hour half-life, may have potential as a bone- scanning agent in nuclear medicine. Such a short-lived nuclide can be administered in large doses without danger of excessive radiation exposure. The combination of the long-lived parent, ""Ti (47 years) and the short-lived daughter 44Sc suggests the possibility of a generator system. In the past, vanadium metal targets were irr.vj?.ted at the beam stop at LAMPF to produce 32Si. After recovery of 32Si, the target solutions contained sufficient 44Ti to warrant development of a recovery procedure. The 32Si recovery procedure has been described in detail.62 The procedure consisted of dissolving the vanadium target in a H2SO4-HNO3 solution followed by the addition of sodium molybdate to form the silico-molybdate complex. This complex was extracted with butanol, leaving 44Ti, 44'46Sc, 22Na,, 54Mn, and vanadium (target) in the aqueous phase. The aqueous phase served as the starting point for this work.

Titanium(IV) reacts with H2O2 to form a yellow complex that is quantitatively sorbed on a silica gel column at pH = 5.5 to 7.5, whereas the peroxo complex of vanadium is not sorbed under these conditions.63"65 Preliminary experiments indicated that not only titanium(IV), but also scandium(III) was quantitatively sorbed on silica gel. The sorbed titanium and scandium were elutec' using 2 to 10M HC1. This solution was convenient for the preparation of a 44Sc generator. Therefore, the following procedure was developed for the recovery of 44Ti:

1. Silica gel (100 to 200 mesh) is activated for 24 hours at 150°C, slurried with distilled water, and poured into a glass column (10-mm i.d. by 150-mm long). 88 ISOTOPE PRODUCTION, SEPARA TION, AND APPLICA TIONS

2. The column is equilibrated with 0.1M acetate buffer solution (pH = 6.5) containing 1% H2O2.

3. To 100 mi of the target solution add:

a. 30 mi of 0.5M acetate buffer (pH = 6.5), and

b. 15 ml of 10% H2O2 dropwise with vigorous agitation; then adjust solution pH to 6.0 to 7.0 using ammonia (the order of addition is essential).

4. Pass the prepared target solution through the silica gel column at a flow rate of 0.5 mi/minute.

5. After the target solution passes through the resin, wash the column with 120 mi of 0.1M acetate buffer (pH = 6.5) containing 1% H2O2; this is necessary for suppressing decomposition of the titanium peroxocomplex during the wash step.

6. The sorbed titanium and scandium are recovered with 100 mi of 2M HC1 containing 1% H2O2.

Two fractions of a dissolved vanadium target were processed using the procedure described above. The results are given in Table 4.13. The final product contained 44Ti and 44-46Sc.

TABLE 4.13. Recovery of 44Ti

Solution (mi) 100 87 Feed (uCi) 26.1 21.2 Eluate (uCi) 0 0.41 Wash (uCi) 0.35 0.38 Product (uCi) 25.0 22.7 Recovered (%) 96 ± 14 107 ± 14

The 44Ti assay was based on the 68- and 78-keV peaks. Because there was a considerable background in this energy region, which resulted from the higher energy gamma rays from impurities and from the two scandium isotopes, a recovery of more than 100% is not considered significant. The vanadium targets used in this study were removed from the proton beam in late 1980. Because of the long decay time between the end of bombardment and processing, no vanadium isotopes remained in the target solution to be used as a tracer for the parent element. An experiment was conducted using 10 mi of the vanadium target solution and 0.1 mi of 48V tracer solution to determine the distribution of the target element in the separation procedure. The results of this "experiment are given in Table 4.14. An excess of 44Ti and 44Sc was found in the eluate of this experiment because the flow rate was faster than the 0.5 mi/minute rate specified in the procedure. ISOTOPE PRODUCTION, SEPARA TION, AND APPLICA TIONS 89

TABLE 4.14. The **V Tracer Experiment

: - •„•'•.. Solution NucBde Food Eluate Wash Product 1 fw 1 (*0 (%)

"Na 100 90.2 8.4 0 I4Mn 100 76.5 9.7 0 "V 100 84.3 14.1 0 4*Sc 100 0 0 100 ^WSc 100 10.1 1.2 88;7

The "Ti —• 44Sc Generator Our initial work on the 44Ti ->- 44Sc generator involved evaluating the generator system described by Greene and Hillman66. Their system employed an anion exchanger and used a mixture of H2C2O4 and HC1 as the eluent. The following procedure was used in this work:

(1) Anion exchange resin (AG1 X8, 200 to 400 mesh) was slurried with distilled water and packed in a glass column (8-mm i.d. by 110-mm long);

44 (2) 30% H2O2 was added to the Ti product solution (1 drop per ml of solution), and the solution was evaporated to near dryness;

(3) The residue was redissolved in 30 ml of 0.1M H2C2O4 and poured onto the resin;

(4) The column was washed with 50 ml of a 0.1MH2C2O4-0.2M HC1 solution; and

(5) The generator was eluted with 30 ml of 0.1M H2C2O«-0.2M HC1 solution while retaining the fraction between 6 and 21 mi.

The results of this procedure are given in Table 4.15. The initial wash (step 4) was used to remove the 4fiSc impurity that was present in the 44Ti feed solution. As seen in Table 4.5, the average recovery of 44Sc is 75% with an average separation factor of 4.1 x 104 and a breakthrough of 1.85 x 10"5. Because this generator is expected to have a long life, work is in progress to develop a system based on inorganic exchange media, which are less subject to radiation damage.

i,. • V. The t'Sc Generator Result! f Milking *

~:73;J;=. 1.85 x I0+. 3.9% 104 79 • 1.77' i lOf ' „ • • 4.4 x 104 1.92 k lOf / 3.9 Xf 104 90 ISOTOPE PRODUCTION, SEPARA TION, AND APPLICA TIONS

APPLICATIONS OF ELECTROCHEMISTRY TO ISOTOPE PRODUCTION

Glenn E. Bentley, Fred J. Steinkruger, and Wayne A. Taylor

Electrochemical methods, for the most part, have been ignored as a technique for separating and purifying radionuclides from irradiated target materials, even though variations in oxidation state stabilities of the elements are intimately involved in the design of chemical separation schemes. Modern electrochemical instrumentation is capable of precisely controlling the potential of a working electrode so that a desired oxidation or reduction reaction may be carried out with little interference from other reactions. This allows us to exploit differences in reduction potentials as a means of separation. We have developed an electrochemical separation of 67Cu from proton irradiated zinc oxide. The product from the separation is free from any radioactive contaminants, with the exception of 64Cu, and has minimal quantities of stable materials present as impurities.

The zinc oxide is dissolved in 3M H2SO4. Following dissolution of the target material, we transfer the solution to an electrolytic cell, which consists of a platinum working electrode, a platinum counter electrode that is isolated from the bulk of the solution by a glass frit, and a silver/silver chloride reference electrode. The electrodes are connected to a potentiostat, which maintains a controlled potential at the working electrode. A potential of-0.15 V (all potentials are vs Ag/AgCl) is applied to the working electrode. This potential is sufficiently cathodic to result in reduction of copper. Zinc, lead or cadmium (both of which are present as impurities in the zinc oxide), or nuclides other than copper formed during the irradiation are not reduced at this potential. Following depositon of the copper onto the platinum electrode, we rinse the electrode

and replace the solution with a clean 0.1M H2SO4 solution. A +0.1-V potential is applied to the working electrode, and the copper is stripped off the electrode into the solution. The potential of the working electrode is again changed to -0.15 V, and the copper is replated onto it. This second pluting operation affords additional decontamination of the copper from any zinc that is

unavoidably carried along with the copper product. The H2SO4 solution is replaced with a 2M HC1 solution, and the copper is again i'emoved from the electrode by applying an anodic potential. The solution is passed through an anion exchange resin column to remove any remaining zinc contamination. Using this technique, we have recovered quantities of 67Cu as large as 5 to 6 Ci.

Anodic Target Dissolution Much of the separation chemistry that is used to purify desired isotopes is dependent upon differences in the behavior of the chloride complexes of the elements produced during an irradiation and the behavior of the target material. By varying the HC1 concentration of a solution containing a variety of elements and using cation and/or anion exchange, it is frequently possible to efficiently separate the desired elements of interest from each other and from the target.

However, when pure metal targets are used, it is often necessary to use HN03 for dissolution. The resulting HNO3 solution must then be laboriously converted to a HC1 solution so that the desired chemistry may be carried out. If the desired isotope is short lived, such as 8.28-hour S2Fe, the time required for the conversion becomes prohibitive. 52 To overcome the limitations of HN03 dissolution for recovery of Fe from proton-irradiated nickel targets, we developed an anodic dissolution technique that results in a HC1 solution. The nickel target disks are supported on a platinum wire, which is the anode of an electrolytic cell. The ISOTOPE PRODUCTION, SEPARA TION, AND APPLICA TIONS 91

cathode of the cell is a 1.3-cm-diam copper rod. The cell electrolyte is 6M HC1. Nickel is dissolved at the rate of approximately 1 g/minute by applying a 10- to 20-V potential across the cell. The resulting current ranges from 50 to 80 A. Hydrogen ions are consumed to form hydrogen gas at the cathode of the cell so that when the dissolution is complete, it is necessary to add concentrated HC1 to adjust the solution to 6M in HC1. The solution is then ready for subsequent chemistry to recover the iron. This technique of anodic dissolution would appear to be a general method for rapidly dissolving metal targets when

HNO3 dissolution is not appropriate.

Potential Radionuclide Generator Development Upon radioactive decay, a nuclide moves from one row of the periodic table to an adjacent row. There may be drastic differences in the electrochemical behavior of elements that are in adjacent rows of the periodic table. Examples include silver and cadmium, selenium and bromine, and mercury and gold. A project has been started to exploit these differences in electrochemical behavior as a basis for a new class of radiochemical generators. A preliminary experiment performed at the end of the last LAMPF run cycle showed that it is possible to quantitatively deposit 77Br onto a silver electrode through an anodic process. Unfortunately, the amount of bromine available was not sufficient to determine if the 77Sem daughter was being oxidized off the electrode. If the selenium is oxidized, this would be the first practical 77Br/77Sem generator developed. Operations have been resumed at the accelerator, and we plan further experiments to explore the use of electrochemical separations methods for generator development.

ANTIBODY RADIOLABELING

R. Scott Rogers

Monoclonal antibodies are produced by using the hybridoma technique developed by Kohler and Milstein, in which spleen cells from an immunized animal are fused with myeloma cells and the resulting hybrid cells are cloned.67 The explosive growth in this field is a result of the utility of resulting homogenious antibodies.68 Labeled antibodies made to a specific tumor antigen may provide a highly specific way of delivering radionuclides to a tumor for diagnosis by radioim- munoassay or radioimmunoimaging and for radioimmunotherapy. We are working to develop chemical methods of labeling antibodies in high radiochemical yield with high specific activity and which result in biologically active antibodies for medical use. It is also important that the antibodies have good in vivo stability. We are collaborating with Dr. Sally DeNardo's group at the University of California, Davis. We will examine the labeling chemistry; they will provide the monoclonal antibodies and do the biological testing. We are interested in three approaches to the radiolabcling of antibodies: radiohalogenation, chelate conjugation, and linking of tagged organic molecules to the proteins. Methods for radioiodination have been used extensively for many years and are well characterized;69"70 In general, electrophilic reagents are generated in situ through oxidation of iodide by chloramine-T, iodogen, enzymes, electrolysis, or iodine monochloride. lodination occurs primarily on tyrosyl residues. Radiochemical yields vary from 75 to 100%. Unfortunately, iodinated proteins are not extremely stable in vivo, liberating free iodide on degradation. Though 92 ISOTOPE PRODUCTION, SEPARA TION, AND APPLICA TIONS

radioiodinated proteins have been used widely, free iodide increases background, thus limiting contrast in radioimmunoimaging and increasing whole body dose in radioimmunotherapy. The bromine carbon bond is stronger than the iodine carbon bond and should be more stable in vivo. The fact that bromine does not concentrate in the thyroid is also important. Radiobromination offers high lethality for radiotherapy of tumors because the Auger electrons produced in the decay of 77Br deposit their energy over a short distance.71 For these reasons, radiobromination of antibodies is of great interest. The literature and our own preliminary work has shown that, for the most part, methods developed for iodination are not applicable to bromination. Some methods for bromination have been published, but in general they suffer from low yields, harsh conditions, or low availability of starting materials. We have radioiodinated the model protein ovalbumin and an ascites mixture (the proteins that are isolated from the peritoneal cavity of a mouse in which a hybridoma is grown) in high yield, using iodogen, enzymo-beads (immobilized lactoperoxidase) and iodobeads (immobilized chloramine-T). However, radiobromination with 77Br with these methods was unsuccessful. We have been successful in brominating ovalbumin in a buffered system (pH = 6.8) in 20% radiochemical yield with 77Br and sodium hypochlorite, although an excessive amount of protein degradation was seen by HPLC. With 82Br of low specific activity and iodobeads as oxidant, we found that some labeling had occurred with no observable protein degradation. Neither of these methods is useful as they stand, but they suggest that two questions must be addressed. The first is the oxidation of radiobromide to an electrophilic form suitable for aromatic substitution, and the second is the stability of the proteins in the presence of the oxidizing agent. Our experience with the labeling of small molecules and model systems will allow us to optimize oxidation. The denaturation of the antibodies may then be addressed by sequestering the oxidizing agent and preventing direct oxidation of the protein. For example, we are examining different methods of forming the hypochlorite of a hydroxyl that contains resin with pores too small to allow the proteins to diffuse into the resin. We have found that t-butyl hypochlorite oxidizes radiobromide to bromine monochloride in solution. We hope to be able to form BrCl in the pores of the resin from the reaction of the resin hypochlorite and bromide (which would freely diffuse into the resin). The BrCl so formed would then be able to diffuse out of the resin to react with the excluded protein. Our preliminary results using a Sephadex resin are promising. Conjugation of chelating agents with proteins is another important method of labeling.72 For this method, a ligand that has a high binding affinity for the nuclide of choice is derivatized to allow covalent bonding to the protein. The activated ligand is then reacted with the protein, linking the ligand and protein. Radiolabeling is accomplished by adding the nuclide to the derivatized protein. This method is promising in that a number of different nuclides could be chelated by the same conjugated protein, which would allow optimization of decay characteristics for different purposes. We are studing the binding properties of porphyrins for nuclides that we produce, such as 67Cu and 65Zn. We will ihen develop methods to conjugate the porphyrins and other chelating ligands to our antibodies. One of the mildest methods of labeling proteins is to link a previously labeled small organic molecule through a reactive amino acid residue of the protein.73 Bolton and Hunter have developed this method by using N-succinimidyl 3-(4-hydroxy,5-iodophenyl)propionate, which attaches a labeled hydroxyphenyl propionic acid to a lysine residue in the protein.74 We plan to prepare the 77Br derivative of this reagent and then examine the conditions for labeling and the stability of the labeled proteins. Activating groups other than N-succinimidyl and groups other than hydroxyphenyl propionate for carrying the radiohalide will also be examined. ISOTOPE PRODUCTION, SEPARATION, AND APPLICATIONS 93

In all the labeling methods, analytical techniques for testing the labeled antibodies for degradation, denaturation, and biological activity are extremely important. We also need sensitive methods for determining specific activity, radiochemical yield, and purity. HPLC is one of the most useful techniques for determining the purity and homogeneity of proteins as well as their stability to various conditions. We have assembled an impressive array of HPLC equipment including a radioactivity detector that allows quantification of as little as a nanocurie of 77Br, 82Br, I3II, and somewhat larger amounts of I2SI. We also use several electrophoresis techniques routinely and have facilities for biostability and biodistribution studies both at INC Division and though our collaborators. With the ready availability of many different nuclides at INC Division and our experience in labeling chemistry, we are developing the radiolabeling of monoclonal antibodies into a major research program.

STUDIES OF RADIOHALOGENATIONS USING TRIMETR YLSILYL INTER- MEDIATES: RADIOHALOGENATIONS OF AMINES FOR BRAIN STUDIES

D. Scott Wilbur

Amines play a major role in regulation of brain activities. Whereas many molecules circulating in the blood cannot cross the blood-brain barrier,75 a variety of amines pass readily into the cerebral cavity. The ability of some amines to pass the blood-brain barrier makes these compounds attractive for radiolabeling. For example, an amine labeled with a gamma-emitting radionuclide might find wide use in single-photon emission computed tomography (SPECT) for evaluation of the 400 000 hospitalized stroke patients in this country.76 The measurement of cerebral blood flow would be beneficial, and radiolabeled amines might also be used to measure brain amine metabolism and to quantify amine protein receptors in different regions of the brain. Metabolism of amines and amine receptor concentrations have been implicated in a number of mental disorders such as schizophrenia, manic depressive psychoses, and Parkinsonism.77 Blau and Kung have studied several different amine-containing compounds that were able to cross the blood-brain barrier.78"80 However, they found that only a few of the compounds stayed in the brain long enough to study the regional blood flow. From their studies they have postulated that the difference in the intracellular brain pH («7.0) and the blood pH («7.4) is enough to keep some amines in the brain for extended periods. In one study81 they were able to demonstrate that 12s 123 I-iodoxylyldiamine, I, would stay in the brain for hours (T,/2 = 18 hours), whereas I- iodobenzylamine, 2, came out of the brain within minutes (T,/2 = 15 minutes). Despite the fact that 1 appeared to be a promising blood-flow agent, the investigators chose to study other compounds82 because the radiolabeling yields obtained for 1 were very poor. Our model compound studies83 using simple compounds similar to 1 and 2 had shown that aryltrimethylsilanes could be used to regiospecifically introduce radiobromine and radioiodine into such molecules. Therefore, a chemical study to investigate the use of arylsilanes in radiolabeling 1 and a benzylamine similar to 2 was carried out. The requisite arylsilanes 9 and 110 94 ISOTOPE PRODUCTION, SEPARA TION, AND APPLICA TIONS

CH2NMe2

were synthesized as outlined in Scheme I. The starting compounds p-bromotoluene, 3, and 4- bromo-/M-xylene, 4, were silylated in high yields to give 5 and 6. The corresponding benzylbromides 7 and 8 were synthesized by reaction with N-bromosuccinimide (NBS), and the benzylbromides were readily converted to the desired dimethylbenzylamines 9 and 10 by reaction with dimethylamine. To study the radiobromination reactions, the corresponding bromo compounds were synthesized in a similar manner. Radiobromination studies were carried out on 9 with S2Br and no-carrier-added 77Br. Surprisingly, the reactions required the use of tert-butylhypochlorite (TBHC) as the oxidant and would only give high yields of the products when the reactions were run in glacial acetic acid at SO to 60°C. Under these reaction conditions, radiochemical yields for 11, obtained within 10 82 77 minutes, were 91% (NH4 Br) and 76% (Na Br). Unfortunately, attempts to radiobrominate 10 were unsuccessful because of the apparent instability of this compound. Radiobrominations yielded a compound that was much more lipophilic than the desired bromo compound. It is believed that this is a labeled dimer of 10. Evidence that supports this theory was obtained from the fact that the pure compound (10) quickly changed from an oil to a white solid upon isolation. This solid has been analyzed by ]H NMR and mass spectral analysis, and the data suggests that a dimer has been formed. None of the radioiodinations of either 9 or 10 have been been attempted.

CH2NMe2 .^ / ^^ ^_ CH2NMe2

HOAc / A Me3Si

11 ISOTOPE PRODUCTION, SEPARATION, AND APPLICATIONS 95

An investigation by Winchell et al.M suggests that simple secondary benzylamines containing bulky substituents on the nitrogen may be retained long enough to study regional brain-blood flow. The synthesis of three more silyl benzylamines that are of interest is underway (Scheme II). The syntheses all begin with /7-trimethylsilylbenzaldehyde 14, which has been synthesized from the bromobenzaldehyde 12 by protecting the aldehyde functionality by the inline 13. Synthesis of the primary benzylamine 16 has been accomplished in high yield. Synthesis of n-cyclohexyl- and n-tert-butylbenzylamines 18 and 20 should be accomplished soon. After these compounds are synthesized, their radiobromination will be studied. All the radiobrominated benzyl amines (that is, reaction of 9, 16,18, and 20) will undergo biological evaluation. Phenethylamines, another class of amines, are interesting with respect to brain studies. These compounds are congeners of the naturally occurring catecholamine, dopamine 21. Changes in substituents on the phenethylamine backbone yield a variety of compounds that produce physiological responses from a light euphoria (for example, amphetamine 22) to hallucinations (for example, mescaline 23 or the more potent DOM 24). The interest in radiolabeling these compounds comes from the fact that they most likely interact with dopaminergic or other catecholaminergic systems. Studies of the interactions may ultimately help delineate how these systems work, and thus, how malfunction of the systems might be treated.

HO CH2CH2NH2 CH2CHNH2 I CH3 HO

21 22

MeO CH2CH2NH2 CH2CHNH2

CH3 MeO OMe OMe

23 24

CH2CHNHC3H7 I CH3

25 96 ISOTOPE PRODUCTION, SEPARA TION, AND APPLICA TIONS

Winchell et al.8S have studied radioiodinated n-isopropyl-^-iodoamphetamine 25 as a brain blood-flow agent. It is not clear that this compound gives an accurate blood-flow image because there may be dopamine receptor interaction. Aside from this fact, a good method of labeling amphetamines with radiohalogens on the aromatic ring has not been reported.86'87 As with the benzylamines, these compounds appeared to be ones that could be labeled with high specific activity by using arylsilane intermediates. Previous investigations of halogenated amphetamines have shown that thepara position produces the largest pharmacological response.M>M Therefore, p-trimethylsilylphenethylamine 27 and p-trimethylsilylamphetamine 32 were synthesized as shown on Schemes III, V, and VI. Two different methods have been studied to synthesize 27. A third method (Scheme IV) will be investigated because development of the methods may be needed for later synthetic efforts. Synthesis of 27 by means of the phenylacetonitrile 26 had been published previously.89 The simplest method was the conversion of commercially available p- bromophenethylamine 29 by means of the protected amine 30. Synthesis of 32 was carried out by employing a Knoevenagel reaction to yield 31. This procedure appears to be much better than the published synthesis.89 The corresponding /j-bromoamphetamine was synthesized in the same

manner, except A1H3 had to be used in the reduction step. Both 27 and 32 were radiobrominated with 82Br by using N-chlorosuccinimide as the oxidant. 82 The reactions were carried out with NH4 Br in MeOH at room temperature and gave 95 and 85% radiochemical yields (for 33 and 34, respectively) within 15 minutes. Studies employing no- carrier-added 77Br and radioiodinations will be carried out in the future.

. CH3CHNH2 <^-. . CH2CHNH2 82Br NCS /' NH4 T ' j R MeOH / A IJ R Me Si k 82 3

27 R == H 33 R = H

28 R == CH3 34 R = CH3

Garnet and Firnau90 have described the synthesis of [18F]-5-fluorophenylalanine 35, and Fowler et al.91 have described the synthesis of a radioiodinated dopamine analog 36, but there have been no syntheses described for radiohalogenated mescaline derivatives. Our model compound studies with trimethylsilanes on phenolic rings have demonstrated that silane intermediates would be a good choice to label compounds such as dimethoxyphenethylamines.92 A synthetic scheme to obtain the desired arylsilanes is shown in Scheme VII. The synthesis begins with vanillin 37, which is readily brominated to yield 38. Methylation of 38 with dimethylsulfate under phase transfer conditions yields 39. Protection of the aldehyde by imine formation is a facile reaction yielding 40. Unlike the simple protected benzaldehydes (for example, 13), lithiation of the highly activated aryl imine 40 is not a good reaction at -78°C. Despite this fact, some of the desired arylsilylbenzaldehyde 41 has been obtained. The synthetic steps remaining to arylsilanes 43 and 45 should be accomplished soon. ISOTOPE PRODUCTION, SEPARA TION, AND APPLICA TIONS 97

CH2CHC02H HO ^^r\^ CH2CH2NH2 I NH2

35 36

Investigations by Budinger et a/.93'94 have yielded both the radiobrominated and radioiodinated DOM derivatives 46 and 47. However, their syntheses did not yield very high specific activity compounds.93 Coenen has reported a method of obtaining 46 in very high specific activity,96 but the reaction only gives a radiochemical yield of 25%. A synthetic pathway for the corresponding arylsilanes is given in Scheme VIII. Synthesis of this compound has only been carried out through the dimethoxyamphetamine 50. Attempts to brominate this compound have been unsuccessful, and protection of the primary amine by acetylation to 51 may be needed.

CH2CHNH8

46 X = 77Br 47 X = 123I

Preliminary radiobromination studies of benzylamines and phenethylamines demonstrate that the aryltrimethylsilane intermediates should work well for radiohalogenations of amines for brain studies. Collaborative studies with Drs. C. Shuie and Alfred Wolf (Brookhaven National Laboratory) are under way to determine if radiofluorinations might also be accomplished using arylsilanes. Studies of the applications of aryltrimethylsilanes and pentafluorosilicates97 in radiohalogenations will continue because results thus far have been very encouraging. 98 ISOTOPE PRODUCTION, SEPARATION, AND APPLICATIONS

CH 3 CH3

R R Br SiMe3

5 R = H

4 R = CH3 6 R = CH3

CH2NMe2 CH2Br

R R

SiMe3 SiMe3

9 R = H 7 R = H

10 R = CH3NMes 8 R - CH2Br

Scheme I: Synthesis of aryltrimethylsilylbenzylamines ISOTOPE PRODUCTION, SEPARA TION, AND APPLICA TIONS 99

H C=NC Hi3 H 6

Br Br

12 13

Me3Si

H OH H \ C=NC H C=NC4H9

MeaSi Me3Si Me3Si

15 17 19

CHaNHa CH2NHC6H13 CH2NHC4H9

Me3Si Me3Si Me3Si

16 18

Scheme II: Synthesis of trimethylsilylbenzylamines

+ (a) C6H13NH2/A (b) H-BuLi/TMSCl; H3O (c) NH2OH/A/EtOK (d) C4HgNH2/A (e) LAH 100 ISOTOPE PRODUCTION, SEPARA TION, AND APPUCA TIONS

CH2Br CH2CN

Me3Si Me3Si 26

CH2CH2NH2

Me3Si 27

Scheme III: Synthesis of trimethylsilylphenethylamine via benzylbromide (a) NaCN (b) LAH

0 II -NOe C-H

CH3

Me3Si Me3Si

14 31

CH2CHNH2 I CH3 Me3Si

Scheme IV: Synthesis of Trimethylsilylamphetamine

(a) EtNO2/NH4OAc (b) LAH ISOTOPE PRODUCTION, SEPARA TION, AND APPLICATIONS 101

0 II C-H C-OH

Me3Si Me3Si

14 28

CH2CH2NH2

Me3Si

Scheme V: Synthesis of trimethylsilylphenethylamine via benzaldehyde (a) NaCN (b) LAH

CH8CH8NH2

Br CH3 CH3

29 30

CH2CH2NH2

Me3Si

Scheme VI: Synthesis of trimethylsilylphenethylamine via bromophenethylamine

+ (a) MeaSi(Cl)CH2CHj(Cl)SiMe2/Et3N (b) n-BuLi/TMSCl; H3O 102 ISOTOPE PRODUCTION, SEPARA TION, AND APPUCA TIONS

0 MeO \ H

MeO MeO \ H MeO MeO

MeO MeO CHaCHaNHa e,f

MeO MeO

SiMe3 SiMe3

41 43

H ,N0 \ 2 MeO C=C MeO CH2CHNH2 V CH3 I CH3 MeO MeO

SiMe3 SiMe3 44 45

Scheme VII: Synthesis of 3,4-Dimethoxy-5-TrimethyIsilylphenethylamines

+ (a) Br2/HOAc (b) (CH3)2 SO4/n-BuNCl/NaOH/H2O/CH2Cl2 (c) C6H13NH2/A (d) n-BuLi/TMSCJ; H3O

(e) NaCN (0 LAH (g) EtNO2/NH4OAc ISOTOPE PRODUCTION, SEPARA TION, AND APPLICA TIONS 103

0 II MeO c MeO c=cX CH3 OMe - XXkA OMe

48 49

MeO CH2CHNHAc MeO CH2CHNH3

CH3 OMe OMe

51 50

MeO CH2CHNH2 MeO

CH3 Br OMe OMe

53 54

MeO CH2CHNH2 I CH3 Me3Si OMe

Scheme VIII: Synthesis of 2,5-Dimethoxy-4-Trimethylsilylamphetamine

(a) EtNO2/NH4OAc (b) LAH (c) NaOAc/Ac2O (d) Br2; NaOH + (e) Me2Si(Cl)CH2CH2(Cl)SiMe2/Et3N (f) «-BuLi/TMSCl; H,O 104 ISOTOPE PRODUCTION, SEPARA TION, AND APPLICA TIONS

STUDIES TOWARD RADIOHALOGENATIONS OF FATTY ACIDS: RADIOPHARMACEUTICALS FOR EVALUATING THE HEART

D. Scott Wilbur and Zita V. Svitra

An accurate assessment of the extent of the damage in myocardial infarcts or ischemia is critically important to heart patients. One method of evaluating damage to the myocardial tissue is to study the metabolic processes in that tissue. Because the major metabolic process in the heart is degradation of nonesterified fatty acids, it is not surprising that researchers from many different groups have been exploring radiolabeled fatty acids as a noninvasive method for evaluating regional myocardial metabolism. The radionuclide of choice for metabolic studies that use labeled fatty acids is "C (Ref. 98), but as a positron emitter, its application is limited to only a few institutions. Radiofluorinated fatty acids have also been studied," but this label has the same shortcoming. Radioiodine- and radiobromine-labeled fatty acids have been studied as the best alternatives.100*101 Studies of radiolabeled fatty acids have been carried out that encompassed modifying the fatty acids chain length,101"103 degree of unsaturation,104 and position of radiohalogen attachment.101'105 Re- searchers have found that long-chain fatty acids (16 to 22 carbons in length) are most effectively extracted, and unsaturation appears to be important. However, the most important factor appears to be the position of the label within the molecule. Addition of bulky halogens to unsaturations within the fatty acid chain or halogenation at the carbon adjacent to the carboxylic acid functionality has led to dramatic decreases in the extraction from the blood. Contrary to this observation, radiohalogen-labeling at the carbon farthest from the carboxylic acid functionality (co-carbon) has shown little difference in extraction from that of the uC-labeled analogs.100'106 Radiohalogen-labeling at the co-carbon has been accomplished in high radiochemical yields by exchange reactions.106"108 Despite this fact, problems still exist for the co-radiohalogenated fatty acids. One of the problems arises from the fact that haloacetic acids are produced as metabolites of co-radiohalogenated fatty acids, and these compounds are extremely toxic substances. A solution to this problem can be obtained by making a very high specific activity radiohalogen- labeled fatty acid. Unfortunately, this is not readily accomplished by exchange reactions.109"110 A second problem arises from the fact that co-radiohalogenated fatty acids are not very stable in vitro or in vivo. This seriously affects the blood activity for imaging studies. Stabilization of the radiohalogen label has been accomplished by attaching the radiohalogens to phenyl or vinyl substitucnts on the co-carbon. Although there are some questions about using these agents to measure metabolism,111'112 much effort has been devoted to the synthesis and evaluation of these compounds.113116 The problems with obtaining high specific activities, long reaction times, and low radiochemical yields have led to an investigation of organosilanes as intermediates to radiohalogen labeled fatty acids.117"119 The investigation has been directed toward the synthesis of a compound (6, 7, or 8 in Scheme I) that could be used to make a series of co-silylated fatty acids (9-12 in Scheme II). Reaction of bromoundecanol with tert-butyldimethylsily! chloride/triethylamine gives a nearly quantitative yield of 2. Reaction of 2 with the lithio methyloxazoiine 3 (Ref. 120), a synthetic equivalent for lithio acetic acid, gives 4 in high yields. Deprotection of the alcohol is a very facile reaction when tetra-n-butylammonium fluoride is used and gives 5 in nearly ISOTOPE PRODUCTION, SEPARATION, AND APPLICATIONS 105

quantitative yields. Some attempts have been made to convert the alcohol in 5 to a tosylate leaving group, but these have not been successful. However, if this reaction cannot be accomplished, conversion to other leaving groups such as a chloro or a bromo should be possible.

CH3

H0CHz(CH2)9CH2Br C4HBSi-0-CH2(CH2)9CH2Br l CH3

.0.

LiCH2 N

CH3 0, I .0,

HOCHB(CHa)ioCHa -^ C4H9Si-0-CHa(CH2)ioCHa ^

CH3

•XCH2(CH2)ioCH2

J> X = 0-Tosyl Z X = C1 8 X = Br

Scheme I

(a) «-BuMejSiCl/Et3N (b) n-Bu4NF (c) CHjC.HjSOjCl/pyr; SOC12; PBr3 106 ISOTOPE PRODUCTION, SEPARA TION, AND APPLICA TIONS

Following the synthesis of 6, 7, or 8, preparations of four different compounds 9 through 12 will be attempted, as shown in Scheme II. Radiohalogen-labeling studies will then be investigated with these compounds. Additionally, comparative radiohalogenation studies will be carried out in collaboration with Drs. F. F. Knapp and M. M. Goodman at Oak Ridge National Laboratory. In this study, a variety of functional groups (for example, boronic acids, alkyltins, mercury chlorides, and triazines) will be compared with respect to radiohalogenations of fatty acids.

X-CH3(CHs)10CH2

Me3Si CH2(CH2)uCH2C02H

10 X = SiMe3

X = SiF5K2

Scheme II

(a) MejSi (b) Me3SiCHCHCH2Br/Mg/Li2CuCl4 (c) AUylBr/Mg; HSiCl3; XF/H20 Ovejyievfr

imm

: -m^m :m <-f ^ PSf il (si?si,i

WASTE MANAGEMENTc

•o" " . o 109 The Nevada Nuclear Wastef Storage Investigations : °" lto GroundwaterChemistry of Yucca Mountain 113 AThermodynamicModeiforAnalcime 119 Crystal Chemical/Valence Studies of Nuclear Waste Forms 119 Radionuclide Migration from Nuclear Explosion Cavities

GEOCHEMISTRY 12i Quantitative Trace-Element Analysis of Geologic Materials

128 The System CaO-SiO2-H2O-CO2 and Implications for the Fenton kill

•• J ELEMENT AND ISOTOPE TRANSPORT AND FIXATION 109 WASTE MANAGEMENT

THE NEVADA NUCLEAR WASTE STORAGE INVESTIGATIONS

Allen E. Ogard

The NNWSI program is part of the effort by the DOE to locate sites across the nation that are technically suitable for a high-level nuclear waste repository. Yucca Mountain, in the southwest corner of the NTS, is the area being investigated by the NNWSI. The mountain is composed of layers of tuff, a volcanic rock that is impermeable but quite porous. Some of the tuff layers contain large quantities of zeolites, a good sorber for most radioactive waste elements. This fact, among others, makes Yucca Mountain a good site to investigate extensively for a possible repository. The main topics under investigation in the Los Alamos NNWSI program are listed below. The program is designed to further define the character of the proposed repository site.

• Water chemistry. Determination of the groundwater chemistry, including particulates, at Yucca Mountain as a function of depth and distance away from the proposed repository. These studies also include modeling of the water composition from the repository to the accessible environment by using data collected from many drill holes in the area.

• Sorption. Because some of the tuff rocks are so highly sorptive, the sorption ratios for nuclear waste elements are being determined. This work also includes experiments on colloid formation of waste elements and on microbiological activities that might influence sorption.

• Solubility measurements and calculations. The EQ3/6 computer code is used to calculate the concentrations of nuclear waste elements in the groundwater of Yucca Mountain. Some actual solubilities of waste elements will be measured in the coming year.

• Transport experiments. Transport of waste elements in some of the tuffs of Yucca Mountain will occur as water flows through fractured tuff. We are measuring diffusion from this flow into the rock matrix as a means of retarding the waste elements.

• Hydrothermal geochemistry. The temperature of the tuff around a «130°C for a period of 800 to 1000 years. This temperature rise could change both the chemistry of the groundwater and the sorptive properties of the tuff; these effects are being examined.

• Modeling — pathway and sensitivity analysis. Water and waste-element transport mechanisms are being modeled to explain what would happen if waste were stored in the Yucca Mountain area. Modeling also helps design experiments to obtain the appropriate data for the final performance assessment of the repository site.

• Program integration. Data from the site characterization and laboratory experiments are interpreted to help design and assess the performance of the proposed repository site. All site- characterization documentation must rigorously comply with federal licensing requirements. 110 ELEMENT AND ISOTOPE TRANSPORT AND FIXATION

• Volcanism. A detailed study of past volcanism in the NTS area has been made, and predictions were made regarding possible future volcanism that could affect the repository.

• Borehole/shaft sealing. Performance tests are made on the long-term seals to be used in the exploratory shaft and repository.

In 1983, some major changes occurred in the NNWSI program. Just before the new fiscal year, a new director was named to the Waste Management Program Office of the DOE, Las Vegas, Nevada office. Don Vieth, the new director, made three substantial changes in the program.

1. The program was to be directed toward building a repository at Yucca Mountain in the near future.

2. The repository would be located in the Topopah Spring Member tuff of the Lnsaturated zone rather than below the water table in the saturated zone. The latter change meant a major redirection of site-characterization research from the saturated to the unsaturated zone of Yucca Mountain.

3. At Los Alamos, the position of Technical Program Officer shifted from line management in the INC Division to the Laboratory's Nuclear Program Office. The position of Project Manager was also moved later in the year from INC-7 to the Nuclear Program Office.

In addition to these changes, other modifications were imposed by the Nuclear Waste Policy Act of 1982 (NWPA), which was passed by Congress in December 1982. This law lists very specific actions and a timetable for the tasks that must be accomplished by the various high-level radioactive waste projects, including NNWSI, before the first site for a repository can be chosen or licensed for construction. The NWPA has had a considerable impact on the NNWSI program at Los Alamos. As a result of the administrative and policy changes mentioned above, there has been a shift in our total effort from research toward planning and other activities designed to implement NWPA.

GROUNDWATER CHEMISTRY OF YUCCA MOUNTAIN

Allen E. Ogard, Patsy L. Wanek, Sixto Maestas, Alan J. Mitchell, Ruben D, Aguilar, and Michael R. Cisneros

To characterize the geology and hydrology of Yucca Mountain, a series of wells in the vicinity of the repository block have been drilled and pumped. During pumping of these wells, samples were collected and analyzed; results are grouped and listed in Tables 5.1 and 5.2. ELEMENT AND ISOTOPE TRANSPORT AND FIXA TION 111

1. Water from Well J-13, a producing well «6 km southwest of the repository block, has been adopted as the area's reference water for laboratory experiments; the main producing zone in Well J-13 is the Topopah Spring Member tuff.

2. Wells USW H-l, H-6, H-5, G-4, H-4, and UE-25b#l are all within or at the edge of the repository block.

3. Wells UE-29a#2 and USW VH-1 are 10 and 7 km, respectively, from the repository block.

4. UE-25p#l is a well drilled to the paleozoic rocks below the tuffs.

5. The Bullfrog unit is an isolated zone found in Well UE-25b#l.

Within a radius of at least 10 km, the compositions of integral water samples from the different wells in the saturated tuff do not change drastically. The waters are a sodium bicarbonate type with 45 to 93 mg/i sodium, 108 to 172 mg/& bicarbonate, and a pH of 6.9 to 7.7. Other major cations are calcium (1.6 to 19.7 mg/£), potassium (1.2 to 5.3 mg/i), and magnesium (0.05 to 1.5 mg/i). Other major anions are fluoride (0.6 to 4.5 mg/(i), chloride (5.8 to 10.0 rag/I), and sulfate

TABLE 5.1. Elemental Concentrations of Groundwaters from the Vicinity of Yucca Mountain Concentration* (mg//) Well No. Ca Mg Na K Li Fe Mn Al Si J-13 11.5 1.76 45 5.3 0.06 0.01 0.01 0.02 31.8 USW H-lb 6.2 <0.1 51 1.6 0.40 20.0 H-6 3.6 0.05 88 1.7 0.11 0.08 0.03 0.07 21.1 H-5 1.6 0.05 93C 3.2 0.13 0.05 0.02 0.05 26.4 G-4 9.2 0.15 56 2.5 0.08 0.04 0.02 0.02 19.6 H-4 10.8 0.19 84 2.6 0.16 0.03 0.005 0.04 25.9 UE-25b#l 19.7 0.68 56 3.3 0.28 0.04 0.004 0.03 31.5 UE-29a#2 11.1 0.34 51 1.2 0.10 0.05 0.03 0.04 25.8 VH-lb 9.9 1.5 78 1.8 0.09 24.5 UE-25p#l 87.8 31.9 110 13.4 0.72 0.26 0.15 0.32 19.1 UE-25b#l Isolated Bullfrog Unit Day 2 18.6 0.74 43 2.8 0.31 0.93 0.43 0.06 28.9 Day 28 17.9 0.01 37 3.0 0.17 0.08 0.07 0.06 28.8 'Ionic or molecular species are not listed; concentration is based on the element. "Data from L. Benson, USGS. ! cData from L. Benson, USGS, is 30% lower. 112 ELEMENT AND ISOTOPE TRANSPORT AND FIXATION

(15.7 to 44.0 mg/i). Integral water samples contain dissolved oxygen as well as varying amounts of nitrate. The detergent concentration is a measure of how completely the waters are cleared of drilling fluids by pumping. If relative sodium, potassium, and calcium contents are considered, the waters fall into three groups. Analyses from Wells H-5 and H-6 are highest in sodium and lowest in calcium content; they are also the two wells farthest to the west and are west of a fault through Yucca Mountain. The second group includes analyses from Wells H-l, H-4, G-4, and UE-29a#2; they show lower sodium content and higher calcium content. Except for Well UE-29a#2, which is 10 km northeast of Yucca Mountain, these wells lie along a north-south line near the eastern edge of the exploration block. The third group includes analyses from Wells UE-25b#l and J-13; they show the lowest sodium content. Both wells are still farther east. It is not clear if these trends have any physical significance for water flow paths or water travel times. The total organic content of the groundwater from Wells J-13 and UE-25b#l has been determined. The quantities of dissolved organics are very low: 0.15 mg/i in Well J-13 water and 0.55 mg/i in Well UE-25b#l water. Little can be said about the individual organic compounds other than that high molecular weight organics (>1000 MW) constitute 50% of the organics present in Well J-13 water and 33% in Well UE-25b#l water. Because of this very low organic content, complexing of waste elements such as americium, neptunium, plutonium, and uranium with naturally occurring organic liquids will probably be very low or nonexistent. The above results were all obtained from water pumped from the saturated tuffs. The Well UE-25p#l was drilled deeper to intersect the paleozoic rocks below the tuffs before pumping and

TABLE 5.2. Concentrations in Groundwaters from Vicinity of Yucca Mountain Concentration

m Well No. F" cr soj- HCO7 NO! o2 Detergent Eh pH J-i3 2.1 6.4 18.1 143 10.1 5.7 N.D. 6.9 USWH-1" 1.0 5.8 19.0 122 7.5 H-6 4.1 7.7 27.5 168 -'5.3 5.6 395 7.4 H-5 1.3 5.7 14.6 122 8.6 6.3 <0.005 353 7.1 G-4 2.4 5.5= 15.7 143 5.5 6.4 402 7.1 H-4 = 4.5 6.2 23.9 172 4.7 5.8 >2 215 7.1 UE-25b#l 1.2 "., 7.1 20.6 134 0.6 1-8 220 7.7 ' UE29a#2 0.6 8.3 22.7 108 18.7 5.7 305 7.0 VH-1* , '2.7 10.0 , 44.0 152 7.5 UE-25p#l 3.5 37.0 129.0 698 <0.1 7.1 <0.2 374 6.7 | I UE-25b#l Isolated Bullfrog Unit C ! O«y2 •"•'' .' 1.5 8.4 20.5 |l47 2.1 «CO.l >2 -40 7.4 >'/.> D«y28 ; .42 •: 6^6 20.3 1130 4.5 1.8 0.02 156 7.4

ajmnit • lit— • c: kDaufromL.len#oo,USGS. .. L : •': • • ELEMENT AND ISOTOPE TRANSPORT AND FIXATION 113

sampling. The concentrations of dissolved solids are higher and can be considered the upper bounds to the quantities of dissolved solids in groundwater along the flow path to the accessible environment. Because pumping all the wells described above gave an integral sample of water (from the entire column of water in the well) and that sample contained oxygen, it was necessary to isolate a single, deep zone with packers and pump it. Tables 5.1 and 5.2 list the results for the water from the Bullfrog unit in UE-25b#l. These results show that nonoxidizing waters in the saturated tuffs have been observed. Preliminary conclusions and postulations drawn fh. -s these results are as follows:

• Other than the oxygen content of the water, there are no major constituents that can rapidly attack the waste-package container materials. These waters are quite dilute.

• HCO"^ and OH~ anions are the major actinide complexing ligands in the water.

• Although the HCO7 concentration of the paleozoic rock water is high, its effect will be small because this water must come into contact with a solid waste element before the solubility of the waste element increases as a result of complex formation. After the waste element is in solution, additional complexing ligands do not increase the concentration.

• Water composition can help define the flowpath.

• Many of the waste elements exhibit minimum solubilities in the pH range found in these waters.

• At best, deeper reducing waters will reduce reptunium and plutonium ions to their more 2 soluble +IV oxidation state but will not reduce UO 2 or

THERMODYNAMIC MODEL FOR ANALCIME

Clarence J. Duffy

The Model Zeolites are an important class of sorptive minerals in Yucca Mountain. To predict the effect of zeolites on the movement of waste elements in Yucca Mountain, we must understand the present distribution and future stability of the zeolite minerals. The important zeolites in Yucca Mountain are clinoptilolite-heulandite, mordenite, and analcime. Of these, analcime is the most studied. A thermodynamic model has been constructed for analcime to examine the parameters that affect the stability of zeolites. The analcimes in Yucca Mountain are more silica rich than NaAlSi2O6«H20, which is the formula commonly used for analcime. The model, therefore, represents analcime as an ideal solid solution between NaAlSi2O6«H20 and Si3O6-1.5 H20. This covers the compositional range of most naturally occurring analcimes with the exception of some samples occurring in silica-undersaturated environments.121 This model does not apply to analcime that is less silica rich than NaAlSi2O6»H20. 114 ELEMENT AND ISOTOPE TRANSPORT AND FIXA TION

The model is based on calorimetric data,122 solubility data for silica in equilibrium with albite and analcime,123 and the compositions of analcimes coexisting with quartz in Yucca Mountain. Other thermodynamic data used in the calculations have been taken from Refs. 124-126. To test the model, we compared its predictions to field observations. However, the parameters that affect analcime stability are seldom all measured. The parameters that the model indicates

have a significant effect on the stability of analcime are (1) activity of water (aH2O), (2) activity of albite (aAb), (3) temperature (T), (4) difference of the lithostatic pressure and fluid pressure (PT-PH2o)» (5) concentration of aqueous silica (msl02(aq)), and (6) state of order of the albite. The Z order parameter124 been used here as the measure of the state of order of albite; Z is equal to 1 for completely ordered albite and equal to zero for completely disordered albite.

1200 V 1 l\ 1 1 II 1 1 i i 1 I 1000 - i p tota l tota l tota l tota l Q_ II 800 - » II 4 1 O \ ^ CM \ aI. I O. 1 ^ «= 2 600 - 1 2" 0.9 . II II a. I - - \ ™ 1 \ K ™-

400 -- r i 11 3 2n 2n II 1 " o I Csl CM CM 3= ° 1 *"**! 1 3= CD 1 =" 3= «9 2 eo ~ 1 _ II 1 II 1 N Nl 1 ^ " Nl 1 11 1 1 1 1 1 i i 1 i i 1 1 298 318 338 358 378 398 418 Temperature (K)

Fig. 5.1. The position of the univariant curve for the assemblage albite-analcime-quartz is shown for various combinations of the Z order parameter and activity (aAb) of albite, the activity of water (aH 0), and the difference between the lithostatic pressure and the pressure of the fluid phase. Analcime plus quartz is stable below the curve; albite is stable above it.

