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LA-871 7-PR # ProgressReport ClC-l 4 REPORT COLLECTION C3o REPRODUCTION COPY

Chemistry-Nuclear Chemistry Division

October 1979–September 1980

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(lN!likLOSALAMOS SCIENTIFIC LABORATORY Post Office Box 1863 Los Alamos. New Mexico 87545 An Affirmative Action/Equal Opportunity. Employer

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This is the fust report in this series.

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IS-6 Composing Section

DISCLAIMKR

This report was pxpued ●$ an acmunl of work sponsored by an agency of the United States Govern- ment. Ncilhcr the United Stales Cowrnment not any agency thereof, n~ any of their employees. makes any warranty, CMWCSJor impliml, or assumes any legal IiabiIi:y or responsibility fm the atmu- ●cy, mmpbtcness, or u$cfulncss of any infotnu!ion, spparatus, product, or ptocesa disclosed, or rep. resenh that its UK would no: infringe privately owned dghts. Reference herein 10 any spedfkc corn. mercbl product, process, or service by trade name, tradcmwk, nunufacturer. or otherwise. doet not necessarily constitute or imply its cndorscmcn:, recommendatbn, or fsvorins by the United Slates Government or my agency thereof. The views and opinbns of authors exve~ed herein do no: nec- RIMIUY state or reflect those of the United SIaies Government or sny s;ency thereof.

UNITED STATES DEPARTMENT OF ENERGY CONTRACT W-7405 -ENG. 36 LA-871 7-PR ProgressReport UC-4 Issued: May 1981

Chemistry-Nuclear Chemistry Division

October 1979–September 1980

Compiled by

FL R. Ryan

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FOREWORD

DIVISIONAL OVERVIEW

Darleane C. Hoffman

It seems appropriate to reflect on the current state of the Division in our frost annual report, prepared 10 years after formation of the Chemistry-Nuclear Chemistry Division in January 1971. On October 1, 1980 two new groups (CNC-3, Medical Radioisotopes Research, and CNC-7, Isotope Geochemistry) were formed in addition to our existing groups (CNC-2, Physical Chemistry-Chemical Physics, CNC-4, Inorganic and Struc- tural Chemistry, and CNC- 11, Nuclear and Radiochemistry. See Organization Chart below.) At the end of FY-1980, we had 155 people in the Dkision, including 95 professional scientists, 75 with the degree of Ph.D. During the year, we had 11 postdoctoral appointees, a postgraduate resident in nuclear medicine, and one of the recipients of the prestigious J. Robert Oppenheimer FeUowship awarded by the Laboratory each year to one or two outstanding young scientists. During the past year

LOS ALAMOS NATIONALLABORATORY CNC ~lVISION m

CNC-2 W-4 Imrganic ●nd Chmical Physics Medical Radioi sotq)e Structural Chadstry and Resewch Physical Ckmistry I I Group Leader t Associata Group Leader - J. H. Sul IIWUL Dlvlsfon Leader - R. A. Pennemm

kputy GrOup Leader - T. U. k?ntm Deputy IWUP Leader - R. R. RYan I I ● Assoc. GmuD L aders