Figure 5.1 shows the temperatures and total pressures where albite, quartz, and analcime

coexist for several combinations of Z, aH20, aAb, and PT-PH20). The positions of these curves are rather insensitive to total pressure. These data are in agreement with data from the Niigata oil field in Japan,127 where the first appearance of authigenic albite forming from analcime is at 393

K. This is consistent with the model but would require that PH20 approach the lithostatic pressure (PTota,) and that Z be somewhat less than 0.8. Field evidence exists for the former, but no information is given on the state of order of the albite. ELEMENT AND ISOTOPE TRANSPORT AND FIXATION 115

Most natural analcimes coexisting with quartz have compositions falling in the range of

X = 0.97 to 0.77 (Refs. 121,128), where X is the mole fraction of NaAlSi206.H20. Compositions calculated from the model range from 0.97 to 0.72, but the very high silica values require the unlikely combination of temperatures near 298 K and pressures of several hundred bars or more. The observed and predicted compositional ranges are in almost perfect agreement. Analcime in tuffs from the Green River formation, Wyoming, has a bimodai compositional distribution.128 Analcimes coexisting with authigenic albite have compositions near X = 0.94, whereas those without authigenic albite are near X = 0.8. These minerals probably reached maximum temperatures in the range of 313 to 343 K, with pressures not exceeding 400 bar. This is generally below the temperature expected to produce the breakdown of analcime plus quartz to albite; however, the authigenic feldspars "are largely restricted to the saline facies, deposited in a sodium carbonate-bicarbonate-chloride brine, from which trona and halite precipitated."128

298 318 338 358 Temperature (K)

Fig. 5.2. The curves shown are equilibrium conditions for the assemblage albite-analcime-quartz as a function of temperature and lithostatic pressure minus fluid pressure. Labels on the curves are the activity of water and the fluid pressure. Analcime plus quartz is stable below the curves; albite is stable above the curves.

As illustrated in Fig. 5.2, the lowering of aH20, in a brine substantially decreases the upper temperature stability of analcime. Lowering PH2O appreciably below PTotal also decreases the stability of analcime. However, we can see from Figs. 5.3 and 5.4 that as PT-PH2o increases, the maximum silica content of the analcime decreases. Therefore, unless PH20 was greater in the saline facies than elsewhere, PH20 was generally near PToW|. The model appears to provide a good explanation for the observations in the Green River formation. The high-silica analcimes have 116 ELEMENT AND ISOTOPE TRANSPORT AND FIXATION

compositions consistent with the conclusion that they formed in relatively fresh water. As the salinity increased and aH 0 consequently decreased in parts of the deposit, the analcime reacted to form albite and less-silica-rich analcime. The activities of water needed seem reasonable because a in a H2o sodium chloride solution saturated with respect to halite is about 0.75. Certainly other ions present in these brines would have further reduced aH2O.

Application to Yucca Mountain Comparison of Figs. 5.3 and 5.4 suggests that the temperature of equilibration in the Green River formation may have been quite low (310 to 320 K). This suggests that at least some reactions may be at equilibrium in Yucca Mountain. Before this hypothesis can be examined, as many variables as possible should be fixed. Water analyses from Yucca Mountain indicate that the waters are quite dilute. Therefore, unlike in the Green River formation, the activity of water is probably not an important variable and can be set equal to 1. The PH;j0 is probably determined by the hydrostatic head. The lithostatic pressure will be approximated by the lithostatic load, using an average rock density of 2 g/cm3. This estimate may need future refinement because of the nonisotropic stress environment in Yucca Mountain.

0.5

Fig. 5.3. The dashed curve is the equilibrium curve for albite-analcime-quartz. The analcime plus quartz field is contoured in mole fraction of NaAlSi2O6*H2O in the equilibrium analcirne. Temperature is 308.15 K. Fluid pressure is 50 bar. The albite has a Z of 0.8 and an activity of 1. ELEMENT AND ISOTOPE TRANSPORT AND T1XAT10N 111

Fig. S.4. The dashed curve is the equilibrium curve for albite-analcime-quartz. The analcime plus quartz field is contoured in mole fraction of NaAlSi206«H2O in the equilibrium analcime. Temperature is 328.15 K. Fluid pressure is 50 bar. The albite has a Z of 0.8 and an activity of 1.

Figure 5.5 shows the temperature-depth relationship for the reaction analcime plus quartz to albite for various albites, as well as the approximate geothermal gradient in the USW G-l drill hole. It is assumed that the standing water table is 580 m below the surface. PH o is taken as 1 bar above the water table and (depth - 5 80)/10 bar below the water table. The lithostatic pressure is depth/5 bar. To determine whether analcime plus quartz is stable, it is necessary to know composition and state of order of the albite. Probe analyses indicate that the authigenic albite in Yucca Mountain is usually quite pure, so that aAb is probably quite close to 1 for much of the authigenic albite in Yucca Mountain. Its state of order is not yet known, but it is unlikely to be more ordered than Z = 0.8. Therefore, analcime appears to be stable with respect to albite in much of Yucca Mountain. Figure 5.6 illustrates one of the reasons that albite persists in Yucca Mountain. If the concentration of aqueous silica in solution is much above that in equilibrium with quartz, analcime is no longer stable. Although analcime is not now present in the Topopah Spring Member, if repository heating were to cause the cristobalite now present to be transformed to the more stable quartz, it might also lead to the transformation of albite to analcime. In view of field observations that vitric tuffs often devitrify to clinoptilolite and mordenite, which later transforms to analcime, it seems likely that the concentration of aqueous silica may also be important in equilibria involving clinoptilolite and mordenite. Detailed models for these phases will provide more insight into the roles of equilibrium and kinetic controls on the mineralogy of Yucca Mountain. At present, it appears that the most important nonequilibrium factor at Yucca Mountain is the high metastable silica activities present in large portions of Yucca Mountain. 118 ELEMENT AND ISOTOPE TRANSPORT AND FIXATION

1 i i 1 1 1 S 1 i i 1 i • Analcine * / \ f 500 - -\ Quartz / /

/ -\ V J 1000 - // / / - V - 1500 - / 7 : Albite \ \ 4 7 .V 2000 HjO ; V / •?/ / / / / V\ zsoo / / \ 1/ / / \ / / J / 3000 1 I V 1 / 1 i 1 1 1 2N 33S 358 371 398 418 Temperatun (K)

Fig. 5.5. Solid curves are equilibrium lines for albite-analcime-quartz for albites of different Z and activity. The dashed line is the approximate geothermal gradient in Drill Hole USW G-l. The relationships between lithostatic pressure, fluid pressure, and depth are given in the text. Analcime plus quartz is stable to the upper left, albite to the lower right.

-2.0 till i iii r i i i i

-2.4 Albite

-2.8 1?

-3.2

-3.S Amlcim

-4.0 i i i i i • i i 2S8 318 33* 358 378 3M 418 Temperature (K)

Fig. 5.6. The solid curve shows the concentration of aqueous silica in equilibrium with analcime plus albite as a function of temperature. The dashed curves show the concentration of aqueous silica in equilibrium with quartz and a-cristobalite. ELEMENT AND ISOTOPE TRANSPORT AND FIXATION 119

CRYSTAL CHEMICAL/VALENCE STUDIES OF NUCLEAR WASTE FORMS

P. Gary EUer, Robert A. Penneman, and Gordon D. Jarvinen

Our work this year has proceeded to synthesis of zirconolite and low-titanium borosilicate glass that are doped with selected rare earths and actinides. These experiments had the following purposes:

1. To develop synthesis procedures before the materials are doped with radioisotopes, notably 242Pu, 237Np, and 241Am. Thus far, we have successfully made neptunium-, plutonium-, and americium-doped glass and zirconolite doped with rare earth.

2. To develop site selection and valence characterization methods including EPR, uv-vis-near ir, Mossbauer, vibrational spectroscopy, and x-ray. We now know appropriate doping levels to conveniently apply these techniques.

3. To observe crystal growth for x-ray studies. We have been focusing on rare-earth stand-ins, but next year, emphasis will be on hot-doped materials.

RADIONUCLIDE MIGRATION FROM NUCLEAR EXPLOSION CAVITIES

Joseph L. Thompson

Since 1974, members of this division have participated in a field study of radionuclide distributions in the vicinity of underground nuclear tests conducted at the NTS. The RNM project is designed to determine (1) the rate and extent of movement of radioactive residues from the tests and (2) the potential for contamination of the biosphere either on or off the NTS. The RNM project is sponsored by the Nevada Operations Office of the DOE and involves personnel from Los Alamos National Laboratory, Lawrence Livermore National Laboratory, the US Geological Survey, and the Desert Research Institute. Contributions of INC Division personnel to the RNM project have been detailed in a number of publications,129"132 and additional results of the project were described in the Division's annual report for 1982.133 This article describes recent experimental work related to the Cambric site at Frenchman Flat and the Cheshire site on Pahute Mesa. At the former site, we are expanding an already considerable data base, whereas at the latter site, we are undertaking new measurements. Since the beginning of experimental work at the Cambric site in 1974, a wealth of information has been obtained, much of it not available from any other source. The Cambric study is one of a very few large-scale field experiments pertaining to radionuclide migration and is the only one carried out in tuffaceous alluvium. When the RNM-1 re-entry hole was drilled, we obtained data on the postshot distribution through the cavity and chimney regions of those radionuclides 120 ELEMENT AND ISOTOPE TRANSPORT AND FIXATION

associated with the test device. We also determined the concentrations of radioactive species in water pumped from selected regions along the re-entry shaft. Using tritium as a reference material, we compared the amounts of the radionuclides in the water with the known Cambric source term and estimated "retention factors" for a number of nuclides. This factor is an indication of both the tendency of the radionuclide to sorb on rock surfaces and its leachability. After a satellite well (RNM-2S) was drilled 91 m from the cavity, water flow from the cavity region to the satellite well was induced, and migration of mobile species could be observed. To date, more than 8 x 106 m3 of water has been pumped from the RNM-2S well. No cationic species such as Cs+ or Sr2+ have been detected in RNM-2S effluent water, which verifies predictions based on laboratory measurements of the very strong tendency of such ions to sorb on tuffaceous material. Neutral species such as tritiated water and 85Kr gas have been transported, as have anionic chloride and iodide. It is important to preserve the continuity of the Cambric study, and our most recent work has emphasized the continued monitoring of the concentrations of mobile radioactive species. The data are becoming sufficiently extensive to allow more exacting tests of several theoretical models that have been applied to this field experiment. For example, the Sauty model described in the INC Division annual report last year133 does not appear to fit the most recent tritium data as exactly as it did the earlier data (Fig. 5.7); this perhaps indicates a need to assign different values in the calculation to the dispersivity and/or to the source term.

0.0 0.5 1.0 T, 1.5 2.0 2.5 i I i 8000-

7000- -1.0

^ 3000-1 2000-

1000-

Volume Pumped (106 m3)

Fig. 5.7. Tritium concentration data (x) for RNM-2S water and calculated elution of tracer after instantaneous tracer injection m a radially converging flow field for Peclet number 10. ELEMENT AND ISOTOPE TRANSPORT AND FIXATION 121

During 1983, we measured radionuclides produced from the Cheshire device, which was detonated on Pahute Mesa in February 1976 at a depth of 1174 m. The Cheshire cavity was formed in rhyolite about 540 m below the water table; the hydraulic head at this depth was higher than at more shallow depths, which implies a natural upward water movement. Because of the differing geologic medium and naturally dynamic hydrology, Cheshire made an interesting contrast to Cambric. Some water samples had been collected in late 1976 from below the Cheshire cavity, but sampling of upper regions was not accomplished because the pump became tightly stuck in the hole when we attempted to raise it. The tritium content of these early samples was higher than expected, which led to the assumption that some water was drawn from the cavity rather than only from the background region below the cavity, as planned. By the fall of 1983, the hole had been cleared, perforations were made at a depth about 40 m below the cavity center, and a new pump was placed in the hole. At this time, we initiated a new pumping and sampling program. We removed over 500 m3 of water and performed a number of analyses to determine the concentrations of various dissolved species, both radioactive and nonradioactive. It appears that the lithium concentration is 2 to 8 times larger than the normal ambient value, which suggests that this element may be more readily dissolved from the postshot debris than from the original minerals. The tritium content (approximately 0.4 u Ci/m£) is more than an order of magnitude lower than the calculated source term, which could indicate that tritium has migrated away from the cavity region or that water representative of the cavity was not obtained. We determined the concentrations of fission products such as 85Kr, 106Ru, 125Sb, and I37Cs, and using tritium as a reference material, we calculated "retention factors." In general, these "retention factors" are somewhat higher for the rhyolite of Cheshire than for the alluvium of Cambric. Plutonium was found to be present in the water, though at a very low concentration. Indeed, only the tritium concentration exceeded the limits specified in the federal guide for drinking water in a controlled area. We anticipate that future work at the Cheshire site will help us resolve questions concerning the present radionuclide concentrations of the cavity water and the movement of radioactive species away from the cavity.

GEOCHEMISTRY

QUANTITATIVE TRACE-ELEMENT ANALYSIS OF GEOLOGIC MATERIALS

Pamela S. Z. Rogers, Timothy M. Benjamin, and Clarence J. Duffy

Geologic materials are complex, heterogeneous mixtures; often, they are fine grained and have varying compositions. Study of these materials requires an instrument capable of providing spatially resolved, in situ, elemental analyses. The electron microprobe is adequate for the task if a sensitivity of 1000 ppm is sufficient. The proton microprobe, which is capable of analysis at the 10-ppm level, can measure trace-element distributions in individual mineral grains. Knowledge of trace-element composition is important to the geochemist because it gives clues to the history of a mineral, including information on cooling rates during formation and subsequent alteration by diffusion, leaching, and dissolution. In situ analysis eliminates the time- 122 ELEMENT AND ISOTOPE TRANSPORT AND FIXATION

consuming and often impossible problem of preparing mineral separates and avoids the ambiguity associated with impurities in the separates. Spatial resolution is also required for studies of mineral zoning and intragrain variations. We have used the proton microprobe at the Los Alamos Van de GraafF Facility, to conduct a series of experiments determining in situ trace-element distributions in a wide range of geologic materials. The technique of particle-induced (in our case proton-induced) x-ray emission (PIXE) has been used for our experiments. In this method, proton bombardment ejects electrons from the atomic orbitals of atoms in the samples (or geologic materials). The vacancies are filled by outer shell electrons, which cascade in and emit x rays with energies characteristic of the element involved. A lithium drifted silicon [Si(Li)] detector has been used to detect the x rays and measure their energies. This information can be combined with independent knowledge of interaction cross sections and x-ray absorption and fluorescence effects to provide quantitative analysis. Operated in this manner, the proton microprobe functions exactly like an electron microprobe but with the important advantage that the background bremsstrahlung radiation is reduced by 2 to 3 orders of magnitude. The reduced background results in a trace-element sensitivity that is greater by a factor of 100 or more than that of the electron microprobe. We have used the proton microprobe for in situ measurement of trace-element concentrations in three categories of geologic materials: terrestrial, meteoritic, and synthetic. The results have yielded qualitative information on such diverse geochemical problems as rare-earth fractionation in meteorites, trace-element migration as a result of in situ retorting of oil shale, anomalous strontium-rubidium fractionation in a suite of volcanic rocks, trace-element leaching in rock/water reactions, and partitioning of siderophile elements in synthetic silicate materials. However, quantitative results are often required. We have spent the past year developing the following method of quantitative analysis that is suitable for thick geologic samples.

Analysis of Durango Apatite Quantitative analysis of PIXE spectra is more difficult than treatment of spectra obtained with electron microprobes because numerous complications result from the greater sample penetration depth of protons and from the detection of many more elements. Because a large number of overlapping peaks are usually detected, accurate values of the integrated counts for peaks of interest must be obtained through peak fitting. Then these peak areas must be related to concentrations. For the latter purpose, we prefer to use calibration standards with compositions similar to the unknown because theoretical corrections between samples of different compositions have not been adequately tested for PIXE analysis. This procedure has been followed in our use of Durango apatite, a calcium fluorophosphate, as a calibration standard for chloroapatite and whitlockite mineral studies of rare-earth element fractionation in meteorites. Durango apatite is an exceptional mineral that contains many trace elements; it is available as large homogeneous crystals suitable for bulk analysis techniques such as x-ray fluorescence and neutron activation. Such trace-element standards for other minerals are rarely available. To use Durango apatite as a calibration standard, we have developed a spectrum fitting program for obtaining accurate peak areas. We have also extended this technique to test a method of internal calibration based on relating the concentration of a trace element to that of a major element in the same sample. Internal calibration assumes that the concentration of the major element is known from electron microprobe or other analysis and is necessary because suitable trace-element standards do not exist for many types of minerals. Because Durango apatite is a relatively well-characterized mineral, it serves as a good test case for the internal calibration technique. ELEMENT AND ISOTOPE TRANSPORT AND FIXATION 123

As an example, the PIXE spectrum of Durango apatite is shown in Fig. 5.8. There is serious overlap of the rare-earth element L lines in the region from 4.5 to 7.5 keV, which is the region of interest. This overlap made it necessary to develop a spectrum-fitting procedure that used a maximum amount of theoretical information and a minimum number of variable fitparameters . For this purpose, we chose an elemental spectrum technique that requires the multiple-peak spectrum of each element be calculated separately from knowledge of subshell cross sections, fluorescence yields, and transition probabilities. The peak positions (energies) and FWHM are calibrated with well-resolved singlet peaks. The relative peak areas for each element must also contain corrections for the effects of decreasing proton energy with penetration depth and x-ray absorption in the sample. These elemental spectra are then fixed, so that spectrum fitting involves simple linear addition of elemental spectral intensities. In this manner, variables are reduced to only one per element.

532

42.5 ~

3 o 31.9 - O o 21-3 -

3 cr 1O6' i Iv' \ o.o 2220 244.6 267.2 2898 312-4 335.0 Channel Number (20eV/Ch)

Fig. 5.8. PIXE spectrum of Durango apatite thick section taken with 2.8-MeV protons, using a 10-mg/cm2 aluminum filter over the Si(Li) detector.

The results of peak fitting for the rare-earth elements in Durango apatite are shown in Fig. 5.9. The vertical bars represent experimental counts per channel; the height of the bars is proportional to the ± lo counting statistics error. Dashed lines represent the scaled elemental spectra that are added together to produce the spectrum fit, which is shown by the solid line. Figure 5.9(a) shows the elemental spectrum of lanthanum in Durango apatite superimposed on the experimental spectrum. Thefour bands in the lanthanum elemental spectrum are produced from a combination of the lanthanum Lctj, La2, L(315 Lp21s, Lp3, Lp4, and Ly, x-ray lines. Figure 5.9(b) shows the primary components lanthanum, cerium, neodymium, and iron with the fit spectrum that would 124 ELEMENT AND ISOTOPE TRANSPORT AND FIXATION

47.0

(a) V 7A/J> 222-0 244.6 267.2 289.8 312.4 335.0 Channel Number (20eV/Ch)

47.0

(0 37.6 - c o o 28.2 - o (b) o

18.8

3 (0

222.O 244.6 267.2 289.8 312-4 336-0 Channel Number (20eV/Ch)

Fig. 5.9. Spectrum deconvolution of the 4.4- to 6.7-keV portion of the Durango apatite spectrum, (a) Elemental spectrum of lanthanum superimposed on the spectrum, (b) Poor spectrum fit cbtained using only the four principle elements lanthanum, cerium, praesodymium, neodymium, gadolinium, terbium, manganese, and iron, (c) Improved fit using 8 elements, which appear in the order lanthanum, cerium, praesodymium, neodymium, gadolinium, terbium, manganese, and iron. ELEMENT AND ISOTOPE TRANSPORT AND FIXATION 125

DURANGO APATITE

50 150 250 350 450 550 650 750 ENERGY=CHANNELX20eV be obtained if only those four elements were considered. Obvious discrepancies between the-fit (solid line) and the experimental spectrum show that additional elements are present. Finally, Fig. 5.9(c) shows the improved spectrum fit obtained from combination of the elemental spectra for lanthanum, cerium, praesodymium, neodymium, gadolinium, terbium, manganese, and iron. Figure 5.9 illustrates that most of the peaks in this region of the spectrum contain components from several elements. For example, the major component of the peak corresponding to the neodymium La position is actually the cerium LPi line. Obviously, Reak fitting that did not consider all of these components would give erroneous results. The reproduction of the Durango apatite spectrum shows that the complicated spectra encountered for geologic materials can be deconvoluted using this approach.

Quantitative Results Use of a consistent set of elemental cross sections also allows us to calculate relative concentrations directly from the results of the peak fit. Determination of absolute values requires that the concentration of one element be known from another source. In the case of Durango apatite, we have used an electron microprobe analysis for calcium to determine that concentration. Concentrations of the trace elements calculated on this basis are listed in Table 5.3 with the lo error that results from uncertainties in the peak half-widths and the peak fitting. For comparison, quantitative analyses from other sources134 and preliminary data from neutron 126 ELEMENT AND ISOTOPE TRANSPORT AND FIXATION

TABLE 5.3. Comparison of Quantitative Results Concentration (ppm) X-Ray Fluorescence1* Neutron and Atomic Optical Element PIXE ±lo Activation1 ±1 o Absorption6 Spectroscopyb

La 3550 93 3660 84 3330 4200-6400 Ce 4410 113 5310 210 4150 4700-7000 Pr 430 47 — — 540 800 Nd 1288 54 1330 190 1230 2000 Mn 80 6 94.6 9.0 100 100-130 Fe 223 7 530 160 350 400 Th 230 16 196.3 6.1 202c — U <15 10.43 0.29 llc — As 882 18 898 22 — 600 Sr 479 12 <75O — 440 580-750 Y 401 11 — — 670 760-1000 Sm <50 — 158.3 8.1 — 200-300 Eu ND — 18.0 1.9 17 <100 Gd 261 — — — <110 200-300 Tb 376 — 12.8 1.3 — 100 Dy 232 — 88.6 6.5 90 100-150 Ho 37 — — — 10 30-40 Er <17 — — — 35 100 Tm 35 — — — 7 10-20 Yb 100 — 39.0 2.7 23 50-80 "Neutron activation data by S. R. Garcia, Los Alamos National Laboratory. bData from Ref. 134. Isotope dilution data from Ref. 134.

activation also are given in Table 5.3. Quantitative agreement between the PIXE and other analyses is good for the four major rare-earth components lanthanum, cerium, praesodymium, and neodymium, as well as for manganese, iron, arsenic, and strontium. This indicates that the spectrum deconvolution makes it possible to use Durango apatite as a standard for these elements. The analysis for thorium also is in good agreement with isotope dilution measurements, but uranium at 10 ppm is at the detection limit. Peaks for the remaining rare-earth elements (listed in the lower section of Table 5.3) are buried under the much larger peaks of the principal rare- earth and iron components and are also sensitive to the exact choice of background. Therefore, the peak areas are not well determined, and this is reflected in the results of the quantitative analyses. ELEMENT AND ISOTOPE TRANSPORT AND FIXATION 127

The use of our peak deconvolution program to determine light rare-earth element concentrations in meteorite samples gives a better example of the sensitivity obtained with PIXE. Quantitative concentrations of these elements in a chloroapatite and a whitlockite grain of the St. Severin meteorite are listed in Table 5.4. The uncertainties listed in Table 5.4 represent lo values resulting from statistical uncertainties in the experimental counts, the peak fitting, and the relative peak intensities. They do not include systematic error in the background assignment. Detection of the rare-earth elements at the 10-ppm level is obtained.

TABLE 5.4. Trace-element Content of Mineral Grains in the Meteorite St. Severin Concentration

Element Chloroapatite Whitlockite

La <30 72 ±23 Ce <30 . 163 ± 30 Pr 5 ± 12 <20 Nd 50 ± 12 140 ± 24 Sm <20 61 ± 17 Cr 79 ± 5 18 ±6 Mn 34 ± 5 128 ± 15 Fe 855 ± 89 2552 ± 267

Durango apatite was chosen for quantitative treatment as an example of a complex geologic material. We have shown that even the severe overlap of the rare-earth element peaks in the Durango apatite spectrum can be deconvoluted using a spectrum-fitting routine constrained to only one fitting parameter per element. By accounting for changes in ionization cross section and x-ray absorption with depth in thick samples, accurate quantitative analyses have been obtained for the four predominant rare-earth elements lanthanum, cerium, praesodymium, and neodymium. This allows us to take Durango apatite as a standard for determining <100-ppm quantities of these elements in meteoritic minerals, although use of a simpler, synthetic standard would be more straightforward. The procedure used to treat the Durango apatite spectrum illustrates how complex spectra from other geologic materials can be interpreted. Calibration standards, similar in composition to the unknown, are preferred for quantitative measurements. However, such standards are not available for many trace elements, which makes an internal calibration scheme necessary. The agreement between our quantitative PIXE results and neutron activation analysis for several elements in Durango apatite is promising. Future work will include further testing of quantitative analysis based on the internal calibration method, using a series of mineral separates for which neutron activation data are available. To refine our spectrum deconvolution, we are performing additional tests of the relative peak intensities calculated for elemental spectra and are working to improve the background subtraction. 128 ELEMENT AND ISOTOPE TRANSPORT AND FIXATION

THE SYSTEM CaO-SiO2-H2O-CO2 AND IMPLICATIONS FOR THE FENTON HILL HYDROTHERMAL SYSTEM

Robert W. Charles

A number of petrologic consequences must be considered when geologic materials are added to a geothermal reservoir. This study will help define the effects of these additives on the life of the reservoir. Additives currently in use are silica sand, montmorillonite clay, and barite. These

additives belong to the system K2O-CaO-BaO-MgO-Al2O3-SiO2-H2O-CO2-SO3. I will present some results from the simpler system CaO-SiO2-H2O-CO2 that address the effects of the additive silica sand. Current drilling practices allow the emplacement of a silica sand in a wellbore for temporary closure. The sand is usually removed by simple flushing. Recent experiments indicate this may not be a practical approach if the sand is emplaced at high temperature in the presence of a CO2-bearing fluid. At Fenton Hill, a north central New Mexico mountain site, the Laboratory has drilled deep holes to connect the hot dry rock reservoir with the surface. In the summer of 1982, approximately 3000 ft of silica sand was emplaced in the wellbores of EE-2 and EE-3, two such wells. Since then, a large volume of CO2 gas has been evolving. Examination of the binary H2O-CO2 (Fig. 5.10) reveals that the probable source of the CO2 is simple unmixing caused by pressure release and/or temperature drop. This leaves the aqueous phase relatively depleted in

CO2 at depth. Will the remaining aqueous fluid react with silica and reservoir calcite to produce a calcium silicate (hydrate)? Will recrystallization of this type impede flow in the reservoir? My experimental work with fluid on the high-H2O portion of the H2O-CO2 binary is designed to answer these questions.

400r

CnticM Point of Wottr

100 10 20 30 40 SO 60 70 SO 90 KX) MOLE* CO*

Fig. 5.10. The binary H2O-CO2. ELEMENT AND ISOTOPE TRANSPORT AND FIXATION 129

The principal phases in this system are the solid phases quartz (Q), calcite (C), wollastonite [CaSiO3 ] (W), and the high-temperature calcium silicate hydrates xonotlite (X)[Ca,jSi6O,.,(OH)2] and tobermorite (T) (approximately CajSijOjj^HjO). These solid phases coexist with an aqueous phase containing CO2. The system may be addressed by relating the five solid phases, two inert components (CaO and SiO2), and two mobile components (H2O and CO2) in the presence of a fluid bearing aqueous CO2. The system has a variance of f = -1 and is a multisystem consisting of (at most) five invariant assemblages with ten possible univariant assemblages. Compositional degeneracies (compositional coincidence of T, X, and W) decrease the net to four univariant points and six univariant curves. A connected net for this system is shown in Fig. 5.11. All reaction relations are shown in Table 5.5. Experimental work done by 135 Greenwood has defined the univariant relation as wollastonite = calcite + quartz in T-XC02 space at 1 and 2 kbar above «55O°C. Using Greenwood's equilibrium study, I found that the stable net consists of [T], [W], and [C] = [Q] stable and [X] metastable. Such a net is oriented schematically in uC(,2 - nH2 space in Fig. 5.12.

Fig. 5.11. Connected net for the system xonotlite [X], tobermorite [T], wollastonite [W], calcite [C], and quartz [Q] with -1 degrees of freedom. Two-phase divariant assemblages (that is, TC) and invariant assemblages (that is, [T]) are shown. 130 ELEMENT AND ISOTOPE TRANSPORT AND FIXATION

TABLE 5.5. Univariant Equilibria Reaction

calcite + quartz = wollastonite + CO2 0 6 wollastonite+ H2O = xonotlite oo

6 calcite + 6 quartz + H2O = xonotlite + 6 CO2 1/6 5 wollastonite + 5 H2O = tobermorite oo 5 calcite+ 5 quartz + 5 H2O = tobermorite+5 CO2 1 6 tobermorite = 5 xonotlite + 25 H2O oo

136 Very little work had been done on CaO-SiO2-H2O-CO2 at temperatures below 500°C. Roy and Buckner et al.131 did some nonequilibrium experiments with calcium silicates at lower

temperature and XCO2 = 0, which at least gave a general idea of the type of phases one may encounter in this system. The experimental approach of the current study is to buffer the fluid composition with respect to Xcc,2 by using silver oxylate and H2O. The solid reactants are added to a precious metal capsule. A weighed amount of H2O and synthesized (and calibrated) Ag2C2O4 are added to yield the desired XCO2. Silver oxalate decomposes at 140°C to silver and CO2. The capsule is then welded and subjected to temperature and pressure in a cold-seal pressure vessel. At the conclusion of the experiment, the capsule is weighed, punctured to release CO2, weighed, allowed to dry at 50° C, and weighed again. These weighings al!ow us to compute the final Xc0 . Experiments show results reproducible to better than Xc02 = 0.01. Preliminary experiments show the fluid rapidly equilibrates at temperatures lower than 500°C. As an example, I will use the reaction wollastonite

= calcite + quartz. Near the univariant curve in T-XC02 space, reactants consisting of the three solid phases plus fluid will rapidly reequilibrate to the XC02 characteristic of the reaction at that temperature. Using this buffering technique, I have extended the curve of Greenwood135 to 400° C thus far.

Reversals at 400 and 450°C are XCO2 = 0.011 ± 0.005 and XCO2 = 0.04 ± 0.02. I expect to tighten the latter bracket and continue the work to higher and lower temperatures. The chemical potential diagram (Fig. 5.12) is closely related to the T-X section. Increasing the temperature is similar to decreasing uH20, and increasing Xco relates to increasing uco . Experimental results indicate that the reaction wollastonite = calcite + quartz becomes nearly vertical at low temperatures. This observation indicates that calcium silicate hydrates will be stable to higher XCOz systems in T - X space (Fig. 5.13). No calcium silicate hydrates have appeared thus far, which indicates that they exist only below 400° C. When we apply these results to Fenton Hill, addition of fluid that keeps XC02 above about 0.01 will allow the assemblage CaCO3 + SiO2 to remain stable. Calcium silicates will be suppressed at least at 400°C. At a lower temperature, a higher Xcc,2 will be necessary to suppress calcium silicate hydrates. This does not preclude cementation of silica sand in the reservoir. In other words, silica and calcite may cement the additive silica sand if calcium silicate does not. ELEMENT AND ISOTOPE TRANSPORT AND FIXATION 131

'co2

HC HO (T)

Fig. 5.12. Stable portion of the net in nco o- s ace Tne T BC MH,o P - I ]> [W], and [C] = [Q] are the xc stable invariant points; (Cj = [Q] is located at infinity.

TC TO

Fig. 5.13. The T-Xcc,2 oriented phase diagram for the system. Arrows indicate experimental work done thus far. Tail of the arrow represents initial Xco, and tip represents final Xco . Greenwood"5 bracket at 55O°C is shown. The two-phase fluid field is not shown.

0.05 0.10 0.15

"CO, - s/- 6,

ACTINIDE CHEMISTRY

135 FOOF Chemistry

13'/ Tertiary Phosphine Complexes of Uranium

140 Attempted Preparation of Pu(OH)jCO3

TRANSITION METAL CHEMISTRY

141 Small Molecule Chemistry ACTINIDE AND TRANSITION METAL CHEMISTR Y 135

ACTINIDE CHEMISTRY

FOOF CHEMISTRY

P. Gary Eller, Larned B. Asprey, and Elizabeth M. Foltyn

We have been developing the chemistry of dioxygen difluoride (FOOF) as a potent, low- temperature fluorinating agent. Our work shows that FOOF is unsurpassed by any known agent in fluorination power at room temperature or below. This remarkable reactivity is apparently the result of the weak O-F bonds that homolytically rupture to form fluorine atoms. As examples of the oxidative power of FOOF, we can easily form (at room temperature or below) the following normally difficult chemical transformations:

XeF2 (Xe + FOOF) ClFj (NaCl + FOOF) CrF5 (CrF3 or stainless steel + FOOF) IrF6 (IrCl3 + FOOF) PuF6 (Pu-incinerator ash + FOOF)

Until now, syntheses of some of the above fluorides have been obtained only photochemically or at elevated temperatures with high fluorine pressures. Important industrial applications based on high-temperature fluorinations (notably with plutonium) have never been brought to fruition because of the tremendous corrosion and thermal decomposition problems under these conditions. FOOF circumvents both of these problems and thus has great applied potential.

Dioxygen difluoride (FOOF) is a thermodynamically unstable molecule with t1/2 «1 second at ambient temperature. However, at lower temperatures it has good thermal stability and can be handled conveniently. We have shown that this material is one of the most powerful oxidative fluorinating agents known. In fact, reactions with FOOF take place at temperatures far below ambient and at subatmospheric pressures, in contrast to reactions with molecular fluorine, which require high pressures and temperatures more than 300°C higher. Thus, it is obvious that FOOF has tremendous advantages over syntheses and processes that presently involve hot fluorine because materials compatibility problems are much more manageable. Furthermore, thermodynamically unstable species sometimes can be prepared and stabilized in pure form only at these lower temperatures. Table 6.1 presents some examples of substances that we have synthesized with FOOF and the conditions required for the most convenient "ordinary" syntheses. Of particular significance is the production of volatile PuF6 from a variety of plutonium materials (PuO2, incinerator ash, 136 A CTINIDE AND TRANSITION METAL CHEMISTR Y

TABLE 6.1. "Conventional" vs FOOF Reaction Conditions Product FOOF Conventional

PuF6 -78 ° C, 200 torr > 250° C, > 1 atm F2 AgF3 " " Unknown except using KrF2 PrF4 " " NajPrFj + HF

SOF4 " " 250°C, 90 atm BrFj C1F5 >200°, «50 atm F2

PuO2F2, and PuF4). FOOF is the only substance capable of volatilizing plutonium at a significant rate below 250°C, and it is effective even at -78°C. Because FOOF is a gas and produces a volatile yet condensible plutonium compound at low temperatures, we can envisage many applications that are important for nuclear industry problems. For example, the fluoride volatility process for plutonium/uranium recovery could once again become viable because catastrophic

PuF6 decomposition at the temperatures required in a hot F2 process does not occur when we use FOOF at low temperatures (for example, see Figure 6.1.) Many times we have observed total plutonium removal from surfaces on exposure to FOOF, which illustrates its potential in decontamination. Also, high-purity PuF6 feed-preparation for various processes should be routinely attainable. FOOF also has potential nonactinide applications. Thus, the nonplutonium entries in Table 6.1 illustrate the advantages of using FOOF in general high-valent fluoride synthesis. For example,

PrF4 is thermodynamically unstable and is obtained only by leaching NaF from Na2PrF6 by HF. Because FOOF operates at low temperature, PrF4 and, possibly, many other unstable high-valent fluorides are accessible in high purity. FOOF could perhaps be used in recovery of strategic materials, such as iridium, that form volatile fluorides. In summary, we have demonstrated that FOOF has great potential for application to a wide range of applied and fundamental problems. ACTINIDE AND TRANSITION METAL CHEMISTRY 137

FOOF (gas)

Fig. 6.1. Flowchart for PuF6 recovery from scrap. Major contaminants (potassium, sodium, and cesium) remain as solid fluorides. PuF6 can be further purified by cryogenic separation and/or thermal decomposition to PuF4 at 300°C.

TERTIARY PHOSPHINE COMPLEXES OF URANIUM

Harvey J. Wasserman, David C. Moody, and Robert R. Ryan, Robert T. Paine,* and Kenneth V. Salazar

Stable uranium complexes containing tertiary phosphine ligands (:PR3) have proven to be elusive species even though the first attempted preparation occurred as early as 1949.138 To date, only two successful syntheses have been reported. Anderson et al.139 prepared the series X4U(DMPE)2 [X = Cl, Br, I, Me, OPh], [DMPE = bis-l,2(dimethylphosphino)ethane, (CH3)2PCH2CH2P(CH3)2] and carried out a crystal structure analysis of (PhO)4U(DMPE)2; Marks et al.140 succeeded in preparing the only known U(III) phosphine complex, (n5- C5Me5)2U(DMPEXH). We report here the preparation and characterization of several trivalent uranium-phosphine complexes based upon a U(BH4)3 core.

•Visiting Staff Member from the University of New Mexico 138 ACTINIDE AND TRANSITION METAL CHEMISTRY

We prepared a THF solution containing «0.9 mmole U(BH4)3(THF)X (as previously reported141) and added to this solution 0.2 mi bis-l,2(dimethylphosphino)ethane in 30 mi THF. The THF was removed by vacuum distillation, the dark-olive-colored paste was extracted into 100 mi diethyl ether, and the solution was filtered. We obtained single crystals suitable for x-ray diffraction analysis by reducing the volume of ether to 30 to 50 mi and cooling it overnight at 0°C. The crystals are olive colored by reflected light and red by transmitted light. Figure 6.2 shows a perspective view of the U(BH4)3(DMPE)2 molecule; the hydrogen atoms are omitted for clarity.

Fig. 6.2. Structure of U(BH4),(DMPE)2. Carbon atoms C(l) and C(2) represent the resolved components of the disordered DMPE ligand.

The molecule resides on a crystallographic two-fold axis of symmetry that passes through the uranium atom and atom B(l). The nonhydrogen atoms surrounding the central U(III) ion produce a regular pentagonal bipyramidal coordination geometry. The DMPE chelate angles are P(l)-U-P(2) = P(l')-U-P(2') = 65.1(3)°, and the interchelate angles are P(l)-U-P(l') = 76.9(2)° and P(2)-U-P(2) = 152.8(4)°. The equatorial borohydride group B(2) acts as a bisector for this last angle, and B(2)-U-P(2) = B(2')-U-P(2') = 76.4(2)°. The frans-diaxial angle is 166(1)°. Although hydrogen atoms of the three tetrahydroborate ligands were not located, two different modes of BH4 attachment in U(BH4)3(DMPE)2 may be distinguished on the basis of U..-B distances.142 Thus, the U"-B(2) separation of 2.84(3) A clearly indicates bidentate coordination and compares well with the U(u-H)2BH2 linkage of 2.86(2) A in U(BH4)4 (Ref. 143). The observed U-"B(1) distance of 2.68(4) A implies a tridentate arrangement, although the 143 corresponding U(u-H)3BH in U(BH4)4 bond length is shorter, with U—.B = 2.34(1) A. ACTINIDE AND TRANSITION METAL CHEMISTRY 139

The two crystallographically unique uranium-phosphorus distances in U(BH4)3(DMPE)2 show the effect of different chemical environments; that is, the phosphorus atoms adjacent to the BH4 ligand are associated with shorter uranium-phosphorus bond lengths than those opposite the BH4 group [U-(2) = 3.051(9) A vs U-P(l) = 3.139(9) A]. Nevertheless, both of these values are consistent with the two previous uranium-phosphine structures: U-P(avg) = 3.104(6) A in

U(OPh)4(DMPE)2 (Ref. 139) and U-P = 3.211(8) and 3.092(8) A in 5 140 0l -C5Mej)2U(DMPEXH). Our principle interest in preparing phosphine complexes of uranium lies in the fact that such ligands may allow us to bridge the gap between transition-metal chemistry, in which phosphine ligands abound, and uranium coordination chemistry, which traditionally uses ligands with more

electronegative donor atoms (fluorine, oxygen, nitrogen, etc.). The U(BH4)3(DMPE)2 species described above is an example of a complex having ligands of widely differing character bonded to the same metal atom. However, it would also be interesting to prepare a chelate ligand, each of the donor atoms of which possesses different coordination properties. A single ligand of this type could bridge between two dissimilar metals and possibly promote activation of an organic ligand.

We have been using the ligand bis(diphenylphosphino)pyridine, Ph2Ppy (Ref. 144), to attempt some of this chemistry with uranium, and although no bimetallic systems have yet been observed, some interesting phosphine complexes of uranium have resulted and have been characterized in full.

We prepared U(BH4)3(Ph2Ppy)2 by reacting a slight excess of Ph2Ppy with U(BH4)3(THF)X in THF, although no reaction took place until we removed almost all THF under vacuum. The purple crystalline product was precipitated by addition of ether and was satisfactorily characterized by elemental analysis and x-ray analysis using single crystals grown from benzene s (see below). We prepared (T| -CJHJ)UCl3(Ph2Ppy) similarly, by reacting (ii'-CjH^UC^ with excess Ph2Ppy in THF, followed by precipitation with ether. This 1:1 adduct of U(IV) was characterized by elemental analysis and by 'H and 31P NMR spectroscopy. At this time, it is not 5 clear that the reaction of (T| -C5Mej)UCl3 with Ph2Ppy cleanly produces an analogous product; further studies are in progress. In contrast with that of U(BH4)3(DMPE)2, the infrared spectrum of U(BH4)3(Ph2Ppy)2 indicates tridentate borohydride binding, with strong bands at 2420, 2300, 2200, and 1120 cm-1. Figure 6.3 shows the results of the single-crystal x-ray diffraction analysis of

U(BH4)3(Ph2Ppy)2. The molecule exhibits crystallographically imposed C2 symmetry, the axis of which lies along the U-B(l) direction. If we regard each borohydride ligand as occupying one coordination site, then the formally 13-coordinate U(III) ion adopts an unusual coordination geometry that closely approaches pentagonal bipyramidal. However, angles within the equatorial plane show large deviations from uniform pentagonal distribution, with B(l)-U-N = B(l)-U-N' = 90.1(1)°, N-U-P = 52.8(1)°, P-U-P' = 74.30(3)°, and N-U-N'= 179.8(2)°. These distortions arise

from the presence of the tridentate equatorial BH4 group, for which U"»B(1) = 2.61(2) A. The axial borohydride ligands are also tridentate; U-B(2) = 2.656(8) A and U-H-B(2) angles are in the range 84(4) to 93(3)°.

The single unique uranium-phosphorus bond length in U(BH4)3(PPh2py)2 is 3.162(1) A, a value that falls within the range of all previously determined uranium-phosphorus distances and is close

to the value of 3.139(8) A obtained for a uranium-phosphorus linkage trans to a bidentate BH4 group in U(BH4)3(DMPE)2. The uranium-nitrogen distance is 2.659(4) A. 140 ACTINIDE AND TRANSITION METAL CHEMISTRY

C2 C2

Fig. 6.3. Perspective view of the U(BH4)3(Ph2Ppy)2 molecule. Hydrogen atoms of the axial tetrahydroborate ligands are stippled.

ATTEMPTED PREPARATION OF PLUTONIUM (IV) DIBASIC MONOCARBONATE,

Pu(OH)2CO3

Alfred H. Zeltmann and Tom Newton

Previous investigations suggest that PuO2»nH2O is readily converted to a basic carbonate. 145 Toth and Friedman report that precipitated Pu(IV) polymer takes up CO2 when exposed to air to produce a material with as much as 1/3 mole of CO2 per mole of piutoniurn. The carbonate 146 was determined by ir absorption spectrum. Kim et al. suggest that PuO2(s) is transformed to Pu(OH)2CO3 in carbonate solutions at pH values near 10. Formation of a basic carbonate of Pu(IV) would have important environmental implications. If its solubility is as low as alleged,146 transpoi t rates in groundwater would be considerably reduced beyond the presently anticipated

rates. We have attempted to find conditions under which PuO2«nH2O can be converted to a carbonate or basic carbonate. Kim et al.146 postulate the reaction

PuO2(s) + CO^ + 2 H2O = Pu(OH)2CO3(s) + 2 OH" ,

238 to explain their data on the solubility of PuO2 in carbonate solutions. This equation may be rewritten as

PuO2(s) + CO2 + H2O = Pu(OH)2CO3(s), ACTINIDE AND TRANSITION METAL CHEMISTRY 141

which shows that the equilibrium formation of the basic carbonate depends on the pressure of + CO2, but it depends on the concentrations of CO3" and H only as they are determined by the carbon dioxide pressure. Accordingly, we have attempted to convert PuO2«nH2O to a basic carbonate by using moderately high pressures of CO2: about 7 atm. The starting material PuO2»nH2O was prepared by adding Pu(IV) in 3M HC1 to excess aqueous ammonia. The resulting precipitate was removed by centrifugation, washed with water, and identified by x-ray diffraction. All the lines observed in the powder pattern correspond to those of crystalline PuO2. The moist soiid, contained in a pyrex tube, was placed in a brass pressure.i'essel. The CO2 pressure was raised to 100 psi, and the mixture was allowed to equilibrate for 300 hours at ambient temperature, 21°C. At the end of that time, a sample was prepared for x-ray powder diffraction by centrifuging the wet precipitate in a capillary tube. The x-ray pattern did not appear different from that of the PuO2>nH2O starting material. There were no lines present that were not attributable to PuO2«nH2O, and the particle size was not changed from the average 20- to 25- A crystallites previously observed. Had there been significant change in the chemical composition of the precipitate, we should have observed a diminution of specific line intensities attributable to PuO2-nH2O even if no new lines appeared that were characteristic of a mixed carbonate salt structure. No new lines did appear. The experiment was repeated at 70° C with no change in results. These results indicate that PuO2«nH2O is converted to a carbonate-containing compound very slowly, if at all, at the temperatures and pressures in our experiments. A carbonate analysis of the final precipitates would be required for complete proof, but it appears that the reported146 easy conversion of the oxide to a carbonate is suspect. We suggest that the apparent incorporation of carbonate into Pu(IV) compounds is probably evidence of absorption of carbon dioxide onto the surface of the Pu(IV) hydroxides. Some additional experiments will be carried out at 600 psi to see whether this pressure of CO2 is sufficient for the reaction.

TRANSITION METAL CHEMISTRY

SMALL-MOLECULE CHEMISTRY

Gregory J. Kubas, Gordon D. Jarvinen, and Robert R. Ryan

Reduction of SO2 with Molybdenum and Tungsten Complexes; Catalysis of the Reaction SO2 + 2H2 -v S + 2H2O

Reducing SO2 with hydrogen to give sulfur and water is an attractive method for removing SO2 from flue gases. However, because this reaction does not occur spontaneously, catalysis is required. Transition-metal complexes, particularly those that form hydrides, are being investigated as catalysts, but reaction shutdown because of sulfiding of the metal has been a major problem. A possible means to circumvent this behavior was suggested by the observation of stoichiometric reduction of SO2 by a metallothiol complex, [W(CO)5(SH)]~. Thus, instead of 142 ACTINIDE AND TRANSITION METAL CHEMISTRY

using metal-bound hydrogen to reduce SO2, one could conceivably use the active hydrogen contained in metal-bound SH groups. Furthermore, a unique preparation of a metallothiol from hydrogen and a dinuclear sulfur-bridged molybdenum complex has been described in the 147 literature. The complex [MeCpMo(S)(SH)]2 (MeCp = methylcyclopentadienyl) catalyzes the reaction of sulfur with H2 in CHC13 solution to give H2S (Ref. 147), and one could easily envision extension to SO2 reduction, which we describe below. The first example of homogeneous catalytic conversion of SO2 and H2 to sulfur and water has been effected at ambient temperature and pressure in a flask containing a stirred chloroform

solution of [MeCpMo(S)(SH)]2. About 90% of the SO2 was consumed within a 2-week period under these extremely mild conditions. Curiously, most of the sulfur product was deposited on the upper walls of the flask above the solution surface, which indicates that a gas phase reaction took

place. The fact that small amounts of H2S were also formed in the reaction pointed to a Claus- type reaction: 2H2S + SO2 —*• 3S + 2H2O. Thus, H2S generated in the solution phase reacted with SO2 gas on the flask surface, producing a type of chemical transport reaction. The H2S could be formed in either of two ways: from S + H2 and/or from a "sulfur-rich" 147 complex and H2. The latter complex, of approximate stoichiometry {[MeCpMo(SXu-S)]2}2(u-S), was found to precipitate from a stoichiometric reduction of SO2 with [MeCpMo(S)(SH)]2 in the absence of H2. No elemental sulfur was detected among the products; thus, the sulfur from the reduced SO2 was incorporated into the catalyst to form a sulfur-bridged species (possibly cross-linking the sulfur ligands of two dimeric units). We found

that this sulfur-rich complex indeed reacted with H2 to reform the catalyst and give H2S. Thus, the following catalytic cycle can be envisioned:

2[MeCpMo(SXSH)]2 + SO2 -+ {[MeCpMo(SXu-S)]2(u-S) + 2H2O

{[MeCpMo(S)(u-S)]2(u-S) + 3H2 -• 2[MeCpMo(S)(SH)]2 + H2S

H2S + 1/2 SO2 -• 3/2 S + H2O ,

where the last reaction takes place on the flask walls, and the overall reaction is

3/2 SO2 + 3H2 -»• 3/2 S + 3H2O .

Thus, the SO2 and H2 do not react directly but indirectly by means of HSS. We obtained further proof for this mechanism by examining a reaction of [MeCpMo(S)(SH)]2 + SO2 + H2 in 2:1:2 ratio. The mixture was stirred so that the walls of the flask were continuously in contact with

solution phase. The result was a nearly quantitative yield of H2S instead'of sulfur.

This system appears to have potential for SO2 conversion, although the reaction rate at ambient temperature is slow. Studies are in progress to increase the rate and to examine the nature of the sulfur-rich complex by x-ray crystallography. Because the SO2-H2S reaction itself normally requires catalysis, perhaps the overall process could be speeded up by increasing the rate of this reaction. At this point, we have not identified the exact catalyst for this Claus reaction on the flask walls. Because a mixture of H2S, SO2, and CHC13 did not yield sulfur under the conditions in the above experiments, an as yet undetermined species must be promoting sulfur deposition. ACTINIDE AND TRANSITION METAL CHEMISTR Y 143

Reduction of S02 with (u-H)2Os3(CO)10 Our studies of reduction of SO2 with transition-metal hydrides have shown wide variations in reactivity of these complexes with SO2, but have yielded rather little mechanistic detail. Often the reactions are too complex or occur too rapidly to allow much insight into the details of the mechanism. However, monitoring the reaction of SO2 and (u-H)2Os3(CO)10 has provided us with some intriguing glimpses of the steps involved in reducing SO2 by a metal hydride complex.

We have shown previously that the reaction of (u-H)2Os3(CO)i0 and SO2 yields an adduct containing the bridging SO2 ligand (u-H)2Os3(CO)10(u-SO2) as the first observable product. This u-SO2 complex is unstable in solution; it gradually converts primarily to a species we formulate as (u-H)Os3(CO)10(SO2H), where a hydride ligand formerly bridging two osmium atoms is now bonded to an oxygen of the coordinated SO2. This formulation is based on NMR and ir data and isolation of the salt [(PhCH2)3NH][HOs3(CO)10(SO2)] upon addition of tribenzylamine to the reaction solution. Preliminary results from an x-ray diffraction study of a crystal of the salt indicate that the anion HOs3(CO),0(SO2)~ closely resembles (u-H)2Os3(CO)10(u-SO2), except for removal of the hydride that singly bridges an Os-Os bond in the neutral complex.

Reduction of SO2 to give H2O occurs at longer reaction times. In fact, some water is always produced along with the (u-H)Os3(CO)10(SO2H) complex. The reaction of (u-H)2Os3(CO)10 with SO2 in liquid SO2 at room temperature yields 0.5 mole of H2O per mole of (u-H)2Os3(CO)10 after several days. In addition to water, the reaction of (u-H)2Os3(CO)i0 and SO2 yields other osmium carbonyl complexes, which we are attempting to characterize. Some of these complexes exhibit a strong broad absorption in the region 850 to 1000 cm"1, which suggests an S-O vibration. A complex containing a bound SO moiety has not yet been structurally characterized and little is known about the chemistry of such species. We expect that further details of SO2 reduction by a metal hydride will be revealed by study of this and related systems. %% w%*' ,d ?" * " >% • 4 - ,-''r > •1 )> r, ^ / - i

- VJ

147 First Examples of Isolable Molecular Hydrogen Complexes: Evidence for a Side-On Bonded H2 Ligand

' 150 Structure of l-H-A_epine-2-One-5*Methoxime

152 Solid State t5NM R of Ammonia Adsorbed on Y Zeolite

155 NMR Coils with SegmentsWired in Parallel

, t „ / 7 1^1 " • ] —?« *> STR UCTURAL CHEMISTR Y, SPECTROSCOPY, AND APPLICA TIONS 147

FIRST EXAMPLES OF ISOLABLE MOLECULAR HYDROGEN COMPLEXES:

EVUDENCE FOR A SIDE-ON BONDED H2 LIGAND

Gregory J. Kubas, Robert R. Ryan, Basil I. Swanson, Phillip J. Vergamini (P-8), and Harvey J. Wssserman

The synthesis of dihydridro transition-metal complexes by oxidative addition of dihydrogen to cocrdinatively unsaturated species is a well-studied reaction because of its importance in catalytic hydrogenation processes. To our knowledge, in no case has an incipient species containing metal- bound molecular hydrogen been isolated. However, it has been commonly proposed148'149 that this type of interaction occurs before H-H bond cleavage, and transient T|2 dihydrogen binding has been proposed150 in "direct hydrogen transfer" reaction modes. We now report the first examples of isolable transition-metal complexes containing a coordinated dihydrogen molecule 2 characterized by a variety of spectroscopic and structural methods to possess n bonded H2. These complexes can be viewed as "frozen out" intermediates in the oxidative addition process and are thus very significant to petrochemical industries and others who rely on this crucial reaction.

We recently discovered reversible binding of small molecules (H2, N2, etc.) to novel 151 coordinatively unsaturated complexes, M(CO)3(PCy3)2 (M = Mo, W; Cy = cyclohexyl). Toluene solutions of M(CO)3(PCy3)2 (M = Mo, W) react readily and cleanly with hydrogen (1 151 atm) and precipitate yellow crystals of mer, /tra«s-M(CO)3(PCy3)2(H2) in 85 to 95% yields. The tungsten P-i-Pr3 i-Pr = isopropyl analogue is isolated in lower yields from hexane, because it is very soluble in hydrocarbon solvents. We could not obtain Mo(CO)3(P-i-Pr3)2(H2) as a solid, although reversible color changes in solution indicate H2 addition. In all complexes, the H2 is extremely labile; storage and handling under an H2-enriched atmosphere is necessary. Immediate discoloration occurs upon exposure of the solids to vacuum or argon, but the original color is

instantly restored upon contact with H2. Bulk loss of H2 from the solids is slow at 20°C (Pdissoc = 10 torr for W(CO)3(P-i-Pr3)2(H2) and 1 torr for the PCy3 analogue), but the H2 can be quantitatively removed from toluene solutions to give M(CO)3(PR3)2 (R = cy, i-Pr) by flushing the solution with argon or exposing it to partial vacuum at 25 to 50°C.

Vibrational spectra of solid samples of the H2, D2, and HD forms (M = W) are consistent with 2 coordination of molecular H2. Of the six fundamentals expected for T) M-H2 binding, four are observed (Table 7.1). Bands at 950 and 1570 cm"1 have been assigned as symmetric and

asymmetric M-H2 stretches, respectively. Both modes exhibit deuterium isotopic shifts close to those predicted for pure M-H2 stretching symmetry coordinates. Most importantly, an entirely new set of bands is observed for the HD complexes, intermediate to those of the H2 and D2 species.152 The H-H stretch is observed at 2690 cm"1 as a broad, weak feature in the Nujol mull ir

spectrum of W(CO)3(PCy3)2(H2), whereas the HD species exhibits a similar absorption at about 2360 cm"1, which we attribute to the H-D stretch. Although the D-D ir stretch was obscured for 1 the D2 complex, Raman spectra show a weak, broad feature at about 1900 cm" , which we assign to this mode, intensified by coupling with the nearby C-0 stretches. The deformation and torsional modes are more difficult to assign because they are weak or 1 unobserved. However, an ir feature that is present at 319 cm" for W(CO)3(PCy3)2(D2) and absent at this frequency for the H2 species is attributed to an M-D2 deformation. Also, the frequencies of several Raman modes in the 400 to 600 cm"1 region, where M-CO stretch and M- C-O deformations occur, are significantly shifted by deuterium substitution. We ascribe these 148 STRUCTURAL CHEMISTRY, SPECTROSCOPY, AND APPLICATIONS

TABLE 7.1. Vibrational Frequencies (cm'1) for Solid W(CO)/PCyp^) and IsotopicaUy Substituted Species* ' HH HD DD

v(HH) 2690 (ir) 2360 (ir) «1900(R) 1570 (ir) «1350 (ir)b «1132 (ir)b 953(ir,R) 791 (ir,R) 7O3(ir,R) b S(WH2) «450(ir) 319 (ir) *Ir samples were Nujol mulls; Raman samples were enclosed in capillaries and excited by 5682 A line of a krypton laser. bPartially obscured.

unusual deuterium shifts to the presence of M-H2 deformation modes strongly coupled to the M- CO stretch and M-C-0 deformation and stress that metal hydride complexes do not exhibit bands in these low-frequency regions.

The *H NMR spectrum of W(CO)3(P-i-Pr3)2(H2) under H2 atmosphere shows a single, broad, temperature- and concentration-independent resonance caused by the H2 ligand at 4.21 ppm upfield from trimethylsilane. No coupling to 31P or 183W is resolved in the temperature range +60 to -85 °C. The broad linewidth (15 to 40 Hz at half-height) over such a large range may result

from exchange and fluxionality involving the H2 ligand and/or dipolar interaction between the two closely separated hydrogen atoms. The chemical shift is comparable to that found for the

hydride ligands in WH4(PEt3)4 (Ref. 153). Unequivocal evidence for direct H-H bonding is provided by the 'H spectrum of W(CO)3(F-i-Pr3)2(HD), which shows splitting of the signal at 4.2 ppm by spin 1 deuterium into a 1:1:1 triplet with JHD = 33.5 Hz. This value is an order of magnitude larger than that found for compounds containing nonbonded hydrogen and deuterium atoms and can be compared to that for HD gas, 43.2 Hz (Ref. 154). The linewidth of the HD

resonances is considerably less broad (8 Hz at 35 °C) than that for the H2 signal (24 Hz), which is 31 l consistent with reduced dipolar broadening. P { H) NMR of W(CO)3(P-i-Pr3)2(H2) shows a 183 31 single resonance with W satellites. No coupling to the H2 protons is resolved at 35°C in the P spectrum.

Suitable single crystals of W(CO)3(P-i-Pr3)2(H2) have been subjected to x-ray and neutron diffraction analyses. By using room-temperature neutron data that were collected at the Los Alamos Pulsed Neutron Source with the Laue TOF method and solved using heavy-atom

coordinates from an earlier room-temperature x-ray study, we have located the H2 ligand. However, large background levels from thermal motion and incoherent scattering from phosphine hydrogens resulted in a small number of usable data. We therefore carried out low- temperature (30 K) experiments at Brookhaven National Laboratory that enabled us to determine the precise location of the H2 after sorting/out a disorder problem. The x-ray data o obtained at -100(5) C yield consistent results concerning the H2 ligand. / STR UCTURAL CHEMISTR Y, SPECTROSCOPY, AND APPLICA TIONS 149

Figures 7.1 and 7.2 show the molecule. The geometry about the tungsten atom is that of a highly regular octahedron, with "cis" interligand angles about tungsten ranging from 88.0(4) to 92.0(6)°. The dihydrogen ligand is symmetrically coordinated in an r\2 mode, with tungsten- hydrogen distances of 1.867(9) and 1.892(9) A. The H-H separation is 0.819(9) A, a value that is

significantly longer than values obtained for free H2 (0.74) A, which indicates a weakening of the H-H bond. The H-H bond is parallel to the P-W-P vector.

At this time, we can only speculate as to why these complexes coordinate H2 rather than forming dihydrides. The bulkiness of the phosphines is apparently a stabilizing factor, possibly discouraging seven coordination. Theoretical studies of a model complex show the existence of a stable side-on bonded hydrogen configuration. We will continue our experiments to further characterize these unique and most significant species.

O w m o o c o H

2 Fig. 7.1. The molecular structure of W(CO)3(P-i-Pr3)j(ri -H2) based on neutron diffraction data taken at 30 K, including all hydrogen atoms. 150 STRUCTURAL CHEMISTRY, SPECTROSCOPY, AND APPLICATIONS

0.819(9)

Fig. 7.2. Coordination sphere around the tungsten atom in the structure shown in Fig. 7.1.

STRUCTURE OF 1-H-AZEPINE-2-ONE-5-METHOXIME

Don T. Cromer, Robert R. Ryan, and D. Scott Wilbur

Reactions of l,4-benzoquinone-4-methoximes with hydrazoic acid in concentrated sulfuric acid (Schmidt reaction conditions) yield novel ring-expanded products.155 The title compound is one of a series of seven-membered ring compounds that was synthesized by means of this reaction. The structure of this compound was investigated to determine the regiochemistry of the methoxime oxygen with respect to the ring nitrogen. It was important to know this orientation because the structural assignments for the new compounds of this series were made by NMR correlations. STR UCTURAL CHEMIStR Y, SPECTROSCOPY, AND APPLICA TIONS 151

The molecular structure of the title compound (see Fig. 7.3) established that the methoxime oxygen is syn to the inserted ring-nitrogen atom. The syn regiochemistry had been tentatively assigned from NMR correlations with that of several other azepine-2-one-5-methoximes. This structure can now be used as a basis for NMR structural assignments of new compounds in this series. The syn regiochemistry is also interesting with respect to the reaction mechanism. Schmidt reaction products are generally considered to be controlled by steric hindrance around the reacting carbonyl group. Clearly, the reacting carbonyl on the starting material (1,4-benzoquinone-4-methoxime) is sterically symmetric, and a mixture of two geometrical isomers would be expected if only the steric hindrance were involved. The fact that only the syn isomer is obtained suggests that either the methoxime has an electronic influence on the direction of nitrogen insertion (vinyl carbon migration), or the syn isomer is thermodynamically favored and the anti-isomer isomerizes under the reaction conditions. The molecule is very nearly planar. Despite this planarity, the bond lengths indicate that there is little if any ^-electron delocalization in the ring, and we needed an unambiguous assignment of which methoxime geometrical isomer the correlations fit. In addition, we were interested in the theoretical prospect that these compounds might exhibit some n-electron delocalization. The title compound seemed the compound of choice to investigate for aromaticity because it has no ring substituents to twist the molecule out of planarity by steric interactions.

Fig. 7.3. Bond distances (A) in l-H-azepine-2-one-5-methoxime. Standard deviations for all heavy atom bonds are 0.002 A except for C(l)-C(2), which is 0.003 A. Standard deviations for bonds to hydrogen are 0.02 A except C(7)- H(8), which are 0.03 A. 152 STRUCTURAL CHEMISTRY, SPECTROSCOPY, AND APPLICATIONS

SOLID STATE 1SN NMR OF AMMONIA ADSORBED ON Y ZEOLITE

Waiiam L. Earl, Atholl A. V. Gibson,* and Jack Lunsford*

Ammonium Y zeolites are the major source of catalysts for cracking petroleum in the US. We have just completed a survey study of these materials to attempt to determine the nature and number of various sites on these catalysts. All of the samples used in this study were prepared by heating the zeolite of interest under 15 vacuum, cooling the sample to room temperature, and then introducing N-enriched NH3 to the sample. The materials were then loaded into rotors in an argon atmosphere for magic angle sample spinning and NMR spectra were obtained under various experimental conditions. Figure 7.4 shows the 15N NMR spectra of a variety of samples that were heated to different temperatures. The two lower spectra represent NH4 on Bronsted sites in the zeolite. We have interpreted the two sharp peaks as being caused by sites in the large and small pores of the zeolite.

-310 -330 -350 -370 -390

Pfm (CH3NO2)

15 15 Fig. 7.4. Cross polarization, magic angle sample spinning, N NMR spectra of NH3 adsorbed on a series of Y I5 zeolites. Spectrum A is from NH4-Y zeolite; it was heated to 340°C and cooled, and NH3 was added to the sample. Spectrum B resulted from the same conditions except that the sample was heated to 400°C. Spectrum C is from 15 Na-Y zeolite; it was heated to 300°C and cooled to room temperature, and NH3 was added. Spectrum D is from NH4-Y zeolite that was heated to 620°C before addition of the "NH3. In all cases, the heating and treatment with "NH3 were performed in a vacuum line, and an attempt was made to exclude air during the packing of the rotor and the subsequent NMR experiment.

•Texas A&M University STRUCTURAL CHEMISTRY, SPECTROSCOPY, AND APPLICATIONS 153

The broad peak in the center is probably caused by a dispersion of different sites of similar but not identical type in the large pores of the zeolite. The spectrum C represents NH3 that has been tightly adsorbed to the zeolite but is not in one of the chemisorbed (Lewis or Bronsted) sites. It is interesting that we see no such NH3 peak for either spectrum A or B, which implies that the strong adsorption requires the presence of the sodium ion. The top spectrum represents an attempt to generate Lewis sites by heating to high temperature. In this case, we find only a broad peak that is probably caused by two effects. First, zeolites that have been heated to high temperatures are extremely sensitive to water, and there may be a loss of structure of the zeolite because of small amounts of water accidentally introduced in handling. Second, NH3 adsorbed on Lewis sites would be expected to have a somewhat broadened NMR resonance caused by magnetic interactions between the 15N nuclear magnetic 'iioment and the 27A1 magnetic moment. Figure 7.5 shows a series of spectra obtained after various amounts of water vapor were introduced to the samples. Unfortunately, it is difficult to control and measure the exact amount of water introduced under our experimental conditions, but it is clear that the spectra are changing as water associates with the NH3. We have interpreted these data in terms of hydration of the NH^ adsorbed on the zeolite. The series of peaks result from ammonium ions with one, two, and three water molecules hydrogen bonded through the protons of the NHJ. Upon total hydration of the NH4 in the zeolite structure, we obtain the uppermost spectrum in Fig. 7.5. There are still a very few ammonium ions "stuck" to the zeolite framework, but the majority of the ammonium ions are totally hydrated and moving around freely within the cages. Our picture of this final state of hydration is that there are water molecules bound to most of the Bronsted + sites and essentially liquid water with NH 4 dissolved in it in the majority of the pores. At this point, it is not possible to remove all of the water and return to the dry NH^-zeolite by heating because some of the water is tightly associated with the NH\ and we lose NH3 with the H2O. In summary, we have found that 15N NMR is potentially very useful for qualitative studies of zeolite sites and adsorption. To obtain quantitative data, it would be necessary to modify our experimental procedures. Hydration of NH4-Y zeolite produces a material in which the ammonium ions are totally hydrated and are very mobile. 154 STRUCTURAL CHEMISTRY, SPECTROSCOPY, AND APPLICATIONS

I I -340 -350 -360 -370 -380

ppm (CH3N02)

I5 13 Fig. 7.5. Cross polarization, magic angle sample spinning, N NMR spectra of NH3 adsorbed on Y zeolite. In all 1! cases the samples were heated to 400° C and cooled to room temperature, and then NH3 was added. Spectrum A is I5 from a sample that was kept dry following the addition of the NH3. Spectrum B is from a sample that was sealed in a rotor and left in the laboratory for several weeks; an unspecified amount of water diffused into the sample during this time. Spectrum C is from a sample placed in an atmosphere with 50% relative humidity for 6 hours. Spectrum D is from a sample that was placed in an atmosphere with 100% relative humidity for 6 days. STRUCTURAL CHEMISTRY, SPECTROSCOPY, AND APPLICATIONS 155

NMR COILS WITH SEGMENTS WIRED IN PARALLEL

Euchi Fukushima, Stephen B. W. Roeder,* and Atholl A. V. Gibson**

In the usual NMR experiments, the sample interacts with an rf coil, which acts as an interface between the sample and the electronics. In the majority of cases, the coil is made a part of a resonant circuit (aiso called tank circuit). For any given sample, the NMR signal increases with increasing frequency and sample size. However, these two parameters are impossible to optimize simultaneously because, in general, the coil inductance is positively correlated with the coil size, whereas the resonant frequency is negatively correlated. Thus, there is a general problem in trying to perform NMR experiments at very high fields and/or for large samples. Furthermore, the problem of the rf radiation being absorbed in the sample becomes more troublesome at the higher frequencies. This is primarily a dielectric effect wherein the rf electric field interacts with the sample as a microwave oven might. Although there are electric fields associated with any time-varying magnetic field, there are also electric fields simply because of the potential difference from one part of the coil to another. The common solution to the first problem is to reduce the number of turns in the coil while keeping constant the overall coil geometry as well as the wire diameter-to-spacing ratio. This works quite well until the spacing between the adjacent turns becomes a significant fraction of the overall dimension of the coil. Thus, even using this approach, there comes a time when either the desirable frequency is too high for the sample size or vice versa. We have an independent approach to this problem that can be used in addition to the above solution: make the coil with two or more coil segments connected in parallel. In doing so, we reduce both the inductance and the ac resistance for a given coil geometry so that the coil can be used at higher frequencies and/or for larger samples. Our suggestion of wiring coil segments in parallel also offers a possibility for reducing the stray rf electric field seen by the sample. The arrangement with the two sub-coils wound in the same direction (shown schematically in Fig. 7.6(a) has a very strong electric field at the center (for example, from the two coil turns closest to the center, which are at the greatest potential difference at any given time). On the other hand, two sub-coils can be connected in such a way that there is electrical symmetry about the center. This can be accomplished by winding the two sub-coils in opposite directions and passing the rf currents in opposite directions, as shown schematically in Fig. 7.6(b). In this arrangement, the ends are at the same potential so that they do not contribute to the electric field as described above. Figure 7.7 shows the frequency dependence of Q for a 10-turn solenoid, 12-mm i.d., 20 mm long, and wound with #14 bare copper wire. The closed circles show the Q for this single coil, and the open circles show the Q for the same coil after it has been broken into two halves and wired in parallel (as shown in Fig. 7.6(b). The single coil could be usable as an NMR coil to not much more than 35 MHz, whereas the parallel coil could be used beyond 70 MHz for a sample of the same volume.

*San Diego State University **Texas A&M University 156 STR UCTURAL CHEMISTR Y, SPECTROSCOPY, AND APPLICA TJONS

(a) (b)

Fig. 7.6. Schematics of (a) two coils in parallel and (b) two coils in parallel with a plane of electrical symmetry.

We have built coils with segments in parallel and have measured various parameters. We find that wiring coils in parallel indeed increases the upper frequency limit for a given sample geometry and increases the possible sample volume at a fixed frequency. In particular, a coil for a particular sample rewound in two parallel segments increases the upper frequency limit by nearly a factor of 2, and the quality factor Q is comparable at the upper limits. Similarly, a coil having a particular upper frequency limit can be rewound in two sections so that, while maintaining the same upper frequency limit, it is suitable for a sample that is three times larger, resulting in a signal-to-noise ratio that is improved by more than 1.6.

300

100 -

0/2 345678

Fig. 7.7. Plot of Q vs square root off, where f = W2it, for a single solenoid (solid circles) and a solenoid of the same dimensions made up of two equal subsections in parallel with a plane of electrical symmetry (open circles). NUCLEAR STRUCTURE AND REACTIONS 159 NUCLEAR FISSION

FISSION FRAGMENT ANGULAR DISTRIBUTIONS IN HEAVY-ION REACTIONS

H. Chip Britt (P-3), Kari Eskola,* Pirkko Eskola,* Malcolm M. Fowler, Avigdor Gavron (P-3), Henner Ohm (P-3), Arnold J. Sierk (T-9), and Jerrj L. Wilhelmy

Recently, there has been considerable interest in angular distributions of fragments produced by heavy-ion induced fission. Unexpectedly high anisotropic angular distributions have been obtained from composite systems having a very low fission barrier.156 We have extended our studies on fission of preactinide nuclei to include the measurement of the angular distribution of fission fragments for a variety of reactions. We are able to demonstrate that the angular distribution can be modeled successfully using the transition-state model, as long as the fission barrier is comparable to the temperature at the saddle point for most of the participating partial waves. The measurements were performed at the Lawrence Berkeley Laboratory's 88-in. cyclotron by using reactions induced by 95- to 291-MeV 12C ions on 174Yb, 198Pt, and 238U and by 140- to 315-MeV 16O ions onI42Nd, 170Er, 192Os, and 238U. The angular distributions were determined using the experimental setup described by van der Plicht et al.,157 with the addition of an annular parallel plate detector positioned around 180° to the beam axis. The annuli subtended angles from 160 to 176° in 2° steps. Using position-sensitive, low-pressure, multiwire detectors and a "start" detector around 90° in the cm. system let us determine the recoil velocity of the composite system for events reaching these detectors. Thus, we were able to detect the fraction of fission events that followed incomplete fusion and low momentum transfer. This fraction was negligible except in the carbon plus uranium and oxygen plus uranium systems. The angular distributions were calculated using the standard transition-state theory158 and moments of inertia from calculated saddle-point shapes with diffuse surfaces. Figure 8.1 presents the results of our anisotropy calculations and the experimental points for reactions induced by 95-MeV 12C and 140-MeV 16O. Comparing the dashed lines to the hollow circles (:2C, 95 MeV) and solid lines to the solid circles (I6O, 140 MeV), we note the good agreement between experiment and calculation, except for the 140-MeV 16O plus 238U. Figure 8.2 presents a similar comparison for 186-MeV 12C and 250-MeV 16O; we again note reasonable agreement except for the carbon plus uranium and oxygen plus uranium systems. The data for these two systems have not been corrected for fission events that result from low momentum transfer. If these events have the same angular distribution as those resulting from near full momentum transfer, no correction is needed. If we assume that these events are isotropically distributed, we estimate a 30 to 40% increase in the experimental value of the anisotropy for oxygen plus uranium and a 20 to 30% increase for carbon plus uranium at these energies, which increases the discrepancy. Our tentative conclusion from these data is that the transition-state model of angular distributions is adequate if most of the participating partial waves have barrier heights at least as large as the temperature at the saddle point. However, the model breaks down when the fission barriers, for a significant fraction of the partial waves contributing to fission, are less than the temperature at the saddle point. The fact that the measured anisotropies generally deviate to the high side of the calculation indicates that either (1) shapes more extended than the saddle point

* Visiting Staff Members from the University of Helsinki, Finland 160 NUCLEAR STRUCTURE AND REACTIONS

are usually involved in determining the angular distribution or (2) the transition to the final, fission-like configuration is too rapid to enable the K quantum number to be completely equilibrated.

I I I I I I I I I I I I I I l 95MeV

4 6 8 10 12 14 16 Center-of-Mass Scattering Angle 6 Fig. 8.1. Experimental results of anisotropy in fission-fragment yields. The top section gives results for 140-MeV "O-induced fission, and the bottom section gives results for 95-MeV 12C-induced fission. The curves correspond to calculations for each set of data under two extreme assumptions; the lower curve assumes no particle emission before fission; the upper curve assumes maximum particle emission before fission consistent with light particle measurements. The solid curves are calculations for I6O-induced reactions, and the dashed curves are calculations for 12-C induced reactions.

»0 250 MeV

0 2 4 6 8 10 12 14 16 Center-of-Mass Scattering Angle 8 (deg) Fig. 8.2. Results as in Fig. 8.1 but for 250-MeV "0- and 186-MeV 12C-induced fission. NUCLEAR STRUCTURE AND REACTIONS 161

FISSION OF POLONIUM, OSMIUM, AND ERBIUM COMPOSITE SYSTEMS

Hans van der Plicht,* Malcolm M. Fowler, Jerry B. Wilhelmy, H. Chip Britt (P-3), Avigdor Gavron (P-3), Zeev Fraenkel,** Franz Plasil,++ and Glenn R. Young++

Fission probability studies159'160 in the actinides have provided extensive data on the fission barrier parameters in this region and have shown the importance of nuclear shell and shape symmetries for the fissioning system. For lighter nuclei, the fission barriers at small angular momentum become large compared with the neutron binding energies; however, for large values of angular momentum, fission can again become a viable decay channel through the centrifugal lowering of the barrier. The limited amount of data in this region has generally been fit with a statistical model analysis using the underlying rotating liquid drop model of Cohen, Plasil, and Swiatecki (CPS).161 The fits to the fission cross section have generally required the CPS barriers to be lowered by some arbitrary renormalization factor. Because of the limited data available and the need to renormalize, it has not been possible to systematically test the predicted angular momentum dependence or the effects of nuclear shell structure on the fission barrier in this region. The purpose of the current experiment was to obtain a representative set of fission cross- section data that could test both the mass and angular momentum dependence of fission barriers in the mass 150 < A < 210 region. Fission cross-section excitation functions were measured from near threshold to xlO MeV/nucleon using 9Be, 12C, IM8O, 24>26Mg, 32S, and MNi beams at the Brookhaven National Laboratory Three-Stage Tandem Accelerator Facility. The systems studied include 210Po formed in 12C- and 18O-induced reactions; 186Os formed in 9Be, 12C, 16O, and 26Mg reactions; and 158Er formed in I6O, 24Mg, 32S, and 64Ni reactions. In addition, the 204 206 208 I6 I8 composite systems ' ' po formed with O and O projectiles were studied. In the experiments, the velocities and emission angles of two coincident fission fragments were measured using position-sensitive, multiwire, proportional, counter "stop" detectors and a thin («200-ug/cm2) gas "start" detector. The measured fission excitation functions and previous data from 4He and UB bombardments162'163 for the 186Os and 21oPo systems are compared to statistical model calculations that use recent angular-momentum-dependent fission barriers calculated by A. J. Sierk.* The fusion cross section was obtained from the recent Bass model,164 which has given cross-section determinations to an accuracy of ±10% in the mass and energy region we are studying. To test the dependence of the nuclear state density on the fission probability, we have used two extreme analyses. The first was a simple Fermi gas estimate, which should be appropriate at high temperatures, and was calculated relative to the appropriate liquid drop mass surface. The second method that was used was to generate the state densities from single-particle based levels, which is similar to the approach used in our previous actinide work.119 However, in this region, uncertainties about the ground state and saddle-point shapes of high angular momentum precluded drawing any reliable conclusions about the need for collective enhance- ments such as are required to fit the heavier actinide region.

'Michigan State University **Weizmann Institute of Science ++Oak Ridge National Laboratory

"Los Alamos National Laboratory 162 NUCLEAR STRUCTURE AND REACTIONS

Typical experimental results and model analyses for the 138Er composite system are shown in Fig. 8.3. The calculated cross sections agree quite well with the experimental data over a very broad region without arbitrary renormalization factors for the calculated barrier heights. In Fig. 8.4, the improvements associated with the use of the new fission barriers are indicated for two reactions. For these cases, the best absolute cross-section agreement is obtained for the Sierk barriers and the microscopic-level density calculations. In general, comparisons with the data give good agreement both for a wide range of mass of the composite system and for a wide mass asymmetry (and thus angular momentum) in the entrance channel. We conclude that the new Sierk model gives a good description of both the mass and angular momentum dependence of fission barriers in this region.

80 100 120 140 EXCITATION ENERGY(MeV)

Fig. 8.3. Fission cross sections for the 138Er composite system. The points are the experimental data, the solid line is a theoretical calculation using Fermi gas-level densities, and the dashed line uses a microscopic-level density formalism. NUCLEAR STRUCTURE AND REACTIONS 163

10' BO 90 100 110 120 130 BOMBARDING ENERY

Fig. 8.4. Comparison of experimental data for two of the studied reactions with predictions of the theoretical statistical model with angular momentum dependent fission barriers from Sierk (S); Mustafa et al. (M) (Ref. 165, and later consultation with the authors); and Cohen, Plasil, and Swiateeki (CVS) (Ref. 161). Calculations use the microscopic-level density formalism.

NUCLEAR REACTIONS

EXCITATION FUNCTIONS FOR PRODUCTION OF HEAVY ACTINIDES FROM REACTIONS OF 48Ca WITH M8Cm

William R. Daniels, Malcolm M. Fowler, Darleane C. Hoffman, Diana Lee*, Kenneth J. Moody*, Glenn T. Seaborg,* Hans R. von Gunten**, GSIf-Mainzf f Cdllaboration

A series of experiments was performed in 1976 at both Berkeley and Dubna (USSR) in an attempt to produce superheavy elements in the reaction of 48Ca with 248Cm. These experiments were performed with projectile energies about 25 MeV above the Coulomb barrier and resulted in an approximately 40- to 50-MeV excitation of the compound system. The results of these experiments were generally negative in that no evidence for superheavy element production was observed. •Nuclear Science Division, Lawrence Berkeley Laboratory ••Eidgenossisches Institut fiir Reaktorforschung, Wiirenlingen, Switzerland, and Anorganisch-Chemisches Institut, University of Bern, Bern, Switzerland f W. Bruchle, M. Brugger, H. Gaggeler, M. Schadel, K. Summerer, and G. Wirth ffTh. Blaich, G. Herrmann, J. V. Kratz, M. Lerch, and N. Trautmann 164 NUCLEAR STRUCTURE AND REACTIONS I Recently, there has been some success in the use of lower bombarding energies to produce heavy elements by either binary transfer reactions or fusion reactions that use lighter heavy ions of energies near the Coulomb barrier. The most noteworthy example of this success is the announced production166'167 of elements 107 and 109 from the irradiation of bismuth with chromium and iron, respectively/These new results suggested that the 1976 experiments should be repeated at considerably lower energies, and in 1982, a large collaboration began that included Lawrence Berkeley Laboratory, Los Alamos National Laboratory, Gesellschaft fur Schwerionenforschung (GSI), and the Universities of Mainz and Bern. Their goal, once again, was to produce superheavy elements from the reaction of 248Cm with 48Ca projectiles at energies near the Coulomb barrier. The plan was to try the reaction at both LBL and GSI, using on-line techniques and radiochemical methods in irradiations with high integrated beam exposures (> 1017 particles) to span the range of possible half-lives from microseconds to years. Although the probability of successful production of superheavy elements was questionable, the production of a wide variety of actinides, both heavier and lighter than curium, was certain.168 Because it was unlikely that this projectile-target combination would be available for study at a later date, we decided to measure the excitation functions for the production of the actinides formed during the superheavy bombardments. We made similar measurements with 40Ca to assess the influence of the very neutron-rich 48Ca on the production of heavy-element isotopes. The results reported here are from the series of irradiations performed at the Super-HILAC at LBL in October 1982. Results of the irradiations performed at GSI in April 1983 will be reported next year.

Experimental Irradiations and Targets. The target of curium oxide was prepared by stepwise electroplating and contained 1.7 mg/cm2 of Cm (96.5% 248Cm; 3.5% 246Cm). The target was mounted on the accelerator in a gas-cooled target holder as shown in Fig. 8.5. T..J beam first passed through a 1.8-mg/cmz HAVAR window that served as the vacuum seal, then through nitrogen cooling gas at about 1-atm pressure, and finally through the 2.4-mg/cm2 beryllium target backing and into the curium target. A thin aluminum foil (40 ug/cm2) was placed over the curium to catch target atoms knocked out by the beam. A gold or copper catcher foil of about 6 mg/cm2 was placed behind this knock-over foil to collect the recoiling products of the reaction. The 248Cm target was irradiated with 239-, 263-, and 288-MeV 48Ca ions; the energy loss in the target was about 16 MeV. (All energies are quoted in the laboratory system and have been

/ corrected for the total energy loss of about 75 MeV in the HAVAR window, N2 cooling gas, and beryllium target foil.)

HAVAR

Al 2 6.2 MI/CM Fig. 8.5. Schematic of target assembly.

N2 BEAU 0.4 «Ca DC/en2 \ He-cooling 27 l/h NUCLEAR STR UCTURE AND RE A CTIONS 165

Chemical Processing. The catcher foils were dissolved in aqua regia containing «100 counts/minute of 238Pu tracer. In the case of gold foils, the dissolved gold was removed by extraction twice with diethyl ether. The aqueous phase was then heated to remove dissolved ether, and the plutonium was adsorbed on an anion exchange resin column (see next paragraph). When copper foils were used, the actinides were coprecipitated on ferric hydroxide by the addition of ammonia, which complexed the copper, leaving it in solution. Several successive precipitations with ammonia were necessary to completely free the precipitate from copper. The final hydroxide precipitate was dissolved in 9M HCl and contacted several times with isopropyl ether to remove the iron. In general, the described separations from copper and iron were not very satisfactory, and these procedures were changed in the later experiments performed at the UNILAC at GSI in Germany. Plutonium was removed from the 9M HCl solution by adsorption on a small anion exchange resin column (AG1-X8, 3-mm diam by 30 mm long). Two column volumes of 9M HCl were then passed through the column to wash through all of the transplutonium(III) actinides. (This effluent was treated to separate the individual actinides as described below.) The plutonium was eluted from the column with 8Af HCl containing 2% NH4I and 3% NH2OH»HC1. The eluent was evaporated to dryness, fumed with concentrated nitric acid, and finally treated with 3M HCl containing NaN02 to ensure that the plutonium was in the (IV) oxidation state. The resulting solution was then boiled until no more brown fumes were evolved, and the Pu(IV) was extracted into 0.5M HDEHP in heptane. The aqueous phase was discarded and the organic phase was washed with 6M HCl. The plutonium was back-extracted into 6M HCl after reduction to the (III) state with 2,5 di-tei tiary butylhydroquinone (DBHQ). Finally, the HCl solution was washed with benzene, placed in a plastic vial, and subjected to gamma spectrometric analysis. After completion of gamma analysis, the solution was evaporated on a platinum plate and analyzed for alpha and spontaneous fission (SF) activity. The chemical yield ranged from 10 to 40%, as was determined from the added 238Pu tracer. The actinide elements from californium through mendelevium were individually separated by elution from a 2-mm-diam by 45-mm-long column of Dowex-50, X12 cation exchange resin (7 to 10 um) with hot (80°C) 0.5M ammonium alpha-hydroxyisobutyrate at a pH of 3.71. After elution of californium, the pH was changed to 3.89 to remove the berkelium, curium, and americium. The individual actinide fractions were collected dropwise on platinum disks, dried, and counted for alpha and SF activity. The activity from sequential disks that belonged to a given fraction was transferred to a single disk with a small amount of 3M HCl. After evaporation of the liquid, the disk for each fraction was flamed and analyzed for alpha, SF, and gamma activities. The chemical yield for the actinide separations ranged from 50 to 75%.

Results The cross sections for production of plutonium, berkelium, californium, einsteinium, and fermium isotopes are given in Table 8.1 for bombardment of 248Cm with 48Ca ions of 239, 263, and 288 MeV. There was an energy loss of about 16 MeV in the target. (The Coulomb barrier for this system is about 236 MeV.) The cross sections for einsteinium and fermium isotopes as a function of bombarding energy are plotted in Fig. 8.6. The peak of the excitation functions appears to occur at the middle energy of 263 to 247 MeV for all of these isotopes, or about 20 MeV above the barrier. This is in agreement with calculations169 for binary transfer reactions, based on ground state Q values and the Coulomb barriers of the initial and final systems, which 166 NUCLEAR STR UCTURE AND REACTIONS

TABLE 8.1. Cros$ Section* for ProductioaofHetvy Actinidet Bombardment of M*Cm with **Ca of Different Energies - . • \, Projectile Energy* 223 to 239 MeV' 247 to 263 MeV 272 to 288 MeV* Nuclide Cross section Std Dev* Crow section Std Dev* Crou section Std Dev* (ub) (H) fob) (*) dib) (%) Pu243 295 17 515 17 1965 18 245 113 19 26lf 17 1050 19 246 22 50 415. 18 413 31 Bk 245 11.7 22 39 15 66.5 19 246 73 16 272 14 482 15 248m 730 17 1690 17 2680 16 250 690 11 1010 11 2920 11 Cf246 0.25 5 1.4 2 1.0 18 248 101 9 238 9 209 6 250 413 22 2540 8 1935 2 252 50.9 21 231 11 224 16 253 0.81 17 8.2 21 4.0 17 254 0.32 28 1.5 10 1.0 23 Es252 9.46 7 28.4 4 24.3 5 253 4.08 17 10.5 9 7.8 13 254m 0.74 30 1.8 6 1.4 16 Fm252 0.02 38 0.09 30 0.06 1? 254 0.28 8 0.94 6 0.71 8 255 0.21 7 0.90 2 0.62 10 256 0.06 30 0.25 10 0.14 17

"Range of projectile energy in target (laboratory system). 'The standard deviations associated with the quoted absolute cross sections are estimated to be ±12%, in addition to the statistical standard deviation given in the table, which is based on the analysis of the decay data The same radiations and abundances were used as in Ref. 170.

show that the excitation energy E* for these products is negative by more than 10 MeV. A similar plot for californium isotopes is given in Fig. 8.7. Mass-yield curves for berkelium, californium, einsteinium, and fermium for 247- to 263-MeV 48Ca projectiles, the maximum of the excitation function, are shown in Fig. 8.8. The berkelium, californium, einsteinium, and fermium mass-yield curves peak at about mass numbers 249, 250, 252, and 2545 respectively. These maxima correspond to effective transfers of H, 2He, 4Li, and 6Be. The yields for the plutonium isotopes are highest at the highest energy, 272 to 288 MeV. The plutonium isotopes form by effective transfer of 2'5He from target to projectile, rather than from projectile to target. The magnitudes of the cross sections are similar to those measured170471 for the same transfers from other neutron-rich heavy-ion projectiles, for example, 18O, 22Ne, and I36Xe, to actinide targets. Maximum cross sections for various mass beryllium transfers for several different systems are shown in Fig,. 8.9. (Similar curves can be constructed for hydrogen, helium, and lithium transfers.) The beryllium transfers from 136Xe projectiles to 238U targets have about the NUCLEAR STRUCTURE AND REACTIONS 167

10- SO0 220 340 200 2*0 3OO Enargy (M»V>

Fig. 8.6. Excitation functions for production of einsteinium and fermium isotopes from irradiation of "'Cm with 48Ca.

• i • .

•.282 "248 g 102l- u I c 0

o o ^253

100 . J2S4 •248 j

; f 200 220 24O 260 2«0 300 Energy (M»V)

Fig. 8.7. Excitation function for production of californium isotopes from irradiation of M'Cm with 4*Ca. 168 NUCLEAR STRUCTURE AND REACTIONS

24BCm + 48C« (247-203 M«V)

248 248 2BO 352 284 266 Product Ma*« Number

Fig. 8.8. Mass yield curves for berkelium, californium, einsteinium, and fermium at the 4*Ca energy corresponding to the maximum yields.

-.10° 2.5 a.

a en - /

I "*Cm-»Fn. • •*O(IJB) o*«Ca

Fig. 8.9. Cross sections for various mass beryllium transfers from 1BO, 4lCa, and 23*U projectiles to "'Cm to produce fermium isotopes and from 136Xc projectiles to 23>U to produce curium isotopes. Values in parentheses give ratio of projectile energy to Coulomb barrier. Data from Refs. 170 to 173. NUCLEAR STR UCTURE AND REA CTIONS 169

same cross sections as from I8O or even 238U projectiles to 248Cm targets. This tends to support the general idea of a binary transfer mechanism that results in a nucleus with low E*, that is, a "cold" nucleus that is not immediately destroyed by prompt fission or particle emission. Production by compound nucleus formation followed by multiple-particle emission would be expected to give very low cross sections because of fission competition, and it would be unlikely that comparable actinide yields would result from such dissimilar compound nuclei as 266104 and 374146. Use of a heavy target such as 254Es should allow production of neutron-rich isotopes of fermium through lawrencium in yields of 1 nb or more. Isotopes of elements 104 and 105 might be produced by boron and carbon transfers, but no data for such transfers to actinide targets are yet available. Systematic studies of the SF half-lives and properties of a range of these neutron- rich nuclides should give a better understanding of the fission process and help develop a - comprehensive, predictive model of nuclear fission.

PRODUCTION OF NEUTRON-RICH BISMUTH ISOTOPES BY TRANSFER REAC- TIONS

Kari Eskola,+ Pirkko Eskola,+ Malcolm M. Fowler, Henner Ohm (P-3), Elizabeth N. Treher,* Jerry B. Wilhelmy, Diana Lee,** and Glenn T. Seaborg**

This work is one in a series of investigations174'176 of nuclear reactions that lead to production of neutron-rich isotopes. The production cross sections of neutron-rich bismuth isotopes can be measured with high sensitivity through the alpha decay of their short-lived polonium daughters. A fast (15-minute), high-yieid (60 to 80%) chemical procedure was developed to separate bismuth isotopes from other reaction products and to prepare thin sources for alpha-particle counting. The 38-year 207Bi was used to determine the chemical yield for each sample. Metallic, isotopically enriched 2(MPb (98.7%) and 2O5T1 (98.4%) targets and HgS, enriched ia 204Hg (98.2%), were irradiated at Lawrence Berkeley Laboratory's 88-in. cyclotron with 99- to 195-MeV 18O ions. Effective residual transfers of 3>4-5H to 208Pb, 7l8He to 2O5T1, and 8Li to 204Hg were observed. Figure 8.10 presents the results of the cross-section measurements for the 208Pb targets. There are three long-lived states, the 60.6-minute (J* =1") ground state, the 25-minute (J* = 9~) m, isomer, T 212 and the 7-minute (J = 15") m2 isomer in Bi. The cross sections for production of each of these states was measured (see Fig. 8.10), and the resulting isomer ratios are plotted as a function of the 18O projectile energy in Fig. 8.11. The observed isomer ratios, especially the consistently low value of om2/omi (<0.04), seem to imply a relatively low angular momentum transfer to the surviving residual nucleus. An attempt was made to intepret the accumulated cross-section data in terms of current models. The commonly used "sum rule" model177 is not compatible with the observed '"flat" cross-section curves. The relatively constant cross sections observed for the high-energy part of the excitation functions are consistent with the assumption that the transfer probability vs the distance between the projectile and target nucleus centers does not vary with incident energy.178

•Squibb Institute for Medical Research +Visiting Staff Members from the University of Helsinki, Finland ++Lawrence Berkeley Laboratory 170 NUCLEAR STRUCTURE AND REACTIONS

The results of these experiments as well as those of Lee et al.175'176 demonstrate that transfer reactions offer a promising means to produce exotic neutron-rich isotopes. For a full understanding of the reaction mechanism of these highly asymmetric transfer processes, more detailed information on angular distributions, excitation energies, and type of reaction participants is necessary.

80 (00 120 MO 160 180 200 LABORATORY ENERGY OF I8O (MeV)

Fig. 8.10. Measured absolute cross sections for production of 21IBi (o), 212Bi (A), and 2l3Bi (D) when 20*Pb is bombarded by 18O ions. The three dashed curves give the individual excitation functions for the ground state (A), the J" = 9" isomer (V), and the J" = 15~ isomer (Q) of 212Bi. The dotted curve (Ref. 179) shows the shape of the excitation function of the compound nuclear reaction 20SPb("O,3n) 223Th for comparison (not in absolute scale). The arrows indicate observed upper limits for production of 2UBi. NUCLEAR STR UCTURE AND REACTIONS 171

80 100 120 140 160 180 200 LABORATORY ENERGY OF IB0 (McV)

2n Fig. 8.11. The experimental isomer ratios for the J* = 9~(m,) and J* = 15" (m2) states of Bi plotted as a function of the I8O projectile energy. The points joined by eye-guiding lines are associated with bombardments of 208Pb M5 204 targets. The individual points relate to T1 (•) and Hg (o) targets and measured values of the ratio (om /a,.