L. B. ASPIWI - Flwrine Cklstry B. B. Hclnteer - Stable Isotopes

f I [NC-7 II Ctic-11 I ISOtOPC Gmchealstry ● I Nuclecr nd Padlochemistry I Group Lezder - E. A. Bryant Group Leader k Associate Deputy Group leader - B. R. Erdal Dlwision Leader - J. E. Sattizahn Assoc. Group Leaders Deputy Group Leader - D. H. 6arr A. J. Gancarz - Isotope ?#mlysis Assoc. Gr Leaders R. J. Wale - 6eachmistry Fwearch K. Molfsbe rq - Radioachmistry J. P. Ralama - Dati Acquisitfm U. R. Danfel\ - Radiochmistry Asst. GrouD Leader ~ - LMPF P. R. Guthals - Atmospheric Projects c1J. B. w 1helm~ - nuclear Resetrch v we have continued our close interactions with scientists from numerous universities and research institutes, both in this country and abroad. Some 50 visiting staR members and consultants contributed to a variety of projects withii the Division, and an additional 30 research visitors used our nuclear chemistry facilities at the Los Alamos Meson Physics Facility (LAMPF). Advisory committees of eminent scientists reviewed our Medical Radioisotopes Research and Stable Isotopes Resource Programs. We hosted an Interm~late Energy Nuclear Chemistry workshop in June 1980 with 97 nuclear scientists (14 from abroad) in attendance. The Second Amual Divisional Information meeting was held in September 1980. This report covers contributions during FY-1980 (October 1, 1979—September 30, 1980) to unclassitled projects and to unclassified work related to the nuclear weapons program. Publications for aU of calendar years 1978 and 1979 as well as FY-1980 are listed and total 198 (see Appendm A). Append~ B lists facilities provided by the Dhision. The following are among our most notable accomplishments for FY- 1980: ● Isotope separation of large amounts (kg/yr) of >99 at.% 13C,lsO, *SN(plus 50% 170) has continued. Catalytic exchange of ‘*CO with ‘3C0 (iiportant in our CO distillation process for achieving 99% ‘3C) has been found to proceed on Y-AIZ03 without the presence of ruthenium. ●-A unique mass spectrometer system for rapid analysis of nitrogen isotope ratios has been developed. It can analyze several hundred samples per day in a fully automated fashion, from chemical processing to data print-out. ● Carbon-13 nuclear magnetic resonance studies of the interaction of the cancer chemotherapeutic agent, a!s-diamine platinum (II), with the vitamin B,z derivatives, adenosylcobalamin and methylcobalamin, have shown that the platinum complex can inactivate the vitamin. This inactivation and resultant B~zdeficiency may cause toxicity sometimes observed in the neural systems of patients with gynecological tumors treated with ci.s-diamine platinum (II).

● ‘I’he vfidity of the use of heavy methanes (’zCD, and 13CD4)as tracers of air movement over distances of 600 km and transit times of -18 h has been demonstrated. ● Radiopharmaceuticsl cold kits, in common usage in nuclear medicine, permit radioactive labeling to be performed under sterile conditions in the clinic or hospital by trained nuclear medicine technologists. The recent development of two radioiodination cold kits in our laboratory will facilitate the use of ’231in diagnostic medicine. ● The c8Ge/c8Ga biomedical positron generator system is expected to play an important role in emission computed tomography studies in man. The development of spallation production of c8Ge at LAMPF is an important step in creating an alternative, economical source for this nuclide. ● The achievement of high spec~lc activity (600-1200 Ci/mmole) labeling of estrogen derivatives is a significant and essential development in the quest to obtain a useful in VIVOestrogen-receptive tumor localizing agent. Thk search for a suitable agent is being conducted as a collaborative project involving Los Alamos, Washington University, the University of Illinois, George Washington University, and the University of Kansas. ● ~er more than 1.1-biilion gallons of water were pumped from a well 90m from the Cambric underground nuclear test, only tritium and *sKr were positively detected. . vi ● Sorption ratios for plutonium on tti, granite, and argillite have been found to be independent of plutonium concentration in the 10-6 to 10–12M range. ● Radiogenic lead mobilized from the mineralized strata at the Oklo mine has been found in the underlying conglomerate at concentrations as high as 3.4%. ● Muonic x-ray studies have provided the fust experimental evidence for the orientation of the molecuk electric dipole in NO as ‘NO+. (Meson capture should be related to electron density and was found to be appropriately larger for nitrogen in NO than in equimolar mixtures of Nz + Oz gas.) ● our measurements of the theoretically important pion single-charge exchange reaction 13C(n+,z0) 13Nas a function of pion energy show that the cross sections are substantially lower than previously reported values and are closer to theoretical predictions. ● A new coupled-channel theory for pion single-charge-exchange reactions was developed that goes beyond the fust-order pion-nucleus interaction and includes the second-order interactions caused by true pion absorption and pion scattering from correlated nucleon pairs. ● Measurements of the excitation fimctions for the pion single-charge exchange reactions 27Al(n-,n0)27Mg, 45SC(Z+,n0)4sTi, and C5CU(Z–,ZO)GSNIshow no structure near the (3,3) pion-nucleon resonance as predicted by the impulse approximation and Fermi gas model, but exhibit a monotonic decrease in cross section approximately proportional to I/E. . C)LUmeasured ratios of the yields of radioactive products resulting from np and rm emission following the capture of a negative pion in selected target nuclei are consistent with an increasing probability for np pairs versus pp pairs in the nuclear surface with increasing target Z. ● Measurements of the intensities of several long-lived radionuclides in lunar rocks were used to show that the average flux of energetic protons emitted from the sun has varied during the last million years. . Cross-section measurements have been made on several unique radioactive targets, for example, (n, 2n) and (n, np) reactions on 83day aaZr and the (p,t) reaction and level stmcture studies on 75-yr ‘48Gd ● We have shown that a state-of-the-m, two-stage mass spectrometer can be used to measure “radiochemical detector” isotope ratios for nuclear weapons test diagnostics. ● Ram~ scattering studies of organic high explosives under extreme temperature (20-600K) and pressures up to 100 kbar show remarkable changes in the vibrational energies, line widths, and relative intensities; the implication is that selective coupling between phonon and molecuhu vibrations may control the energy transfer from the shock wave to the bonds that are broken in detonation. . We have demonstrated a new experimental method for obtaining simple, in- terpretable Raman spectra for molecules whose spectra are usually unresolved or too complex for interpretation. The spectra were simplifkd by cooling the molecules in a free jet expansion and were obtained using ultrahigh-resolution coherent Raman techniques. ● Theoretical techniques were developed that, for the first time, enabled us to calculate rate constants for adsorption and resorption of atoms and molecules from solid surfaces. These techniques are unique in that they can be applied to sutllcently large systems (102-103 atoms) to allow examination of the effects of adsorbate concentration and surface geometry on the rate constants.

vii ● We have shown that Monte CarlO methods can be used to calculate electronic structures of molecules. This development is significant because it is applicable to larger molecules and because it allows calculation of properties where a molecular system is interacting with an extended system, as with chemisorbed H2 on a crystal lattice. ● An atlas of uranium emission lines has been prepared, and it was demonstrated that the easily measured optogalvanic etTectin a uranium hollow cathode discharge tube can be used to caliirate laser wavelengths simply and accurately. ● The structure of actinide molybdates, which can form during nuclear fuel reprocessing, is poorly known. We have completed the structure of U(MoO&. . Carbamy]methylenephosphonates are valuable as acid extractants of actinides, and the fwst crystal structure containing this Iigand has been determined. ● Unusual bonding and reactivity of Soz (with catalytic posslWIities) are found on its coordination to molybdenum and tungsten carbonyls. We have found that SOZcan be reduced to sulfur at medium terpperature by H2 over a catalytic surface of ruthenium on AIZOJ. ● Rich new dynamics have been dkcovered in high-resolution studies of impuri- tydoped solids, including site-to-site exchange on the vibrational time scale. These results greatly expand our understanding of guest-host interactions and energy relaxation in condensed phase materials.

CNC DIVISIONAL PERSONNEL AND FINANCIAL SUMMARY FY-1980 FTEb Funding’ Average ($ K) Level

DOE PROGRAMS Defense $3010 39 Supporting Research 2347 28 Energy Research (ER) 1154 11 Geothermal Energy (RA) 273 3 Atmospheric Projects (EV) 530 5 Medical Radioisotopes (EV) 890 11 Stable Isotopes Development (EV) 410 4 Stable Isotopes Inventory 586 7 TOTAL DOE PROGRAMS $9200 108 OTHER PROGRAMS NASA 83 1 NIH (Stable Isotopes Resource) 184 2 NV: Defense Radionuclide Migrations 150 2 Nevada Nuclear Waste Storage Investigations 768 8 OtEce of Waste Isolation 650 8 Miscellaneous 395 5 TOTAL OTHER PROGRAMS $2230 26” 0VEIL4LL TOTAL $11430 134 ‘Excludingcapital equiDment. bFI’E = full time equivalent rounded to nearest whole number. Not included are 12 postdoctoral appointeesand 1J. Robert OppenheimerFellow. ... Vlu CONTENTS

ABSTRACT ...... 1

I. ADVANCED ANALYTICAL METHODS ...... 1 A. Thermally Induced Laser Pulsing: A New Technique to Measure Weak Absorption of Solutions ...... 1 B. Noise Considerations, Signal Magnitude, and Detection Limits in a Hollow Cathode Discharge by Optogalvanic Spectroscopy ...... 2 C. An Atlas of Uranium Emission Intensities in a Hollow Cathode Discharge ...... 4 D. The Optogalvanic Effect as a Detector for Intracavity Atomic Absorption in a cw Dye Laser ...... 5 E. Ultrasensitive Analysis of Heavy Methane ...... 5