NUCLEAR CHEMISTRY AT THE LOS ALAMOS MESON PHYSICS FACILITY

PREDICTIONS OF THE QUASI-FREE MODEL FOR THE PIONIC PION PRODUC- TION ON THE DEUTER0N

Lon-Chang Liu, Rajeev S. Bhalerao, and Eliazer Piasetzky (MP-4)

Pion-induced single-pion production in complex nuclei is of fundamental theoretical interest because it provides a new means to study the pion field inside a nucleus. On a free nucleon, the pionic pion production threshold is at an incident pion kinetic energy of T,, ~ 170 MeV. In a nucleus, for simple kinematic reasons, the threshold for pion production is shifted downward as the mass of the nucleus increases. Consequently, we expect that the (n,2n) reaction can have appreciable cross sections even at pion energies of «300 MeV, an energy domain accessible at LAMPF. 172 NUCLEAR STRUCTURE AND REACTIONS

We choose to first study the reaction TC d —>- n+n nn for the following reasons.

1. The deuteron provides the simplest nuclear environment in which pion production involving more than one nucleon can occur.

2. The internal structure of the deuteron has been extensively studied.

3. Because the deuteron is a loosely bound system, we expect the medium modification of the basic production amplitude caused by the presence of the other nucleon will be minimal.

4. The basic production process rc~p —*• n+n~n has the largest cross section among all itN —>KKN processes of the energy domain in which we are interested.

5. Because the double-charge-exchange reaction (TT,JI+) cannot occur on a deuteron, detection of a rc+ represents the signature of the pion production. Consequently, a single-arm detection system can be used to achieve higher counting rates in the initial phase of experimental studies. (The discussion above applies equally to the mirror reaction rc+d —*• n~it+pp.).

In the deuteron, the simplest pion production mechanism is the quasi-free process in which the pion is produced on a single nucleon, and the second nucleon acts as a spectator (Fig. 8.12(a). However, more interesting mechanisms are those in which both nucleons are actively involved, as shown in Figs. 8.12(b) to 8.12(d). In addition, higher order, two-nucleon processes exist that

involve both TTN and NN rescatterings. At Tw > 250 MeV, there is evidence that the basic

(c)

Fig. 8.12. Diagrams contributing to the reaction it d —> n+n nn: (a) Born approximation, (b) JT production followed by ;iN rescattering, (c) Jt production followed by NN rescattering, and (d) deuteron breakup followed by it production. In all diagrams, £2d is the wave matrix for the distortion of the pion wave; the open circle is the dpn vertex; the shaded circle is the production amplitude; and the solid circle is the JiN or NN scattering amplitude. NUCLEAR STR UCTURE AND REA CTIONS 173

production could proceed by means of intermediate JIN and nn resonances, including the A(1232) resonance (Fig. 8.13).18O>181 Considering the fact that the TIN rescattering can also proceed through the formation of a A(1232), we then have a situation in which two A(1232) can be present simultaneously. Recently, G. E. Brown et al. have proposed a double-A model to explain certain features of pion absorption by nuclei.182 It seems useful to further examine this mechanism by the use of other nuclear reactions, such as the iCd —*• rc+Jt~nn reaction. In this report, we only briefly describe our calculations of the diagrams shown in Figs. 8.12(a) and (b). We have also omitted the distortion of the incoming pion wave. This approximation should not affect our conclusion concerning the relative importance of these two diagrams.

(b) (c)

Fig. 8.13. Pion-induced single-pion production on a nucleon (Isobar model). Each of these diagrams is further supplemented by diagrams obtained from crossing the pion lines.

In the plane-wave Born approximation of Fig. 8.12(a), the double differential cross section in the cm. system, which corresponds to detecting the n+ at a given energy and a given angle, can be written as

d2q _ K f -&s- JJV / \ dcos9, * J (E4/M) ^ \da>* dcos8,V Jv

(1) where the subscripts 1 and 4 refer, respectively, to the n+ and the spectator neutron, and K is a kinematical factor. The quantities denoted with * are defined in the cm. frame of the ji~p system, and J = (dco*/do),) (dcosO^/dcosBj) is the Jacobian of transformation. The u and v' are the spin projections of the neutrons, and the v and X are, respectively, the spin projections of the proton and the deuteron. The «j) is the wave function of the deuteron, and Q is the momentum variable. In the nonrelativistic limit, Q = k0 + P4, where k0 is the cm. momentum in the rcd system. Calculated cross sections shown in this report are based on the deuteron wave function of Ref. 183. Use of other deuteron wave functions has led to essentially identical results. 174 NUCLEAR STRUCTURE AND REACTIONS

We have used experimental d2o/dtodcos8 values for the reaction 7i~p —»• n4jr~nn as the input to our calculations and have parameterized them according to

1 dVdco dcose = f V Ao (^'(cosfi) ) x Ph3(tf,cos8), (ij =0,1,2) (2)

Here, Ph3 is the three-body phase space integrated over the other variables, and W is the invariant mass of the n~p system. Because the experimental double-differential cross sections are averaged over the spin of the nucleons, the use of Eq. (2) also requires the introduction of an appropriate spin average in Eq. (1). When the diagrams of Figs. 8.12(a) and 8.12(b) are included, the differential cross sections are given by

dk2 kid (E4/M) ("ETMT 2^7 ^

x 5(

2 + [(a)1+E4-E4) -< + ie 1'4')} (3)

Here, we use CO; = (k] + M^)l/2, (i = 1,2) and E, = (P2 + M2)1/2, 0' = 3,4) to denote, respectively, the pion and nucleon energies in the final state. W is the total energy of the nd system and is given by 2 I/2 2 1/2 + W = (k + M^) + (k + M^) . Further, Tu,u denotes the 7i n scattering amplitude. The momentum variable of the deuteron wave function is Q' = 1/2 ko + P4'. We can show that this expression reduces to Eq. (1) when the rescattering term is absent. An exact evaluation of Eq. (3)

requires knowledge of the phase of the production amplitude Mp/ll. Because we are using experimental cross sections to infer M, we have neglected the phase of MvW and carried out the spin average over M,,,,,. As a further simplification, we have calculated the rescattering by using on-shell geometry. This approximation might be justified by the fact that the average separation between the two nucleons in the deuteron is large compared to the range of JtN scattering. Results of our calculations are presented in Fig. 8.14. The solid curves represent cross sections obtained from a four-body phase-space calculation, assuming M^ x = constant. The other four curves are based on Eqs. (1) and (2) and the quasi-free model; they correspond to the cross sections calculated with cos9, = 0.75 (the dashed curve), 0.25 (the dot-dashed curve), -0.25 (the dotted curve), and -0.75 (the crossed curve), respectively. We note that the phase-space result is independent of cosS^ The solid curve has been normalized to yield the same total production cross section as was obtained with the quasi-free model. With respect to the phase-space calculation, use of the quasi-free model shifts the maximum of the cross sections to a higher value + of T15 the kinetic energy of n in the four-body cm. system. The shift is larger for smaller values of 9,+(denoted 0,). NUCLEAR STRUCTURE AND REACTIONS 175

300

€0 T [M»V] Fig. 8.14. Double-differential cross section for the reaction n~d -»• n+7t"nn at T,- = 256 and 331 MeV. The quantities f and fi denote, respectively, the kinetic energy and the solid angle of n+ in the cm. frame of the four-body system.

The differential cross sections predicted by the quasi-free model at TK~ = 256 MeV agree fairly well with the preliminary data obtained at LAMPF (Exp. 783, LAMPF-MIT-Tel Aviv collaboration). The inclusion of n+n rescattering increases the calculated cross sections. The increase is larger for smaller values of cos9j. For cosG, = +0.75, calculated cross sections are, respectively, increased by about 4 and 6% at 256 and 331 MeV. For cosG, = -0.75, the Ji+n rescattering increases the cross sections in the region where there is a maximum by about 20 and 30% at 256 and 331 MeV, respectively. We are now generating theoretical results that are based on the use of microscopic theories for the basic 7tN —y nrcN process and on full calculations of all the diagrams shown in Fig. 8.12. Because the average energy for nN rescattering at 256 and 331 MeV is equivalent to free pion- nucleon scattering at pion energies between 60 and 100 MeV (well below the A(1232) resonance energy), we plan to carry out studies of the n~d —*• 7t+7t~nn reaction at higher energies to look for a clearer signature of the double-A mechanism.

A NEW LOOK AT (n,nN) REACTIONS

Yoshitaka Ohkubo and Lon-Chang Liu

Pion-induced single-nucleon removal reactions, the (7t,7tN) reactions, have been extensively studied at LAMPF and other meson facilities. Although most of the measured excitation functions, angular distributions, and energy spectra of the outgoing pion and nucleon seem to support the conventional quasi-free knockout mechanism, ratios of measured (rc~,JiN) to (7t+'jrN) cross sections indicate otherwise. For example, at Tlt= 180 MeV, the free A(1232) resonance 176 NUCLEAR STRUCTURE AND REACTIONS

184 185 12 n I2 + n energy, the ratio ' ofo[ C(jt-,jiN) CJ to o[ C(n ,rtN) C] [denoted O(TT)/O(71+)] is 1.6. However, simple isospin considerations pertinent to quasi-free knockout models lead to a ratio of «2.9. The first attempt to understand this discrepancy was made by Hewson, who supplemented the quasi-free knockout model with charge exchange between the outgoing nucleon and the residual nucleus.186 Thus, in Hewson's model, the processes that can lead to a ratio of nC nucleus that is observed in the radiochemical experiments of Refs. 184 and 185* are quasi-free elastic scattering,

7t± + 12C^Jt± + 1IC + n; (1)

quasi-free pion charge exchange,

0 JT+ + '2c ->• it + "C + p; and , (2)

quasi-free elastic scattering followed by nucleon charge exchange,

n* + I2C -• jt1 + nB + p -* 7t± + nC + n. (3)

Process (3) is absent in the conventional quasi-free knockout model. We emphasize that because processes (1) and (3) lead to the same final state, they must be added coherently so that the interference between these processes can be taken into account. As we shall see, this interference is important. Hewson's calculations led to a cross-section ratio that is considerably smaller than the free-space value of ^;2.9. However, because he neglected both the rc~N isospin I = 1/2 channel and the distortion of the pion wave functions, he was unable to predict the magnitude of the cross sections. Silbar and Sternheim188 simplified the Hewson model to obtain with ease the energy dependence of the measured cross-section ratios for 12C, as reported in Refs. 184 and 185. If P represents the probability of NCX before the nucleon leaves the nucleus, and (1-P) represents the probability that the nucleon emerges in its original charge state, then the ratio, according to Silbar and Sternheim, becomes

_ G(7T+) (1 -PX^+n _^ *+„ + »„+„ _^ *°p) + P°*+p _^ *+p ' (4) with

[l-exp(-cyexPd)] 2 ' (5)

and °ex = PTn"!-9 (6)

Here, the cross sections appearing in the right side of Eq. (4) are the free ;r~N cross sections. The p, d, and Tn are, respectively, the nuclear density, the average distance traveled by the nucleon, and the nucleon kinetic energy. The constant P in Eq. (3) was treated as an adjustable parameter

•Hewson's calculation addressed the experimental data obtained by Chivers el ai. (Ref. 187); however, it appears that their data were incorrect. The reliable data were obtained by Dropesky et al (Refs. 184 and 185). NUCLEAR STRUCTURE AND REACTIONS 177

to fit the experiment. Because of the apparent success of the model in reproducing the 12C experimental data, many efforts have been made to further test this simplified version of the Hewson model.189-190 However, we see from Eq. (4) that terms representing interferences between the NCX and the pure quasi-free process have been erroneously omitted. Because of this omission, the identification of P with the NCX probability in the Silbar-Sternheim model is, in. fact, meaningless. Recently, we have calculated the cross sections 0(71* ) and their ratios for 12C, taking into account the interference effect. We have included in our calculation the n~N isopin I = 1/2 component that Hewson neglected. We have also calculated the distortions of the pion and the nucleon by using realistic pion-nucleus and nucleon-nucleus optical potentials191"192 and the Eikonal approximation. In Fig. 8.15, we show the cross-section ratios. The cross-section ratios given by our detailed quasi-free calculations differ already from the free n~N scattering cross- section ratios, even when NCX is absent. (Compare dashed and dotted curves in Fig. 8.15). The effects of initial- and final-state pion-nucleus charge exchanges are not shown in shown in this figure because they are quite small.

I -»•

100 200 300 (MeV)

Fig. 8.15. Cross-section ratios for the 12C(jt±,rcN)"C reactions. The dotted curve represents the ratio of free JI N cross sections, o(n"n -»• n'n)/\a(n+n -• n+n) + o(n+n -» Jt°p)]. The dashed curve is the result of calculations based on pure quasi-free scattering processes (1) and (2). The solid curve represents calculations based on processes (1), (2), and (3), including interference efFects. The experimental data are shown as the shaded area (Refs. 184 and 185).

In Fig. 8.16, we compare our calculated cross sections with the experimental data184'185 for the 12C(jr,TtN)HC and 12Cn+,nN)MC reactions. Our calculations are able to reproduce reasonably well the energy dependence and the absolute magnitude of the cross sections. It is worth pointing out that, so far, there has been no published calculation that can account for both the observed cross-section ratios and individual cross sections. In Fig. 8.17, we show important contributions to ofitT ) that arise from the interference between NCX and pure quasi-free knockout processes. For 12C, we have found that the interference is constructive at all energies. However, for some other nuclei, this interference could be destructive. To obtain a reliable understanding of the magnitude of (n,nN) cross sections, it is 178 NUCLEAR STRUCTURE AND REACTIONS

O 100 200 300 TV (MeV)

Fig. 8.16. Cross sections for the "Cfr^rcN^C reactions as a function of pion kinetic energy. Shaded areas and solid curves have the same meaning as in Fig. 8.15.

. 1 1 1 1 1 w~ - -

o 1in0 - M - ^ - oC

3 IT* £20 -- --- — __ -

—•^ —- 1 1 | 100 200 300 T_ (MeV)

Fig. 8.17. Per cent of NCX and interference contributions to o[l2C(Tt±,nN)I1C]. The solid curves represent interference; dashed curves represent NCX.

clearly necessary to treat carefully this interference phenomenon. In the case of 12C, the inclusion of interference has, by accident, little effect on the calculated cross-section ratios. Again, we have no reason to assume this insensitivity is true for other nuclei. References 184 and 185 noted that the intranuclear cascade model failed to represent the data. It now becomes clear that in principle one should not expect that model to explain the data because the quantum-mechanical interference aspect of the reaction 12C(7r±,7tN)11C is absent in the theory. Our study shows that it is dangerous to construct nuclear reaction models that are based on classicaJ concepts. Indeed, only a correct theoretical framework will produce meaningful studies of reaction dynamics and nuclear structure. NUCLEAR STRUCTURE AND REACTIONS 179

TIME-OF-FLIGHT ISOCHRONOUS (TOFI) SPECTROMETER

Jan M. Wouters, David J. Vieira, Hermann Wollnik,* Harald A. Enge,** James R. Sims (Group MP-8), Donald C. Clark (Group MP-8), and the TOFI Collaborationf

TOFI, which is being constructed jointly by INC and MP Divisions, is designed to measure, in a systematic fashion, the ground state masses of the light neutron-rich nuclei with A<70 that lie far from the valley of beta-stability. The scientific goals and overall design of the TOFI spectrometer were described in the 1982 Annual Report.193 During the past year, the spectrometer optical design phase was completed and the engineering and construction phases were begun. In particular, the position and specifications of all optical elements have been defined, enabling the refurbishment of appropriate quadrupole magnets and the designing of the main spectrometer dipole magnets. The installation of TOFI has also started; water cooling lines have been added, and the former Group MP-7 machine shop was altered to accommodate the transport line and spectrometer. This year's report summarizes the final design for the spectrometer and describes the engineering and construction work.

Design of Spectrometer Dipole Magnets The optical design of the TOFI spectrometer is based on an achromatic system composed of four identical unit cells; each cell consists of an integral function, 81° dipole bending magnet sandwiched between two identical drift lengths. (A paper describing the details of the optical design has been prepared for publication.194) The design of these dipole magnets constituted the major development effort during the last year. After the overall optical properties of the spectrometer were specified, preliminary designs for the dipole bending magnets were drawn up, modeled (using the POISSON magnet code), and further refined until a magnet design was obtained that satisfied the overall optical properties. This final design (Fig. 8.18) uses a basic H magnet structure and produces a maximum field of 8 kG with a uniformity of 1 part in 104 extending 12 cm horizontally and 5 cm vertically on either side of the beam center line. To achieve this uniformity, Rose shims were added to the inside and outside edges of the pole pieces. In addition, correction coils that consist of copper patterns etched on printed circuit boards will be attached to the pole tip surfaces of each magnet. The shape of these coils will compensate for any nonuniformities in the measured magnetic fields of the uncorrected dipole magnets. An air gap, known as a Purcell gap, will also be left between the pole piece and yoke to ensure that these components are mechanically decoupled; this will prevent any distortion of the pole tip (and thus, distortion in the field) after the dipole magnet is energized. Shaping the poles at the entrance and exit to the magnet will provide vertical focusing, and radial focusing will be achieved through proper selection of the bend angle. Specifically, to obtain proper vertical focusing, the poles' entrance and exit edges will be rotated 23.3° with respect to normal entry of the beam. Precise chamfering of the edges will permit alignment of the effective field boundary (EFB) with the physical pole tip edge, facilitating the position of the magnets as well as making the EFB more field-strength independent. Correction iron pieces, called "organ

•Permanent address: University of Giessen, West Germany "Permanent address: Massachusetts Institute of Technology f A collaboration with scientists from the following institutions: Los Alamos, Clark University, Brookhaven National Laboratory and the University of Giessen Fig. 8.18. (a) Layout and (b) cross-section views of a TOFI spectrometer dipole magnet. NUCLEAR STRUCTURE AND REACTIONS 181

pipes", will be attached at the entrance and exit of each pole tip so that small adjustments may be made to the profile of the (EFB). These "pipes" consist of small rectangular blocks that are arranged in a row across the pole edge and can be raised or lowered, thereby decreasing or increasing the field in that region. Finally, mirror plates, located outside the coil at the entrance and exit to each magnet and consisting of l-in.-thick steel plate, are used to define, adjust, and rotate the position of the EFB. Tuning these different knobs through field measurements and/or empirical optimization with radioactive sources will allow us to trim the magnets without expensive remachining of the pole tips. Figure 8.19 shows the calculated magnetic field shape in the magnets as determined by the POISSON code. The anticipated optical aberrations of the spectrometer are expected to introduce a time deviation of less than 50 picoseconds for ions that have identical mass-to-charge ratios but follow different trajectories through the spectrometer and are confined within the solid angle and energy acceptances of ft = 2.5 msr and AE/E = 8%, respectively.

oouu 9000 Useable Reid Region 8000

turn 7000 \ Effective Field 6000 Boundary - 5000 1 - \ 3. 4000 - \ 8800 3000 -

2000 8100 - \ 1000

nnnn 0 i i i 2 4 6 8 10 12 14 16 18 20 413 SO 60 70 80 90 10 X-Dislance Fhjm Midplane (cm) Z-Distance Fbom Midpoint (cm)

(a) (b)

Fig. 8.19. Magnetic field profile as calculated by the POISSON magnet code. Curve (a) shows profile in cross section, and curve (b) shows profile along beam axis.

Project Status All engineering drawings for the dipole magnets are essentially complete, and the copper conductor for the coils has been ordered. Bids have been received for the coil fabrication, and a contract should be signed by October 1983. Related efforts include designs of the vacuum system, control system, detector boxes, and collimators. Another high-priority task is the design and fabrication of all components needed to install the first section of the transport line during the 1984 winter shutdown of LAMPF. In preparation for this installation, all quadrupole magnets in the secondary beam transport line have been refurbished, and the first quadrupole triplet stand is being designed. When this first section of the transport line is completed, the remainder of the transport line and TOFI can be installed 182 NUCLEAR STRUCTURE AND REACTIONS

independently of the LAMPF beam operation. Moreover, completion of this part of the transport line will enable the characterization and performance optimization of one key component: the mass-to-charge filter. New detector developments will be tested using this first section of the transport line.

Future Plans Assembly and off-line testing of the spectrometer are the most important goals to be completed during 1984. Orders for all subassemblies of the dipoles and their support structure should be placed by December 1983. Field map measurements should commence during summer 1984, and off-line tests using alpha and fission sources will begin in the fall. Work will continue in preparation for the LAMPF shutdown and installation of the first section of the transport line through fail 1983 and winter 1984; the line should be completed in early 1985. The first on-line experiment, which is scheduled for summer 1985, will be directed towards the testing and optimizing of TOFI with the goal of investigating the rapid onset of prolate deformation that has been observed in the neutron-rich sodium isotope region.195*196

LAMPF He JET COUPLED MASS SEPARATOR PROJECT

Merle E. Bunker, Willard L. Talbert, Jr., and John W. Starner

Introduction The technical feasibility of constructing a He-jet coupled on-line mass-separator facility at LAMPF is under investigation. The He-jet system would rapidly transport short-lived fission and spallation products from a target chamber to the ion source of a remote separator. The He-jet technique, as a method for transporting radioisotopes to an isotope separator, has two main advantages: (1) it provides access to the isotopes of a number of elements that cannot be efficiently extracted for study at any other type of on-line facility, either present or proposed, and (2) low cost. Except for gaseous products, all elemental species are transported efficiently with a He-jet system, including the refractory metals such as zirconium, niobium, molybdenum, technecium, palladium, ruthenium, and rhodium. In contrast, the relatively massive targets that must be used (because of the low beam currents) at other major on-line separator facilities almost completely retain the refractory-meial radionuclides, making it virtually impossible to study these activities. Use of the thin targets required in the He-jet method necessitates a very large incident beam current, of the order of that available at LAMPF, to produce a sufficient yield of individual radioisotopes for detailed study. The separated ion beams extracted from the proposed separator would be directed to various experimental devices that are capable of determining basic nuclear properties such as half-life, spin, nuclear moments, mass, and nuclear structure. The data acquired would have a broad application to theories" of nuclear matter and such related topics as nucleosynthesis of the elements. Emphasis initially would be placed on the study of short-lived neutron-rich fission products. Fission is the only way to reach very neutron-rich nuclei, and among the refractory metals alone it appears that we would have a good chance of identifying and making measurements on at least 150 previously unobserved isotopes. These prospects would inevitably attract a sizeable international user group. NUCLEAR STRUCTURE AND REACTIONS 183

This project was initiated in FY 1981 with a proposal to conduct experiments at LAMPF. The initial FY 1982 experiments, which used a rather simple target chamber and activity collection arrangement, yielded very promising results on the activity transport efficiency for both fission and spallation reaction products. The experiments were carried out with little flexibility;onl y one target-chamber pressure was used, only one aerosol sodium chloride was employed, and beam current and aerosol furnace temperature variations were not made over wide ranges. Hence, plans were made for further investigations at LAMPF in FY 1983. The additional experiments were designed to investigate the influences of beam current variations, aerosol furnace temperatures, and target-chamber pressures. It was also proposed that lead chloride be studied as an alternate aerosol.

New Results In preparation for the second set of experiments, several activities were undertaken. An extensive program to measure aerosol properties was initiated, using equipment that was purchased or borrowed from Group HSE-5. From these measurements, it was established that both sodium chloride and lead chloride aerosols had favorable number densities and sizes and that the capillary transport line had a noticeable, but not drastic, filtering effect on aerosol sizes. In the second set of experiments, a new target-chamber design was needed to determine pressure effects on transport efficiency and transport time. With assistance from LATA and MP Division, a new target-chamber concept was developed that allowed the target-chamber thickness to be changed for each pressure of interest (the chamber thickness corresponding to the fission-product range in helium at the pressure used). Finally, analytical calculations were made to predict the transit times through the capillary. The above preparations were accompanied by a series of discussions with MP-Division staff, which resulted in (1) the inclusion of space for a He-jet target facility in the plans to reconstruct the beam-stop area of LAMPF and (2) provision for space in the new LAMPF staging area for an isotope-separator system. The above experiments were performed in November 1982, and most of the experimental objectives were met successfully. The LAMPF operations staff provided an intense, steady, tightly focused beam, which made it unnecessary to proceed with plans to continue these studies with a Line-A (main beam) experiment. The major results of the experiments are summarized below. A moving tape collector was used at the collector chamber to rapidly transport collected samples of activity to a weli-shielded detector. The tape collector provided us with the capability of observing short-lived activities, of half-life 1 to 5 seconds. The observed counting rates of 238U (p,f) products were very high, and in the resulting spectra, many of the gamma-ray peaks cannot be identified from previously reported, studies. The transport efficiencies for the more refractory element activities averaged about 60%, measured absolutely. At higher target-chamber pressures (up to 600 kPa), the short-lived activity levels were much higher than those observed at 200 kPa, in keeping with faster transport caused by higher flow rates. Figure 8.20 shows a comparison of the elements observed at LAMPF (Experiment 629) with those accessible at two other major on- line facilities (ISOLDE197 and TRISTAN198) where fission-product activities are studied. Transit time measurements were performed for various conditions, with the best result being 230 milliseconds for a target-chamber pressure of 500 kPa. The calculated prediction for the transit time at this pressure over a capillary length of 22 m is 320 milliseconds. Because the calculation is based on an average flow velocity in the capillary, the experimental result suggests 184 NUCLEAR STRUCTURE AND REACTIONS

,H ^Ll B 0 H n F No ,AI ^s' ,f' , K Sc ,,V r jNJ_ 9 2 iS if' T9° r 4Nb Jc A ,Cd i 4 9 4" Ja g« Jr 7^ 7^ 7 7*" w •8" 104 105 106 107 109

LANTHANIDE SERIES sLa

rfc |jh |tfa

ELEMENTS. SEEN AT SEEM AT n EXPT. 629 ISOLDE a TRISTAN

Fig. 8.20. Periodic chart showing elements directly produced in LAMPF Experiment 629 (He-jet feasibility experiment) and at the on-line isotope separator facilities ISOLDE and TRISTAN.

that the aerosols are herded into the central part of the capillary during flow, thus acquiring a larger-than-average flow velocity. The transit time measurements are convincing that activities as short as 300 milliseconds could be readily studied with the proposed He-jet on-line mass- separator system. During variation of the proton beam current over a range of 1.5 to 6.1 uA, we observed no variation in the transport efficiency. Postexperiment scans of the beam-induced activity in the 238U target foils indicated that, at the highest current, a beam current density of 45 A/cm2 had been achieved. In comparison, the highest expected beam current density on Line A is about 35 uA/cm2. From these data, we conclude that a well-designed He-jet target chamber should function satisfactorily in the intense LAMPF beam, which resolves one of the major concerns we have had about the feasib1' .ity of the planned on-line facility. The highest target-chamber pressures used (500 and 600 kPa) resulted in capillary flow for which the Reynolds number exceeded conventional laminar flow design limits (value of 2200). However, the activity rate continued to increase when these pressures were used. The conclusion is that any turbulence resulting from the flow did little to disturb the transport of the heavy aerosols. The temperature dependence of the amount of transported activity verified that the activity attaches to the aerosols according to total aerosol surface area. This fact had been indicated in unrelated studies at aerosol laboratories for aerosols in the size range employed (less than 0.1 um). Aerosol samples were collected for electron microscopy, and aerosol size-distribution measurements were made on activity-loaded aerosols. The electron microscope pictures of the lead chloride aerosols revealed that the aerosol particles are not spherical but resemble chains of smaller nucleations, resulting in a very high ratio of surface area to mass. NUCLEAR STRUCTURE AND REACTIONS 185

Reports of these experimental results have been presented to the LAMPF Program Advisory Committee and Experimental Area Development Committee, to DOE/HENP, and at the Spring 1983 American Physical Society Meeting in Baltimore.199

Status and Future Plans The availability 'of H~ beam at LAMPF is too infrequent and too short to be able to make systematic studies of target design parameters to optimize the design for a Line-A target chamber. We have therefore installed a He-jet target chamber in a neutron beam port at the OWR to continue these studies and arrive at an optimum configuration regarding (1) the effect of using multiple capillaries rather than only one; (2) capillary and helium supply line placement that would result in the highest target volume sweep rate; and (3) evaluation of the candidate aerosol materials sodium chloride, lead chloride, and potassium chloride to determine which will provide the highest transport efficiency. The experiments are expected to take about 6 months to complete. We have started intensive preparations to develop a compelling case for funding the proposed on-line mass-separator system. Included in these preparations are cross-section (and thus, expected activity) estimates and regions of particular interest for studies that will complement those carried out at other facilities. As an example, Fig. 8.21 illustrates "unexplored territory" available at a LAMPF on-line system—areas for which other facilities have no capabilities. A proposal will be submitted to DOE/HENP for funding that would commence in FY 1985.

known muaes 80- 300 ms limit (Takahashi et «l) \* .;• ^BH possible only «• 60- •" wUh He jet ppr- §0M-. j III. Z 40-

20-

0- i i i i i 0 20 40 60 80 100 120 M0 160 180 N

Fig. 8.21. Chart ofnuclides illustrating present limits of measured masses, 300-millisecond limits (according to gross theory of beta-decay, see Ref. 200) and regions of nuclei uniquely available with a He-jet system at LAMPF. 8,

NUCLEAR FISSION

159 Fission Fragment Angular Distributions of Heavy-Ion Reactions 161 Fission of Polonium, Osmium, and Erbium Composite Systems

NUCLEAR REACTIONS

163 Excitation Functions for Production of Heavy Actinides from Reactions of "Cavrith^Cm 169 Production of Neutron-Rich Bismuth Isotopes by Transfer Reactions

NUCLEAR CHEMISTRY AT THE LOS ALAMOS MESON FACILITY

171 Predictions of the Quasifree Model for the Pionic Pion Production on the Deuteron 175 A New Look at the (it, *N) Reactions 179 Time-of-Flight Isochronous (TOFI) Spectrometer 182 LAMPF He-Jet Coupled Mass Separator Project IRRADIA TION FA CILITIES 189

OMEGA WEST REACTOR

Herbert T. Williams, Alvin R. Lyle, Michael M. Minor, and Merle E. Bunker

Operations The Omega West Reactor (OWR), shown in Fig. 9.1, provides experimentalists with an intense source of thermal and epithermal neutrons. Thermal fluxes as high as 9 x 1013 n/cm2s are accessible at the normal reactor power level of 8 MW. During FY 1983, 25 Los Alamos groups and 6 outside laboratories made use of the reactor facilities. Approximately 12 000 samples were irradiated and over 1200 experiment hours were logged by users. Following is a partial list of experimental activities supported by the reactor operation during the fiscal year.

Weapons

• Radiochemical diagnostics (Group INC-11): Tracers for radiochemical procedure development, neutron activation analysis (NAA) of shot-hole rock, activation of fissile elements for interlaboratory calibrations, neutron cross-section measurements, production of sources for detector calibration.

• NAA of airborne debris (Patrick Air Force Base) I

• Neutron radiography of weapon components (Group WX-3)

• NAA of weapon components (Group INC-5)

Inertial Confinement Fusion

• Activation of microspheres for radiochemical diagnostics (LLNL)

Laser Isotope Separation

• Tunable laser crystal production by neutron irradiation (Group CHM-6)

Space Reactor Program (SP-100)

• Neutron radiography of heat pipes (Group WX-3)

Nuclear Safeguards

• Spent-fuel scans for development of safeguard techniques and instrumentation (Group Q-4)

• Training of IAEA personnel (Group Q- \) 190 IRRADIATION FACILITIES

Fig. 9.1. Cutaway view of the OWR. IRRADIATION FACILITIES 191

Waste Isolation

• NAA for trace elements in Nevada basalts (Group INC-7)

• Uranium assay of water and leachates (Group INC-7)

• Tracers for water migration studies (Group INC-7)

Resource Assessments

• NAA for resource study of Alaska (Groups ESS-2 and INC-5)

• NAA for resource study of Caribbean islands (Groups ESS-2 and INC-5)

Geothermal and Geochemical

• Tracers for hot dry rock project (Group INC-3)

• Geological study of Nevada Test Site (Group ESS-2)

• Geological and geochemical studies of volcanic areas (Group ESS-1, University of New Mexico, and Western Washington University)

Environmental Assessments

• NAA of environmental surveillance samples from Los alamos and other laboratories (Groups HSE-8 and LS-6)

• NAA of Texas lignite samples (Group CHM-1)

• NAA of uranium mill tailings (SNL)

Health and Safety

• NAA of urine for fissile material (Group HSE-5)

• NAA for j.esence of PCBs in oils (Group CHM-1)

• Calibration and testing of thermoluminescent radiation detectors (Group HSE-1 and LLNL)

Research

• Yields of short-lived fission products (Group INC-11 and Washington University)

• NAA for boron in meteorites (Group INC-7) 192 IRRADIATION FACILITIES

• Helium retention in uranium tritide (Group WX-5)

• Uranium and plutonium tritide structure studies (Group WX-5)

• NAA for platinum-group metals study of Cretaceous-Tertiary extinction (Group INC-11)

• Nuclear structure using radionuclide decay (Group INC-5)

• Nuclear structure using (n,y) measurements (P-Division)

New Experimental Activities

• A He-jet radionuclide transport system has been set up at the OWR to study the performance of various target-chamber configurations and aerosols. These studies will help optimize the design of a proposed He-jet coupled isotope-separator facility at LAMPF (Groups INC-5 and INC-11).

• An aluminum-iron-sulfur filter that transmits primarily 24-keV neutrons has been installed in the west 6-in. port of the OWR. This device was designed both as a 24-keV irradiation facility for Group INC-11 calibration foils and as a potential 24-keV beam facility for prompt (n,y) studies by the Physics Division Neutron Measurements Group (Group P-15).

• A fast-chemistry system using high-speed centrifuges, known internationally as a SISAK system, has been set up on the south face of the OWR for the purpose of measuring absolute fission yields of several short-lived fission products. The fission products are generated by neutron irradiation of a 235U solution, which is pumped through a loop of tubing that penetrates the OWR thermal column (a joint Group INC-11, Washington University project).

• A dynamic neutron radiography setup has been assembled by Group INC-5 and the Fabrication & Assembly Group of WX Division for use with the pinhole radiography geometry at the OWR discussed in the 1982 INC-Division Annual Report.201 This setup allows video observation and recording of fluid or component motion inside a sealed assembly.

«***• .<„;..,...a.. - , ~r.*3i8Z&s'?:rt*. —

Om«f» West Reactor

3 a °

I 195 Accelerator-Based Mass Spectrometry of l6Be 200 Development of a Gas Ionization Detector for Direct Mass Measurements at LAMPF

" O

ffJ- •.-. ^Jip- • - • ^ ;*««• JSP ADVANCED ANALYTICAL TECHNIQUES: DEVELOPMENT AND APPLICATIONS 195

ACCELERATOR-BASED MASS SPECTROMETRY OF 10BE

Malcolm M. Fowler, Jerry B. Wilhelmy, Larry J. Rowton (P-9), and Joseph R. Tesmer (P-9)

Beryllium-10 is being investigated for its utility in the weapons diagnostics program. The long 10Be half-life (1.6 x 1010 years) and the small samples available from chemical extraction of postshot debris preclude the use of conventional analytical techniques. With this application in mind, INC Division and Group P-9 started an accelerator-based mass spectrometry program to demonstrate the feasibility of measuring 10Be/9Be ratios at the 10~10 level by using samples containing only about 50 ug of beryllium. This level of sensitivity would be directly applicable to the weapons diagnostic efforts. We are developing a method that will use nuclear particle identification techniques to sort the high-velocity ions emerging from the accelerator. This will allow discrimination from isobaric or nearly isobaric contaminants such as 10B. In addition, the sample size required will be comparable to that available from weapons tests; it will also allow us to measure much smaller 10Be/'Be ratios than are possible when using conventional single-stage mass spectrometry. In this program, we will benefit from many developments at other institutions, but we will not be merely copying existing technology because we must establish new methods to handle these extremely small samples of beryllium. After the method is developed, we will apply the technique to the detection of other unstable isotopes in medium and heavier weight elements, which are of interest in weapon detector diagnostics. We plan to survey historical samples for the presence of 10Be to evaluate its potential as a test diagnostic. Our approach has been essentially the same as that used at several other laboratories. Figure 10.1 outlines the accelerator setup at Los Alamos. We use cesium ions to produce negative ions of beryllium by sputtering and charge exchange. The negative ions are accelerated to the center of the tandem and stripped to become positive atomic ions. The positive ions are then accelerated to ground, mass-selected, and detected. Our tandem will run at up to «10 MV on terminal, and we routinely are running at «9 MV, which gives «39 MeV Be4+ from BeO~. Some details of the sample holder and ion source are shown in Fig. 10.2. The cesium ions are accelerated through the sample holder from the back and then stopped and made to impact on the front of the sample holder. The cesium ions cause the target atoms to sputter and form negative ions by charge exchange; the ions are then accelerated and focused as they leave the ion source. The main difference in our approach in the ion source is that small copper cups are used to hold the samples, and the cups are then pressed into the conventional inverted-cone sample holder. The small sample dictates that we dilute it with some matrix material such as copper before we press the sample into the small cups. We have used both silicon and gas ionization AE-E particle identification telescopes for detection. We plan to use gas detectors exclusively in the future because of the low cost and freedom from radiation damage. The detector being used was developed at LBL,202 This detector has an ion counter «7 cm long that is filled with «50 torr of isobutane. These conditions result in the losses of x2 MeV for alpha particles and «10 MeV for beryllium in the AE detector. We are still using a solid-state E detector in the telescope, but future counters will be all gas. 196 ADVANCED ANALYTICAL TECHNIQUES: DEVELOPMENT AND APPLICATIONS

Cesium Ionizer

High Voltage- 1OMV

Sample *~\ Ox Quadrupole Lens (changeable) Analyzing Magnet

Ion Source Magnet Carbon Foil Removable Faraday Cup

Switch Magnet

Absorber AE Detector E Detector

Fig. I O.I. Schematic of Los Alamos Van de Graaff Facility for accelerator-based mass spectrometry of 10Be.

1 BeO" Cs"

-20 kV 1 -.2 kV

-m\ |«-1

Sputter -T- Target T 8 mm 1.2 mm Negative Ions Copper or Aluminum

Fig. 10.2. Details of the ion source and source holder for production of BeO" and BeH~. ADVANCED ANALYTICAL TECHNIQUES: DEVELOPMENT AND APPLICATIONS 197

We plan to use an absorber to stop heavy ions and 10B to prevent high count rates in the telescope, especially when it is run at 0°. Figure 10.3(a) shows the ranges of 39-MeV 10Be and 10B in various absorbers; Fig. 10.3(b) shows the residual energy of 10Be after it passes through an absorber just thick enough to stop 10B. The residual energy is not too dependent on the absorber Z, but lov/er Z foils generally are lower density, which requires the use of thicker foils to achieve the same absorption. We plan to use a foil that is both the absorber and entrance window for the gas telescope. We have not looked at the ion-energy straggling caused by the absorber, but we don't feel it will seriously degrade the particle identification performance. Alternatives include (1) no absorber (if count rates are low), or (2) a thinner absorber so that I0B is stopped in the AE telescope. The latter would be useful to reduce the straggling in the AE + E signals.

(a)

10 2O 30 40 SO SO 7O 80 90 1OO

(b)

10 20 30 4O SO 6O 7O 8O 9O 1OO

Fig. 10.3. Ranges of I0Be and 10B in various absorbers. Part (a) shows ranges for 39-MeV "Be and 10B. Part (b) shows residual energy of 10Be after it passes through an absorber thick enough to just stop I0B. 198 ADVANCED ANALYTICAL TECHNIQUES: DEVELOPMENT AND APPLICA TIONS

We have investigated producing negative ions that contain beryllium by using the standard Van de Graaff sputtering source. For sputtering targets, we have tried pure beryllium, beryllium- copper alloy, beryllium oxide, and mixtures of beryllium and beryllium oxide in various matrices. The mixtures generally contained «100 ug of beryllium in a total of a 10 mg (that is, xl% beryllium). In these studies, we have produced beam currents of a few nanoamperes to a few 10s of nanoamperes and have scattered the beryllium ions from thin gold targets to protect the counter telescopes. We had hoped that some of the combinations would be relatively more prolific producers of either BeH~ or BeO~, but the test samples have shown fairly similar behavior. There is no clear choice between BeH~ and BeO~, but it seems that BeO~ gives more reproducible beams. Use of beryllium oxide is certainly more attractive from the aqueous chemistry point of view. Using one of our prepared samples of beryllium oxide (100 ug) in a copper matrix (1% beryllium in copper), we have demonstrated that we can run for several hours at a constant beam of > 1010 ions/second. In addition, we have operated for several hours using only the generating voltmeter for machine stabilization. This result is of great importance in cases where we have essentially no beam being accelerated. We are now preparing several standards of 10Be in 9Be. These will be calibrated by mass spcctrometry at the higher levels (Be10/Be9 = 10~4). More dilute samples will then be prepared. We can estimate the sensitivity to be expected with our current system. A 50-ug sample of beryllium contains 3 x 1018 atoms of beryllium; if we assume an ionization efficiency of 10~4, then we could produce 3 x 10+14 beryllium ions from this sample. If we produce a beam of 6 x 109 Be3+/second (1 nA), then we could operate for «50 000 seconds before consuming the sample. Finally, if the 10Be/9Be ratio is 1 x 10"10, this would imply that 0.6 10Be3+ ions/second would be produced, giving 5% counting statistics for 1000 seconds of beam time. Assuming this estimate is valid, we should be able to analyze 50-ug samples of beryllium for 10Be when the sample is only one part 10Be in 1010 parts 9Be. Figure 10.4 shows some test data that indicate the performance of the detection system. These tests were run with 9Be ions of «30 MeV. The accelerated beam was too intense to measure directly, so it was scattered off a thin gold target for the test runs. The upper part of Fig. 10.3 shows two views of the particle identification spectrum. The lower part of the figure shows the resolution of the gas ionization detector for the total energy as well as for the AE measurement. ADVANCED ANALYTICAL TECHNIQUES: DEVELOPMENT AND APPLICA TIONS 199

E+AE

10=

Pulsar Pulsar • o

10"

5c 3 o 10Z2

101 "

150 3OO 45C 600 15O 3OO 45O E+AE AE

Fig. 10.4. Typical experimental data obtained with beryllium ions. Parts (a) and (b) are particle identification plots in two views; parts (c) and (d) depict the energy resolution of the AE detector and the total energy. 200 ADVANCED ANALYTICAL TECHNIQUES: DEVELOPMENT AND APPLICATIONS

DEVELOPMENT OF A GAS IONIZATION DETECTOR FOR DIRECT MASS MEASUREMENTS AT LAMPF

Chandra Pillai,* Jan M. Wouters, David J. Vieira, Gilbert W. Butler, Hans Sann,** Arthur M. Poskanzer,f Alexandra Olmi,** and Kamran Vazirif f

In the proton-induced fragmentation of uranium, reasonably large yields of neutron-rich light- mass nuclei that lie far from the valley of p-stability are produced. At LAMPF, where a high- intensity (800-uA) 800-MeV proton beam is available, an experiment designed to undertake the direct mass measurements of these exotic neutron-rich nuclei is being attempted by using a combined total energy and TOF technique. In the nonrelativistic limit, the mass of a recoiling reaction product can be written as M = 2ET2/D2, where E is the kinetic energy and T is the measured TOF over a fixed distance D. Thus, to achieve good mass resolution (AM/M = 0.5-1.0%), both energy and TOF must be measured simultaneously with good resolution (AE/E < 0.5% and AT/T < 0.25%). Because in general the desired time resolution can be achieved (at the expense of solid angle acceptance) by selecting the appropriate distance, the mass resolution using this technique is ultimately limited by the energy resolution. In this report, we describe the development of a small solid-angle gas ionization detector, which was designed and constructed with the goal of achieving the best possible energy resolution and, thus, the best possible mass resolution for the light-mass reaction products of interest in this experiment (that is, isotopes of beryllium through aluminum with energies of 2 to 4 MeV/amu). After carefully reviewing the current state-of-the-art energy detection systems and considering our particular experimental requirements, a gas ionization counter was selected with a design similar to those developed at the GSI heavy ion accelerator facility in Darmstadt, West Germany.203-204 The major advantages of such gas ionization counters are that (1) they do not suffer from radiation damage effects because the gas can be easily replenished or circulated; (2) the stopping medium has a much lower density than that of silicon detectors, which results in less electron-ion pair recombination; (3) the mean atomic number of the stopping medium (for

example, CH4 or CF4) is less than that of silicon, which is expected to produce smaller end-of- range nuclear collision fluctuations; and (4) because the anode can be subdivided and the gas pressure easily varied, the detector can simultaneously serve as a total energy counter and a uniform (but variable) thickness transmission counter to give stopping power (dE/dx) information from which the atomic number (Z) of the ion can be determined. With the assistance of Dr. Hans Sann and Dr. Arthur Poskanzer, a detector to meet our particular needs was designed, and the major components of the counter were fabricated at LBL. These components were then shipped to Los Alamos, where the detector was assembled, tested, and optimized. Figure 10.5 shows a cross sectional view of the gas ionization counter. The active volume of the counter has the dimensions of (X by Y by Z) 7.6 by 8.1 by 111.2 cm3 and is housed in a 15- cm-diam stainless steel tube. Limited by transverse range straggling, the counter can accept solid angles as large as «1 msr, although only 5 to 10 usr are required in the present experiment. The

•Oregon State University ••Gesellschaft fur Schwerionenforschung (GSI), Darmstadt, W. Germany fLawrence Berkeley Laboratory ffUtah State University ADVANCED ANALYTICAL TECHNIQUES: DEVELOPMENT AND APPLICA TIONS 201

Got Inltt

I.I cm

CoHlnwiof

0 Z 4 6 8 KJ Seal* cm

Fig. 10.5. Schematic of the gas ionization counter.

long length of the counter enables the use of low gas pressures and thin, self-supporting gas isolation windows (60- to 100-mg/cm2 polypropylene); this helps to keep energy straggling in the window to a minimum. The Frisch-grid consists of 200-um, gold-plated tungsten wire with 1-mm spacing and has a screening efficiency of 99.05%. A uniform electric field gradient is established between the cathode and the grounded Frisch-grid by applying a negative voltage to the cathode. An equipotential wire cage and equipotential copper strips on a G-10 printed circuit board (on which the window is mounted) surround the active volume of the counter and help maintain a uniform electric field. Each wire or strip is placed on-potential by a resistive divider network that

is coupled to the cathode voltage. The anode is divided into four sections: AE1, AE2, E, and EreJ. The first two anode sections provide dE/dx information about the particle, after which the

remaining energy is deposited in the E anode section. The EreJ anode section serves to "reject" particles that travel beyond the E anode. All anode sections are operated at a common positive bias. Typically, at a gas pressure of 70 torr methane, the catnode is operated at a voltage of -560 V (E/p m 1 V/cm-torr), and the anode voltage is at +280 V (E/p s< 3 V/cm-torr). These voltages have been optimized to achieve the minimum cathode-to-Frisch-grid drift time (that is, minimum detector dead time) and to obtain the best energy resolution. A gas handling system makes it possible to maintain the gas pressure to better than 0.1 torr under normal flowing conditions (static operation is also possible with this system). Particles enter the counter through two defining collimators (1.1 cm in diameter).and the gas isolation window (1.4 cm in diameter). Once inside the gas counter, electron-iori pairs are produced along the particle's path with a ion-pair density that is proportional to the particle's specific energy loss. The electrons are separated from the positive ions under the influence of the electric field between the cathode and the Frisch-grid. The electrons drift toward and pass through the Frisch-grid to be collected on each anode section. Because the Frisch-grid serves to screen the positive ions, the height of the charge signal collected at the anode gives a measure of the total number of electron-ion pairs, and thus the energy, deposited in that particular anode section. The total energy is obtained by summing the AE1, AE2, and E signals after the gains of each anode section have been matched. 202 ADVANCED ANALYTICAL TECHNIQUES: DEVELOPMENT AND APPLICATIONS

In Fig. 10.6 and Fig. 10.7, the energy resolution of the detector is shown for a mixed 148Gd/229Th alpha source and for elastically scattered lfiO from a gold target at 30° (lab), respectively. The latter measurements were performed at the Los Alamos Van de Graaff facility with the expert assistance of Dr. Alexandra Olmi. For the 8.375-MeV alpha line of 229Th, a total energy resolution of 107 keV (FWHM) was measured. Out of this total, 70 keV is attributed to the electronic noise of the system as measured with a pulser. From the Van de Graaff test run, an energy resolution of 474 keV was obtained for elastic scattered 16O ions at an incident energy of 80 MeV; 200 keV of this total can be attributed to kinematic energy shift of the elastic scattered peak that results from the finite angular acceptance of our system (± 0.9°) Removing this contribution gives an operating energy resolution of 340 keV out of a total energy of 78.1 MeV or 0.44%. This is in keeping with our design goal of achieving better than 0.5% energy resolution. Additional alpha tests in which the drift time of the electron cloud was measured from the time of creation (as obtained from a separate, fast-timing detector located in front of the ion counter) to the time when the electrons are first sensed by the anode provide a measure of the mean vertical position of the particle's track. In tests using a collimated 241Am alpha source, we achieved better than 2-mm position resolution.