IL ATMOSPHERIC CHEMISTRY AND TRANSPORT ...... 7 A. The Heavy Methane Tracer Program ...... 7 B. A 600-km Atmospheric Tracer Field Test ...... 8 C. Project Airstream and Related Efforts in Atmospheric Chemical Measurements ...... 9

III. BIOCHEMISTRY ...... 12 A. Carbon-13 Nuclear Magnetic Resonance Analysis of Metabolic Pathways for Glutamate Biosynthesis by Microbacterium ammoniaphilum ...... 12 B. Nuclear Magnetic Resonance Studies of an Isotonically Labeled Enzyme: Dihydrofolate Reductase ...... 13 C. Development of a Data Base for Carbon-13 Enriched Molecules ...... 14

IV. BIOMEDICAL RESEARCH ...... 15 A. Radioisotopes ...... 15 1. Bromine-77 Labeled Steroids for Detection of Hormone-Associated Tumors ...... 15 2. Radiohalogenating Fatty Acids in the Omega Position ...... 15 3. Isotopic Exchange Procedures for Labeling Radiopharmaceuticals with Short-Lived Isotopes ...... 17 4. Strontium-82 and Rubidium-82 Biomedical Shipments in FY 1980 ...... 18 5. Bromine-77 Biomedical Shipments in FY 1980 ...... 19 B. The National Stable Isotopes Resource ...... 19

V. ELEMENT MIGRATION AND FIXATION: GEOCHEMICAL STUDIES ...... 21 A. Element Migration at the Key Lake Uranium Ore Deposit ...... 21 B. Migration from Nuclear Explosion Cavities ...... 23 C. Radionuclide Transport and Retardation in Tuff ...... 25 D. The Leaching of Spent Fuel Elements in Water ...... 27 E. Preliminary Considerations Concerning Actinide Solubilities ...... 29 F. Rock-Water Interactions ...... 31 G. The Application of Fluid Chemistry Studies to a Hot Dry Rock System: Neutron Activation Studies ...... 33

ix H. Permeability Measurements ...... 34 I. Element Transport in Solids: The In~eraction of Water and Fenton Hill Granite ...... 36 J. Amphiboles on the Join Pargasite-Ferropargasite ...... 37

VI. INORGANIC CHEMISTRY ...... 38 A. Small Molecule Chemistry ...... 38 1. Alumina Catalyzed Isotope Exchange in CO ...... 38 2. Catalytic Reduction of SO2 ...... O 38 3. Novel Reactivity and Structure of Ru(CO),(q2S0,.SO~PPh~)2 ...... 40 4. Coordinatively Unsaturated Mo(O) and W(O) Complexes and Their Reactions with Small Molecules ...... 41 5. Molybdenum and Tungsten SOZ Complexes ...... 43 B. Actinide Chemistry ...... 45 1. Uranium(V) Fluoride Chemistry ...... 45 2. Uranium(V) Alkoxides ...... 46

3. Interactions of 4f and 5f Cyclopentadienides with SO 2 ...... ,., , 47 4. Actinide Extractant Chemistry ...... 48 5. Valence, Size, and Coordination Demands of Actinides as Applicable to t Storage in Synthetic Materials ...... 49 6. Actinide Molybdates ...... 51 7. Bond-hngths and Bond Strengths in Actinide Flourides ...... 52 8. Actinide Oxo Chemistry ...... 53 9. Fluorination Reactions of UFC with Organic Compounds ...... 54

VII. ISOTOPE SEPARATION AND ANALYSIS ...... 55 A. Separation of Stable Isotopes (Carbon, Nitrogen, and Oxygen) and Production of Labeled Compounds ...... 55 B. Automatic Nitrogen Analysis ...... 56 C. Modernization of Isotope Separators ...... 57

VIII. ATOMIC AND MOLECULAR COLLISIONS ...... 57 A. Molecular Dynamics of the NO and Ozone Chemical Reaction ...... 57 B. High-Repetition-Rate Pulsed Gas Beam Source ...... 59 C. Coupling of Chemical Reaction with Ambipolar Diffusion in a Flowing Aflerglow Experiment: Application to Ion-Molecule Reactions of Uranium Hexafluoride ...... 59 D. Ion-Molecule Reactions by the Flowing Afterglow Technique: A New Technique: A New Determination of DOzg~(F#-F) and of the Ionization

Potential of SF 5 ...... 61

IX. MOLECULAR SPECTROSCOPY ...... 62 A. Ultrahigh-Resolution Coherent Raman Spectroscopy in Molecular Beams ...... 62 B. Remote Detection of Ionizing Radiation by Raman Scattering from Nz+ ...... 63 C. Optogalvanic Double-Resonance Spectroscopy: Experimental Observations ...... 64 D. Locking of cw Dye Laser Emission onto the Wavelength of Molecular Fluorescence by Intracavity Gain: Example Iz ...... 66 E. Photoionization of Polymers of Hydrogen Sulfide and of Carbonyl Sulfide ...... 67 F. Evaluation of the Vibrational Transition Moment for the UzBands of “ND~ and lsNDq ...... 69

x G. Low-Temperature Impurity-Doped Solids ...... 69 1. High-Resolution Infrared Absorption Studies of SFC and SeFc Trapped in Noble Gas Solids ...... 69 2. Dynamic Site Exchange and Vibrational Dephasing on a Picosecond Time Scale ...... 72 3. Estimation of True Line Shapes, Widths, and Intensities for Sharp Absorption Peaks in Low-Temperature Matrices ...... 75 H. Laser and Photo-Chemistry ...... 76 1. Isotonically Selective Dissociation of SPFb Using a High-Energy Pulsed C02 Laser ...... 76 2. Photoreduction of UFG at 10 K . ...?...... 77

X. MUONIC X RAYS ...... 77 A. Muonic X-Ray Evidence for the Molecular Dipole Orientation ‘NO+ ...... 77 B. Target Density Effects in Muonic Atom Cascades ...... 78 -. - XI. NUCLEAR COSMOCHEMISTRY ...... 79 A. Variations of Average Solar-Proton Fluxes During the Last 10 Million Years ...... 79 B. Silver Isotopic Anomalies in Iron Meteorites: Cosmic-Ray Production and Other Possible Sources ...... 82 C. Gamma-Ray Spectroscopy of Comets ...... 84 D. Boron Abundances in the Early Solar System ...... 87

XII. NUCLEAR STRUCTURE AND REACTIONS ...... 90 A. Measurement of 14 MeV Neutron Cross Sections on Radioactive Nuclkies ...... 90 B. Determination of the Half-Lives of a7Zr, *’MY,and *78Y...... 91 c. Determination of the Half-Life of ‘48Gd ...... 92 D. The (p,t) Reaction on the Exotic Target 148Gd ...... 93 E. Search for Neutron-Deficient Light Nuclei near the Proton Drip Line ...... 94 F. Production of Nuclides Far from Stability ...... 95 G. Pion-Nucleus Reactions ...... 98 1. Pion Single-Charge Exchange in Complex Nuclei ...... 98 2. A Covariant Coupled-Channel Theory for Pion-Nucleus Single-Charge Exchange Reactions ...... 100 3. Yields of Two-Nucleon-Out Products from Stopped Negative Pion Reactions ...... IcI1

XIII. RADIOCHEMICAL SEPARATIONS ...... 103 A. The Chemical Isolation of Spallogenic c8Ge from RbBr ...... 103 B. A ‘72Hf-172Lu,Isotope Generator for Preclinical Nuclear Medicine ...... 103 C. Chemical Recovery of 52Fefrom Nickel ...... 105

XIV. THEORETICAL CHEMISTRY ...... lO7 A. Theoretical Chemical Dynamics ...... 107 ( 1. The Dynamics of Cluster Growth ...... 107 2. Unimolecular Dissociation of Van der Wads Molecules ...... 108 3. Low-Energy Ion Channeling ...... 108

xi 4. Adsorption/Desorption Kinetics ...... 108 5. Energy Transfer, Reaction, and Dissociation as a Function of Initial State for H+HZ on an Accurate ab initio Potential Energy Surface ...... 109 B. Monte Carlo Based Electronic Structure Techniques ...... 112

XV. UNCLASSIFIED WEAPONS RESEARCH ...... 113 A. Bismuth: ANew Weapons Radiochemical Detector ...... 113 B. Vibrational Spectra and Normal Coordinates of High Explosives under Ambient Conditions ...... 114 C. Raman Spectra of High Explosives under Extreme Pressure and Temperature Conditions ...... 115