1O"1

FWHM 107 kiv

ENERGY (MeV)

Fig. 10.6. Energy spectrum of a mixed I48Gd/n9Th alpha source. Because the U8Gd alpha line at 3.18 MeV is stopped in the AE2 anode section, only a AEI ° AE2 coincidence was required to accumulate this spectrum. ADVANCED ANALYTICAL TECHNIQUES: DEVELOPMENT AND APPLICA TIONS 203

10s 1 1 1 i 1

_ io4 FWHM - 474 keV

io3 - -

O O -

\ ii. if

10 -

1 I 30 40 50 60 70 80 Energy (MeV)

2 Fig. 10.7. Energy spectrum of 80-MeV elastic scattered "O from a i65-mg/cm gold target at Gllb = 30°. The other small peaks arise from small target impurities.

After setting up the detector in the Thin Target Area of LAMPF, we acquired test data by measuring 800-MeV proton-induced uranium fragmentation reaction products. Figure 10.8 shows the Z resolution for the elements of nitrogen through silicon in the 40- to 65-MeV energy range. In this example, the Z of each event has been calculated using a pressure and temperature stabilized AE2-E table lookup method. The analysis of these data gives a Z resolution AZ/Z resolution AZ/Z (FWHM) =s 3.1% for Z = 10. We anticipate further improvements in the Z resolution when the above calculations have been mass corrected and additional analysis involving AE1+AE2 vs E and/or AE2 vs TOF dependences have been incorporated. We have developed a small solid-angle gas ionization detector with an energy resolution of 0.44%, a Z resolution of 3.1%, and a vertical position resolution of 2.0 mm. Combining this energy resolution with our present timing resolution of 0.27% (for example, «200 ps out of a 75-ns flight time), we expect a mass resolution (AM/M) on the order of 0.70%. By accumulating sufficient statistics during the fall 1983-84 and winter beam cycles at LAMPF, we plan to demonstrate that direct mass measurements for neutron-rich fragmentation products such as 14Be, 17B, 20N, and 24F with mass measurement accuracies of «1.0 MeV are possible using this total-energy/TOF technique. 204 ADVANCED ANALYTICAL TECHNIQUES: DEVELOPMENT AND APPLICATIONS

U + 800 MEV P

9 11 13 ATOMIC NUMBER

Fig. 10.8. Histogram of the calculated atomic number of Z = 7 - 14 reaction products that result from 800-MeV proton-induced uranium fragmentation. A pressure and temperature stabilized AE2-E table lookup method was used in this calculation. A TMOSPHERIC CHEMISTRY AND TRANSPOR T 207

TRACKING ANTARCTIC WINDS

Eugene J. Mroz, Mohammed Alei, W. Oeward Efurd, Paul R. Guthals, and Allen S. Mason

For the early Antarctic explorers, the often fierce winds of Antarctica posed a real threat to life. For today's Antarctic scientists the wind is little more than an annoyance. To the meteorologist, it presents a challenge. Where does the wind come from? Where is it going and why? What are the implications for the weather and climate of the region? Scientists from other disciplines share the meteorologist's interest. Glaciologists are unravelling the history of climate in Antarctica as recorded in layers of snow and ice. The details of the transport mechanisms are important for understanding the transport to that continent of water as well as natural and man-made gases and particles. Antarctica still has the cleanest air on the Earth. It is a unique laboratory for studying man's impact on the atmosphere and on an important, isolated region of the Earth.

Whence the Wind? From a meteorological perspective, the Antarctic continent is a high, cold, and reflective dome. Air near the surface ci/axs off the Antarctic dome much like water from a mountain. It is channeled by valleys and gliders, diverted by mountains, but ultimately drains off the continent and out over the -»unding ocean. Dumg this drainage process, it is turned westward by the Coriolis force and o jmes part of the narrow band of easterly winds that prevail along the Antarctic coastal regions. This drainage process is called katabatic flow. It occurs year-round but is stronger and more persistent in winter than in summer.205 To make up for the air lost from the continent by the katabatic winds, there must be an equally large and continuous supply of air to the continent. This supply comes from the upper levels of the Antarctic atmosphere.206 This region is characterized by generally westerly winds. They can be visualized as slowly spiralling poleward from about 65 °S latitude and sinking toward the surface of the continent until the air becomes part of the katabatic flow. Figure 11.1 presents a schematic view of the meridional circulation in Antarctica. This oversimplified view of Antarctic circulation has been complicated by results from studies of Antarctic atmospheric chemistry. It has become increasingly clear that there are marked seasonal differences in the atmospheric chemistry at the South Pole. The aerosol concentration in summer is higher than in winter by a factor of 10 or more.207 The summer aerosol consists mainly of sulfate but also contains significant amounts of aluminum and cosmogenic radionuclides.208*209 The presence of aluminum indicates that one source for the summer aerosol is the weathering and suspension of exposed soils and the subsequent transport poleward by the circulation pattern described above. The presence of elevated levels of sulfate and cosmogenic radionuclides indicates that the stratosphere is also a source of aerosol to the surface of the continent. Some of the sulfate may be of volcanic origin;210'211 Mt. Erebus is an active volcano less than 1500 km from the South Pole. In winter, the continental and stratospheric sources are much weaker. The aerosol concentration at South Pole is reduced to just a few particles per cubic centimeter of air. The winter aerosol, like the summer aerosol, consists mainly of sulfate, but the concentration of sodium chloride is much higher in winter than in summer. This indicates that sea salt is transported from the open ocean around Antarctica to the South Pole. Similar seasonal effects have been observed for carbon dioxide and ozone.212 The influence of man can also be seen in the presence of fluorocarbons and other anthropogenic trace gases. 208 A TMOSPHERIC CHEMISTRY AND TRANSPORT

1OO

200

South Pole Byrd Hallett

Fig. 11.1. Wind velocity vectors in the meridional plane for June-July.

We started by asking where the wind comes from. Now our question is the same, but the focus is different. What are the relative strengths and time dependences of the continental, oceanic, stratospheric, volcanic, and anthropogenic sources to the continent? What is the nature of the meridional flow from the middle to high southern latitudes? Our approach to answering these questions is to release a tracer at a time and place of our choosing; we will use subsequent air samples to examine the meridional transport of air to the continent.

The Antarctic Tracer Experiment Los Alamos National Laboratory has developed two atmospheric tracers that are detectable 213 12 13 thousands of kilometers from the point of reJease. The tracers CD4 and CD4 are analogues of methane and are called heavy methanes because of their higher molecular weights. The key to the use of these tracers at such long ranges is the state-of-the-art mass spectrometry capability at Los Alamos. This capability allows detection of a few parts of tracer in 1018 parts of air. The first release is planned for January 1984 with subsequent releases in July and October 13 1984. The first two releases will be of CD4 at about 18 OOO-ft (5.5-km) altitude and at about 65°S latitude between New Zealand and Antarctica. The third event will be a release of both tracers. One tracer will be released near the surface, and the other tracer will be released at about 18 000 ft. Samples will be collected both on the ground and by aircraft. Ground-level samples will be collected after each release at Amundsen-Scott, Palmer, and McMurdo Stations of the US Antarctic Research Program. Samples will also be collected at Halley Bay (United Kingdom), A TMOSPHERIC CHEMISTRY AND TRANSPORT 209

ANTARCTICA ATLANTIC OCEAN 0° INDIAN OCEAN

SVOWA (JAPAN) WEDDELL HALLEV (UK) PALMER(USA)

AMUNDSEN-SCOTT SOUTH POLE (USA) 90° W 9O°E

CASEV (AUSTRALIA) PACIFIC OCEAN

DUMON7 DURVILLE (FRANCE) KILOMETERS

Fig. 11.2. Location of sampling sites.

Syowa (Japan), Dumont D'Urville (France), and Casey and Mawson (Australia) with the cooperation of the personnel at these stations (Fig. 11.2). The sampler to be used at these stations consists of a small pump that fills a plastic bag with air at a constant rate (Fig. 11.3). The bag is periodically emptied by a compressor into a pressure vessel until the required amount of air (about 360 £) is collected. Airborne sampling will be conducted by piggybacking the equipment on C-130 aircraft during the logistics flights that follow the releases in January and October 1984. These samplers collect methane from the air on activated charcoal at liquid nitrogen temperature (Fig. 11.4). During the past season (1982-1983), prototype whole-air and cryogenic samplers were tested in Antarctica. After collection, the samples will be returned to Los Alamos for analysis. The tracer data will be interpreted in conjunction with meteorological data to define both the path taken by the tracer from the release point to the sampling location and its dispersion during transit. 210 ATMOSPHERIC CHEMISTRY AND TRANSPORT

Fig. 11.3. Whole-air sampler to be deployed at eight stations throughout Antarctica.

Fig. 11.4. Cryogenic sampler for airborne sampling. 207 T*«cicl«g Antarctic Winds

is-f ^A \ 213 Geochemical Anomolies at Biological Crisis Zones in the Fossil Record 214 Nuclide Production Rates by Primary Cosmic-Ray Protons EAR TH AND PLANETAR Y PROCESSES 213

GEOCHEMICAL ANOMALIES AT BIOLOGICAL CRISIS ZONES IN THE FOSSIL RECORD

Charles J. Orth, James S. Gilmore, Jere D. Knight, and Leonard R. Quintana

After our discovery and detailed geochemical study of the iridium-rich zone at the Cretaceous/Tertiary (K/T) boundary at several locations in the Raton Basin, we collected and analyzed samples from outcrops at a location 1300 km to the north, near Jordan, Montana. In both cases, the iridium abundance anomaly coincides stratigraphically with the K/T boundary as defined by extinction of fossil pollen populations. Although the two locations are widely separated, the similarities in the character of the deposits at the K/T boundary in Montana and New Mexico are striking: (1) the iridium anomaly occurs in a thin layer of kaolinitic clay at the base of a thin coal bed; (2) the peak iridium concentration reaches levels about 500-fold higher than local background and its surface density averages about 40 ng/cm2; (3) the iridium anomaly is accompanied by enhanced concentrations of scandium, titanium, vanadium, chromium, and antimony; (4) several of the same Cretaceous age pollen taxa become extinct at the top of the thin (2-mm) clay bed; and (5) the K/T clay bed exhibits an elemental abundance pattern and clay mineralogy distinct from those of similar-appearing beds in other coal beds in the Cretaceous (below) and Paleocene (above); it is likely that these non-K/T kaolinitic clay beds are the result of alteration of tephra from local acid volcanoes. The fact that the K/T clay layer persists for at least 1300 km with only a factor of 2 variation in thickness suggests that the source of the fallout material was located at some distance from either Montana or New Mexico. A volcanic explosion cannot be completely excluded as the source of the boundary clay and the iridium anomaly. However, our elemental abundance data and the conclusions of clay mineralogists from the USGS are more compatible with a source consisting of finely divided ejecta from impact of a large asteroid, as hypothesized by the Alvarez team214 at the University of California, Berkeley. Investigators who have studied the size and frequency distribution of lunar and terrestrial impact craters and of earth-crossing asteroids and comets have concluded that asteroidal objects as large as 10 km in diameter probably collide with the earth every 50 to 100 million years, and comet nuclei of similar size may have comparable collision rates. Thus, we might expect to find several more significant iridium anomalies in strata laid down since the early Cambrian (about 570 million years ago); obvious zones in which to search would be at other extinction boundaries in the fossil record, of which there are at least seven. Previously, we searched for iridium anomalies at two Late Cambrian (s;520 and 525 million years ago) trilobite extinction boundaries and at the Late Devonian (365 million years ago) Frasnian/Famennian marine invertebrate mass extinction boundary, all with negative results. Recently, we sampled across the Ordovician/Silurian boundary zone (430 million years ago) at one of the best preserved sites: Anticosti Island in the Gulf of St. Lawrence. Preliminary results again indicate the absence of a significant excess of iridium. The Berkeley group215 has reported a negative result for the Permian/Triassic (245 million years ago) mass extinction boundary in China. On the positive side, several researchers have reported iridium anomalies at the Eocene/Oligocene boundary («35 million years ago) in Deep Sea Drilling Project cores collected in the floor of the Caribbean Sea and the Pacific and Indian Oceans. Although a microtektite deposit and extinction of radiolarians (planktonic marine organisms) in low latitudes are associated with this iridium anomaly, there are strong arguments that suggest these observations 214 EARTH AND PLANETARY PROCESSES

are an artifact of a major marine depositional hiatus or erosional unconformity. Clearly, a continental freshwater boundary site is needed to resolve the issue. The absence of iridium anomalies at five older mass extinction boundaries suggests that the K/T event was less common than indicated by the predicted frequency of large body impacts. However, the impact of a comet or a large achondrite (which contains less iridium than other meteorities) would be less likely to produce an iridium signal detectable above crustal background than would the chondrite impact suggested for the K/T boundary event.

NUCLIDE PRODUCTION RATES BY PRIMARY COSMIC-RAY PROTONS

Robert C. Reedy

The energetic particles in the cosmic rays are about 90% protons and induce a wide variety of nuclear reactions in extraterrestrial matter.216 Relatively low energy (aslO- to 100-MeV) particles are emitted occasionally from the sun—the so-called solar cosmic rays (SCR). The SCR particles are rapidly stopped in matter (within a few centimeters) and produce a high density of product nuclei very near the surface. The high-energy (ssl-GeV) galactic cosmic-ray (GCR) particles produce a large cascade of secondary particles, especially neutrons, that penetrate meters into solid matter. The flux of GCR particles in the solar system varies with solar activity and is lowest at periods of maximum solar activity. Most studies of cosmogenic nuclides have been for large objects (the moon and meteorites) and for long periods of time (averaged over many solar cycles). Recently, there has been more interest in cosmogenic nuclide production in very small objects217 and also in the production variations over a solar cycle,218 outside the solar system,219 or for periods of unusual solar activity.220 The spectrum of solar protons is well approximated by an exponential function in rigidity;221 it 5 216 220 has an average spectral shape over the last 10 years of Ro = 100 MV. Castagnoli and Lai recently gave an equation for the spectral shape of the GCR as a function of a solar modulation parameter (M). Production rates for seven cosmogenic nuclides were calculated with these proton spectra and with cross sections for proton-induced reactions (see Table 12.1). For the GCR protons, spectra like those for the last two solar minima and maxima216'220 were used, as well as one that is similar to the average over a solar cycle. A fourth GCR spectrum was without modulation, like that of the GCR particles outside the solar system in the local interstellar space (IS). Such an unmodulated spectrum is expected in the solar system during the long periods of essentially no solar activity that occur about every few hundred years.216*220 The typical production rates of these nuclides observed in meteorites (with usual radii of 10 to 30 cm) are also shown in Table 12.1. EARTH AND PLANETARY PROCESSES 215

TABLE 12.1. NuclJde Production Rates by Primary Cosmic-Ray Protons, Assuming C2-Chondritic Chemistry

•y 10* years Solar Solar Solar Local Typical Ay SCR Max. GCR Av GCR MiruGCR IS GCR Meteorite

Parameter Ro = 100 M = 950 M = 550 M = 375 M = 0 (MV) MeV) (MeV) (MeV) (MeV)

Integral Flux* 70 1.21 1.80 2.39 4.33 Nuclide (atoms/minute/kg)

3 He 566. 190. 318. 459. 1258. 900. 10Be 4.1 5.0 8.1 11.5 28.6 22. i21Ne 395. 11.6 20.8 31.7 117. 150. 26A1 344. 3.9 7.5 11.9 56. 60. 36C1 0.9 1.8 3.1 4.5 11.2 7. 3IAr 72. 3.3 5.5 8.0 24.4 20. "Mn 590. 7.6 13.6 20.8 90. 105. •In protons/cmVs: solar protons for E > 10 MeV, GCR for E > 1 GeV.

Production by solar protons usually dominates that by primary GCR protons. Only nuclides made mainly by high-energy protons, such as 10Be and 36CI, have very low production rates by the low-energy solar protons. These high rates by solar protons only occur very near the surface, and solar-proton production rates become relatively unimportant below depths of a few centimeters.216'221 In most meteorites, production by solar protons is usually not obse.-vable because the surface layers are removed by ablation during the meteorite's passage through the earth's atmosphere. The ratio of the amount of a nuclide readily made by solar protons (for example, 26A1) to that of a high-energy product (such as I0Be) is a good indicator of the object's size when it was irradiated in space. Activities of 26A1 and I0Be were measured in several groups of small (0.3- to 0.5-mm) spherules collected from sediments on the ocean floor.217 The 26Al/10Be ratio and the 26A1 activity were quite high in several of them, which indicates that those spherules probably came from parent bodies less than a few centimeters in diameter. Studies of such small objects would be interesting because they may be different from the forms of solar system matter found in most meteorites. The production rates of nuclides by GCR protons in interstellar space are high, similar to the rates produced by both primary and secondary GCR particles in meteorites. The relatively low energy protons normally removed by solar modulation in the inner solar system have produced about the same number of nuclides as are made by secondary neutrons in meteorites. These high production rates, plus the relatively low loss of product nuclides by recoil in small grains,219 mean 216 EAR TH AND PLANE!AR Y PROCESSES

that one should be able to identify grains that were irradiated in interstellar space and then incorporated in meteorites. The cross sections as a function of energy for making secondary neutrons are similar in shape to those for producing 3He. The 3He production rate in interstellar space is 4 times that for the average over a solar cycle, and the flux of protons above 1 GeV in . interstellar space is 2.4 times that for the solar-cycle average. Thus, the production rates of r cosmogenic nuclides by GCR particles that have not been modulated are higher (by factors up to 3 to 4) than those observed near the earth during long periods of typical solar activity. During periods of normal solar variations, the extremes in the activity of the sun and its subsequent modulation of the GCR particles are represented by the solar minimum and maximum used in Table 12.1. The ratio of 2,4 for the 3He production rates between these extremes is about the variation that would be expected for the production of secondary neutrons. When Evans et al.218 measured the activities of short-lived radionuclides in a number of meteorites that fell from 1967 to 1978, the activities varied by about a factor of 3. Some of these variations probably were caused by differences in the meteorites' sizes or shapes or in the sample location. However, the calculations reported here show that most of these radioactivity variations are caused by the solar modulation of the GCR-particle flux. The observed radioactivity variations correlated well with other indicators of solar activity.218 Larger variations in nuclide production rates would be expected if the solar activity exceeded one or both of the average extremes used here. In Table 12.1, the ratio of the GCR production rates typically observed in meteorites to the solar-cycle-averaged rates for primary GCR protons ranged from 2.3 to 8.0. Because the flux of primary protons inside a meteorite is attenuated by nuclear interactions, the ratios of observed activities to those made only by the primary GCR protons should be even larger. These relatively low contributions by the primary particles illustrate the importance of secondary particles in nuclide production in large objects like meteorites. This big difference between nuclide production by primaries only and by the fully developed secondary cascade present in most meteorites indicates that small meteorites without a fully developed cascade could have some unusual production rates or ratios. Studies of such small meteorites also would help us understand the production and transport of secondary particles in meteorites. The calculations and results in Table 12.1 show that the production of cosmogenic nuclides can vary considerably with both the size of the extraterrestrial object and the amount of the solar modulation of the primary GCR particles. Very small objects have high production rates by solar protons. Typical meteorites are large enough that the cascade of secondary particles dominates nuclide production. Intermediate-size objects could have some unusual production rates and ratios. Temporal and spatial variations in nuclide production can also result from differing GCR- particle modulation. Variations by factors of 2 to 3 can occur during a normal solar cycle, and even larger deviations can occur when solar modulation is much stronger or weaker than usual. APPENDIX: PUBLICATIONS 219

PUBLICATIONS

INC-3 / / / J. W. Barnes, M. A. Ott, P. M. Wanek, G. E. Bentley, K. E. Thomas, F. J. Steinkruger, and H. A. O'Brien, Jr., "Iodine-123 Yields from 800-MeV Proton Irradiation of CsCl Target" (Abstract), J. Nucl. Med. 24, P24 (1983).

W. Cole, S. DeNardo, C. Meares, G. DeNardo, and H. O'Brien, "Development of Copper-67 Chelate Conjugated Monoclonal Antibodies for Radioimmunotherapy" (Abstract), J. Nucl. Med. 24, P30 (1983).

R. E. Gibson, W. C. Eckelman, B. Francis, H. A. O'Brien, J. K. Mazaitis, D. S. Wilbur, and R. C. Reba,"[77Br]-17- a-Bromoethynylestradio!: In Vivo and In Vitro Characterization of an Estrogen Receptor Radiotracer," Int. J. Nucl. Med. Biol. 9, 245-250 (1982).

R. A. Goldstein, N. A. Mullani, D. J. Fisher, S. K. Marani, H. A. O'Brien, and K. L. Gould, "Quantification of Regional Myocardial Flow with Rb-82 Despite Pharmacologic Intervention" (Abstract), J. Nucl. Med. 24, P30 (1983).

D. A. Miller, P. M. Grant, J. W. Barnes, G. E. Bentley, and H. A. O'Brien, Jr., "Research-Scale Experimentation on the Production and Purification of Spallogenic Germanium-68 at Los Alamos for Nuclear Medicine Applications," in Applications of Nuclear and Radiochemistry, R. M. Lambrecht and N. Morcos, Eds. (Pergamon Press, New York, 1982), Chap. 4, pp. 37-44.

H. A. O'Brien, Jr., and P. M. Grant, "Biomedical Positron Generators," in Applications of Nuclear and Radiochemistry, R. M. Lambrecht and N. Morcos, Eds. (Pergamon Press, New York, 1982), Chap. 6, pp. 57-68.

A. P. Selwyn, R. M. Allan, A. L'Abbatc, P. Horlock, P. Camici, J. Clark, H. A. O'Brien, Jr., and P. M. Grant, "Relation Between Regional Myocardiai Uptake of Rubidium-82 and Perfusion: Absolute Reduction of Cation Uptake in Ischemia," Am. J. Cardiolog. 50,112-121 (1982).

D. S. Wilbur, K. W. Anderson, W. E. Stone, and H. A. O'Brien, Jr., "Radiohalogenation of Non-Activated Aromatic Compounds Via Aryltrimethylsilyl Intermediates," J. Label. Cmpds. Radiopharm. 19, 1171-1186 (1982).

D. S. Wilbur, W. E. Stone, and K. W. Anderson, "Regiospecific Incorporation of Bromine and Iodine into Phenols Using Trimethylsilylphenol Derivatives," J. Org. Chem. 48, 1542-1544 (1983).

D. S. Wilbur and Z. V. Svitra, "Organopentafluorosilicates: Reagents for Rapid and Efficient Incorporation of No-Carrier-Added Radiobromine and Radioiodine," J. Label. Cmpds. Radiopharm. 20, 619-626 (1983).

D. S. Wilbur, Z. V. Svitra, and H. A. O'Brien, Jr., "Applications of Aryltrimethylsilanes in Radiobrominations" (Abstract), J. Nucl. Med. 24, P43 (1983).

INC-4

M. A. Andrews, J. Eckert, J. A. Goldstone, L. Passell, and B. I. Swanson, "Incoherent Inelastic Neutron Scattering, Infrared, Raman and X-ray Diffraction Studies of Pentacarbonylmethylmanganese, Mn(CO)3CH3," J. Am. Chem. Soc. 105, No. 8, 2262-2269 (1983).

J. R. Brainard, J. Y. Hutson, R. E. London, and N. A. MatwiyofT, "Metabolism As It Happens," Los Alamos Science No. 8, 4-64 (1983). 220 APPENDIX: PUBLICATIONS

J. R. Cann, R. E. London, N. A. MatwiyofT, and J. M. Stewart, "A Combined Spectroscopic Study of the Solution Conformation of Bradykinins," in Kinins - III, Pt. A, H. Fritz, G. Dietze, and G. L. Haberlind, Eds. (Plenum, New York, 1983), pp. 495-500.

David A. Cremers and T. L. Cremers, "Picosecond Dynamics of Conformation Changes in Malachite Green Dye Produced by Photoionization of Malachite Green Leucocyanide," Chem. Phys. Lett. 94, 102-106(1983).

T. L. Cremers, P. G. Eller, R. A. Penneman, and C. C. Herrick, "Orthorhombic Uranium(IV) Molybdenum(VI)

Oxide, UMo2O8," Acta Cryst. C39, 1163-1165 (1983).

T. L. Cremers, P. G. Eller, and R. A. Penneman, "Orthorhombic Thorium(IV) Molybdate, Th(MoO4)2," Acta Cryst. C39, 1165-1167(1983).

Claude C. Herrick and Robert A. Penneman, "Fusion of Acid Oxides for Potentially Radiation-Resistant Waste Forms," Nucl. Technol. 60, No. 2, 253-256 (1983).

L. H. Jones and B. I. Swanson, "On Rotation of CH3F Isolated in Rare Gas Matrices," J. Chem. Phys. 77 (12), 6338-6340(1982).

Llewellyn H. Jones and Basil I. Swanson, "Orientational Ordering, Site Structure, and Dynamics for Octahedral Molecules in Low Temperature Matrices: SF6 and SeF6 in Rare Gas Solids," J. Chem. Phys. 79 (3), 1516-1522 (1983).

Gregory J. Kubas, "Preparation and Use of W(CO)3(NCR)3 (R = Et, Pr) as Improved Starting Materials for Syntheses of Tricarbonyl(n6-cycloheptatriene)tungsten and Other-Substituted Carbonyl Complexes," Inorg. Chem. 22, No. 4, 692-694(1983).

G. J. Kubas, G. D. Jarvinen, and R. R. Ryan, "Stereochemical and Electronic Control of M-SO2 Bonding Geometry 6 1 2 in d Molybdenum and Tungsten SO2 Complexes: Novel T) •+*• -n SO2 Linkage Isomerization in Mo(CO)2(PPh3)2(CNR)(SO2) and Structures ofMo(CO)3(P-i-Pr3)2(S02) and [Mo(CO)2(py)(PPh3Xn-SO2)]2," J. Am. Chem. Soc. 105, No. 7,1883-1891 (1983).

G. C. Levy, D. J. Craik, Y-C Chou, and R. E. London, "13C NMR Relaxation and Conformational Flexibility of the Deoxyribose Ring," Nucleic Acid Res. 10 (19), 6067-6083 (1982).

R. E. London, "Enzyme Structure and Interaction with Inhibitors," Los Alamos Science No. 8, 68-71 (1983).

R. E. London, N. A. Matwiyoff, C. J. Unkefer, and T. E. Walker, "Synthesizing Labeled Compounds," Los Alamos Science No. 8, 66-67(1983).

R. E. London, W. E. Wageman, and R. L. Blakley, "i3C-NMR Studies of Selectively Carboxymethylated [Methyl- I3C]methionine-labeled Bacterial Dihydrofolate Reductase," FEBS Lett. 160, Nos. 1,2, 56-60(1983).

John G. Malm, "The Reaction of Uranium Hexafluoride with Silver Fluoride in Anhydrous Hydrogen Fluoride and

the Chemical Properties of the Product Ag2UF8," J. Fluorine Chem. 23, No. 3, 267-282 (1983).

N. A. Matwiyoff, "Recent Applications of 13C NMR Spectroscopy to Biological Systems," in Stable Isotopes (4th Analytical Chemistry Symposia Series, Vol. 11) H.-L. Schmidt, H. Forstel and K. Heinzinger, Eds. (Elsevier, Amsterdam, 1982), pp. 573-585.

N. A. Matwiyoff, B. B. Mclnteer, and T. R. Mills, "Stable Isotope Production—A Distillation Process," Los Alamos Science No. 8, 65 (1983).

B. B. Mclnteer, J. L. Lyman, A. C. Nilsson, and G. P. Quigly, "A Practical Enrichment Technique for 33-Sulfur(34- Sulfur)," in Synthesis and Applications of Isotopically Labeled Compounds, W. P. Duncan and A. B. Susan, Eds. (Elsevier, Amsterdam, 1983), pp. 397-402. APPENDIX: PUBLICATIONS 221

T. R. Mills, "Sulfur Isotope Separation by Distillation," in Synthesis and Applications of Isotopicatiy Labeled Compounds, W. P. Duncan and A. B. Susan, Eds. (Elsevier, Amsterdam, 1983), pp. 40y-410.

David C. Moody, Alexander J. Zozulin, and Kenneth V. Salazar, "Improved Synthesis of UC13(THF)X and the Preparation of 15-Crown-5 Derivatives of Trivalent Uranium," Inorg. Chem. 21, No. 10, 3856-3857 (1982).

R. A. Penneman, "William H. Zachariasen," in Crystallography in North America, D. McLachlan, J. P. Glusker, and H. Steinfink, Eds. (American Crystallographic Association, 1983), Chap. 2, pp. 108-111.

R. A. Penneman, "Status of Plutonium Chemistry—Round Table Discussion," in Plutonium Chemistry (ACS Symposium Series 216), W. T. Carnall and G. R. Choppin, Eds. (American Chemical Society, Washington, DC, 1983), App. A, pp. 453-458.

R. A. Penneman and G. R. Choppin, "The Chemistry of the Transplutonium Elements," in Opportunities and Challenges in Research with Transplutonium Elements (National Academy Press, Washington, DC, 1983), App. F, pp. 231-285.

R. A. Penneman and P. G. Eller, "Valence Stabilities, Size Effects, and Actinide Storage Considerations" (invited paper), Radiochim. Acta 32, 81-87 (1983).

M. A. Phillippi, R. J. Wiersema, J. R. Brainard, and R. E. London, "Analysis of Hydrocarbon Chain Conformation Using Double Quantum Coherence "C NMR," J. Am. Chem. Soc. 104, No. 25, 7333-7334 (1982).

J. M. Ritchey, D. C. Moody, and R. R. Ryan, "Reactivity of Pt(PCy3)2 and Pt[P(t-Bu)3]2 with SO2 and CS2," Inorg. Chem. 22, No. 16, 2276-2280 (1983).

B. I. Swanson, S. F. Agnew, L. H. Jones, R. L. Mills, and D. Schiferl, "Spectroscopic Studies of Molecular Interactions of Oxygen-16 and Oxygen-18 in the High-Density e-Phase," J. Phys. Chem. 87, No. 14, 2463-2465 (1983).

Basil I. Swanson, Lucia M. Babcock, David Schiferl, David C. Moody, Robert L. Mills, and Robert R. Ryan,

"Raman Study of SO2 at High Pressure: Aggregation, Phase Transformations and Photochemistry," Chem. Phys. Lett. 91, 393 (1982).

B. I. Swanson and L. H. Jones, "High Resolution Infrared Studies of Site Structure and Dynamics for Matrix Isolated Molecules," in Vibrational Spectra and Structure, Vol. 12, J. R. Durig, Ed. (Elsevier, Amsterdam, 1983), Chap. 1, pp. 1-67.

C. J. Unkefer, R. E. London, T. W. Whaley, and G. H. Daub, "13C and JH NMR Analysis of Isotopically Labeled Benzo[a]pyrenes," J. Am. Chem. Soc. 105, No. 4, 733-735 (1983).

W. H. Woodruff, K. A. Norton, B. I. Swanson, and H. A. Fry, "Cryoresonance Raman Spectroscopy of Plastocyanin, Azurin, and Stellacyanin. A Reevaluation of the Identity of the Resonance-Enhanced Modes," J. Am. Chem. Soc. 105, No. 3, 657-658 (1983).

INC-5

D. R. Dreesen, M. E. Bunker, E. J. Cokal, M. M. Demon, J. W. Starner, E. F. Thode, L. E. Wangen, and J. M. Williams, "Research on the Characterization and Conditioning of Uranium Mill Tailings; Vol. 1, Characterization and Leaching Behavior of Uranium Mill Tailings," Los Alamos National Laboratory report LA-9660-UMT, Vol. 1 (June 1983). 222 APPENDIX: PUBLIC A TIONS

S. R. Garcia, W. K. Hensley, M. M. Minor, M. M. Denton, and M. A. Fuka, "Automated Multidetector System for Instrumental Neutron Activation Analysis of Geological and Environmental Materials," in Atomic and Nuclear Methods in Fossil Energy Research, R. H. Filby, B. S. Carpenter, and R. C. Ragaini, Eds. (Plenum, 1982), pp. 133-139.

M. E. Bunker, "Early Reactors - From Fermi's Water Boiler to Novel Power Prototypes," Los Alamos Science 4, No. 7, 124-131 (1983).

W. L. Talbert, Jr., M. E. Bunker, J. W. Starner, S. C. Soderholm, V. J. Novick, and R. F. Petry, "Studies of He-jet Activity Transport at LAMPF," (abs.) Bull. Am. Phys. Soc. 28, 646 (1983).

INC-7

B. Crowe, R. Amos, F. Perry, S. Self, and D. Vaniman, "Aspects of Possible Magmatic Disruption of a High-Level Radioactive Waste Repository in Southern Nevada," Los Alamos National Laboratory report LA-9326-MS (October 1982).

B. M. Crowe, M. E. Johnson, and R. J. Beckman, "Calculation of the Probability of Volcanic Disruption of a High- Level Radioactive Waste Repository Within Southern Nevada, USA," Radioact. Waste Manage. Nuc. Fuel Cycle 3 (2), 167-190(1982).

W. R. Daniels, B. R. Erdal, D. T. Vaniman, and K. Wolfsberg, Comps., "Research and Development Related to the Nevada Nuclear Waste Storage Investigations, January 1—March 31, 1982," Los Alamos National Laboratory report LA-9327-PR (October 1982).

E. Vine Treher and A. C. Wahl, "The Chemical Behavior of Tracer-Level Technetium Isotopes," Int. J. Appl. Radiat. Isot. 33 (10), (1982).

E. N. Treher and N. A. Raybold, "The Elution of Radionuclides Through Columns of Crushed Rock from the Nevada Test Site," Los Alamos National Laboratory report LA-9329-MS (October 1982).

K. Wolfsberg, W. R. Daniels, B. R. Erdal, and D. T. Vaniman, Comps., "Research and Development Related to the Nevada Nuclear Waste Storage Investigations, April 1—June 30, 1982," Los Alamos National Laboratory report LA-9484-PR (October 1982).

J. C. Cobb, B. C. Eversole, P. G. Archer, R. Taggert, and D. W. Efurd, "Plutonium in Human Tissues Related to Smoking, Age, Residence Near Rocky Flats and Eastern Colorado," Environmental Protection Agency report EPA-600/4-82-069 (November 1982).

D. W. Efurd, G. W. Knobeloch, R. E. Perrin, and D. W. Barr, "Neptunium-237 Production From Atmospheric Nuclear Testing," Los Alamos National Laboratory report LA-9585-MS (November 1982).

A. E. Norris. et al., "Geochemistry Studies Pertaining to the G-Tunne! Radionuclide Migration Field Experiment," Los Alamos National Laboratory report LA-9332-MS (November 1982).

W. R. Daniels, K. Wolfsberg, R. S. Rundberg, A. E. Ogard, J. F. Kerrisk, C. J. Duffy, et al., "Summary Report on the Geochemistry of Yucca Mountain and Environs," Los Alamos National Laboratory report LA-9328-MS (December 1982).

D. T. Vaniman, B. M. Crowe, and E. S. Gladney, "Petrology and Geochemistry of Hawaiite Lavas from Crater Flat, Nevada," Contr. Mineral. Petrol. 80, 341-357 (1982).

T. M. Benjamin, R. W. Charles, and R. J. Vidale, "Thermodynamic Parameters and Experimental Data for the Na- K-Ca Geothermometer," J. Volcanol. Geotherm. Res. 15, 167-186 (1983). APPENDIX: PUBLIC A TIONS 223

R. W. Charles and G. K. Bayhurst, "Sentinel Gap Basalt Reacted in a Temperature Gradient," Los Alamos National Laboratory report LA-9481-MS (January 1983).

D. B. Curtis and A. J. Gancarz, "Radiolysis in Nature: Evidence from the Oklo Reactors," SKBF KBS report 83-10 (February 1983).

J. C. Cobb, B. C. Eversole, P. G. Archer, R. Taggert, and D. W. Efurd, "Plutonium Burdens in People Living Around the Rocky Flats Plant," Environmental Protection Agency report EPA-600/S4-82-069 (March 1983).

B. M. Crowe, D. T. Vaniman, and W. J. Carr, "Status of Volcanic Hazard Studies for the Nevada Nuclear Waste Storage Investigations," Los Alamos National Laboratory report LA-9325-MS (March 1983).

W. R. Daniels, B. R. Erdal, and D. T. Vaniman, Comps., "Research and Development Related to the Nevada Nuclear Waste Storage Investigations, July 1—September 30, 1982," T-os Alamos National Laboratory report LA-9577-PR (March 1983).

B. R. Erdal, B. M. Crowe, W. R. Daniels, B. J. Travis, R. S. Rundberg, and K. Wolfsberg, "Retardation of Waste Elements at a Potential Repository Site in Tuff at Yucca Mountain, Nevada" (Abstract), in Program of the 185th American Chemical Society National Meeting, Division of Nuclear Chemistry and Technology (American Chemical Society, 1983).

C. M. Miller and N. S. Nogar, "Calculation of Ion Yields in Atomic MuUiphoton Ionij;ari';n Spectroscopy," Anal. Chem. 55,481-488(1983).

T. L. Norris, A. J. Gancarz, D. J. Rokop, and K. W. Thomas, "Half Lite of 26A1" (Abstract), in Lunar and Planetary Science XIV(Lunar Planetary Institute - Universities Space Research Association, Houston, Texas, 1983), Part 1, p. 568.

C. J. Maggiore, T. M. Benjamin, P. J. Hyde, P. S. Z. Rogers, S. Srinivasan, J. Tesmer, D. S. Woolum, and D. S. Burnett, "Chemical History with a Nuclear Microprobe," IEEE Trans. Nucl. Sci. NS-30 (2), 1224-1227 (1983).

W. A. Sedlacek, E. J. Mroz, A. L. Lazrus, and B. W. Gandrud, "A Decade of Stratospheric Sulfate Measurements Compared with Observations of Volcanic Eruptions," J. Geophys. Res. 88 (C4) 3741-3776 (1983).

W. R. Daniels, Comp. and Ed., "Laboratory and Field Studies Related to the Radionuclide Migration Project, October 1. 1981—September 30, 1982," Los Alamos National Laboratory report LA-9691-PR (May 1983).

E. S. Gladney, W. A. Sedlacek, and W. W. Berg, "Comparative Determination of Bromine and Iodine in Three Air Sampling Media via Instrumental Thermal and Epithermal Neutron Activation Analysis," J. Radioanal. Chem. 78 (1), 213-225(1983).

A. E. Ogard, W. R. Daniels, and D. T. Vaniman, Comps., "Research and Development Related to the Nevada Nuclear Waste Storage Investigations, October 1—December 31, 1982," Los Alamos National Laboratory report LA-9666-PR (May 1983).

D. J. Rokop and E. N. Treher, "The Development of an Isotopic Dilution Technique to Determine Femtogram Amounts of "Tc, 98Tc, and "Tc," in Proceedings of the Meeting of the American Society of Mass Spectrometry (American Society of Mass Spectrometry, Boston, Massachusetts, 1983).

T. Benjamin, R. Charles, and R. Vidale, "Thermodynamic Parameters and Experimental Data for the Na-K-Ca Geothermometer," J. Volcan. Geotherm. Res. 15, 167-186 (1983). 224 APPENDIX: PUBLICATIONS

L. V. Benson, J. H. Robinson, R. K. Blankennagel, and A. E. Ogard, "Chemical Composition of Ground Water and the Locations of Permeable Zones in the Yucca Mountain Area, Nevada," US Geological Survey report USGS- OFR-83-854 (1983).

3. M. Crowe, D. Vaniman, R. Amos, F. Perry, and S. Self, "Aspects of Possible Magmatic Disruption of a High- Level Radioactive Waste Repository in Southern Nevada," J. Geol. 91, 259-276 (1983).

N. S. Nogar, C. M. Miller, S. W. Downey, and R. K. Sander, "Resonant Multiphoton Ionization for the Detection of Technetium," in Proceedings of the Los Alamos Conference on Optics '82 (SPIE, 1983), Vol. 380, p. 291.

R. J. Vidale, "Pore Solution Compositions in a Peltic System at High Temperatures, Pressures, and Salinites, Studies in Metamorphism and Metasomatism," Am. J. Sci. 233-A, 298-313 (1983).

K. Wolfsberg, D. T. Vaniman, and A. E. Ogard, Comps., "Research and Development Related to the Nevada Nuclear Waste Storage Investigations January 1—March 31, 1983," Los Alamos National Laboratory report LA-9793-PR (June 1983).

R. H. Wood, D. S. Magowan, K. S. Pitzer, and P. S. Z. Rogers, "Comparison of Experimental Values of \°2, Cp°2, and C^ for Aqueous NaCl with Predictions Using the Born Equation at Temperatures from 300 to 573.15K at 17.7 MPa," J. Phys. Chem. 87, 3297-3300(1983).

B. M. Crowe, "Volcanic Hazard Assessment for Disposal of High-Level Radioactive Waste" (Abstract), Trans. Am. Geophys. Union 64, 860 (1983).

K. Wolfsberg, W. Ditz, and H. O. Denschlag, "Einfuhrung eines neuen Fitprogrammes auf der Rechenanlage HB 66/80 des hiesigen Rechenzentrums," in "Jahresberich 1982," Institut fur Kernchemie Universitat Mainz report IKMz 83-2 (July 1983).

S. Barr, T. Kyle, W. Clements, and W. Sedlacek, "Plume Dispersion in a Nocturnal Drainage Wind," Atmos. Environ. 17 (8), 1423-1429 (1983).

D. B. Curtis, T. M. Benjamin, and A. J. Gancarz, "The Oklo Reactors: Natural Analogs to Nuclear Waste Repositories," in Advances in the Science and Technology of the Management of High-Level Nuclear Waste (US DOE, Washington, DC, 1981) Vol. I, pp. 255-283.

H. H. Meixler, K. Wolfsberg, and H. O. Denschlag, "Nuclear Charge Distribution in Fission: Fractional Cumulative Yields of Isotopes of Krypton and Xenon in "'Cffa,,,!) and 23OCf(Spf)," Can. J. Chem. 61, 665-670 (1983).

C. M. Miller and N. S. Nogar, "Continuous Wave Lasers for Resonance Ionization Mass Spectrometry," Anal. Chem. 55, 1606-1608 (1983).

R. J. Vidale, "Water-Rock Interaction in Pelitic Systems," in Proceedings of the Fourth International Conjerence on Water-Rock Interactions (Misasa, Japan, 1983).

F. Goff, D. Bish, R. Vidale, R. Charles, J. Gardner, and C. Grigsby, "Sulphur Springs: An Acid-Sulfate System in Valles Caldera, New Mexico, USA," in Proceedings of the Fourth International Conference on Water-Rock Interactions (Misasa, Japan, 1983).

E. J. Mroz, A. S. Mason, and W. A. Sedlacek, "Stratospheric Sulphate from El Chichon and the Mystery Volcano" Geophys. Res. Lett. 10 (9), 873-876 (1983). APPENDIX: PUBLICATIONS 225 INC-11

M. Blecher, K. Gotow, R. L. Burman, M. V. Hynes, M, J. Leitch, N. S. Chant, L. Rees, P. G. Roos, F. E. Bertrand, E. E. Gross, F. E. Obenshain, T. P. Sjoreen, G. S. Blanpied, B. M. Preedom, and B. G. Ritchie, "Isospin Effects in n* Elastic Scattering from 12C, I3C, and 14C at 65 and 80 MeV," Phys. Rev. C 28, 2033-2041 (1983).

M. D. Cable, J. Honkanen, R. F. Parry, H. M. Thierens, J. M. Wouters, Z. Y. Zhou, and J. Cerny, "Beta-Delayed 22 Proton Decay of an Odd-Odd TE = -2 Isotope, A1," in "Nuclear Science Division Annual Report 1981-1982," Lawrence Berkeley Laboratory report LBL-15207 (1983), pp. 58-59.

J. L. Clark, P. E. Haustein, T. J. Ruth, J. Hudis, and A. A. Caretto, "Measurement of Inclusive n~ Production with 200 MeV Protons: A Radiochemical Study of the 209Bi(p,jrXn)21°-x At Reactions," Phys. Rev. C 26, 2073-83 (1982).

W. R. Daniels, B. R. Erdal, and D. T. Vaniman, Comps., "Research and Development Related to the Nevada Nuclear Waste Storage Investigations, July 1—September 30, 1982," Los Alamos National Laboratory report LA-9577-PR (March 1983).

W. R. Daniels, Ed. and Comp., "Laboratory and Field Studies Related to the Radionuclide Migration Project, October 1, 1981—September 30, 1982," Los Alamos National Laboratory report LA-9691-PR (May 1983).

B. J. Dropesky, "Activation Studies of the Interactions of Kaons, Antiprotons, and High-Energy Pions with Complex Nuclei," in "Proceedings of the Third LAMPF II Workshop," Los Alamos National Laboratory report LA-9933-C (July 1983), Vol. 2, pp. 912-929.

B. J. Dropesky, "Nuclear Chemistry Facilities at LAMPF II," in "Proceedings of the Third LAMPF II Workshop," Los Alamos National Laboratory report LA-9933-C (July 1983), Vol. 2, pp. 980-985.

P. Englert, S. Theis, R. C. Reedy, and J. R. Arnold, "On the Production of Cosmogenic Nuclides by High-Energy Secondary Particles: Simulation Experiments with Beam Stop Neutrons," in Lunar and Planetary Science XIV (Lunar and Planetary Institute, Houston, 1983), pp. 174-175.

K. Eskola, P. Eskola, J. B. Wilhelmy, M. M. Fowler, E. N. Treher, and H. Ohm, "Production of 211-212>213Bi from Pb, Tl, and Hg by 18O Ions," "Current Trends in Heavy Ion Reactions Studies," Symposium, American Chemical Society Meeting, Washington, DC, August 29—September 2, 1983.

P. Eskola, K. Eskola, J. B. Wilhelmy, M. M. Fowler, J. Van der Plicht, J. G. Boissevain, H. C. Britt, A. Gavron, Z. Fraenkel, A. Weismann, F. Plasil, T. Awres, and G. Young, "Fission of Polonium, Osmium, and Erbium Composite Systems," Symposium, American Chemical Society Meeting, Washington, DC, August 29—September 2, 1983.

E. R. Flynn, J. Van der Plicht, J. B. Wilhelmy, L. G. Mann, G. L. Struble, and R. G. Lanier, "146Gd and 144Sm Excited by the (p,t) Reaction on Radioactive Targets," Phys. Rev. C 28, 97-104 (1983).

J. S. Gilmore, J. D. Knight, C. J. Orth, C. L. Pilmore, and R. N. Tschudy, "Trace Element Patterns at a Non-marine Cretaceous-Tertiary Boundary," Nature 307, 224-228 (1984).

D. E. Hobart, V. E. Norvell, P. G. Varlashkin, H. E. Hellwege, and J. R. Peterson, "Optically Transparent Porous Metal Foam Electrode," Anal. Chem. 55, 1634 (1983). 226 APPENDIX: PUBLICA TIONS

D. E. Hobart, P. G. Varlashkin, K. Samhoun, R. G. Haire, and J. R. Peterson, "Spectroscopic and Redox Properties of Curium and Californium Ions in Concentrated Aqueous Carbonate-Bicarbonate Media," (invited paper), Rev. Chim. Miner. 20, 817(1983).

J. D. Knight, C. J. Orth, M. E. Schillaci, R. A. Naumann, F. J. Hartmann, and H. Schneuwly, "Target-Density Effects in Muonic-Atom Cascades," Phys. Rev. A 27, 2936-2945 (1983).