REFERENCES ...... O.. SOSSOOO. . .. SO.SO"""S"O1l7

APPENDIX A. PUBLICATIONS ...... OSO 133

APPENDIX B. DIVISION FACILITIES ...... 153

xii CHEMISTRY-NUCLEAR CHEMISTRY DIVISION OCTOBER 1979—SEPTEMBER 1980

Compiled by

R. R. Ryan

ABSTRACT

Tlds report presents the research and development programs pursued by the Chemistry-Nuclear Chemistry Division of the Los Alamos National Laboratory. Topics covered include advanced analytical methods, atmospheric chemistry and transport, biochemistry, biomedical research, element migration and f~ation, inorganic chemistry, isotope separation and amdysis, atomic and molecular collisions, molecular spectroscopy, muonic x rays, nuclear cosmochemistry, nuclear structure and reactions, radiochemical separations, theoretical chemistry, and unclassified weapons research.

I. ADVANCED ANALYTICAL METHODS width of each pulse is strongly dependent on the absorptivity of the solution. The frequency of the pulsing A. Thermally Induced Laser Pulsing: A New Tech- depends only upon the degree of mistilgnment of the nique: to Measure Weak Absorption of Solutions (D. cavity and the thermal conductivity of the solvent, not A. Cremers and R. A. Keller) upon the absorptivity of the solution. Such data can serve as a calibration curve to determine the concentra- Pulsed operation of a normally continuously operating tion of a dye in an unknown solution (Fig. 2). dye laser is achieved by inserting into the laser cavity a Experimentally and theoretically it is found that the cell containing a solution having a small absorptivity (a energy absorbed during a pulse is a constant, independ- ~ 10-4cm-1). When the output coupler mirror is tilted ent of the solution absorptivityy; that is, off-axis, the laser goes into pulsed operation (Fig. 1). The (aO+ a)PAt = constant ,

PULSED SOLUTION T> OPERATION CELL 7 where iii z u 1- Z . aO= solvent absorptivity , ‘u as = solute absorptivity , P = power of laser beam in cavity ,

Fig. 1. and Thermally induced laser pulsing: A new technique to measure weak absorption of solutions. At = pulse width. previously reported value of aO < 10-s cm-’. This represents one of the smallest absorptivities yet measured for a solution.

B. Noise Considerations, Signal Magnitude, and Detec- tion Lnits in a Hollow Cathode Discharge by OP- togalvanic Spectroscopy (R. A. Keller and E. F. Zalewski*)

The optogalvanic effect is very sensitive for the hLuJJ+- detection of weak absorption in a hollow cathode -7 -6 -5 ‘4 ‘3 discharge, which leads to applications in spectroscopy In (absorptivity) and analytical determinations. It is therefore important to understand the limiting noise sources and the rela- Fig. 2. tionship between the magnitude of the impedance change Dependence of pulse width on absorptivity of solutions. Experimentally (aO+ a,) P At = constant. and the number of photons absorbed. Extensive measurements were made of the noise across a 25-kQ ballast resistor in series with a hollow cathode discharge tube. Total noise was measured with a Absorption of this amount ofenergy turns the laser off limited band-pass oscilloscope, and the frequency re- and causes the observed reciprocal relation between sponse of the noise was measured with a spectrum pulse width and absorptivity (Fig. 2). a&lyzer. Both measurements demonstrated that the Thermally induced laser pulsing can also be used to noise was statistical in nature (&/n where n is the measure the absorptivity of a pure solvent as demon- number of electrons moving in the circuit). strated in Fig. 3 for CCl& At low values of solute The magnitude of the laser-induced voltage change absorptivity, the pulse width remains constant, indicating across the ballast resistor and the number of photons aO>>a,. The absorptivity of CC4 is found by fitting the absorbed by the atomic species were simultaneously equation, (aO+ aJPAt = constant, to the data. The v~ue measured for uranium, sodium, europium, and zirconium we obtain is aO= 9.2x 10–6 cm-l, which agrees with a in hollow cathode discharges. The results are summarized in Table I. The last column shows that the

150 magnitude of the laser-induced impedance change per photon absorbed is essentially a constant. This ratio does not depend upon the ionization potential of the element, the mobility of the positive ion produced, the fti gas 100 (neon or argon), or the current in the discharge tube. The numbers in the last column can be translated into an efficiency E -10-3 (number of extra electrons produced per photon absorbed). 50 Knowledge of the impedance change per photon absorbed by the atomic .-system...- --—-and the—statistical nature of the circuit noise ‘make it possible to calculate detection limits. For example, the calculated detection limit for 0 ~ uranium is 106atoms/cm3. -14 -12 A mechanism that tits the data and appears to be quite In(solute absorptivity) plausible involves the use of the atomic system merely as a method of transferring laser energy into the electrons. Fii. 3. In a hollow cathode. discharge there is an equilibrium Determination of the absorptivity of a pure solvent: .— aO(CC14)= 9.2 x 10”’ cm-’. ‘National Bureau of Standards, Washington, D. C. TABLE I

RATIO OF THE LASER-INDUCED VOLTAGE CHANGE TO THE LASER POWER ABSORBED: U, Na, Eu, and Zr’

LP. f Element (eV) (MA) (i) (m&)b (~t~ (~!)d (mV?~\)d’e u 6.1 24.9 5915.4 21.5 2.0 16 8.2 * 2 Uf 6.1 25.5 5915.4 26.5 2.7 33 12 Na 5.1 13.0 5895.9 0.277 0.09 0.956 11 +2 Na 5.1 13.0 5889.9 0.265 0.09 0.973 11 +2 Eu 5.7 15.6 6018.2 28.2 2.6 17.3 7 *1 Zr 6.8 30.6 6134.6 12 0.5 2.1 4 *1 Zfl 6.8 25.8 6134.6 10 0.5 3.2 6 +1 ‘With the exceptionof one Zr tube, the ffl gas was neon (-5 torr); the ballast resistor was 26.9 k~. bThe laser was not single frequency, but its output consisted of three modes with an intermodeseparation -1.5 GHz. Only the center mode,whichcontained about one-halfof the intensity,overlappedthe absorption band.

‘Single pass absorption. ‘The sign of AV depends upon whether AV is measured across the tube or the ballast resistor. The sign given here is for measurement across the ballast resistor. ‘When error bars are given, two or three measurements were made. These values were reproduciblefrom day to day. rDifferentdischarge tube. ‘Ar fti gas (-5 torr).

established between the electron energy distribution and increases. However, if an electron experiences few col- I the atomic excitation distribution such that the electron lisions on the way to the anode, the energy is not temperature (TJ and the electronic excitation tem- distributed among all the electrons, and the effective perature in the atom (TJ are equal to the fwst approx- electron temperature does not change. imation. This equilibrium occurs because of many elastic The etliciency measured here (E w 10-3) compares and superelastic collisions between the atomic system quite well with fluorescence detection when one con- and the electrons. Laser irradiation is a small per- siders the quantum yield of fluorescence, the limited turbation in this process. However, the numerous elec- elliciency of collection of photons emitted over 4 n sr, tron collisions prevent a significant change of the energy and the conversion of collected photons into electrons. level pop~lation, and the energy supplied to the atomic However, a big advantage of fluorescence is that the - system by the laser is faltered off to the electrons. This noise in the detection circuit is small in the absence of energy transfer dktorts the electron energy distribution signal. and creates an excess of electrons at an energy corre- Previous workers have suggested that isotonically sponding to that of the laser photons. The increased selective irradiation of a species in a gaseous discharge energy in the electrons results in a decrease in the followed by cataphoresis is a possible method for isotope impedance of the dkcharge. If the transit time of the enrichment. If our mechanism is correct, irradiation of a electrons to the anode is long with respect to the particular species would not be a viable isotope enrich- electron-electron collision frequency, the excess energy is ment scheme because it does not lead to preferential distributed among all the electrons, and the effective T, ionization of that species. C. An Atlas of Uranium Emission Intensities in a trometer at Kitt Peak National Observatory result in a Hollow Cathode Dkcharge3 (B. A. Palmer, R. A. Keller, set of wave-number standards superior to any other with and R: Engleman, Jr.) a comparable number of lines. The uranium emission spectrum has numerous very sharp lines widely dis- This atlas, a series of graphs depicting the spectrum of tributed throughout the ir, visible, and uv spectral uranium and accompanied by tables of wave numbers, regions, resulting in a selection of strong lines in any relative intensities, and assignments (see Fig. 4), provides given region of the spectrum. an excellent source of information on the spectrum of This report provides an excellent source of informa- uranium. Its wave-number accuracy makes this atlas tion on the uranium spectrum. The tables list not only the useful for calibration of spectrographs, mono- wave numbers of the strong lines, but also the stage of chromators, and tunable lasers. The relative intensities of ionization, energy levels, and J values for most of these the spectral lines measured are accurate to +8%, a result transitions. This detailed knowledge is useful in working of the spectrometer used, and are useful in mapping the with uranium in plasmas, furnaces, or isotope enrich- spectrum and determining relative oscillator strengths (gf ment. We are currently processing the data for similar values). compilations in the ir and uv spectral regions. The spectral lines from our lamp, a commercially’ To check further the accuracy of the wave numbers available hollow cathode discharge tube, are sharp and reported in the uranium atlas and to provide several reproducible. The sharpness of the lines and the excellent benchmarks of higher accuracy, we measured the wave wave-number accuracy of the Fourier transform spec- numbers of 10 uranium lines.’ The optogalvanic effect