J. D. Knight and J. E. Sattizahn, "Tracking the Isotopes," Los Alamos Science No. 8,2-23 (1983).

Y. Ohkubo, N. T. Porile, C. J. Orth, and L.-C. Liu, "Excitation Functions of the 127I (n, nxn) Reactions in the Region of the (3,3) Resonance," Phys. Rev. C 27,1146 (1983).

C. J. Orth, J. S. Gilmore, J. D. Knight, C. L. Pillmore, R. H. Tschudy, and J. E. Fassett, "Indium Abundance Measurements Across the Cretaceous-Tertiary Boundary in the San Juan and Raton Basins of Northern New Mexico," Geol. Soc. Am. Spec. Pap. 190(1982), pp. 423-433.

A. E. Norris, Comp., "Geochemistry Studies Pertaining to the G-Tunnel Radionuclide Migration Field Experiment," Los Alamos National Laboratory report LA-9332-MS (November 1982).

T. L. Norris, A. J. Gancarz, D. J. Rokop, and K. W. Thomas, "Half-Life of 26A1," J. Geophys. Res. 88, Suppl. B331- B333 (1983).

R. Parry, M. Cable, J. Honkanen, J. Wouters, S. Zhou, Z. Y. Zhou, and J. Cerny, "Beta Endpoint Measurements of Neutron-Deficient Cesium Isotopes," in "Nuclear Science Division Annual Report 1981-1982," Lawrence Berkeley Laboratory report LBL-15207 (1983), pp. 68-69.

R. C. Reedy, J. R. Arnold, and D. Lai, "Cosmic-Ray Record in Solar System Matter," Ann. Rev. Nucl. Part. Sci. 33, 505-537(1983).

R. S. Rundberg, J. L. Thompson, and S. Maestas, "Radionuclide Migration: Laboratory Experiments with Isolated Fractures," in Scientific Basis for Nuclear Waste Management, S. V. Topp, Ed. (North-Holland, New York, 1982), pp. 239-248.

K. W. Thomas, "Production of Microcurie Amounts of Carrier-Free 26A1," Radiochem. Acta 33, 213-215 (1983).

D. J. Vieira and W. L. Talbert, Jr., "LAMPF II Nuclear Chemistry Working Group Report from the Nuclei-Far- From-Stability Section," in "Proceedings of the Third LAMPF II Workshop," Los Alamos National Laboratory report LA-9933-C (July 1983), Vol. 2, pp. 886-905.

K. Wolfsberg, D. T. Vaniman, and A. E. Ogard, Comps., "Research and Development Related to the Nevada Nuclear Waste Storage Investigations, January 1—March 31, 1983," Los Alamos National Laboratory report LA-9793-PR (July 1983).

K. Wolfsberg, B. P. Bayhurst, P. L. Wanek, F. O. Lawrence, S. D. Knight, A. J. Mitchell, A. E. Ogard, and S. S. Levy, "Research and Development Related to Sorption of Radionuclides on Soils," Report to US Environmental Protection Agency Contract No. EPA-INC7-3/83-1 (1983). APPENDIX: PUBLICA TIONS 227

INC-DO

J. R. Brainard, J. Y. Hutson, R. E. London, and N. A. Matwiyoff, "I3C NMR Spectroscopy/l3C Labeled Substrates in In Vivo Metabolic Profiling," in Stable Isotopes in Nutrition (American Chemical Society, in press).

J. R. Brainard, J. Y. Hutson, R. E. London, and N. A. Matwiyoff, "Metabolism as it Happens," Los Alamos Science No. 8, 42-62(1983).

B. R. Erdal, A. E. Ogard, B. M. Crowe, R. S. Rundberg, W. R. Daniels, D. L. Bish, and D. T. Vaniman, "Some Geochemical Considerations for a P rte.iial Site in Tuff at Yucca Mountain, Nevada," in Proceedings of the US/FRG Bilateral Workshop on Standardization of Methods of Measuring Migration of Radionuclides in Geomedia (1982).

D. C. Hoffman, "Spontaneous Fission Properties and Production of Heavy Element Isotopes," in Accounts of Chemical Research (in press), LA-UR-83-2467.

D. C. Hoffman, "What Lies Ahead," Los Alamos Science No. 8, 72-76 (1983).

D. C. Hoffman, W. R. Daniels, J. L. Thompson, R. S. Rundberg, S. L. Fraser, K. Wolfsberg, and K. S. Daniels, "A Review of a Field Study of Radionuclide Migration from an Underground Nuclear Explosion at the Nevada Test Site," in Proceedings of the International Conference on Radioactive Waste Management (International Atomic Energy Agency, in press).

O. L. Keller, Jr., D. C. Hoffman, R. A. Penneman, and G. R. Choppin, "Accomplishments and Promise of Transplutonium Research," Phys. Today (in press).

D. Lee, K. J. Moody, M. J. Nurmia, G. T. Seaborg, H. R. von Gunten, and D. C. Hoffman, "Excitation Functions for Production of Heavy Actinides from Interactions of 1BO with 248Cm and 249Cf," Phys. Rev. C. 27, 2656-2665 (1983).

H. A. Lindberg, "Management and Professional Development," in Proceedings of the International Technical Communications Conference (Society of Technical Communicators, Washington, DC, 1983).

R. E. London, C. J. Unkefer, T. E. Walker, and N. A. Matwiyoff, "Synthesizing Labeled Compounds," Los Alamos Science No. 8, 66-67 (1983).

N. A. Matwiyoff, B. B. Mclnteer, and T. R. Mills, "Stable Isotope Production—A Distillation Process," Los Alamos Science No. 8, 64-65 (1983). 228 APPENDIX: PUBLICATIONS

N. A. Matwiyoff, "Recent Applications of 13C NMR Spectroscopy to Biological Systems," in Stable Isotopes, H.-L. Schmidt, H. Forestel, and K. Heinzinger, Eds., Analytical Chemistry Symposia Series, Vol. 11 (Elsevier, Amsterdam, 1982), pp. 573-585.

N. A. Matwiyoff, C. J. Unkefer, and T. E. Walker, "Problems and Prospects in Future Applications of Stable Isotopes in the Life Sciences and Medicine" (invited review), in Proceedings of the International Symposium on Isotopes (in press).

K. Wolfsberg, W. R. Daniels, B. R. Erdal, and D. T. Vaniman, Comps., "Research and Development Related to the Nevada Nuclear Waste Storage Investigations, April i—June 30, 1982," Los Alamos National Laboratory report LA-9484-PR (October 1982). APPENDIX: PUBLICA TIONS 229

PAPERS ACCEPTED FOR PUBLICATION

INC-3

G. E. Bentley, F. J. Steinkruger, and P. M. Wanek, "Electrochemistry as a Basis for Radiochemical Generator Systems," in Proc. Symp. on New Radionuclide Generator Systems for Nuclear Medicine, 185th American Chemical Society National Meeting, Seattle, Washington, March 20-25, 1983.

D. T. Cromer, R. R. Ryan, and D. S. Wilbur, "Structure of 1 -H-Azepine-2-1 -5-Methoxime, C7HBN2O2," Acta Cryst. (C).

H. A. O'Brien, Jr., "Overview of Radionuclides Useful for Radioimmunoimaging and Current Status of Preparing Radiolabeled Antibodies," Radioimmunoimaging (Elsevier Biomedical Press, New York)].

H. A. O'Brien, Jr., J. W. Barnes, G. E. Bentley, F. J. Steinkruger, K. E. Thomas, M. A. Ott, F. H. Seurer, and W. A. Taylor, "The Development of Short-Lived Radionuclides at Lbs Alamos," in Proc. International Symposium on the Developing Role of Short-Lived Radionuclides in Nuclear Medical Practice, Washington, DC, May 3-5, 1982.

F. J. Steinkruger, G. E. Bentley, H. A. O'Brien, Jr., M. A. Ott, F. H. Seurer, W. A. Taylor, and J. W. Barnes, "Production and Recovery of Large Quantities of Radionuclides for Nuclear Medicine Generator Systems," in Proc. Symp. on New Radionuclide Generator Systems for Nuclear Medicine, 185th American Chemical Society National Meeting, Seattle, Washington, March 20-25, 1983.

K. E. Thomas, "Recovery and Isolation of Curie Quantities of Hafnium and the Lanthanides from LAMPF- Irradiated Tantalum Targets," Radiochim. Acta.

K. E. Thomas, "Proposal for the Production of Carrier-Free Osmium-191," in Proc. International Conference on Single-Photon Ultrashort-Lived Radionuclides, Pan American Health Organization, Washington, DC, May 9-10, 1983.

K. E. Thomas and J. W. Barnes, "Large Scale Isolation of Strontium-82 for Generator Production," in Proc. Symp. on New Radionuclide Generator Systems for Nuclear Medicine, 185th American Chemical Society National Meeting, Seattle, Washington, March 20-25,1983.

D. S. Wilbur, Z. V. Svitra, R. S. Rogers, and W. E. Stone, "Radiohalogen Labeling Studies at Los Alamos," in Proc. International Symposium on the Developing Role of Short-Lived Radionuclides in Nuclear Medical Practice, Washington, DC, May 3-5,1982.

INC-4

S. F. Agnew, B. I. Swanson, L. H. Jones, R. L. Mills, and D. Schiferl, "Chemistry of N2O4 at High Pressure: Observation of a Reversible Transformation between Molecular and Ionic Crystalline Forms," J. Phys. Chem.

L. Cocco, B. Roth, C. Temple, Jr., J. A. Montgomery, R. E. London, and R. L. Blakley, "Protonated State of Methotrexate, Trimethoprim and Pyrimethamine Bound to Dihydrofolate Reductase," Arch. Biochem, Biophys.

D. T. Cromer, R. R. Ryan, and D. Scott Wilbur, "Structure of l-H-Azepine-2-One-5-Methoxime, C,H8NjO2," Acta Cryst. C.

P. Gary EUer and Phillip J. Vergamini, "Nuclear Magnetic Resonance and Chemical Studies of Uranium(V) Alkoxides," Inorg. Chem. 230 APPENDIX: PUBLICATIONS

H. A. Fry, L. H. Jones, and J. E. Barefield, "Observation and Analysis of Fundamental Bending Mode of T2O," J. Mol. Spectrosc.

O. L. Keller, Jr., D. C. Hoffman, R. A. Penneman, and G. R. Choppin, "Accomplishments and Promise of Transplutonium Research," Phys. Today.

G. J. Kubas, R. R. Ryan, B. I. Swanson, P. J. Vergamini, and H. J. Wasserman, "Characterization of the First Examples of Isolable Molecular Hydrogen CompLxes, M(CO)3(PRj)2(H2) (M = Mo, W; R = Cy, i-Pr). Evidence for a Side-On Bonded H2 Ligand," J. Am. Chem. Soc.

G. C. Levy, D. J. Craik, A. Kumar, and R. E. London, "A Critical Evaluation of Models for Complex Molecular Dynamics: Application to NMR Studies of Double and Single Stranded DNA," Biopolymers.

R. E. London, "Carbon-13 Labeling Strategies in Macromolecular Studies: Application to Dihydrofolate Reduc- tase" (invited chapter), in Topics in Carbon-13 NMR Spectroscopy, G. C. Levy, Ed. (Wiley), in press.

D. C. Moody and R. T. Paine, "Low Valent Actinides as Hydrogenation Catalysts," J. Catal.

E. J. Peterson, E. M. Foltyn, and E. I. Onstott, "Thermochemical Splitting of Sulfur Dioxide with Cerium(IV) Oxide," J. Am. Chem. Soc.

P. E. Pfeffer, K. B. Hicks, M. H. Frey, S. J. Opella, and W. L. Earl, "I3C-UC Dipolar Interactions Provide a Mechanism for Obtaining Resonance Assignments in Solid State 13C NMR Spectroscopy," J. Magn. Reson.

J. M. Ritchey and D. C. Moody, "Platinum(O) Complexes with Bulky Phosphines: Trinuclear SO2 and CS2 Complexes," Inorg. Chim. Acta.

D. Schiferl, D. T. Cromer, R. R. Ryan, A. C. Larson, R. Le Sar, and R. L. Mills, "Structure of N2 at 2.9 GPa and 300 K," Acta Cryst.

C, J. Unkefer, R. M. Blazer, and R. E. London, "In Vivo Determination of the Pyridine Nucleotide Reduction Charge by Carbon-13 NMR Spectroscopy," Science.

C. J. Unkefer, R. D. Walker, and R. E. London, "Hydrogen-1 and Carbon-13 Nuclear Magnetic Resonance Conformational Studies of the His-Pro Peptide Bond; Conformational Behavior of TRH," Int. J. Pept. Protein Res.

H. J. Wasserman, A. J. Zozulin, D. C. Moody, R. R. Ryan, and K. V. Salazar, "Crystal and Molecular Structure of Triscyclopentadienyltetrahydrofuranuranium(III), (-n'-CjHj^U'OCjH,," J. Organomet. Chem.

W. H. Woodruff, K. A. Norton, B. I. Swanson, and H. A. Fry, "Temperature Dependence of the Resonance Raman Spectra of Plastocyanin and Azurin Between Cryogenic and Ambient Conditions," Proc. Nat. Acad. Sci. (US).

INC-11

J. S. Gilmore, J. D. Knight, C. J. Orth, C. L. Pillmore, and R. H. Tschudy, "Trace Element Patterns at a Nonmarine Cretaceous/Tertiary Boundary," Nature.

J. S. Gilmore, G. J. Russell, H. Robinson, and R. E. Prael, "Fertile-to- Fissile Conversion and Fission Measurements for Thorium Bombarded by 800-MeV Protons," Proceedings of the Seventh Meeting of the International Collaboration on Advanced Neutron Sources (ICANS-VII) Chalk River Nuclear Laboratories, Chalk River, Ontario, Canada, September 12-16,1983. APPENDIX: PUBLICATIONS 231

G. R. McGhee, Jr., J. S. Gilmore, C. J. Orth, and E. Olsen, "Negative Evidence for Indium Anomaly at Late Devonian Mass Extinction Horizon," Nature.

C. J. Orth, J. D. Knight, L. R. Quintana, J. S. Gilmore, and A. R. Palmer, "A Search for Iridium Abundance Anomalies at Two Late Cambrian Biomere Boundaries in Western Utah," Science.

R. J. Prestwood, K. W. Thomas, D. R. Nethaway, and N. L. Smith, "Measurement of 14-MeV Neutron Cross Sections for *"Zr and MY," Phys. Rev. C.

PATENT APPLICATION

INC-4

E. Fukushima, S. B. W. Roeder, R. A. Assink, and A. A. V. Gibson, "Improved Nuclear Magnetic Resonance Apparatus Having Semitoroidal Coil for Use in Topical NMR and NMR Imaging," DOE docket number S-58,406, March 1983. (DOE has also applied for European patent.) 232 APPENDIX: PRESENTATIONS

PRESENTATIONS

INC-3

G. E. Bentley, "Determination of Lead and Uranium in Geologic Samples by D.C. Plasma Emission Spectroscopy," 1982 Pacific Conference on Chemistry and Spectroscopy, San Francisco, California, October 27-29,1982.

J. A. Mercer-Smith, "First Life on the Primordial Earth," Dimensions in Science: Man and Molecules, American Chemical Society Radio Program #1160, April 1983.

H. A. O'Brien, Jr., "Overview of Radionuclides Useful for Radioimmunoimaging and Current Status of Preparing Radiolabeled Antibodies," Radioimmunoimaging Symposium, Albuquerque, New Mexico, November 4-6,1982.

H. A. O'Brien, Jr., "Iodine-123 Production at Los Alamos and Production and Potential of New Short-Lived Radionuclides," 1983 Rocky Mountain Nuclear Medicine Conference, Denver, Colorado, April 15-16,1983.

K. E. Thomas, "Proposal for the Production of Carrier-Free Osmium-191," International Conference on Single- Photon Ultrashort-Lived Radionuclides. Pan American Health Organization, Washington, DC, May 9-10, 1983.

D. S. Wilbur, Z. V. Svitra, and R. S. Rogers, "New Labeling Methods for 123I and Other Radiohalogens," 1983 Rocky Mountain Nuclear Medicine Conference, Denver, Colorado, April 15-16,1983.

D. S. Wilbur, Z. V. Svitra, R. S. Rogers, and W. E. Stone, "Radiohalogen Labeling Studies at Los Alamos," International Symposium on the Developing Role of Short-Lived Radionuclides in Nuclear Medical Practice, Washington, DC, May 3-5, 1982.

D. S. Wilbur, Z. V. Svitra, and H. A. O'Brien, Jr., "Applications of Aryltrimethylsilanes in Radiobrominations," Thirtieth Annual Meeting of the Society of Nuclear Medicine, St. Louis, Missouri, June 7-10,1983.

S. Yan, F. J. Steinkruger, and H. A. O'Brien, Jr., "Recovery of Titanium-44 from a Proton-Irradiated Vanadium Target," American Chemical Society Meeting, Washington, DC, August 28-September 2, 1983.

INC-4

R. W. Alkire, Phillip J. Vergamini, and Allen C. Larson, "Single Crystal Structure Determination of TI3PSe4 and Tl3AsS4 by (TOF) Neutron Diffraction at the Los Alamos National Laboratory Pulsed Neutron Facility," American Crystallographic Association, University of Missouri, Columbia, Missouri, March 14-18, 1983.

James R. Brainard, "In Situ NMR Studies of Metabolism in Perfused Organs" (invited paper), National Institutes of Health and Environmental Sciences, Research Triangle Park, North Carolina, September i, 1983.

M. Pamela Bumsted, "Introduction to Forum on Stable Isotopic and Metals Composition, Nutrition, and Human Adaptation," Xlth International Congress of Anthropological and Ethnological Sciences, Phase II, D-006, Vancouver, Canada, August 21,1983.

M. Pamela Bumsted, Thomas W. Boutton, Ramon M. Barnes, and George J. Armelagos, "Prehistoric Variability of Metal and 13C/12C Content in Bone: Dietary and Gender Factors, Xlth International Congress of Anthropological and Ethnological Sciences, Phase II, Session D-6, Vancouver, Canada, August 20-25, 1983.

William L. Earl, "Nuclear Magnetic Resonance Measurements of Molecular Dynamics in Solids," Los Alamos Polymer Working Group Meeting, November 17, 1982. APPENDIX: PRESENTATIONS 233

William L. Earl, "Status of CP Related Materials Studies," 8th Semiannual Deflagration to Detonation Transition Project Meeting, Sandia National Laboratories, Albuquerque, New Mexico, January 20,1983.

William L. Earl, "Cross Polarization—Magic Angle Spinning I5N NMR," Second Brukers CXP Users Conference, Pleasanton, California, April 8-9, 1983.

13 William L. Earl, "Adsorption Studies on NH4-Y Zeolite by N NMR," Symposium on Nuclear Magnetic Resonance at the 25th Rocky Mountain Conference sponsored by the Rocky Mountain Society for Applied Spectroscopy and the Rocky Mountain Chromatography Discussion Group, Denver, Colorado, August 16, 1983.

Herbert A. Fry, Llewellyn H. Jones, and James E. Barefield, "Observation and Analysis of the Fundamental Bending

Mode of T2O," 38th Symposium on Molecular Spectroscopy, Columbus, Ohio, June 13-17,1983.

Herbert A. Fry, Basil I. Swanson, and Llewellyn H. Jones, "Far Infrared Matrix Isolation Spectroscopy," Gordon Conference on Spectroscopy of Matrix-Isolated Species, Colby-Sawyer College, New London, New Hampshire, July 18-22, 1983.

Eiichi Fukushima, Alan Rath, and S. B. W. Roeder, "A New Proposed Coil Design for Topical Magnetic Resonance" (poster session), 27th Annual Meeting of the Biophysical Society, San Diego, California, February 13-16, 1983.

D. E. Hoekenga, J. R. Brainard, J. Y. Hutson, and N. A. Matwiyoff, "Carbon-13 NMR Studies of Glycogen Synthesis and Mobilization in Perfused Guinea Pig Heart," 2nd Annual Meeting, Society of Magnetic Resonance in Medicine, San Francisco, California, August 16-19, 1983.

J. Y. Hutson, J. R. Brainard, C. J. Unkefer, R. E. London, and N. A. Matwiyoff, "Studies on the Effects of Altered Oxidation-Reduction State on Pyridine Nucleotide Ratios and Gluconeogenic Flux in the Perfused Hamster Liver," 2nd Annual Meeting, Society of Magnetic Resonance in Medicine, San Francisco, California, August 16-19, 1983.

A. C. Larson, "Prediction of Crystal Density," Biennial Review of the Naval Sea Systems Command Explosives Research and Development Programs, Charleston, South Carolina, December 6-10, 1982.

A. C. Larson, P. J. Vergamini, and R. W. Alkire, "Development of the Single Crystal Diffractometer for the Los Alamos Pulsed Neutron Facility (WNR)," American Crystallographic Association, University of Missouri, Columbia, Missouri, March 14-18, 1983.

N. A. Matwiyoff, J. R. Brainard, J. Y. Hutson, and R. E. London, "13C Enriched Substrates for in Situ and in Vivo Metabolic Profiling Studies by l3C NMR," ACS Symposium on Stable Isotopes in Nutrition, Washington, DC, August 28—September 3, 1983.

R. A. Penneman, "Transplutonium Chemistry—Status and Future," 186th Annual American Chemical Society Meeting, Washington, DC, August 28—September 2, 1983.

P. E. Pfeffer, K. B. Hicks, M. H. Frey, S. J. Opella, and W. L. Earl, "Solid State 13C CP-MAS Studies of Glucose. Coupling in 13C Labelled Compounds as a Method for Making Chemical Shift Assignments," 24th Experimental Nuclear Magnetic Resonance Spectroscopy Conference, Asilomar, California, April 10-14, 1983.

John M. Ritchey, "Reactivity of Tertiary Phosphines - Zerovalent Platinum Complexes with Carbon Disulfide and Sulfur Dioxide" (invited paper), University of New Mexico, Albuquerque, New Mexico, May 3, 1983.

Basil I. Swanson, "High Resolution Infrared Studies of Guest Host Interactions and Dynamics in Low Temperature Matrices" (invited paper), Fort Lewis College, Durango, Colorado, October 8,1982.

Basil I. Swanson, "Spectroscopic Studies of Small Moleolecules at High Pressures. Observation of a Strong Infrared- Active O-O Stretch in the High Density Red Phase of Oxygen" (invited paper), Sandia Laboratories, Albuquerque, New Mexico, October 12,1982. 234 APPENDIX: PRESENTATIONS

Basil I. Swanson, "High Resolution Infrared Studies of Guest Host interactions and Dynamics in Low Temperature Matrices" (invited paper), Bell Laboratories, Murray Hill, New Jersey, October 21, 1982; Princeton University, Princeton, New Jersey, October 22, 1982; Brookhaven National Laboratory, Upton, New York, October 23-24, 1982; and Massachusetts Institute of Technology, Cambridge, Massachusetts, October 25-26, 1982.

Basil I. Swanson, "High Pressure Studies of Oxygen," Workshop on Shock Compression Chemistry in Materials Synthesis and Processing, Seattle, Washington, March 28-29,1983.

Basil I. Swanson, "Chemistry at High Pressures. Spectroscopic Studies of Small Molecules at High Densities" (invited paper), Chemistry Faculty Seminar, Washington State University, Pullman, Washington, March 30,1983.

Basil I. Swanson, "High Resolution IR Studies of Site Structure and Dynamics for Matrix Isolated Molecules," Gordon Conference on Spectroscopy of Matrix-Isolated Species, Colby-Sawyer College, New London, New Hampshire, July 18-22, 1983.

•:Basil I. Swanson, "Spectroscopic Studies of Nitric Oxide at High Densities," Office of Naval Research Workshop on Energetic Material Initiation Fundamentals, Chestertown, Maryland, August 15-17, 1983.

Clifford J. Unkefer and Robert E. London,"/« Vivo Determination of the Pyridine Nucleotide Reduction Charge by Carbon-13 NMR Spectroscopy," 74th Annual Meeting, American Society of Biological Chemists, San Francisco, California, June 5-9, 1983.

1 2 P. J. Vergamini, G. J. Kubas, R. R. Ryan, H. J. Wasserman, and A. C. Larson, "Structure of W(CO)3(PPr3 )2(Ti -H2), the First Example of Molecular Hydrogen Bound to a Metal," American Crystallographic Association, University of Missouri, Columbia, Missouri, March 14-18, 1983.

T. E. Walker, R. E. London, N. A. Matwiyoff, and Pat J. Langston-Unkefer, "Biosynthetic Approaches to the Synthesis of "C and 1JN Enriched Amino Acids," 74th Annual Meeting, American Society of Biological Chemists, San Francisco, California, June 5-9, 1983.

Harvey J. Wasserman, "Structural Studies on High Oxidation State Organometallic Complexes of Tantalum and Tungsten" (invited paper), University of New Mexico, Albuquerque, New Mexico, April 28, 1983.

W. H. Woodruff, K. Norton, B. I. Swanson, H. A. Fry, B. G. Malmstrom, I. Pecht, D. F. Blair, W. Cho, G. W. Campbell, V. Lum, V. M. Miskowski, S. I. Chan, and H. B. Gray, "Cryo-vibrational Spectroscopy of Blue Copper Proteins," 1st Intern. Conf. on Bioinorganic Chemistry, Florence, Italy, June 13-17, 1983.

INC-5

M. E. Bunker and W. L. Talbert, Jr., "He Jet/ISOL Project for the Study of Nuclei Far from Stability," review for DOE/HENP, Gaithersburg, Maryland, March 25, 1983.

M. E. Bunker, "Scientific Justification for a He-Jet Coupled Isotope Separator Facility at LAMPF," DOE review of LAMPF, Los Alamos National Laboratory, Los Alamos, New Mexico, April 6-8, 1983.

M. E. Bunker and W. L. Talbert, Jr., "Proposal for On-Line Isotope Separator," review for INC-Division Visiting Committee on Nuclear and Radiochemistry, Los Alamos National Laboratory, Los Alamos, New Mexico, July 7-8, 1983.

M. M. Minor, "Dynamic Neutron Radiography," Fifth Annual INC Divisional Information Meeting, Los Alamos National Laboratory, Los Alamos, New Mexico, September 21-22, 1983. APPENDIX: PRESENTATIONS 235

S. R. Garcia, "Study of Systematic Errors in Neutron Activation Analysis," Fifth Annual INC Divisional Information Meeting, Los Alamos National Laboratory, Los Alamos, New Mexico, September 21-22,1983.

M. E. Bunker, "Scientific Justification for the Proposed On-Line Mass Separator at LAMPF," Fifth Annual INC Divisional Information Meeting, Los Alamos National Laboratory, Los Alamos, New Mexico, September 21-22, 1983.

INC-7

T. M. Benjamin, D. B. Curtis, and A. J. Gancarz, "Fission Product Transport at the Oklo Natural Reactors," 95th Annual Meeting of the Geological Society of America, New Orleans, Louisiana, October 18-21, 1982.

B. R. Erdal, D. L. Bish, B. M. Crowe, W. R. Daniels, A. E. Ogard, R. S. Rundberg, D. T. Vaniman, and K. Wolfsberg, "Some Geochemical Considerations for a Potential Repository Site in Tuff," US/FRG Bilateral Workshop, Berlin, Munich, October 25-29, 1982.

R. Guthals, "Los Alamos Atmospheric Tracers—Development and Application," Office of Health and Environmen- tal Research, Atmospheric Sciences Program Directors Meeting, Gettysburg, Pennsylvania, October 19, 1982.

P. R. Guthals, "High Altitude Sampling Program/Project Airstream Overview," Office of Health and Environmental Research, Atmospheric Sciences Program Directors Meeting, Gettysburg, Pennsylvania, October 20, 1982.

D. B. Curtis, "The Geochemistry of Technetium—Studies of the Oklo Natural Reactors," Nuclear and Radio- chemistry Seminar, Lawrence Livermore National Laboratory, November 17, 1982.

M. M. Fowler, "Accelerator Based Molecular Mass Spectrometry Applied to the Analysis of Heavy Methanes," USDOE/ISA LAGER Meeting, Washington, DC, November 17S 1982.

C. J. Maggiore, T. M. Benjamin, P. J. Hyde, P. S. Z. Rogers, S. Srinivasan, J. Tesmer, D. S. Woolum, and D. S. Burnett, "Chemical History with a Nuclear Microprobe," Conference on the Application of Accelerators in Research and Industry, Denton, Texas, November 9-10, 1982.

R. J. Vidale, "The Geochemistry of Sulfur Springs and Other Hot Springs in the Jemez Mountains," Women in Science Seminar, Los Alamos National Laboratory, Los Alamos, New Mexico, November 3,1982.

W. W. Dudley and B. R. Erdal, "Site Characterization for Evaluation of Nuclear Waste Isolation at Yucca Mountain, Nevada," NWTS Annual Information Meeting, Las Vegas, Nevada, December 6-9, 1982.

E. J. Mroz and W. A. Sedlacek, "Atmospheric Aerosols from El Chichon," American Geophysical Union Meeting, San Francisco, California, December 9-15, 1982.

P. R. Guthals, "Atmospheric Studies at Los Alamos," Eastern New Mexico University Science Department Seminar, Portales, New Mexico, January 21, 1983.

E. J. Mroz, A. S. Mason, and W. A. Sedlacek, "Stratospheric Sulphate from El Chichon and the Mystery Volcano," E! Chichon Data and Publications Meeting, NASA Langley Research Center, Hampton, Virginia, January 5,1983.

N. S. Nogar and C. M. Miller, "Resonance Ionization Mass Spectrometry," Sandia National Laboratories Colloquium, Albuquerque, New Mexico, January 28, 1983.

E. J. Mroz, A. S. Mason, and W. A. Sedlacek, "Stratospheric Sulfate from El Chichon and the Mystery Volcano," El Chichon Principal Investigators Meeting, NASA Goddard Space Flight Center, Greenbelt, Maryland, February 8-10, 1983. 236 APPENDIX: PRESENTATIONS

P. R. Guthals, "Atmospheric Studies at Los Alamos," Graduate Students' Industrial Seminar Committee Meeting, Washington State University, Pullman, Washington, March 10,1983.

N. Kaffrell, H. Tetzlaff, N. Trautmann, P. Hill, S. Hogland, G. Skarnemark, J. Alstad, K. Wolfsberg, P. De Gelder, and E. Jacobs, "Neutron-Rich Nuclei in the Mass Region A=l 10," Meeting of the Deutsche Physikalisahe Gesellschaft, Munster, West Germany, March 21-25,1983.

C. M. Miller, "Resonance Ionization Mass Spectrometry at the Los Alamos National Laboratory," US DOE, Washington, DC, March 23,1983.

E. J. Mroz, "Status of the Los Alamos Antarctic Tracer Experiment," Workshop on Polar Meteorology, Boulder, Colorado Chapter of the American Geophysical Union, Boulder, Colorado, March 17-18, 1983.

T. L. Norris, A. J. Gancarz, D. J. Rokop, and K. W. Thomas, "Half Life of Al," Lunar and Planetary Science XIV Conference, Houston, Texas, March 14-18,1983.

S. W. Downey, N. S. Nogar, R. K. Sander, and C. M. Miller, "Resonant Multiphoton Ionization for the Detection of Technetium," Los Alamos Conference on Optics, Santa Fe, New Mexico, April 13,1983.

D. L. Bish, D. T. Vaniman, R. S. Rundberg, K. Wolfsberg, W. R. Daniels, and D. E. Broxton, "Natural Sorptive Barriers in Yucca Mountain, Nevada, for Long Term Isolation of High Level Waste," International Conference on Radioactive Waste Management, Seattle, Washington, May 16-20, 1983.

D. B. Curtis, D. J. Rokop, and D. E. Handel, "The Development of Mass Spectrometric Techniques for the Determination of Neutron Produced Isotopes of Terbium," Meeting of the American Society of Mass Spectrometry, Boston, Massachusetts, May 5-13,1983.

D. C. Hoffman, W. R. Daniels, K. Wolfsberg, J. C. Thompson, R. S. Rundberg, S. L. Fraser, and K. S. Daniels, "A Review of a Field Study of Radionuclide Migration From an Underground Nuclear Explosion Cavity at the Nevada Test Site," International Conference on Radioactive Waste Management, Seattle, Washington, May 16-20, 1983.

C. M. Miller and N. S. Nogar, "Resonance Ionization at Los Alamos," 31st Annual Conference on Mass Spectrometry and Allied Topics, Boston, Massachusetts, May 11, 1983.

N. S. Nogar, S. W. Downey, and C. M. Miller, "Applications of Resonance Ionization Mass Spectroscopy," Meeting of Atoms-83, Los Alamos, New Mexico, May 19,1983.

D. J. Rokop and E. N. Treher, "The Development of an Isotopic Dilution Technique to Determine Femtogram Amounts of 7Tc, 9BTc, and "Tc," Meeting of the American Society of Mass Spectrometry, Boston, Massachusetts, May 5-13, 1983. * •

B. M. Crowe, "Geology and Tectonic Setting of a Late Cenozoic Volcanic Belt in the Southcentral Great Basin," University of California at Los Angeles Earth Sciences Symposium Series, Los Angeles, California, May 26-27, 1983.

P. R. Guthals, "Atmospheric Studies at Los Alamos (Chemistry)," presented to the US House of Representatives Science and Technology Subcommittee on Natural Resources, Agricultural Research and Environment (NRARE), Washington, DC, June 3, 1983.

P. R. Guthals, "History of Sampler Aircraft (Nuclear Bomb Clouds)," Joint Sampling Working Group Meeting, Offutt Air Force Base, Nebraska, June 8-9,1983. APPENDIX: PRESENTATIONS 237

T. M. Benjamin, C. J. Duffy, C. J. Maggiore, P. S. Z. Rogers, D. S. Woolum, D. S. Burnett, and M. T. Murrell, "Microprobe Analyses of Rare Earth Element Fractionation in Meteoritic Minerals," Third International Con- ference on Particle Induced X-Ray Emission and Its Analytical Applications, Heidelberg, West Germany, July 18-22, 1983.

P. S. Z. Rogers, C. J. Duffy, T. M. Benjamin, and C. J. Maggiore, "Geologic Applications of Nuclear Microprobes: Progress and Problems," Third International Conference on Particle Induced X-Ray Emission and Its Analytical Applications, Heidelberg, Germany, July 18-22,1983.

P. S. Z. Rogers, C. J. Duffy, T. M. Benjamin, and C. J. Maggiore, "Geochemical Applications of Nuclear Microprobes," Third International Conference on Particle Induced X-Ray Emission and Its Analytical Applications, Heidelberg, West Germany, July 18-22, 1983.

T. M. Benjamin, C. Maggiore, P. Rogers, C. Duffy, "Geologic Applications of the Los Alamos Nuclear Microprobe" (Invited paper), Joint Meeting, Electron Microscopy Society of America and Microbeatn Analysis Society, Phoenix, Arizona, August 8-12, 1983.

M. M. Fowler, E. J. Mroz, and P. R. Guthals, "Heavy Methanes (Mass-20 and -21) as Atmospheric Tracers," Meeting of the International Association of Meteorology and Atmospheric Physics, Hamburg, Federal Republic of Germany, August 15-27, 1983.

M. M. Fowler, E. j. Mroz, and P. R. Guthals, "Heavy Methanes (Mass-20 and -21) as Atmospheric Tracers," IUGG XVIII General Assembly, Hamburg, West Germany, August 26, 1983.

P. R. Guthals, "Project Airstream Technical Operations," presented at Environmental Measurements Laboratory, New York City, New York, August 3, 1983.

C. M. Miller, "Laser Applications to Ultrasensitive Analysis," Twenty-Seventh Annual Meeting of the Society of Photo-Optical Instrumentation Engineers, San Diego, California, August 22, 1983.

C. M. Miller, N. S. Nogar, and S. W. Downey, "Selective Laser Ionization for Mass Spectral Isotopic Analysis," Twenty-Seventh Annual Meeting of the Society of Photo-Optical Instrumentation Engineers, San Diego, California, August 23, 1983.

E. J. Mroz, W. A. Sedlacek, and A. S. Mason, "In Situ Measurements of Stratospheric Sulfate Following the 1982 El Chichon Eruptions," Meeting of the International Association of Meteorology and Atmospheric Physics, Hamburg, Federal Republic of Germany, August 15-27, 1983.

W. A. Sedlacek, "Behavior of Stratospheric Nitric Acid: 1971-1982," Meeting of the International Association of Meteorology and Atmospheric Physics, Hamburg, Federal Republic of Germany, August 15-27, 1983.

T. M. Benjamin, C. J. Maggiore, P. S. Z. Rogers, and C. J. Duffy, "Geologic Applications of the Los Alamos Nuclear Microprobe," 186th Meeting of the American Chemical Society, Washington, DC, August 28-September 2, 1983.

K. Eskola, P. Eskola, M. M. Fowler, D. C. Hoffman, H. Olm, E. N. Treher, J. B. Wilhelmy, D. Lee, and G. T. Seaborg, "Transfer Reactions to Produce Neutron Rich Isotopes," Eleventh European Conference on Physics and Chemistry of Complex Nuclear Reactions, Autrans, France, September 5-9,1983. '

F. Goff, D. Bish, R. Vidale, R. Charles, J. Gardner, and C. Grigsby, "Sulphur Springs: An Acid-Sulfate System in Valles Caldera, New Mexico, USA," Fourth International Conference on Water-Rock Interactions, Misasa, Japan, August 28-September 8, 1983.

R. J. Vidale, "Water-Rock Interaction in Pelitic Systems," Fourth International Conference on Water-Rock Interactions, Misasa, Japan, August 28-September 8, 1983. 238 APPENDIX: PRESENTATIONS

INCH

D. L. Bish, D. T. Vaniman, R. S. Rundberg, K. Wolfsberg, W. R. Daniels, and D. E. Broxton, "Natural Sorptive Barriers in Yucca Mountain, Nevada, for Long-Term Isolation of High-Level Waste," IAEA International Conference on Radioactive Waste Management, Seattle, Washington, May 16-20,1983, IAEA-CN-43/461 (1983).

K. Eskola, P. Eskola, D. C. Hoffman, H. Olm, E. N. Treher, J. B. Wilhelmy, D. Lee, and G. T. Seaborg, "Transfer Reactions to Produce Neutron Rich Isotopes," XI European Conference on Physics and Chemistry of Complex Nuclear Reactions, Autrans, France, September 5-9,1983. .

J. S. Gilmore, G. J. Russell, H. Robinson, and R. E. Prael, "Fertile-to-Fissile Conversion and Fission Measurements for Thorium Bombarded by 800-MeV Protons," Seventh Meeting of the International Collaboration on Advanced Neutron Sources (ICANS-VII), Chalk River Nuclear Laboratories, Chalk River, Ontario, Canada, September 12-16, 1983, and Accelerator Breeder Workshop, Chalk River Nuclear Laboratories, Chalk River, Ontario, Canada, September 19-20, 1983.

D. C. Hoffman, W. R. Daniels, K. Wolfsberg, J. L. Thompson. R. S. Rundberg, S. L. Fraser, and K. S. Daniels, "A Review of a Field Study of Radionuclide Migration from an Underground Nuclear Explosion at the Nevada Test Site," IAEA International Conference on Radioactive Waste Management, Seattle, Washington, May 16-20, 1983.

C. J. Orth, J. S. Gilmore, J. D. Knight, and A. R. Palmer, "Iridium Abundance Measurements Across Two Late Cambrian Biomere Boundaries in Western Utah," Geological Society of America National Meeting, New Orleans, Louisiana, October 18-21, 1982.

C. J. Orth, "Iridium, Large Body Earth Impacts, and Biological Crises in the Fossil Record," Los Alamos Theoretical Colloquium, Los Alamos National Laboratory, Los Alamos, New Mexico, November 8, 1982.

C. J. Orth, J. S. Gilmore, J. D. Knight, C. L. Pillmore, and R. H. Tschudy, "Search in the San Juan Basin for the Cretaceous-Tertiary Iridium Anomaly: Comparisons with Raton Basin Results," Geological Society of America, Rocky Mountain and Cordilleran Sections Meeting, Salt Lake City, Utah, May 2-4, 1983.

C. J. Orth, "Iridium, Large Body Earth Impacts, and Biological Crises in the Fossil Record," Second Annual Milton Kahn Lecture, University of New Mexico, Chemistry Department, Albuquerque, New Mexico, May 6, 1983.

R. C. Reedy, P. Englert, S. Theis, and J. R. Arnold, "On the Production of Cosmogenic Nuclides by High-Energy Secondary Particles: Simulation Experiments with Beam Stop Neutrons," 14th Lunar and Planetary Science Conference, Houston, Texas, March 15-19, 1983.

R. C. Reedy, P. Englert, and J. R. Arnold, "Interaction of Cosmic Ray Secondaries in Extraterrestrial Matter: Simulations with High-Energy Protons and Neutrons," Second Meeting of the European Union of Geosciences, Strasbourg, France, March 28-31, 1983.

D. J. Vieira, J. M. Wouters, G. W. Butler, C. Pillai, K. Vaziri, S. Rokni, and L. P. Remsberg, "Progress Toward Making Direct Mass Measurements of Light Neutron-Rich Nuclei at LAMPF," 187th American Chemical Society National Meeting, St. Louis, Missouri, April 8-13, 1983.

INC-DO

W. W. Dudley and B. R. Erdal, "Site Characterization for Evaluation of Nuclear Waste Isolation at Yucca Mountain, Nevada," NWTS Annual Information Meeting, Las Vegas, Nevada, December 6-9, 1982. APPENDIX: PRESENTATIONS 239

B. Erdal, A. E. Ogard, B. M. Crowe, R. S. Rundberg, W. R. Daniels, D. L. Bish, and D. T. Vaniman, "Some Geochemical Considerations for a Potential Repository Site in Tuff at Yucca Mountain," US/FRG Bilateral Workshop on Standardization of Methods of Measuring Migration of Radionuclides in Geomedia, Berlin and Munich, West Germany, October 25-29, 1982.

K. Eskola, P. Eskola, M. M. Fowler, D. C. Hoffman, H. Olm, E. N. Treher, J. B. Wilhelmy, D. Lee, and G. T. Seaborg, "Transfer Reactions to Produce Neutron Rich Isotopes," XI European Conference on Physics and Chemistry of Complex Nuclear Reactions, Autrans, France, September 5-9, 1983.

D. C. Hoffman, "Fission Properties of Heavy Element Isotopes," Institute of Atomic Energy, Beijing, China, October 19, 1982.

D. C. Hoffman, "Excitation Functions for Production of Actinides and Superheavy Element Experiments," Institute of Atomic Energy, Beijing, China, October 20, 1982.

D. C. Hoffman, "Radionuclide Migration and Nuclear Waste Isolation Research," Institute of Atomic Energy, Beijing, China, October 20, 1982.

D. C. Hoffman, "Actinide Production and Properties and Superheavy Element Experiments," Institute of Atomic Energy, Beijing, China, October 23, 1982.

D. C. Hoffman, "Spontaneous Fission Properties of Heavy Actinides," Institute of Modern Physics, Lanzhou, China, October 26, 1982.

D. C. Hoffman, "Production of Actinides by Transfer Reactions and Superheavy Element Experiments," Institute of Modern Physics, Lanzhou, China, October 26, 1982.

D. C. Hoffman, "Research Activities in INC Division, Fission Properties and Production of Actinides, New Elements and Current Superheavy Element Experiments," Fudan University, Shanghai, China, November 1, 1982.

D. C. Hoffman, "Research Activities in INC Division, Production of Actinides and New Elements," Institute of Nuclear Research, Jiading (Shanghai), China, November 2, 1982.

D. C. Hoffman, "Potential for Radionuclide Migration from the Site of an Underground Nuclear Explosion," American Chemical Society, Central New Mexico Section, Los Alamos, New Mexico, November 19, 1982.

D. C. Hoffman, "Current Problems in Identification of New Elements" and "Spontaneous Fission Properties," Actinide Chemistry Class, University of New Mexico-Los Alamos, April 19, 1983.

D. C. Hoffman, "Nuclear Syntheses Needed for Chemical Investigations," US DOE Chemical Sciences Meeting following the Workshop on Future Directions for Transplutonium Element Research, Washington, DC, June 13, 1983.

D. C. Hoffman, W. R. Daniels, K. Wolfsberg, J. L. Thompson, R. S. Rundberg, ,S. L. Fraser, and K. S. Daniels, "A Review of a Field Study of Radionuclide Migration from an Underground Nuclear Explosion at the Nevada Test Site" (invited paper), IAEA International Conference on Radioactive Waste Management, Seattle, Washington, May 16-20, 1983.

D. C. Hoffman, "Spontaneous Fission Properties and Production of New Heavy Element Isotopes," Physical Chemistry Seminar, University of California, Berkeley, September 27, 1983.

I3 N. A. Matwiyoff, "Biomedical NMR studies with C Labeled Substrates," Los Angeles; University of California, Department of Pharmacology, February 10, 1983. 240 APPENDIX: PRESENTATIONS

N. A. Matwiyoflf, "NMR Spectroscopy in Medicine," American College Nuclear Physicians 9th Annual Meeting, Puerto Rico, March 12, 1983.

N. A. Matwiyoff, "NMR Spectroscopy in Nuclear Medicine," Society of Nuclear Medicine Meeting, Vail, Colorado, March 29,1983.

N. A. Matwiyoff, "I3C NMR Spectroscopy and "C Enriched Substrates for Metabolic Profiling," Society of Magnetic Resonance in Medicine Meeting, San Francisco, California, August 16, 1983.

N. A. Matwiyoff, "Stable Isotopes and NMR in Nutritional Studies" (invited paper), American Chemical Society Meeting, Washington, DC, August 30, 1983.

N. A. Matwiyoff, "NMR Spectroscopy in Medicine," American Chemical Society Lecture Tour, University of Texas, El Paso, Texas; Midland/Odessa, Texas; Big Springs, Texas; Amarillo, Texas; and Texas Tech University, Lubbock, Texas; September 1983.

185th National ACS Meeting

The following presentations were given at the 185th National Meeting of the American Chemical Society, Seattle, Washington, March 20—25, 1983.

J. W. Barnes, M. A. Ott, P. M. Wanek, F. H. Seurer, F. J. Steinkruger, K. E. Thomas, G. E. Bentley, and H. A. O'Brien, jr., "Production of Iodine-123 at Los Alamos National Laboratory"

G. E. Bentley and P. M. Wanek, "Applications of Ion Chromatography in the Production of Radiobromine and Radioiodine"

G. E. Bentley, F. J. Steinkruger, and P. M. Wanek, "Electrochemistry as a Basis for Radiochemical Generator Systems"

B. R. Erdal, B. M. Crowe, W. R. Daniels, B. J. Travis, R. S. Rundberg, and K. Wolfsberg, "Retardation of Waste Elements at a Potential Repository Site in Tuff at Yucca Mountain, Nevada"

B. R. Erdal, B. M. Crowe, A. E. Ogard, K. Wolfsberg, W. R. Daniels, R. S. Rundberg, D. L. Bish, and D. T. Vaniman, "Some Geochemical Considerations for a Potential Site in Tuff at Yucca Mountain, Nevada"

D. C. Hoffman, "Spontaneous Fission Properties and Production of Heavy Element Isotopes" (invited paper, Nuclear Chemistry Award Address)

Gregory J. Kubas, Robert R. Ryan, and Gordon D. Jarvinen, "Reduction of SO2 by Transition Metal Hydrides; Insertion of SO2 into the M-H Bond in CpMo(CO)3H" (poster session)

Gregory J. Kubas, R. R. Ryan, Phillip J. Vergamini, and H. J. Wasserman, "Characterization of 2 W(CO)3(PPr3')2(Ti -H2), the First Example of a Molecular Hydrogen Complex"

R. C. Reedy, P. Englert, and J. R. Arnold, "The Use of Spallation Reactions to Measure High-Energy Neutron Spectra and Isotope Production Rates" APPENDIX: PRESENTATIONS 241

K. E Thomas and J. W. Barnes, "Large-Scale Isolation of Strontium-82 for Generator Production"

D. S. Wilbur, "Radiobrominations: an Overview of the Problems Encountered Using Very High Specific Activity"

D. S. Wilbur and Z. V. Svitra, "Radiohalogenations of Aryl and Alkyl Groups Via Organopentafluorosilicates"

12th and 13th Radiochemistry ILWOG

Weapons diagnostics and related subjects were discussed at the 12th and 13th Radiochemistry Interlaboratory Working Group Meetings (ILWOG-12 and -13), with participants from McClellan AFB, Patrick AFB, Lawrence Livermore National Laboratory, and four divisions of Los Alamos. The following presentations were given by INC- Division staff at ILWOG-12, Los Alamos, New Mexico, October 19—21, 1982.

I. Binder, "RB as a Radiochemical Detector"

D. B. Curtis and D. J. Rokop, "Mass Spectrometric Developments and Results for the Tb Detector"

D. W. Efurd, "Am by Thermal Ionization Mass Spectrometry"

A. J. Gancarz, "The LANL Hosta-Nebbiolo Tests: Good News and Bad News"

P. R. Guthals, "Safeguard C—A Readiness to Test in Prohibited Environment?"

T. L. Norris, "The Half-Life of 26A1"

The talks listed below were given by INC staff members attending ILWOG-13 at Lawrence Livermore National Laboratory, Livermore, California, April 5—7, 1983.

I. Binder, "The Failure of Arsenic as a Radiochemical Detector"

I. Binder, "Does Rb Have Gas Sampling Problems?"

D. W. Efurd, "Progress in Chemistry and Mass Spectrometry of Americium"

A. J. Gancarz, "Yield Systematics Using Isotope Ratios and Prompt Diagnostic Data"

A. J. Gancarz, "Proof of the Pu-242 + U-233 Bomb-Fraction Tracer Principle"

A. J. Gancarz, "Progress in Developing the Am-243 Detector"

C. M. Miller, "Developments in Resonance Ionization Mass Spectrometry"

W. A. Sedlacek, "Variations in Stratospheric HNO3 from 1971 to 1982: Effects of Chinese Testing" 242 APPENDIX: PRESENTATIONS

38th Southwest and 6th Rocky Mountain Combined Regional Meeting of the ACS

The following talks were given at the 38th Southwest and 6th Rocky Mountain Combined Regional Meeting of the American Chemical Society, El Paso, Texas, December 2—3,1982.

Llewellyn H. Jones, "High Resolution Infrared Studies of Guest Host Interactions and Dynamics in Low Temperature Matrices"

G. J. Kubas and R. R. Ryan, "Reduction of SO2 by Transition Metal Hydrides; Insertion of SO2 into the M-H Bond in CpMo(CO)3H"

John M. Ritchey and David C. Moody, "Platinum(O) Complexes with Bulky Phosphines: Trinuclear SO2 and CS2 Complexes"

Basil I. Swanson, Stephen F. Agnew, David Schiferl, and Robert Mills, "Spectroscopic Studies of Small Molecules at High Pressures. Observation of a Strong Infrared-Active 0-0 Stretch in the High Density Red Phase of Oxygen"

W. H. Woodruff, K. A. Norton, B. I. Swanson, and H. A. Fry, "Cryo-Resonance Raman Spectroscopy of Plastocyanin, Azurin, and Stellacyanin. A Re-evaluation of the Identity of the Resonance Enhanced Modes"

46th Annual Meteoritical Society Meeting

The foliowing presentations were given at the 46th Annual Meeting of the Meteoritical Society in Mainz, West Germany, September 5—9, 1983.

P. Englert, R. C. Reedy. R. Fox, and J. R. Arnold, "Thick Target Irradiations as Simulations of Cosmic Ray Bombardments"

M. Freundel, L. Schultz, and R. C. Reedy, "The Production Rate of Cosmogenic 38Ar in Eucrites"

R. E. McGuire, J. N. Goswami, R. Hha, D. Lai, and R. C. Reedy, "Recent Fluxes of Solar Protons"

R. C. Reedy, M. S. Spergel, O. W. Lazareth, and P. W. Levy, "Production Rates of Cosmogenic 60Co, 39Ni, and "Cl in Stony Meteorites"

R. C. Reedy, "Nuclide Production by Primary Cosmic Rays in Very Small Objects"

R. C. Reedy, C. Tuniz, C. M. Smith, R. K. Moniot, T. H. Kruse, W. Savin, D. K. Pal, and O. F. Herzog, "I0Be Contents of Core Samples from the St. Severin Meteorite"

S. Theis, P. Englert, and R. C. Reedy, "Production of Cosmogenic Radionuclides by High-Energy Spallation Neutrons" APPENDIX: PRESENTA TIONS 243

Fifth Annual INC Division Information Meeting

The following talks were given at the Fifth Annual INC Division Information Meeting held in Los Alamos September 21—22, 1983.

Stephen F. Agnew, "Raman Spectroscopy at High Densities"

Larned B. Asprey, "Preparation and Properties of a Convenient Fluorinating Agent, FOOF"

Phil Bendt, "The 24-keV-Neutron Filtered-Beam Facility at OWR"

Timothy M. Benjamin, "Nuclear Microprobe Analyses of Rare Earth Element Fractionation in Meteoritic Minerals"

Rajeev S. Bhalero, "How Does a Pion Knock Out Another Pion from a Nucleus?"

Irwin Binder, "Any New Radiochemical Detectors on the Horizon?"

Merle E. Bunker, "Scientific Justification for the Proposed On-Line Mass Separator at LAMPF"

Robert W. Charles, "Some Experimentally Determined Phase Equilibria in the System CaO-SiO2-CO2-H2O"

Don T. Cromer, "Prediction of Densities of Organic Explosives"

David B. Curtis/Alexander J. Gancarz, "Radiolysis in the Oklo Reactors"

William R. Daniels, "SISAK—What is it? Recent and Proposed Experiments"

Clarence J. Duffy, "A Thermodynamic Model for Analcime"

William L. Earl, "NMR Studies of Solids"

P. Gary Eller, "Review of Lippizan Chemistry"

Malcolm M. Fowler, "Results from Recent Heavy-Element Experiments"

Herbert A. Fry, "Far-Infrared Matrix Isolation Spectroscopy: Hindered Rotation"

Sammy R. Garcia, "Study of Systematic Errors in Neutron Activation Analysis"

Judith C. Hutson, "In Situ NMR Studies of Perfused Organ Metabolism"

Llewellyn H. Jones, "Orientational Ordering and Site-Selective Photochemistry of UF6 Isolated in Rare Gas Solids"

Thomas A. Kelley, "The Future of Computing at TA-48"

Sylvia D. Knight, "Effects of Drilling Polymer and Bacteria on Sorptive Properties of Strontium and Plutonium on Tuff'

Michael J. Leitch, "Research with TRIUMF's Time-Projection Chamber"

Lon-Chang Liu, "Eta Meson Physics at LAMPF"

Berthus B. Mclnteer, "Selenium Isotope Separation Progress" 244 APPENDIX: PRESENTATIONS

Thomas R. Mills, "Design of a Neon Isotope Separation Sysi.cn;"

Michael M. Minor, "Dynamic Neutron Radiography"

Eugene J. Mroz/Allen Mason/Bill Sedlacek, "El Chichon Update"

Thomas L. Norris, "Nobel Gas Weapons Diagnostics"

Janet Mercer-Smith, "Utilization of Metal Chelates as an Approach to Radiolabeling Complex Organic Com- pounds"

Thomas W. Newton, "Actinide Carbonate Complexes—Classical Methods for Speciation"

. Yoshitaka Ohkubo, "A New Look at (JT, 71N) Reactions"

Charles J. Orth, "Recent Results from the Search for Iridium Anomalies in the Geologic Record"

Chandra Pillai, "Plans for Mass Measurements of Light Neutron-Rich Nuclei Using a Time-of-FIight Technique"

Larry Robinson, "Use of the SISAK-II Fast Chemistry System for Fission Yield Measurements"

Pamela S. Z. Rogers, "Quantitative Trace-Element Analysis by PIXE"

R. Scott Rogers, "Preliminary Results in Radiolabeling Monoclonal Antibodies"

Fred J. Steinkruger, "Production and Recovery of Iron-52 and Vandium-48 from a Proton-Irradiated Nickel Target"

235 m Willard L. Talbert, "Nuclear Excited States—A Proposal to Measure the nlh Fission Cross Section of U "

Kenneth E. Thomas, "Production of Radioisotopes of Osmium and Tungsten from Lead Targets"

Joseph L. Thompson/Robert S. Rundberg, "A Kinetic Effect in Actinide Sorption"

Thomas E. Walker, "Biosynthesis of Labeled Amino Acids"

Philip M. Wanek, "INC-3 Capabilities to Perform Animal Imaging and Biodistribution Measurements"

Harvey J. Wasserman, "The First Example of a Bound Hydrogen Molecule"

Jan M. Wouters, "Status Report on the TOFI Spectrometer"

D. Scott Wilbur, " Organosilanes in Radiohalogenations"

Shuheng Yan, "Recovery of Titanium-44 from a Proton-Irradiated Vanadium Target" APPENDIX: LIST OF FA CILITIES 245

FACILITIES AND EQUIPMENT Group Capability Contact

INC -3 Medical Isotopes Research Harold A. O'Brien Radioisotope Production Facility at the Los Ala- mos Meson Physics Facility, where large quantities of most radionuclides can be produced; includes: Hot cells for high-level gamma- and beta- active materials Purification and handling facilities Analytical support capability for research, development, and quality control for radioactive isotopes in medicine; includes: Dionex ion chromatograph Spectrametrics dc-coupled argon-plasma emission spectrometer Varian NMR spectrometer Model EM 36OA Perkin-Elmer ir spectrometer Model 283 Hewlett-Packard gas chromatograph mass spectrometer Model 5992 Packard radiochromatography scanner Model 7201 Three high-performance liquid chromatographs (Waters) Animal counting system Picker gamma camera Model 4-11

INC-4 Isotope and Structural Chemistry Ir spectrometers for spectroscopic studies of small molecules in gas, liquid, and solid phases, including inert gas matrices and under extreme conditions of temperature and pressure (diamond anvil cells) and fingerprinting of actinide and transition metal complexes; spectral range from 19 to 5000 cm"1, temperature control down to 4 K; includes: Perkin-Elmer Model 180 Llewellyn H. Jones Perkin-Elmer Model 683 NicoletFTIR Model 7199 Digital FTIR Model FTS-20S Perkin-Elmer Model 521 P. Gary Eller Nicolet FTIR Model 20SX 246 APPENDIX: LIST OF FACILITIES

FACILITIES AND EQUIPMENT

Raman spectrometers for determining vibration spectra of solids, including explosives, phase transitions, pressure-induced chemistry of small molecules, copper blue proteins, actinide and transition-metal complexes, solitons, spectral range from 2 to 10 000 cm"1, temperature control of 4 K, pressure control to 200 kbar (diamond anvil cells); includes: Two Spex 1403 monochromators Lasers for photochemistry and Raman spec- Basil I. Swanson troscopy; includes: Spectra Physics Model 171 (argon ion) Spectra Physcs Model 171 (krypton ion) Coherent Model 52G (argon ion) Lumonics Model TE431T-2 (Excimer) Lumonics Model EPO33V (dye head) Coherent dye laser

Tachists Model 125G(CO2, pulsed) Apollo Model 570 (CO2, cw) UV-VIS spectrometers for studies of actinide and P. Gary Eller transition-metal complexes, organic explosives, small molecules under pressure (diamond cell spectroscopy); includes: Two Perkin-Elmer Model 330 Cryogenic Separation Facility for preparation Thomas R. Mills of large amounts of stable isotopes that can then be used in other studies. NMR spectrometers for 13C, I9F, 31P, and 'H Clifford J. Unkefer spectroscopy on actinide and transition-metal James R. Brainard complexes; I3C and 'H studies related to organ perfusion, metabolic pathways, and bio-organic synthesis; 31P topical probes; structure and dynamics in organic explosions, polymers, and zeolites; includes: Varian XL-100 Fourier transform NMR spectrometer for 13C, 31P, and 'H in solution. Bruker WM-300 wide-bore spectrometer for high-resolution, multinuclear NMR of liquids. Varian EM-390 for 1SF, 31P, and 'H in solution (cw). APPENDIX: LIST OF FACILITIES 247

FACILITIES AND EQUIPMENT

Related equipment includes:

Amplifier Research broadband amplifier (2-200MHz, 100 Wcw) Hewlett-Packard Model 4193 vector im- pedance meter Data General Corp. Nova-line computer with 7-track magnetic tape, cassettes, 10-Mbyte disk X-ray diffraction instrumentation for structural Robert R. Ryan determination of a large class of materials, including actinide and transition-metal complexes, organic explosives, and small molecules at high pressures; single-crystal x-ray diffraction from -200 to 1000°C and in diamond anvil cells, precision and Weissenberg photography, powder diffraction; includes: Picker FACXI single-crystal diffractometer Enraf Novius single-crystal diffractometer Precision and Weissenberg single-crystal cameras Powder cameras "Hot" laboratory capabilities for actinide and P. Gary Eller fluorine chemistry; includes: Actinide glovebox lines for preparative work and interpretation; includes: Two VAX-11/780 computers using the VAX/VMS system and a rich environment of commercial and local software Several other PDP-11/60, PDP-11/34, and LSI-11 systems Fluorine vacuum systems Nicolet SX-20 FT-IR with Csl optics Perkin-Elmer 330 UV-VIS-NIR spectrometer with data system Preparative microwave systems X-ray powder diffraction system 248 APPENDIX: LIST OF FACILITIES

FACILITIES AND EQUIPMENT

Equipment for biochemical synthesis; includes: Thomas E. Walker Hewlett-Packard 571OA gas chromatograph with TC detector and HP 3390A integrator Hewlett-Packard 5710A gas chromatograph with FID detector and HP 339OA integrator Extranuclear SpectrEL quadrupole mass spectrometer with solid, gas, and GC imputs (used with HP 5710A instrument with FID detector); data system includes a Data Gen- eral Nova 3 computer, Camac interface, and 10-Mbyte disk. Perkin-Elmer liquid chromatograph, including Series 3B LC, LC-75 spectrophotometric detector, and Sigma 15 data station Perkin-Elmer Model 297 ir spectrophoto- meter TOF and automated nitrogen isotope ratio mass B. B. Mclnteer spectrometer Instrumentation for chemical kinetics, chemical Robert R. Ryan dynamics, spectroscopy, and ultrasensitive analysis; includes: Fast-flow tube Single-beam and crossed molecular beam machine Stopped-flow kinetics apparatus for plutonium studies Instrumentation for thermochemical studies, includes: High-temperature solution calorimeter Combustion calorimeter Room-temperature solution calorimeter Perkin-Elmer TGS-2 thermogravimetric balance Differential thermal analysis equipment APPENDIX: LIST OF FA CILITIES 249

FACILITIES AND EQUIPMENT

INC-5 Research Reactor OWR (8 MW); includes: Merle E. Bunker Fourteen thermal and epithermal rabbit facilities In-core irradiation facilities (thermal flux 9xl013n/cm2s) Triple-axis neutron diffractometer for neutron scattering studies Double-axis powder diffractometer for neutron transmission studies Neutron radiography facilities Two neutron-capture gamma-ray facilities Capability for producing relatively large quantities of isotopes by capture of thermal neutrons. Automated instrumental neutron-activation analy- Michael M. Minor sis for 39 elements; analysis of solid materials (soils, rocks, and particulate filters) and liquids (up to 40 mi); includes: Three automated neutron-activation systems with on-line data reduction; capable of handling up to 400 samples per day Several Ge(Li) gamma-ray spectrometers tied John W. Starner to a local PDP-11/60 for data reduction

INC-7 Isotope Geochemistry High-pressure mass spectrometry measurements David B. Curtis for most elements; seven mass spectrometers; Donald J. Rokop includes: Two single magnetic stage instruments with pulse counting and/or Faraday cage ion detection; 10~9to 10~12-g-sample size for plutonium, americium, and neptunium; 10~8 to 10~12-g-sample size for uranium Two instruments with two magnetic stages and pulse counting and/or Faraday cage ion detector; 0.25 to 1.0 standard cm3 sample size I3 6 11 for CD4; 10" to lO" g for terbium, bismuth, and technicium 250 APPENDIX: LIST OF FACILITIES

FACILITIES AND EQUIPMENT

One resonance (laser) ionization (12 in.-68°) instrument with a single magnetic stage and pulse counting and/or Faraday cage ion detection; 10~6to 10~9-g-samplesize; includes dye and ring dye lasers One single-magnetic-stage instrument with pulse counting and/or Faraday cage ion detection; used for geochemistry studies on lead, uranium, neodymium, and strontium; 10~6 to 10~8-g-sample si?.e One single stage (6-in.) instrument with current integration ion detection; rSO.Ol standard cm3; used for noble gases (helium, neon, argon, krypton, and xenon) Two single-magnetic-stage instruments with Faraday cage ion detection; 10~5 to 10~8-g- sample size for uranium and plutonium. Anaerobic sampling of pumped groundwaters and Allen E. Ogard high-precision field analysis and laboratory analysis; trailer equipped for anion analysis by ion chromatography, cation analysis by atomic absorption spectrometry, alkalinity, dissolved oxygen, sulfide, Eh, and detergents; full laboratory analytical facilities Atmospheric tracer experiments using an Paul R. Guthals airborne platform (WB-57F) (collaboration with National Aeronautics and Space Administration) Physical and chemical characterization of Allen S. Mason aerosols in the stratosphere Inorganic trace constituent analysis (in Eugene J. Mroz situ and laboratory) in upper troposphere and lower stratosphere; includes: Quadrupole mass spectrometer with gas chromatograph (masses to 1000) Particle-size and mass distribution analysis William A. Sedlacek in atmosphere

Instruments for analysis and handling of Ernest A. Bryant samples; includes: Perkin-Elmer 404 atomic absorption spectrometer APPENDIX: LIST OF FA CILITIES 251

FACILITIES AND EQUIPMENT

Several high-performance liquid chromatographs (Waters and Spectron Physics) X-ray fluorescence spectrometer Chemical autoanalyzer used for atmospheric samples (Technicon Autoanalyzer II) Two potentiostat-coulometers, PAR Model 173 Two Dionex anion chromatographs Rare-gas handling system for mass spectrometers Polarographic analyzer/stripping voltam- meter, PAR Model 264 Microscopy equipment for analysis of Robert W. Charles particulates and geologic samples; includes: SEM with nondispersive x-ray analyzer

INC-11 Nuclear and Radiochemistry Extensive facilities for measurement and William R. Daniels handling of radioactivity; includes: Many automatic beta- and gamma-counting systems Many alpha-, beta-, and gamma-ray spectrometers Computer control for data collection and data reduction Facilities for handling alpha-emitting materials Ultraviolet, visible, near-ir spectrometers; William R. Daniels •ncludes: Hewlett-Packard 8450A uv/visible spectrometer Several Cary-14 spectrometers Two magnetic deflection isotope separators John P. Balagna Several local computer systems for data John P. Balagna reduction 252 APPENDIX: AD VISOR Y COMMITTEES

ADVISORY COMMITTEES

VISIT1NQ COMMITTEE FOR NUCLEAR AND RADIOCHEMISTRY

Chairman: Lawrence Wilets, University of Washington, Seattle, Washington, 1981-83.

John O. Rasmussen, Lawrence Berkeley Laboratory, Berkeley, California, 1981-83.

Robert Vandenbosch, University of Washington, Seattle, Washington, 1981-83.

Gregory R. Choppin, Florida State University, Tallahassee, Florida, 1982-84.

Donald S. Burnett, California Institute of Technology, Pasadena, California, 1983-85.

Rod Spence (Consultant, Los Alamos National Laboratory) substituted for Dr. Rasmussen.

MEDICAL RADIOISOTOPES

Chairman: Thomas F. Budinger, Lawrence Berkeley Laboratory, Berkeley, California, 1979-83.

Raymond E. Counsell, University of Michigan, Ann Arbor, Michigan, 1979-83.

Sally J. DeNardc, Davis Med'cal Center, Sacramento, California, 1981-85.

Paul V. Harper, Franklin McLean Memorial Research Institute, Chicago, Illinois, 1979-83.

Thomas P. Haynie, M.D., Anderson Medical Center, Houston, Texas, 1979-83.

Alfred P. Wolf, Brookhaven National Laboratory, Upton, New York, 1981-85.

STABLE ISOTOPES RESOURCE ADVISORY COMMITTEE

Chairman: Robert Barker, Cornell University, Ithaca, New York, 1975-83.

Neal Castagnoli, University of California Medical Center, San Francisco, California, 1982-83.

Harry Hogenkamp, University of Minnesota, Minneapolis, Minnesota, 1975-83.

Oleg Jardetsky, Stanford University, Stanford, California, 1982-83. APPENDIX: DIVISIONAL SEMINARS 253

DIVISIONAL SEMINARS

"Volcanic Hazard Studies for the Nevada Nuclear Waste Storage Investigations: Current Status and Future Research Directions," Bruce M. Crowe, INC-7, November 19, 1982.

"True Pion Absorption and Its EfFects on Other Pion-Nucleus Reactions," Lon-Chang Liu, INC-11, December 10, 1982.

"The Los Aiamos Nuclear Microprobe," Timothy M. Benjamin, INC-7, January 14, 1983.

"Discovery and Characterization of the First Example of Molecular Hydrogen Bound to a Metal," Gregory J. Kubas, INC-4, April 8, 1983.

SPECIAL DIVISIONAL SEMINARS

"Pion Studies at the Bevalac," John O. Rasmussen, Lawrence Berkeley Laboratory, February 2, 1983.

"Cosmic-Ray-Produced 81Kr in Meteorites," Jane Crabb, Mainz, West Germany, March 11, 1983.

"New Mass Measurements: What Are They Telling Us?" Peter Haustein, Brookhaven National Laboratory, March 17, 1983.

"Consequences of Radioactive Decay in the Bulk-Phase Solid State," Joseph R. Peterson, University of Tennessee, March 18, 1983.

"Investigations on the Chemical Behavior of Radioiodine in Surface and Groundwater Systems," Horst Behrens, Munich, West Germany, March 29, 1983.

"Aspects of Cosmochemistry: Reaction Products of Cosmic Particle Radiation in Extraterrestrial Bodies," Peter Englert, Universitat zu Koln, West Germany, April 22,1983.

"Positron Emission Tomography in Biological Research," Jorge R. Barrio, University of California, Los Angeles, California. May 6, 1983.

"He-Jet Coupled Mass Separators—History, Perspective, and the Future," Dennis M, Moltz, University of South Carolina, May 11, 1983.

"The Migration of Uranium Series Nuclides Down-Gradient of Ore Deposits in the Alligator Rivers Uranium Province Northern Territory, Australia," Peter L. Airey, Australian Atomic Energy Commission, May 18, 1983.

"Research Activities in the Institute of Radiochemistry," Hans Ache, Karlsruhe, West Germany, May 25, 1983.

"High-Level Radioactive Waste Disposal in the Permian Basin: Computer Simulation of Hydrologic and Geochemical Processes," Randy L. Bassett, Stauffer Chemical Company, Denver, Colorado, May 26, 1983.

"Soviet Nuclear Physics—From Nuclear Weapons to International Cooperation" and "Proposed Searches for the X" Particle," Sergei Polikanov, Darmstadt, West Germany, June 1, 1983. 254 APPENDIX: DIVISIONAL SEMINARS APPENDIX: DIVISIONAL PERSONNEL

"The In Situ Measurement of Retardation Factors Using Uranium and Thorium Decay Series Nuclides," William C. Graustein, Yale University, June 27, 1983.

"Gold Target Fragmentation with Intermediate-Energy Heavy Ions," Kjell Anders Aleklett, Nykoping, Sweden, July 11,1983.

"Coordination Chemistry of Lanthanides and Actinides," Daohong Zhu, Lawrence Berkeley Laboratory, September 12, 1983.

"New Directions for Tandem Accelerator Mass Spectrometry in Geophysics and Elementary Particle Physics," David EJmore, University of Rochester, New York, September 14, 1983.

"Preliminary Evaluation of Flow and Transport at Yucca Mountain, Nevada," F. Harvey Dove, Pacific Northwest Laboratory, Richiand, Washington, September 30, 1983.

LIST OF DIVISIONAL PERSONNEL BY GROUP

INC-DO (667-4457) INC-4 (667-6045) Building RC-2, TA-48 Buildings 3 and 150, TA-21; Building 88, TA-46 •Darleane C. Hoffman, Division Leader +*Robert A. Penneman, Group Leader •Nicholas A. MatwiyofF, Deputy Division Leader •Robert R. Ryan, Deputy Group Leader •Donald W. Barr, Associate Division Leader F. Ruth Capron, Administrative Assistant *Bruce R. Erdal, Associate Division Leader •Dale E. Armstrong Helen A. Lindberg, Assistant Division Leader •Lamed B. Asprey Jody H. Heiken. Technical Editor/Writer •Don T. Cromer Audrey L. Giger, Administrative Assistant •William L. Earl Barbara J. Anderson, Administrative Assistant Deborah S. Ehler Joann W. Brown, Secretary Scott A. Ekberg Janey Howard, Secretary •Phillip G. Eller +Carolyn A. Smith, Secretary -(•Elizabeth M. Foltyn •Eiichi Fukushima INC-3 (667-4675) Michael G. Garcia Radiochemistry Building, TA-48 +*Chung Hwa Han •Harold A. O'Brien, Jr., Group Leader •Judith C. Hutson •David C. Moody, III, Deputy Group Leader •Gordon D. Jarvinen Karen E. Peterson, Secretary •Llewellyn H. Jones (Laboratory Fellow) •John W. Barnes Toby E. Kain +*Glenn E. Bentlev Jean King Martin A. Ott •Gregory J. Kubas Neno J. Segura +• Allen C. Larson Franklin H. Seurer Charles A. Lehman, Jr. *F. J. Steinkruger •Robert E. London •Zita V. Svitra +Eileen A. Martinez Wayne A. Taylor •Berthus B. Mclnteer •Kenneth E. Thomas Raymond C. Medina •Phillip M. Wanek •Thomas R. Mills •Daniel S. Wilbur Joe G. Montoya APPENDIX: DIVISIONAL PERSONNEL 255

Ramon Romero Lia M. Mitchell Kenneth V. Salazar •Eugene J. Mroz Francis A. Schmahl •A. Edward Norris •Basil I. Swanson •Thomas L. Norris •Clifford J. Unkefer •Allen E. Ogard Raymond C. Vandervoort •Richard E. Perrin •William E. Wageman +Nancy A. Raybold •Thomas E. Walker •Pamela Z. Rogers •Donald J. Rokop INC-5 (667-4151) C. Elaine Roybal Omega Site, TA-2 •William A. Sedlacek •Merle E. Bunker, Group Leader +*Elizabeth N. Treher •Michael M. Minor, Deputy Group Leader •Rosemary J. Vidale Cathy Schuch, Secretary Patsy L. Wanek +Sarabel Serna, Secretary •Kurt Wolfsberg +*Michael M. Denton Bruce P. Eide INC-11 (667-4546) •Sammy R. Garcia Radiochemistry Building, TA-48; LAMPF Building, +Richard Gomez TA-53 +Alex P. Kent •James E. Sattizahn, Group Leader •Alvin R. Lyle •William R. Daniels, Deputy Group Leader Janet S. Newlin Merlyn E. Holmes, Administrative Assistant Danny O. Ramsey Marcella L. Kramer, Secretary Thomas C. Robinson Voncille V. Armijo •John W. Starner •John P. Balagna •Herbert T. Williams Roland A. Bibeau •Gilbert W. Butler INC-7 (667-4498) Michael R. Cisneros Radiochemistry Building, TA-48 +Sandra M. Cisneros •Ernest A. Bryant, Group Leader •David D. Clinton •Alex J. Gancarz, Jr., Deputy Group Leader Joy Drake Kathleen S. Kelly, Secretary •Bruce J. Dropesky Ruben D. Aguilar Patricia A. Elder •Mohammed Alei •Martha L. Ennis Joseph C. Banar •James D. Gallagher •Barbara P. Bayhurst Carla E. Gallegos Gregory K. Bayhurst •Gregg C. Giesler •Timothy M. Benjamin •James S. Gilmore •Irwin Binder •Genevieve D. Grisham •John H. Cappis Gary T. Hanson •Robert W. Charles •Sara B. Helmick •George Corchary •David E. Hobart •Bruce M. Crowe Gregory M. Kelley •David B. Curtis •Thomas A. Kelley •Clarence J. Duffy Jack H. Knight Suzann Dye •Sylvia D. Knight •Deward W. Efurd •Gordon Knobeloch •Malcolm M. Fowler Marjorie E. Lark •Paul R. Guthals •Francine O. Lawrence Deva E. Handel •Michael J. Leitch Julia M. Jaramillo Shari Lermuseaux •Allen S. Mason Lelia Z. Liepins •Charles M. Miller •Lon-Chang Liu 256 APPENDIX: DIVISIONAL PERSONNEL

Calvin C. Longmire Graduate Research Assistants -f-Joseph Longshore Sharon L. Blaha, INC-11 Sixto Maestas Bridget R. Burns, INC-7 +E. Loretta McCorkle Carol J. Burns, INC-4 Alan J. Mitchell Kathryn S. Daniels, INC-7 Thomas A. Myers Gerhard Feige, INC-11 •Thomas W. Newton Susan L. Fraser, INC-11 Glenda E. Oakley James Gilbert, INC-3 Petrita Q. Oliver James Griffith, INC-7 •Charles J. Orth (Laboratory Fellow) Elizabeth M. Overmyer, INC-4 •Rene J. Prestwood Leonard M. Quintana, INC-11 Tony Rael Larry Robinson, INC-11 •Robert C. Reedy Mark E. Schaffner, INC-11 •Robert S. Rundberg Andrew A. Sicree, INC-11 •Virginia L. Rundberg Wendy Stone, INC-3 Raymond G. Schofield Martha Sykes, INC-7 +Alice Staritsky Linda K. Trocki, INC-11 Richard L. Stice •Willard L. Talbert, Jr. Undergraduate Assistants •Kimberly W. Thomas Cindy L. Jaramillo, INC-11 Larry S. Ulibarri Douglas R. Manatt, INC-4 Levi Valencia Audrey Martinez, INC-DO •David J. Vieira Cali C. Matheny, INC-4 •Jerry B. Wilhelmy (Laboratory Fellow) •Jan M. Wouters •Alfred H. Zeltmann

Long-Term Visiting Staff Members Rajeev S. Bhalerao, INC-11 Nathan Bower, INC-7 Joseph L. Thompson, INC-11 William H. Zoller, INC-7

Postdoctoral Appointees Stephen F. Agnew, INC-4 James R. Brainard, INC-4 M. Pamela Bumsted, INC-4 G. Larighorne Farmer, INC-7 Herbert A. Fry, INC-4 Yoshitaka Ohkubo, INC-11 Raymond S. Rogers, INC-3 Harvey j. Wasserman, INC-4

•Staff Member +No longer working in INC Division P«b!ic«tiODf and Presentations 245 list of Facilities

253 Divisional Seminars 254 list ofDivisioBal Personnel by Group

, , V '

T- 'References

- #

-.*- REFERENCES 259

1. P. S. Z. Rogers, T. M. Benjamin, C. J. Duffy, J. R. Tesmer, and C. J. Maggiore, "Applications of an Ion Accelerator to Weapons Diagnostics," in "Isotope and Nuclear Chemistry Division Annual Report FY 1982," Los Alamos National Laboratory Report LA-9797-PR (June 1983), pp. 22-24.

14 15 2. G. M. Begun and W. H. Fletcher, "Infrared and Raman Spectra of N2 O4 and N2 O4," J. Mol. Spectrosc. 4, 388-397 (1960).

3. T. P. Melia, "Decomposition of Nitric Oxide at Elevated Pressures," J. Inorg. Nucl. Chem. 27, 95-98 (1965).

4. J. R. Ohlsen and J. Laane, "Characterization of the Asymmetric Nitric Oxide Dimer O=N=O=N by Resonance Raman and Infrared Spectroscopy," J. Am. Chem. Soc. 100, 6948-6955 (1978).

5. I. C. Hisatsune and J. P. Devlin, "The Raman Spectrum and the Structure of N2O3," Spect'ochim. Acta 16, 401-406 (1960).

6. B. I. Swanson, S. F. Agnew, L. H. Jones, R. L. Mills, and D. Schiferl, "Spectroscopic Studies of Molecular Interactions of Oxygen-16 and Oxygen-18 in the High Density €-Phase," J. Phys. Chem. 87, 2463-2465 (1983).

7. L. H. Jones, B. I. Swanson, and H. A. Fry, "Preferred Orientation of Guest Molecules in Low-Temperature Matrices: SF6 in Xenon," Chem. Phys. Lett. 87, 397-399 (1982).

8. L. H. Jones and B. I. Swanson, "Orientational Ordering, Site Structure, and Dynamics for Octahedral Molecules

in Low Temperature Matrices: SF6 and SeF6 in Rare Gas Solids," J. Chem. Phys. 79, 1516-1522 (1983).

9. A. C. Sinnock and B. L. Smith, "Refractive Indices of the Condensed Inert Gases," Phys. Rev. 181, 1297-1307 (1969).

10. L. S. Bartell, L. O. Brockway, and R. H. Schwendeman, "Refined Procedure for Analysis of Electron

Diffraction Data and Its Application to CC14," J. Chem. Phys. 23, 1854-1859 (1955).

11. L. Pauling, The Nature of the Chemical Bond (Cornell University Press, Ithaca, New York, 1960), p. 260.

12. L. H. Jones and B. I. Swanson, "Quantification of Orientational Ordering of SF6 in Solid Xenon Matrices," submitted to J. Chem. Phys.

13. M. L. Klein and J. A. Venables, Rare Gas Solids, Vol. II (Academic Press, New York, 1977), p. 969.

14. D. W. Robinson, "Spectra of Matrix Isolated Water in the 'Pure Rotation Region'," J. Chem. Phys. 39, 3430-3432 (1963).

15. J. A. Cugley and A. D. E. Pullin, "Far-infrared Spectrum at HNCO and DNCO in an Argon Matrix," Chem. Phys. Lett. 19, 203-217 (1973).

16. A. Behrens-Griesenbach and W. A. P. Luck, "Low Frequency Motions of Water Isolated in Low Temperature Matrices," J. Mol. Struct. 80,471-476 (1982).

17. E. Knozinger and R. Wittenbeck, "Intermolecular Motional Degrees of Freedom of H2O and D2O Isolated in Solid Gas Matrices," J. Am. Chem. Soc. 105, 2154-2158 (1983).

18. H. Friedmann and S. Kimel, "Interpretation of Spectra of HC1 and DC1 in an Argon Matrix," J. Chem. Phys. 41, 2552-2553 (1964).

19. H. Friedmann and S. Kimel, "Rotation-Translation Coupling Spectrum of Matrix Isolated Diatomic Molecules in the Near and Far Infrared," J. Chem. Phys. 44,4359-4360 (1966). 260 REFERENCES

20. H. Friedmann and S. Kimel, "The Rotation-Translation-Coupling Effect in Noble-Gas Crystals Containing Molecular Impurities," J. Chem. Phys. 47, 3589-3605 (1967).

21. R. L. Redington and D. E. Milligan, "Molecular Rotation and Ortho-Para Nuclear-Spin Conversion of Water Suspended in Solid Ar, Kr, and Xe," J. Chem. Phys. 39, 1276-1291 (1963).

22. H. A. Fry, L. H. Jones, and B. I. Swanson, "The High Resolution Spectroscopy of the 1(1,1) •<- 0(0,0) Transition of Water in Argon and Krypton Matrices," submitted to Chem. Phys. Lett.

23. S. F. Trevino, E. Prince, and C. R. Hubbard, "Refinement of the Structure of Solid Nitromethane," J. Chem. Phys. 73(6), 2996-3000(1980).

24. R. D. Bardo, "The Role of Excited Electronic States in the Bond-Scission Process in Detonation Reactions," Proceedings of the 7th Symposium on Detonations, Naval Surface Weapons Center, White Oak, Silver Spring, Maryland, June 16-19, 1981, p. 93.

25. R. D. Bardo and W. H. Jones, "A Theoretical Calculation of the 0° Isotherm for Shocked Nitromethane," American Physical Society Topical Conference on Shock Waves in Condensed Matter, Santa Fe, New Mexico, July 18-21, 1983, Abstract IVD-6.

26. F. Zarilli, "Shock-Induced Molecular Excitation in Solids," American Physical Society Topical Conference on Shock Waves in Condensed Matter, Santa Fe, New Mexico, July 18-21, 1983, Abstract IVD-7.

27. F. Borsard, C. Tombini, and A. Minil, "Raman Scattering Temperature Measurements Behind a Shock Wave," Proceedings of the 7th Symposium on Detonations, Naval Surface Weapons Center, White Oak, Silver Spring, Maryland, June 16-19, 1981, pp. 1010-1015.

28. J. R. Stine, "Prediction of Crystal Densities of Organic Explosives by Group Additivity," Los Alamos National Laboratory report LA-8920 (August 1981).

29. M. J. Kamlet and C. Dickenson, "Chemistry of Detonations III,'' J. Chem. Phys. 48,43-50 (1968).

30. W. R. Busing, "WMIN, A Computer Program to Model Molecules and Crystals in Terms of Potential Energy Functions," Oak Ridge National Laboratory report ORNL-5747 (1981).

31. K. Mirsky, "The Determination of the Intermolecular Energy by Empirical Methods," in Computing in Crystallography, H. Schenk, R. Otlhof-Hazenkamp, H. van Konigsveldt, and G. S. Bassi, Eds. (Delft University Press, 1978), pp. 169-182.

32. R. Engelke, "Effect of a Physical Inhomogeneity on Steady-State Detonation Velocity," Phys. Fluids 22, 1623-1630 (1979).

33. T. R. Mills, M. Goldblatt, and R. C. Vandervoort, "Separation of Stable Isotopes (Carbon, Nitrogen, and Oxygen) and Production of Labeled Compounds," in "Chemistry-Nuclear Chemistry Division, October 1979- September 1980," Los Alamos Scientific Laboratory report LA-8717-PR (May 1981), p. 55.

2 34. W. L. Nelson and M. J. Bartels, "Derivatives of (3-Adrenergic Antagonists. Preparation of Propranolol-3,3- H2 and Propranolol-"O," J. Labelled Comp., in press.

35. S. Oae, R. Kiritani, and W. Tagaki, "The Oxygen Exchange Reaction of Phenol in Acidic Media," Bull. Chem. Soc. Japan 39, 1961-1967 (1966).

36. M. S. Kharasch and W. B. Reynolds, "Factors Determining the Course and Mechanisms of Grignard Reactions. X. The Oxidation of Grignard Reagents—Effect of Metallic Catalysts," J. Am. Chem. Soc. 65,501-504 (1943). REFERENCES 261

37. T. E. Walker and M. Goldblatt, "The Synthesis of Oxygen-18 Enriched Napththoi and Phenol from "O2," J. Labelled Comp., in press.

38. T. E. Walker, C. H. Han, V. H. Kollman, R. E. London, and N. A. Matwiyoff, "I3C Nuclear Magnetic Resonance Studies of the Biosynthesis by Microbacterium ammonilphilum of L-Glutamate Selectively Enriched with Carbon-13," J. Biol. Chem. 257, 1189-1195 (1982).

39. R. E. London, "Carbon-13 Labeling Strategies in Micromolecular Studies: Application to Dihydrofolate Reductase," in Topics in Carbon-13 NMR Spectroscopy, G. C. Levy, Ed. (Wiley, New York), Vol. 4, in press.

40. R. E. London, W. E. Wageman, and R. L. Blakley, "Carbon-13 NMR Studies of Selectively Carboxymethylated [Methyl-"C] Methionine Labeled Bacterial Dihydrofolate Reductase," FEBS Lett. 160, 56-60(1983).

41. J. M. Gleisner and R. L. Blakley, "The Structure of Dihydrofolate Reductase: I. Inactivation of Bacterial Dihydrofolate Reductase Concomitant with Modification of a Methionine Residue at the Active Site," J. Biol. Chem. 250, 1510-1587(1975).

42. J. M. Gleisner and R. L. Blakley, "The Structure of Dihydrofolate Reductase: Identification of Methionine Residues Carboxymethylated by Iodoacetate with Loss of Catalytic Activity," Eur. J. Biochem. 55, 141-146 (1975).

43. J. R. Brainard, J. Y. Hutson, R. E. London, and N. A. Matwiyoff, "Metabolism As It Happens," Los Alamos Science, Number 8, 42-64 (1983).

44. C. J. Unkefer, R. M. Blazer, and R. E. London, "In Vivo Determination of the Pyridine Nucleotide Reduction Charge by Carbon-13 NMR Spectroscopy," Science 222, 62-65 (1983).

45. H. B. White, III, "Biosynthetic and Salvage Pathways of Pyridine Nucleotide Coenzymes," in The Pyridine Nucleotide Coenzymes, J. Everse, B. Anderson, and K. S. You, Eds. (Academic Press, 1982), pp. 225-248.

46. D. J. Hnatowich, S. Kulprathipanja, and S. Treves, "An Improved 19lOs —* 191lrm Generator for Radionuclide Angiography," Radiology 123, 189-194 (1977).

47. C. Cheng, S. Treves, A. Samuel, and M. A. Davis, "A New Osmium-191 —*• Iridium-191m Generator," J. Nucl. Med. 21, 1169-1176(1980).

48. B. L. Holman, G. I. Harris, R. D. Neirinckx, A. G. Jones, and J. Idoine, "Tantalum-178—A Short-lived Nuclide for Nuclear Medicine: Production of the Parent W-178," Nucl. Med. 19, 510-513 (1978).

49. R. D. Neirinckx, M. A. Davis, and B. L. Holman, "The 178W/178Ta Generator: Anion Exchange Behavior of I78W and 178Ta," Int. J. Appl. Radiat. Isot. 32, 85-89 (1981).

50. C. E. Cummings, A. E. Ogard, and R. H. Shaw, "Target Insertion and Handling System for the Isotope Production Facility," Proc. 26th Conf. Remote Systems Technology, Washington, DC, November 12-16,1978 (American Nuclear Society, Inc., La Grange Park, Illinois, 1979), pp. 201-206.

51. G. E. Bentley, J. W. Barnes, T. P. DeBusk, and M. A. Ott, "Fabrication, Cladding, and Handling of Irradiation Targets for Isotope Production at LAMPF," Proc. 26th Conf. Remote Systems Technology, Washington, DC, November 12-16, 1978 (American Nuclear Society, Inc., La Grange Park, Illinois, 1979), pp. 378-381.

52. H. A. Meyers and R. J. Nagle, Jr., "The Half-Life of mW," J. Inorg. Nucl. Chem. 35, 3985-3989 (1973).

53. F. J. Steinkruger, "Iron-52 -»• Manganese-52m System," in "Isotope and Nuclear Chemistry Division Annual Report FY 1982," Los Alamos National Laboratory report LA-9797-PR (June 1983), p. 67. 262 REFERENCES

54. S. N. Bhosale and S. M. Khopkar, "Reversed-Phase Extraction Chromatography of Iron(III) with Tri-n-Butyl Phosphate on Silica Gel," Talanta 20, 889-891 (1979).

55. F. W. E. Strelow, R. Rethemeyer, and C. J. C. Bothma, "Ion Exchange Selectivity Scales for Cations in Nitric Acid and Sulfuric Acid Media with a Sulfonated Polystyrene Resin," Anal. Chem. 37,106-111 (1965).

56. K. E. Thomas and J. W. Barnes, "Isotope Production from Molybdenum Targets," in "Isotope and Nuclear Chemistry Division Annual Report FY 1982," Los Alamos National Laboratory report LA-9797-PR (June 1983), pp. 58-63.

57. K. E. Thomas, "Ge(Li) Detector Calibrations and Gamma-Ray Counting from a Hot Cell," in "Isotope and Nuclear Chemistry Division Annual Report FY 1982," Los Alamos National Laboratory report LA-9797-PR (June 1983), pp. 70-73.

58. J. W. Barnes, M. A. Ott, P. M. Wanek, F. H. Seurer, K. E. Thomas, t\ J. Steinkruger, and G. E. Bentley, "Iodine-123 Production," in "Isotope and Nuclear Chemistry Division Annual Report FY 1982," Los Alamos National Laboratory report LA-9797-PR (June 1983), pp. 64-66.

59. P. M. Grant, R. E. Whipple, J. W. Barnes, G. E. Bentley, P. M. Wanek, and H. A. O'Brien, Jr., The Production and Recovery of "Br at Los Alamos for Nuclear Medicine Studies, J. Inorg. Nuci. Chem. 43, 2217-2222 (1981).

60. J. W. Barnes, M. A. Ott, P. M. Wanek, F. H. Seurer, F. J. Steinkruger, K. E. Thomas, G. E. Bentley, and H. A. O'Brien, Jr., "Production of Iodine-123 at Los Alamos National Laboratory," 185th American Chemical Society National Meeting, Seattle, Washington, March 20-25, 1983, Los Alamos National Laboratory document LA-UR-82-3084.

61. H. Small, T. S. Stevens, W. C. Bauman, "Novel Ion Exchange Chromatographic Method Using Conductimetric Detection," Anal. Chem. 17, 1801-1809 (1975).

62. S. R. Garcia and P. Polak, "Separation of Silicon from Vanadium Spallation Targets," in "Isotope and Nuclear Chemistry Division Annual Report FY 1982," Los Alamos National Laboratory report LA-9797-PR (June 1983), pp. 67-69.

63. Z. Cizek, J. Dolezal, and Z. Sulcek, "Determination of Small Amounts of Titanium in Pure Molybdenum, Tungsten, Vanadium, and Their Oxides After Separation on Silica Gel," Anal. Chim. Acta 100,479-483 (1978).

64. Z. Cizek, Z. Sulcek, and J. Dolezal, "Sorption of the Peroxocomplex of Titanium on Silica Gel and Its Analytical Use," Chromatographia 15, 18-24 (1982).

65. Z. Cizek, Z. Sulcek, and J. Dolezal, "Separation of Trace Amounts of Titanium by Sorption of the Titanium Peroxocomplex on Silica Gel," Chromatographia 15, 760-764 (1982).

66. M. W. Greene and M. Hillman, "A Scandium Generator," Int. J. Appl. Radiat. Isot. 18, 540-541 (1967).

67. G. Kohler and C. Milstein, "Continuous Culture of Fused Cells Secreting Antibody of Predefined Specificity," Nature 265, 495 (1975).

68. D. E. Yelton and M. D. Scharff, "Monoclonal Antibodies: Powerful New Tool in Biology and Medicine," Ann. Rev. Biochem. 50, 657-680 (1980).

69. W. C. Eckelman, C. H. Paik, and R. C. Reba, "Radiolabeling of Antibodies," Cancer Res. 40, 3036-3042 (1980). REFERENCES 263

70. K. A. Krohn, K. C. Knight, J. F. Harwig, and M. J. Welch, "Differences in the Sites of lodination of Proteins Following Four Methods of Radioiodination," Biochem. Biophys. Acta 490, 497 (1977).

71. A. I. Kassis, S. J. Adelstein, C. Haydock, K. S. R. Sastry, K. D. McElvany, and M. J. Welch, "Lethality of Auger Electrons from the Decay of Bromine-77 in the DNA of Mammalian Cells," Radiat. Res. 90,362 (1982).

72. C. F. Meares, D. A. Goodwin, C. S-H. Leung, A. G. Girgis, D. J. Silvester, A. D. Nunn, and P. J. Lavender, "Covalent Attachment of Metal Chelates to Proteins: The Stability In Vivo and In Vitro of the Conjugates of Albumin with a Chelate of Indium-111," Proc. Natl. Acad. Sci. USA 73(11), 3803 (1976).

73. J. J. Langone, "Radioiodination by Use of the Bolton-Hunter and Related Reagents," in Methods in Enzymology, J. J. Langone and H. Van Vunakis, Eds. (Academic Press, New York, 1981), Vol. 70, pp. 112-127.

74. A. E. Bolton and W. M. Hunter, "The Labelling of Proteins to High Specific Activities by Conjugation to a 125I- Containing Acylating Agent," Biochem. J. 133, 529 (1973).

75. H. Davson, "The Blood-Brain Barrier," J. Physiol. 225, 1-28 (1976).

76. T. C. Hill, "Single-Photon Emission Computed Tomography to Study Cerebral Function in Man," J. Nucl. Med. 21, 1197-1199(1980).

77. P. L. McGeer, J. C. Eccles, and E G. McGeer, Molecular Neurobiology of the Mammalian Brain (Plenum Press, New York, 1978), Chap. 8, pp. 493-500.

78. K. M. Tramposch, H. F. Kung, and M. Blau, "Radioiodine Labeled Amines as Brain Imaging Agents," in Applications of Nuclear and Radiochemistry, R. Lambrecht and N. Morcos, Eds. (Pergamon Press, New York, 1982).

79. K. F. Kung and M. Blau, "Regional Intracellular pH Shift: A Proposed New Mechanism for Radio- pharmaceutical Uptake in Brain and Other Tissues," J. Nucl. Med. 21, 147-152 (1980).

80. H. F. Kung and M. Blau, "Synthesis of Selenium-75 Labeled Tertiary Diamines: New Brain Imaging Agents," J. Med. Chem. 23, 1127-1130(1980).

81. K. M. Tramposch, H. F. Kung, and M. Blau, "Synthesis and Tissue Distribution Study of Iodine-Labeled Benzyl- and Xylylamines," J. Med: Chem. 25, 870-873 (1982).

82. H. F. Kung, K. M. Tramposch, and M. Blau, "A New Brain Perfusion Agent: [I-123]HIPDM: N,N,N'Triimethyl-N'-[2-Hydroxy-3-Methyl-5-Iodobenzyl]-l,3-Propanediamine," J. Nucl. Med. 24, 66-72 (1983).

83. D. S. Wilbur, K. W. Anderson, W. E. Stone, and H. A. O'Brien, Jr., "Radiohalogenation of Non-Activated Aromatic Compounds Via Aryltrimethlsiyl Intermediates," J. Label. Cmpds. Radiopharm. 19, 1171-1188 (1982).

84. H. S. Winchell, R. M. Baldwin, and T. H. Lin, "Development of I-123-Labeled Amines for Brain Studies: Localization of 1-123 lodophenylalkyl Amines in Rat Brain," J. Nucl. Med. 21,940-946 (1980).

85. H. S. Winchell, W. D. Horst, L. Braun, W. H. Oldendorf, R. Hattner, and H. Parker, "N-Isopropyl-[123I-p- Iouoamphetamine Single-Pass Brain Uptake and Washout; Binding to Brain Synaptosomes; and Localization in Dog and Monkey Brain," J. Nucl. Med. 21, 947-952 (1980).

86. R. M. Baldwin, T. H. Lin, and J. L. Wu, "Synthesis and Brain Uptake of Isomeric 123Modoamphetamine Derivatives" (Abstract), J. Label. Cmpds. Radiopharm. 19, 1305-1306 (1982). 264 REFERENCES

87. D. Duterte, E. Morier, M. Le Poncin-Lafihe, J. R. Rapin, and R. Rips, "Synthesis of p-l2iI-Amphetamine," J. Label. Cmpds. Radiopharm. 20, 149-155 (1983).

88. R. W. Fuller, "Structure-Activity Relationships Among the Halogenated Amphetamines," Ann. NY Acad. Sci. 78,147-159(1978).

89. M. Frankel, M. Broze, D. Gertner, and A. Zilkha, "Synthesis of Trimethylsilylphenethylamines," J. Chem. Soc. (C) 379- * 82 (1966).

90. E. S. Garnett and G. Firnau, "["F]-5-Fluoro-DOPA As a New Brain Scanning Agent, in Radio- pharmaceuticals and Labelled Compounds (International Atomic Energy Agency, Vienna, 1973), Vol. 1.

91. J. S. Fowler, R. R. McGregor, A. P. Wolf, A. N. Ansari, and H. L. Atkins, "Radiopharmaceuticals. 16. Radiohalogenated Dopamine Analogs. Synthesis and Radiolabeling of 6-Iododopamine and Tissue Distribution Studies in Animals," J. Med. Chem. 19, 356-360 (1976).

92. D. S. Wilbur, W. E. Stone, and K. W. Anderson, "Regiospecific Incorporation of Bromine and Iodine into Phenols Using (Trimethylsilyl)phenol Derivatives,"!. Org. Chem. 48,1542-1544 (1983).

93. T. Sargent, T. F. Budinger, G. Braun, A. J. Shulgin, and U. Braun, "An Iodinated Catecholamine Congener for Brain Imaging and Metabolic Studies," J. Nucl. Med. 19, 71-76 (1978).

94. T. Sargent, D. A. Kalbhen, A. T. Shulgin, H. Stauffer, and N. Kusubou, "A Potential New Brain-Scanning Agent: 4-"Br-2,5-Dimethoxyphenylisopropylamine(4-Br-DPIA)," J. Nucl. Med. 16, 243-245 (1975).

95. G. Braun, A. T. Shulgin, and T. Sargent, "Synthesis of l23I-Labeled 4 Iodo-2,5-Dimethox- yphenylisopropylamine," J. Label Cmpds. Radiopharm. 16, 767-773 (1978).

96. H. H. Coenen, "Synthesis of 77Br-Labeled 2-(4-Bromo-2,5-Dimethoxyphenyl)-isopropylamine With High Specific Activity," J. Label. Cmpds. Radiopharm. 18, 739-746 (1980).

97. D. S. Wilbur and Z. V. Svitra, "Organopentafluorosilicates: Reagents for Rapid and Efficient Incorporation of No-Carrier-Added Radiobromine and Radioiodine," J. Label. Cmpds. Radiopharm. 20, 619-626 (1983).

98. E. S. Weiss, E. F. Hoffman, M. E. Phelps, M. J. Welch, P. D. Henry, M. M. Ter-Pogossian, and B. E. Sobel, "External Detection and Visualization of Myocardial Ischemia with "C-Substrates In Vitro and In Vivo" Circ. Res. 39,24-32(1976).

99. E. J. Knust, M. Schuller, and G. Stocklin, "Synthesis and Quality Control of Long-Chain "F-Fatty Acids," J. Label. Cmpds. Radiopharm. 17, 353-363 (1979).

100. N. D. Poe, G. D. Robinson, and N. S. MacDonald, "Myocardial Extraction of Labeled Long-Chain Fatty Acid Analogs," Proc. Soc. Exp. Biol. Med. 148, 215-218 (1975).

101. H.-J. Machulla, G. Stocklin, C. Kupfernagel, C.Freundlieb, A. Hock, K. Vyska, and L. E. Feinendegen, "Comparative Evaluation of Fatty Acids Labeled with C-ll, Cl-34m, Br-77, and 1-123 for Metabolic Studies of the Myocardium: Concise Communication,";. Nucl. Med. 19, 298-302 (1978).

102. C. A. Otto, L. E. Brown, D. M. Wieland, and W. H. Bierwaltes, "Radioiodinated Fatty Acids for Myocardial Imaging: Effects of Chain Length," J. Nucl. Med. 22,613-618 (1981).

103. E. J. Knust, C. Kupfernagel, and G. Stocklin, "Long-Chained 1BF-Labeled Fatty Acids for the Study of Myocardial Metabolism; Odd-Even Effects" (Abstract), J. Label. Cmpds. Radiopharm. 16, 143-144 (1978). REFERENCES 265

104. W. H. Beierwaltes, R. D. Ice, M. J. Shaw, and U. Y. Ryo, "Myocardial Uptake of Labeled Oleic and Linoleic Acids," J. Nucl. Med. 16, 842-845 (1975).

105. G. D. Robinson and A. W. Lee, "Radioiodinatod Fatty Acids for Heart Imaging: Iodine Monochloride Addition Compared with Iodine Replacement Labeling," J. Nucl. Med. 16,17-21 (1975).

106. G. D. Robinson, "Synthesis of 123I-16-Iodo-9-Hexadecanoic Acid and Derivatives for Use as Myocardial Perfusion Imaging Agents," Int. J. Appl. Radiat. Isot. 28, 149-156 (1977).

107. P. Laufer, H.-J. Machulla, H. Michael, H. H. Coenen, A. S. El-Wetery, G. Kloster, and G. Stocklin, "Preparation of co'23I-Labeled Fatty Acids by 123I-For-Br Exchange: Comparison of Three Methods," J. Label. Cmpds. Radiopharm. 18, 1205-1214(1980).

108. H.-J. Machulla, K. Dutschka, and C. Astfalk, "Improved Synthesis of 17-I23I-Heptadecanoic Acid for Routine Preparation," Radiochem. Radioanal. Lett. 47,189-192(1981).

109. H.-J. Machulla and K. Dutschka, "lodination Methods for Routine Preparation of 17-123I-Heptadecanoic Acid and 15-(I23I-Phenyl)Pentadecanoic Acid," J. Radioanal. Chem. 65, 122-130(1981).

110. M. Argentini, M. Zahner, and P. A. Schubiger, "Comparison of Several Methods for the Synthesis of w- Iodine-123-Heptadecanoic Acid," J. Radioanal. Chem. 65, 131-138 (1981).

111. H.-J. Machulla, M. Marsmann, and K. Dutschka, "Biochemical Concept and Synthesis of a Radioiodinated Phenylfatty Acid for In Vivo Metabolic Studies of the Myocardium," Eur. J. Nucl. Med. 5, 171-173 (1980).

112. H. H. Coenen, M.-F. Harmand, G. Kloster, and G. Stocklin, "15-(p-[73Br]Bromophenyl)Penladecanoic Acid: Pharmacokinetics and Potential as a Heart Agent," J. Nucl. Med. 22, 891-896 (1981).

113. H.-J. Machulla, M. Marsmann, K. Dutschka, and D. van Beuningen, "Radiopharmaceuticals. II. Radio- bromination of Phenylpentadecanoic Acid and Biodistribution in Mice," Radiochem. Radioanal. Lett. 42, 243-250 (1980).

114. H.-J. Machulla, M. Marsmann, and K. Dutschka, "Synthesis of Radioiodinated Phenylfatty Acids for Studying Myocardial Metabolism," J. Radioanal. Chem. 56, 253-261 (1980).

115. H.-J. Machulla, K. Dutschka, D. van Beuningen, and T. Chen, "Development of 15-(p- 123I-Phenyl)Pentadecanoic Acid for In Vivo Diagnosis of the Myocardium,'" J. Radioanal. Chem. 65, 279-286 (1981).

116. G. W. Kabalka, S. A. R. Sastry, and K. Muralidhar, "Synthesis of Iodine-125 Labeled Aryl and Vinyl Iodides," J. Label. Cmpds. Radiopharm. 19, 795-799 (1982).

117. D. S. Wilbur, K. W. Anderson, W. E. Stone, and H. A. O'Brien, "Radiohalogenation of Non-Activated Aromatic Compounds Via Aryltrintethylsilyl Intermediates," J. Label. Cmpds. Radiopharm. 19, 1171-1188 (1982).

118. D. S. Wilbur, W. E. Stone, and K. W. Anderson, "Regiospecific Incorporation of Bromine and Iodine into Phenols Using (Trimethylsilyl)Phenol Derivatives," J. Org. Chem. 48, 1542-1544 (1983).

119. D. S. Wilbur and Z. V. Svitra, "Organopentafluorosilicates: Reagents for Rapid and Efficient Incorporation of No-Carrier-Added Radiobromine and Radioiodine," J. Label. Cmpds. Radiopharm. 20, 619-626 (1983).

120. A. I. Meyers, D. L. Temple, R. L. Nolen, and E. D. Mihelich, "Oxazolines. IX. Synthesis of Homologated Acetic Acids and Esters," J. Org. Chem. 39, 2778-2783 (1974). 266 REFERENCES

121. D. S. Coombs and J. T. Whetten, "Composition of Analcime from Sedimentary and Burial Metamorphic Rocks," Geol. Soc. Am. Bull. 78, 269-282 (1967).

122. G. K. Johnson, H. E. Flotow, P. A. G. O'Hare, and W. S. Wise, "Thermodynamic Studies of Zeolites: Analcime and Dehydrated Analcime," Am. Mineral. 67, 736-748 (1982).

123. J. J. Hemley, unpublished data, cited in Ref. 2, p. 746.

124. H. C. Helgeson, J. M. Delany, H. W. Nesbitt, and D. K. Bird, "Summary and Critique of the Thermodynamic Properties of Rock Forming Minerals," Am. J. of Sci. 278-A, 229 (1978).

125. J. V. Walther and H. C. Helgeson, "Calculation of the Thermodynamic Properties of Aqueous Silica and the Solubility of Quartz and Its Polymorphs at High Pressures and Temperatures," Am. J. Sei. 277, 1315-1351 (1977).

126. H. C. Helgeson and D. H. Kirkham, "Theoretical Prediction of the Thermodynamic Behavior of Aqueous Electrolytes at High Pressures and Temperatures, I. Summary of the Thermodynamic/Electrostatic Properties of the Solvent," Am. J. Sci. 274,1089-1198 (1974).

127. A. Iijima and M. Utada, "Present Day Zeolitic Diagensis of the Neogene Geosynclinal Deposits in the Niigata Oil Field, Japan," Am. Chem. Soc. Adv. Chem. Ser. 101, Molecular Sieve Zeolites-1, 342-349 (1971).

128. A. Iijima and R. L. Hay, "Analcime Composition in Tuffs of the Green River Formation of Wyoming," Am. Mineral. 53, 184-201(1968).

129. D. C. Hoffman, R. Stone, and W. W. Dudley, Jr., "Radioactivity in the Underground Environment of the Cambric Nuclear Explosion at the Nevada Test Site," Los Alamos Scientific Laboratory report LA-6877-MS (July 1977).

130. D. C. Hoffman, "A Field Study in Radionuclide Migration," in Radioactive Waste in Geologic. Storage, S. Fried, Ed., ACS Symposium Series 100 (Am. Chem. Soc., Washington, DC, 1979), p. 149.

131. D. C. Hoffman and W. R. Daniels, "Assessment of the Potential for Radioi.jclide Migration from a Nuclear Explosion Cavity," in Proceedings of the American Geophysical Union Symposium on Groundwater Contamination, San Francisco, California, December 7-11, 1981 (in preparation, 1982).

132. D. C. Hoffman, W. R. Daniels, K. Wolfsberg, J. L. Thompson, R.S. Rundberg, S.L. Fraser, and K. S. Daniels, "A Review of a Field Study of Radionuclide Migration from an Underground Nuclear Explosion," IAEA International Conference on Radioactive Waste Management, Seattle, Washington, May 16-20, 1983. IAEA- CN-43/469 (1983).

133. "Migration from Nuclear Explosion Cavities: The Cambric Experiment," in "Isotope and Nuclear Chemistry Division Annual Report FY 1982," Los Alamos National Laboratory report LA-9797-PR (June 1983), pp. 101-109.

134. E. J. Young, A. T. Myers, E. L. Munson, and N. M. Conkling, "Mineralogy and Geochemistry of Fluorapatite from Cerro de Mercado, Durango, Mexico," US Geological Survey Prof. Paper 650-D (1969), pp. D84-D93.

135. H. J. Greenwood, "Wollastonite: Stability in H2O-CO2 Mixtures and Occurrence in a Contact-Metamorphic Aureole Near Salmo, British Columbia, Canada," Am. Mineral. 52, 1669-1680 (1967).

136. D. M. Roy, "Studies in the System CaO-Al2O3-SiO2-H2O; IV. Phase Equilibria in the High Lime Portion of the System CaO-SiO2-H2O," Am. Mineral. 43, 1009-1028 (1958).

137. D. A. Buckner, D. M. Roy, and R. Roy, "Studies in the System CaO-Al2O3-SiO2-H2O; II. The System CaSiO,- H2O," Am. J. Sci. 258, 132-147 (1960). REFERENCES 267

138. J. A. Allison and F. G. Mann, "The Constitution of Metallic Salts. Part XIV. The Action of Trialkyl- phosphines and -arsines on Tetrahalides of Tin and Uranium," J. Chem. Soc. 2915-2919 (1949).

139. P. G. Edwards, R. A. Anderson, and A. Zalkin, "Preparation of X4M(Me2PCH2CHjPMej)2 where X is Halide, Methyl or Phenoxy and M is Thorium or Uranium," J. Am. Chem. Soc. 103, 7792-7794 (1981).

140. M. R. Duttera, P. J. Fagan, T. J. Marks, and V. W. Day, "Synthesis, Properties, and Molecular Structure of a Trivalent Organouranium Diphosphine Hydride," J. Am. Chem. Soc. 104, 865-867 (1982).

141. D. C. Moody and J. D. Odom, "The Chemistry of Trivalent Uranium: The Synthesis and Reaction Chemistry of the Tetrahydrofuran Adduct of Uranium Trichloride, UC13(THF)X," J. Inorg. Nucl. Chem. 41, 533-535 (1979).

142. R. G. Teller and R. Bau, "Crystallographic Studies of Transition Metal Hydride Complexes," Struct. Bonding 44, 1-82 (1980).

14J. £. R. Bernstein, W. C. Hamilton, T. A. Keiderling, S. J. La Placa, S. J. Lippard, and J. J. Mayerle, "14- Coordinate U(IV). The Structure of Uranium Borohydride by Single-Crystal Neutron Diffraction," Inorg. Chem. 11, 3009-3016 (1972).

141 J. P. Farr, M. M. Olmstead, F. E. Wood, and A. L. Batch, "Formation and Reactivity of Some Heterobinuclear Rhodium/Platinum Complexes with 2-(Diphenylphosphino)pyridine as a Bridging Ligand," J. Am. Chem. Soc. 105, 792-798 (1983).

145. L. M. Toth and H. A. Friedman, "The IR Spectrum of Pu(IV) Polymer," J. Inorg. Nucl. Chem. 40,807 (1978).

146. J. I. Kim, C. Lierse, and F. Baumgartner, "Complexation of the Plutonium (IV) Ion in Carbonate-Bicarbonate Solutions," in W. T. Carnall and G. R. Choppin, Ed., "Plutonium Chemistry," Am. Chem. Soc. Symposium Series 216, 317-334(1983).

147. M. Rakowski DuBois, M. C. VanDerveer, D. L. DuBois, R. C. Haltiwanger, and W. K. Miller, "Characteriza- tion of Reactions of Hydrogen with Coordinated Sulfido Ligands," J. Am. Chem. Soc. 102,7456-7461 (1980).

148. P. J. Brothers, "Heterolytic Activation of Hydrogen by Transition Metal Complexes," Prog. Inorg. Chem. 28, 1-61 (1981) and references within.

149. M. J. Mays, R. N. F. Simpson, and F. P. Stefanini, "Cationic Complexes of Iridium. Part II. Kinetic Studies on the Reductive Elimination of Hydrogen from [IrH^CCO^LjJJBPI^ (L = tertiary phosphine or tertiary arsine)," J. Chem. Soc. (A) 3000-3002 (1970).

150. H. H. Brintzinger, "Mechanisms of Dihydride Activation by Zirconocene Alkyl and Hydride Derivatives. A Molecular Orbital Analysis of a 'Direct Hydrogen Transfer' Reaction Mode," J. Organometal. Chem. 171, 337-344 (1979).

151. G. J. Kubas, "Five-cc-ordinate Molybdenum and Tungsten Complexes, [M(CO)3(PCy3)2], which Reversibly add Dinitrogen, Dihydrogen, and Other Small Molecules," J. Chem. Soc, Chem. Commun. #2, 61-62 (1980).

152. In contrast, see G. G. Eberhardt and L. Vaska, "Homogeneous Catalysis with trans- Chlorocarbonylbis(triphenylphosphine)iridium(I)," J. Catal. 8,183-188 (1967).

153. P. Meakin, L. J. Gugenberger, W. G. Peet, E. L. Muetterties, and J. P. Jesson, "Stereochemically Nonrigid Eight-Coordinate Molybdenum and Tungsten Tetrahydrides," J. Am. Chem. Soc. 95, 1467-1474 (1973).

154. B. D. Nageswara Rao and L. R. Anders, "Nuclear Spin Relaxation and Double Resonance in HD Gas," Phys. Rev. A 140, 112-117(1965). 268 REFERENCES

155. D. S. Wilbur, "Part I: An Investigation of the Mechanism of Ketene Dimerizations. Part II: Synthesis of Azepine Diones," Ph.D. Thesis, University of California, Irvine, California (1978).

156. B. B. Back, R. R. Betts, K. Cassidy, B. G. Glagola, J. E. Gindler, L. E. Glendenin, and B. D. Wilkins, "Experimental Signatures of Quasifission Reactions," Phys. Rev. Lett. 50, 818 (1983).

157. J. van der Plicht, H. C. Britt, M. M. Fowler, J. B. Wilhelmy, A. Gavron, Z. Fraenkel, F. Plasil, T. C. Awes, and G. R. Young, "Fission of Polonium, Osmium, and Erbium Composite Systems," Phys. Rev. C 28,2022 (1983).

158. L. C. Vaz and J. M. Alexander, Phys. Rep. (in press).

159. H. C. Britt, "Experimental Survey of the Potential Energy Surfaces Associated with Fission," Physics and Chemistry of Fission 1979, Vol. I (IAEA, Vienna, 1980), p. 3.

160. S. BjVrnholm and J. E. Lynn, "The Double-Humped Fission Barrier," Rev. Mod. Phys. 52, 725 (1980).

161. S. Cohen, F. Plasil, and W. J. Swiatecki, "Equilibrium Configurations of Rotating Charged or Gravitating Liquid Masses with Surface Tension. II," Ann. Phys. (N.Y.) 82, 557 (1974).

162. L. G. Moretto, S. G. Thompson, J. Routti, and R. C. Gatti, "Influence of Shells and Pairing on the Fission Probabilities of Nuclei Below Radium," Phys. Lett. 38B, 471 (1972).

163. T. Sikkeland, J. E. Clarkson, N. H. Steiger-Shafrir, and V. E. Viola, "Fission-Excitation Functions in Interactions of "B, I2C, 14N, and 19F with Various Targets," Phys. Rev. C 3, 329 (1971).

164. R. Bass, "Nucleus-Nucleus Potential Deduced from Experimental Fusion Cross Sections," Phys. Rev. Lett. 39, 265 (1977).

165. M. G. Mustafa, P. A. Baisden, and H. Chandra, "Equilibrium Shapes and Fission Barriers of Rotating Nuclei with a Macroscopic Two-Center Model," Phys. Rev. C 25, 2524 (1982).

166. G. Miinzenberg et al., "Investigation of Isotopes with Z > 100," Proceedings of the Fourth International Conferencon Nuclei Far from Stability, June 1981, Geneva, European Center for Nuclear Research, CERN Report 81-09 (1981) p. 755.

167. G. Munzenberg et al., "Observation of One Correlated Small X-Decay in the Reaction 38Fe on 209Bi 267109," Z. Physik A309, 89 (1982).

168. E. K. Hulet et al., "Scaling Variable Distributions for Antineugreno-Nuclear Interactions," Phys. Rev. Lett. 39, 385 (1977).

169. D. C. Hoffman and M. M. Hoffman, "Calculated Excitation Energies for Transcurium Products of Binary Heavy Ion Reactions," Los Alamos National Laboratory document LA-UR-82-824 (1982).

170. D. Lee, H. von Gunten, B. Jacak, M. Nurmia, Y.-F. Liu, C. Luo, G. T. Seaborg, and D. C. Hoffman, "Production of Heavy Actinides from Interactions of 160,180,20Ne, and "Ne with 24lCm," Phys. Rev. C 25, 286 (1982).

171. D. Lee, K. J. Moody, M. J. Nurmia, G. T. Seaborg, H. R. von Gunten, and D. C. Hoffman, "Excitation Functions for Production of Heavy Actinides from Interactions of "O with "'Cm and 24'Cf," Phys. Rev. C 27, 2656 (1983).

172. M. Schadel et al., "Actinide Production in Collisions of 23SU with 24'Cm," Phys. Rev. Lett. 41, 469 (1978).

173. M. Schadel et al., "Actinide Production in Collisions of 23!U with 24lCm," Phys. Rev. Lett. 48, 852 (1982). REFERENCES 269

174. H. C. Britt, W. Faubel, M. M. Fowler, D. C. Hoffman, E. N. Treher, J. Van der Plicht, J. B. Wiihelmy, D. Lee, M. Nurmia, G. T. Seaborg, "Neutron Excess Transfer Reactions," American Chemical Society Meeting, Las Vegas, Nevada, March 28-April 2,1982, Los Alamos National Laboratory document LA-UR-81-3563.

175. D. Lee, H. von Gunten, B. Jacak, M. Nurmia, Y.-F. Liu, C. Luo, G. T. Seaborg, and D. C. Hoffman, "Production of Heavy Actinides from Interactions of "0, "0,20Ne, and 22Ne with MICm," Phys. Rev. C 25, 286 (1982).

176. D. Lee, K. J. Moody, M. J. Nurmia, G. T. Seaborg, H. R. von Gunten, and D. C. Hoffman, "Excitation Functions for Production of Heavy Actinides from Interactions of "O with 248Cm and 249Cf," Phys. Rev. C 27, 2656 (1983).

177. J. Wilczynski, K. Siwek-Wilczynska, J. van Driel, S. Gonggrijp, D. C. J. M. Hageman, R. V. F. Janssens, J. Lukasiak, and R. H. Siemssen, "Incomplete-Fusion Reactions in the I4N + 1!9Tb System and a 'Sum-Rule Model' for Fusion and Incomplete-Fusion Reactions," Phys. Rev. Lett. 45, 606 (1980).

178. D. Gardes, R. Bimbot, J. Maison, L. de Reilhac, M. F. Rivet, A. Fleury, F. Hubsrt, and Y. Llabador, "Excitation Functions for Quasielastic Transfer Reactions Induced with Heavy Ions in Bismuth," Phys. Rev. C 18, 1298 (1978).

17<\ K. Eskola, "Study of 66-Sec Isomeric State of 222Ac," Phys. Rev. C 5, 942 (1972).

180. R. A. Arndt, J. B. Cammarata, Y. N. Goradia, R. H. Hackman, V. L. Teplitz, D. A. Dicus, R. Aaron, and R. S. Longacre, "Isobar Production in re~p ->- n+re~n Near Threshold," Phys. Rev. D 20, 651 (1979).

181. D. M. Manley, "Measurement and Isobar Model Analysis of the Doubly Differential Cross Section for the n+ Production in Jt~p —*• 7t+7i~n." Ph.D. thesis, University of Wyoming, Los Alamos National Laboratory report LA-9101-T (November 1981).

182. G. E. Brown, H. Toki, W. Weise, and A. Wirzba, "Double-A(1232) Formation in Pion-Nucleus Absorption," Phys. Lett. 118B, 39 (1982).

183. R. Reid,"Local Phenomenological Nucleon-Nucleon Potentials," Ann. Phys. (NY)50,411 (1968).

184. B. J. Dropesky, G. W. Butler, C. J. Orth, R. A. Williams, G. Friedlander, M. A. Yates, and S. B. Kaufman, "Excitation Functions for the Reactions 12C(7i±,nN)"C over the Region of the (3,3) Resonance," Phys. Rev. Lett. 34, 821 (1975).

185. B. J. Dropesky, G. W. Butler, C. J. Orth, R. A. Williams, M. A. Yates-Williams, G. Friedlander, and S. B. Kaufman, "Absolute Cross Sections for the I2C(jt±,JtN)lxC Reactions between 40 and 600 MeV," Phys. Rev. C 20, 1844 (1979).

186. P. W. Hewson, "Charge Exchange in Nuclei Following Pion Inelastic Scattering," Nucl. Phys. A 133, 659 (1969).

187. D. T. Chivers, E. M. Rimmer, B. W. AUardyce, R. C. Witcomb, J. J. Domingo, and N. W. Tenner, "Pion Reaction with Light Nuclei at the 3-3 Resonance," Nucl. Phys. A 126, 129 (1969).

188. M. M. Sternheim and R. R. Silbar, "Effects of Nucleon Charge Exchange on the (n,jtN) Puzzle," Phys. Rev. Lett. 34, 824 (1975).

189. S. B. Kaufman, E. P. Steinberg, and G. W. Butler, "(n.JiN) Reactions on 23Mg and 197Au," Phys. Rev. C 20, 262 (1979). 270 REFERENCES

190. B. J. Lieb, H. S. Plendl, C. E. Stronach, H. O. Funsten, and V. G. Lind, "(JI±,JIN) Reactions on UN, 19F, "Na, "Al, and "P near the A(1232) Resonance," Phys. Rev. C 26, 2084 (1982).

191. R. S. Bhalerao, L. C. Liu, and C. M. Shakin, "Systematic Features of the Pion-Nucleus Interaction," Phys. Rev. C 21,1903 (1980).

192. B. A. Watson, P. P. Singh, and R. E. Segel, "Optical-Model Analysis of Nucleon Scattering from lp-Shell Nuclei Between 10 and 50 MeV," Phys. Rev. 182, 977 (1969).

193. D. J. Vieira, J. M. Wouters, G. W. Butler, L. P. Remsberg, A. M. Poskanzer, H. Wollnik, and D. S. Brenner, "TOFI (Time-of-Flight Isochronous) Spectrometer for the Mass Measurements of Nuclei Far From Stability," in "Isotope and Nuclear Chemistry Division Annual Report FY 1982," Los Alamos National Laboratory report LA-9797-PR (June 1983), pp. 168-172.

194. J. M. Wouters, D. J. Vieira, H. Wollnik, H. A. Enge, S. Kowalski, and K. L. Brown, "Optical Design of the TOFI (Time-of-Fiigbt Isochronous) Spectrometer for Mass Measurements of Exotic Nuclei," to be submitted to Nucl. Instr. Meth.

195. C. Thibault, R. Klapisch, C. Rigaud, A. M. Poskanzer, R. Prieels, L. Lessard, and W. Reisdorf, "Direct Measurement of the Masses of "Li and 26"32Na with an On-Line Mass Spectrometer," Phys. Rev. C 12, 644 (1975).

196. C. Thibault, "4th International Conference on Nuclei Far From Stability, Helsingor (Denmark)," European Center for Nuclear Research CERN report 81-09 (June 198!).

197. H. L. Ravn, "Experiments with Intense Secondary Beams of Radioactive Ion," Phys. Rep. 54, 202 (1979).

198. F. K. Wohn, "TRISTAN II-Extension of Capabilities to Non-Gaseous Fission Products," Proc. Isotope Separator On-Line Workshop, Brookbaven National Laboratory, October 31-November 1, 1977, Brookhaven National Laboratory Report BNL-50847 (1978).

199. W. L. Talbert, Jr., M. E. Bunker, J. W. Starner, S. C. Soderholm, V. J. Novick, and R. F. Petry, "Studies of He- jet Activity Transport at LAMPF," Bull. Am. Phys. Soc. 28, 646 (1983).

200. K. Takahashi, M. Yamada, and T. Kondoh, "Beta-Decay Half-Lives Calculated on the Gross Theory," At. Data Nucl. Data Tables 12, 101 (1973).

201. "Isotope and Nuclear Chemistry Division Annual Report FY 1982," Los Alamos National Laboratory report LA-9797-PR (June 1983), pp. 177-180.

202. M, M. Fowler and R. C. Jared, "A Gas Ionization Counter for Particle Identification," Nucl. Instr. Meth. 124, 341-347 (1975).

203. H. Sann, H. Damjantschitsch, D. Hebbard, J. Junge, D. Pelte, B. Povh, D. Schwalm, and D. B. Tran Thoai, "A Position-Sensitive Ionization Chamber," Nucl. Instr. Meth. 124, 509 (1975).

204. U. Lynen, H. Stelzer, A. Gobbi, H. Sann, and A. Olmi, "Large-Area, Two-Dimensional Position-Sensitive Detectors," Nucl. Instr. Meth. 162, 657 (1979).

205. Thomas R. Parish, "Surface Airflow over East Antarctica," Mon. Weather Rev. 110, 26-32 (1982).

206. Morton J. Rubin and William S. Weyant, "The Mass and Heat Budget of the Antarctic Atmosphere," Mon. Weather Rev. October-December, 487-493 (1963). REFERENCES 271

207. Austin W. Hogan and Stephen Barnard, "Seasonal and Frontal Variation in Antarctic Aerosol Concentra- tions," J. Appl. Meteorol. 17, 1458-1465 (1978).

208. W. Maenhaut, W. H. Zoller, and D. G. Coles, "Radionuclides in the South Pole Atmosphere," J. Geophys. Res. 84, 3131-3138(1979).

209. William C. Cunningham and William H. Zoller, "The Chemical Composition of Remote Area Aerosols," J. Aerosol Sci. 12, 367-384 (1981).

210. Lawrence F. Radke, "Sulphur and Sulphate from Mt. Erebus," Nature 299, 710-712 (1982).

211. Robert J. Delmas, "Antarctic Sulphate Budget," Nature 299, 677-678 (1982).

212. Geophysical Monitoring for Climatic Change, No. 10 Summary Report 1981 (US Dept. Commerce, Washington, DC, 1982), pp. 21-40.

213. Malcolm M. Fowler and Sumner Barr, "A Long-Range Atmospheric Tracer Field Test," Atmos. Environ, (in press).

214. L. W. Alvarez, W. Alvarez, F. Asaro, and H. V. Michel, "Extraterrestrial Cause of Cretaceous-Tertiary Extinction," Science 208, 1095-1108 (1980).

215. F. Asaro, L. W. Alvarez, W. Alvarez, and H. V. Michel, "Geochemical Anomalies near the Eocence-Oligocene and Permian-Triassic Boundaries," Geol. Soc. Am. Spec. Paper 190, 517-528 (1982).

216. R. C. Reedy, J. R. Arnold, and D. Lai, "Cosmic-Ray Record in Solar System Matter," Science 219, 127-135 (1983).

217. G. M. Raisbeck, F. Yiou, J. Klein, R. Middleton, Y. Yamakoshi, and D. E. Brownlee, "26A1 and 10Be in Deep Sea Stony Spherules; Evidence for Small Parent Bodies," in Lunar and Planetary Science XIV (Lunar and Planetary Institute, Houston, 1983), pp. 622-623.

218. J. C. Evans, J. H. Reeves. L. A. Rancitelli, and D. D. Bogard, "Cosmogenic Nuclides in Recently Fallen Meteorites: Evidence for Galactic Cosmic Ray Variations During the Period 1967-1978," J. Geophys. Res. 87, 5577-5591 (1982).

219. J. Ray and H. J. Volk, "The Retention of Spallation Products in Interstellar Grains," *carus 54, 406-416 (1983).

220. G. Castagnoli and D. Lai, "Solar Modulation Effects in Terrestrial Production of Carbon-14," Radiocarbon 22, 133-158 (1980).

221. R. C. Reedy and J. R. Arnold, "Interactions of Solar and Galactic Cosmic-Ray Particles with the Moon," J. Geophys. Res. 77, 537-555 (1972). Index

* • .•....-•:-;-• *•*....

I*.-

P?- INDEX 275

INDEX OF AUTHORS

AGNEW, STEPHEN F. Spectroscopic Studies of Molecules at High Pressure 29

AGUILAR, RUBEN D. Ground water Chemistry of Yucca Mountain 110

ALEI, MOHAMMED Tracking Antarctic Winds 207

ASPREY, LARNED B. FOOF Chemistry 135

BARNES, JOHN W. Iodine-123 85

BARR, Don W. (p,xn) Measurements on Strontium Isotopes 23

BENJAMIN, TIMOTHY M. Application of the Los Alamos Nuclear Microprobe to National Security Programs 19 Quantitative Trace-Element Analysis of Geologic Materials 121

BENTLEY, GLENN E. Applications of Electrochemistry to Isotope Production 90 Characterization J LAMPF-Produced Radiohalogens 85 Production and Recovery of 52Fe from an Irradiated Nickel Target 79

BHALERAO, RAJEEV S. Predictions of the Quasi-free Model for the Pionic Pion Production on the Deuteron 171

BUNKER, MERLE E. LAMPF He-Jet Coupled Mass Separator Project 182 Omega West Reactor 189

BUTLER, GILBERT W. Development of a Gas Ionization Detector for Direct Mass Measurements at LAMPF 200

CHARLES, ROBERT W. The System CaO-SiO2-H2O-CO2 and Implications for the Fenton Hill Hydrothermal System 128

CISNEROS, MICHAEL R. Groundwater Chemistry of Yucca Mountain 110

CROMER, DON T. Density Prediction for Octonitrocubane 53 High-Pressure Diffraction Studies in Diamond Anvil Cells 49 Structure of l-H-Azepine-2-One-5-Methoxime 150

DANIELS, WILLIAM R. Excitation Functions for Production of Heavy Actinides from Reactions of 4lCa with ""Cm 163 276 INDEX

DUFFY, CLARENCE J. Application of the Los Alamos Nuclear Microprobe to National Security Programs 19 A Thermodynamic Model for Analcime 113 Quantitative Trace-Element Analysis of Geologic Materials 121

EARL, WILLIAM L. Characterization of Kraton Polymers by NMR 55 High Resolution NMR Studies of Nitromethane 57 Solid State 15N NMR of Ammonia Adsorbed on Y Zeolite 152

EFURD, DEWARD W. Tracking Antarctic Winds 207

ECKBERG, SCOTT A. High Resolution Infrared Spectral Studies of Guest-Host Interactions and Dynamics in Low-Temperature Impurity-Doped Solids 38

ELLER, P. GARY Crystal Chemical/Valence Studies of Nuclear Waste Forms 119 FOOF Chemistry 135

ESKOLA, KARI Fission Fragment Angular Distributions of Heavy-Ion Reactions 159 Production of Neutron-Rich Bismuth Isotopes by Transfer Reactions 169 (p,xn) Measurements on Strontium Isotopes 23

ESKOLA, PIRKKO Fission Fragment Angular Distributions of Heavy-Ion Reactions 159 Production of Neutron-Rich Bismuth Isotopes by Transfer Reactions 169

FOLTYN, ELIZABETH M. FOOF Chemistry 135

FOWLER, MALCOLM M. Accelerator-Based Mass Spectrometry of 10Be 195 Excitation Functions for Production of Heavy Actinides from Reactions of48 with 248 163 Fission Fragment Angular Distributions of Heavy-Ion Reactions 159 Fission of Polonium, Osmium, and Erbium Composite Systems 161 Production of Neutron-Rich Bismuth Isotopes by Transfer Reactions 169 (p,xn) Measurements on Strontium Isotopes 23

FRY, HERBERT A. High Resolution Infrared Spectral Studies of Guest-Host Interactions and Dynamics in Low-Temperature Impurity-Doped Solids 38

FUKUSHIMA, EIICHI NMR Coils with Segments Wired in Parallel 155

GILMORE, JAMES S. Geochemical Anamolies at Biological Crises Zones in the Fossil Record 213 (p,xn) Measurements on Strontium Isotopes 23 INDEX 277

GUTHALS, PAUL R. Tracking Antarctic Winds 207

HOFFMAN, DARLEANE C. Excitation Functions for Production of Heavy Actinides from Reactions of 48Ca with 2<8Cm 163 Overview 3

JARVINEN, GORDON D. Crystal Chemical/Valence Studies of Nuclear Waste Forms 119 Small Molecule Chemistry 141

JONES, LLEWELLYN H. High Resolution Infrared Spectral Studies of Guest-Host Interactions and Dynamics in Low-Temperature Impurity-Doped Solids 38 Spectroscopic Studies of Molecules at High Pressure 29

KNIGHT, JERE D. Geochemical Anamolies at Biological Crises Zones in the Fossil Record 213

KUBAS, GREGORY J.

First Examples of Isolable Molecular Hydrogen Complexes: Evidence for a Side-On Bonded H2 Ligand 147 Small Molecule Chemistry 141

LARSON, ALLEN C. Density Prediction for Octonitrocubane 53 High-Pressure Diffraction Studies in Diamond Anvil Cells 49

LIU, LON-CHANG A New Look at the (TI.TIN) Reactions 175 Predictions of the Quasi-free Model for the Pionic Pion Production on the Deuteron 171

LONDON, ROBERT E. In Situ and In Vivo Metabolic Studies by NMR Spectroscopy 72 NMR Studies of Chemically Modified Dihydrofolate Reductase 70 The National Stable Isotopes Resource 61

LYLE, ALVIN R. Omega West Reactor 189

MAESTAS, SIXTO Groundwater Chemistry of Yucca Mountain 110

MASON, ALLEN S. Tracking Antarctic Winds 207

MATWIYOFF, NICHOLAS A. The National Stable Isotopes Resource 61

MILLS, THOMAS R. Separation of Stable Isotopes—Production 64

MINOR, MICHAEL M. Omega West Reactor 189 278 INDEX

MITCHELL, ALAN J. Ground water. Chemistry of Yucca Mountain 110

MOODY, DAVID D. Tertiary Phosphine Complexes of Uranium 137

MROZ, EUGENE J. Tracking Antarctic Winds 207

NEWTON, THOMAS W. Attempted Preparation of Pu(OH)2COj 140

O'BRIEN, HAROLD A. Recover) of 44Ti from a Proton-Irradiated Vanadium Target and Development of a 44Ti -» 44Sc Generator 87

OGARD, ALLEN E. Groundwater Chemistry of Yucca Mountain 110 The Nevada Nuclear Waste Storage Investigations 109

OHKUBO, YOSHITAKA A New Look at the (TI.JTN) Reactions 175

ORTH, CHARLES J. Geochemical Anamolies at Biological Crises Zones in the Fossil Record 213

OTT, MARTIN A. Iodine-123 85 INC-3 Isotope Production Activities in FY 1983 82

OVERMYER, ELIZABETH Density Prediction for Octonitrocubane 53

PENNEMAN, ROBERT A. Crystal Chemical/Valence Studies of Nuclear Waste Forms 119

PETERSON, KAREN E. INC-3 Isotope Production Activities in FY 1983 82

PRESTWOOD.RENEJ. (p,xn) Measurements on Strontium Isotopes 23

QUINTANA, LEONARD R. Geochemical Anamolies at Biological Crises Zones in the Fossil Record 213

REEDY, ROBERT C. Nuclide Production Rates by Primary Cosmic-Ray Protons 214

ROGERS, PAMELA S.Z. Application of the Los Alamos Nuclear Microprobe to National Security Programs 19 Quantitative Trace-Element Analysis of Geologic Materials 121

ROGERS, R. SCOTT Antibody Radiolabeling 91 INDEX 279

RYAN, ROBERT S.

First Examples of Isolable Molecular Hydrogen Complexes: Evidence for a Side-On Bonded H2 Ligand 147 Density Prediction for Octonitrocubane 53 High-Pressure Diffraction Studies in Diamond Anvil Cells 49 Small Molecule Chemistry 141 Structure of l-H-Azepine-2-One-5-Methoxime 150 Tertiary Phosphine Complexes of Uranium 137

SALAZAR, KENNETH V. Tertiary Phosphine Complexes of Uranium 137

SEURER, FRANKLIN H. INC-3 Isotope Production Activities in FY 1983 82

STARNER, JAMES W. LAMPF He-Jet Coupled Mass Separator Project 182

STEINKRUGER, FRED J. Applications of Electrochemistry to Isotope Production 90 Production and Recovery of 32Fe from an Irradiated Nickel Target 79 Recovery of 44Ti from a Proton-Irradiated Vanadium Target and Development of a 44Ti —• 44Sc Generator 87

SWANSON, BASIL I. First Examples of Isolable Molecular Hydrogen Complexes: Evidence for a Side-On Bonded H2 Ligand 147 High Resolution Infrared Spectra! Studies of Guest-Host Interactions and Dynamics in Low-Temperature Impurity-Doped Solids 38 INS and Optical Spectroscopic Studies of Organic Explosives 52 Spectroscopic Studies of Molecules at High Pressure 29

3VITRA, ZITA V. Studies Toward Radiohalogenations of Fatty Acids: Radiopharmaceuticals for Evaluating the Heart 104

TALBERT, WILLARD L. LAMPF He-Jet Coupled Mass Separator Project 182

TAYLOR, WAYNE A. Applications of Electrochemistry to Isotope Production 90 Progress with Isotope Production from Molybdenum Targets 80 Recovery of 44Ti fi exit u Proton-Irradiated Vanadium Target and Development of a 44Ti —» 44Sc Generator 87

THOMAS, KENNETH E. INC-3 Isotope Production Activities in FY 1983 82 Iodine-123 85 Progress with Isotope Production from Molybdenum Targets 80 The Production of Radioisotopes of Tungsten and Osmium Using Lead Targets 75

THOMPSON, JOSEPH L. Radionuclide Migration from Nuclear Explosion Cavities 119

TREHER, ELIZABETH N. Production of Neutron-Rich Bismuth Isotopes by Transfer Reactions 169 (p,xn) Measurements on Strontium Isotopes 23 280 INDEX

VANDERVOORT, RAYMOND C. Separation of Stable Isotopes—Production 64

VIEIRA, DAVID J. Development of a Gas Ionization Detector for Direct Mass Measurements at LAMPF 200 Time-of-Flight Isochronous (TOFI) Spectrometer 179

WAGEMAN, WILLIAM E. NMR Studies of Chemically Modified Dihydrofolate Reductase 70

WALKER, THOMAS E. The Chemical Synthesis and Biosynthesis of Compounds Enriched with Stable Isotopes 65

WANEK, PATSY L. Ground water Chemistry of Yucca Mountain 110

WANEK, PHILIP M. Characterization of LAMPF-Produced Radiohalogens 85 Iodine-123 85

WASSERMAN, HARVEY J.

First Examples of Isolable Molecular Hydrogen Complexes: Evidence for a Side-On Bonded H2 Ligand 147 Tertiary Phosphine Complexes of Uranium 137

WILBUR, D. SCOTT Structure of l-H-Azepine-2-One-5-Methoxime 150 Studies of Radiohalogenations Using Trimethylsilyl Intermediates: Radiohalogenations of Amines for Brain Studies 93 Studies Toward Radiohalogenations of Fatty Acids: Radiopharmaceuticals for Evaluating the Heart 104

WILHELMY, JERRY B. Accelerator-Based Mass Spectrometry of I0Be 195 Fission Fragment Angular Distributions of Heavy-Ion Reactions 159 Fission of Polonium, Osmium, and Erbium Composite Systems 161 Production of Neutron-Rich Bismuth Isotopes by Transfer Reactions 169 (p,xn) Measurements on Strontium Isotopes 23

WILLIAMS, HERBERT T. Omega West Reactor 189

WOUTERS, JAN M. Development of a Gas Ionization Detector for Direct Mass Measurements at LAMPF 200 Time-of-FIight Isochronous (TOFI) Spectrometer 179

YAN, SHUHENG Recovery of 44Ti from a Proton-Irradiated Vanadium Target and Development of a 44Ti —»• "Sc Generator 87

ZELTMANN, ALFRED H. Attempted Preparation of Pu(OH)2CO3 140

ttU.S. GOVERNMENT PRINTING OFFICE: 1984—776-101/1039 An Affirmative Action/Equal Opportunity Employer

The three previous reports in this series, unclassified, are LA-8717-PR, LA-9381-PR, and LA-9797-PR.

DISCLAIMER

This report was prepared as an account of work sponsored by an agency of the United States Government. Neither the United States Government nor any agency thereof, nor any of their employees, makes any warranty, express or implied, or assumes any legal liability or responsibility for the accuracy, completeness, or usefulness of any information, apparatus, product, or process disclosed, or represents that its use would not infringe privately owned rights. Reference herein to any specific commercial product, process, or service by trade name, trademark, manufacturer, or otherwise, does not necessarily constitute or imply its endorsement, recommendation, or favoring by the United States Government or any agency thereof. The views and opinions of authors expressed herein do not necessarily state or reflect those of the United States Government ot any agency thereof.

Printed in the United States of America Available from National Technical Information Service US Department of Commerce S285 Port Royal Road Springfield, VA 22161

Microfiche (A0I)

NTIS NTIS NTIS NTIS Page Range Price Code Page Range Price Code Page Range Price Code Page Range Price Code

001-025 A02 151 175 A08 301-325 A14 451-475 A20 026050 A03 176-200 A09 326-350 AI5 476-500 A2I 051 075 A04 201 225 AI0 351-375 AI6 501 525 A22 076-100 A05 226-250 All 376-400 AI7 526550 A23 101-125 A06 251 275 A12 401-425 AI8 551-575 A24 126 150 A07 276300 AI3 426-450 A19 576-600 A25 601-up* A99

'Contact NTIS for a price quote.