uw8M(m 1N7 E(EVEN) J(E) E (ODD) J(OI

5.6s ?628 4 zzsm 3 1.n p; 11677 7 !m. ; e 6 1.s4 s. 19 26971 ? leeks 7 3.4s 2s979 8 100s9 7 1::? 20712 0 38Ba ?

::%’ 245S0 ? ?64S e 2.73 30498 I;;fl 7 1.?6 24118 : 2 1.s3 23932 s ?80s 2?1%4 4 102s4 : ;:: 16929 s 6 25793 3 eesf! 2 2::? 2Be05 3 3E68 3 22780 5762 ::; 1?559 : z 31442 9 t4%! e 2:63 14e5e 7 31S02 8

1::7 23197 7 6249 6

Fig. 4. Sample page from uranium atlas.

4 was used to center a tunable dye laser in an optical LASER transition, and the wave number of the dye laser was compared to the wave number of an iodine-stabilized He-Ne laser by using a lambda meter. The absolute wave 1 numbers of these 10 lines were measured to an accuracy CATHOQE CtWPER

of +0.0006 cm–l. The average difference between the SAMPLE “ atlas measurements and present work is +0.0009 cm-l, wtilch is well withh the estimated accuracy of the atlas. Fig. 5a. OGE detector of int.racavity absorption.

I , , I 1 I I I I D. The Optogalvanic Effect as a Detector for Intracavi- 0,8 - ty Atomic Absorption in a cw Dye Lasers (E. F.

Zalewski,* R. A. Keller, and C. T. Apel) G ~ 0.6 -

The detection of trace optical absorption can be d m enhanced several orders of magnitude by placing g 0,4 - samples inside the cavity of a broadband laser. The 2 0 absorption within the laser cavity inhibits lasing at wavelengths corresponding to the optical absorption. :0.2 Sensitive detection of laser output reduction on the absorption line requires a spectrograph with resolution oo~

high enough to resolve the absorption line (5 m). SODIUM CONCENTRATION (Ppb) Irradiation of gaseous discharges, at wavelengths corresponding to optical transitions of species present in the Fig. 5b. * Intracavity absorption of sodium atoms in a flame. discharge, causes easily measurable changes in the impedance of the discharge (OGE). We have demonstrated the use of OGE as a simple, sensitive detector for intracavity absorption to replace the spectrograph. An analytical flame is placed inside the cavity of a cw dye laser oscillating with a bandwidth -4 A centered on the sodium absorption (see Fig. 5a). The laser output is directed into a hollow cathode discharge containing sodium, producing an optogalvanic signal. As sodium is (1 -J I 10 aspirated into the flame, the laser intensity at the sodium SODIUM CONCENTRATION Ippb) absorption wavelength and the OGE signal decrease. Note that the laser power remains constant. In Fig. 5b Fig. SC. Comparison of intracavity and extracavity absorption. the normalized AOGE vs sodium is plotted. The S/N at 1 ppb is greater than 10, which is equivalent to the best reported sensitivity for sodium in flame atomic absorp- In essence this is the substitution of a one hundred tion spectroscopy. A comparison of the flame inside and dollar discharge tube for a several hundred thousand outside the laser cavity is shown in Fig. 5c. The dollar spectrograph. enhancement in sensitivity is -4000. It is apparently possible to increase sensitivity at least 100 times by using a longer flame and operating the laser closer to E. Ultrasensitive Analysis of Heavy Methane (M. M. threshold, where the enhancement factor should ap- Fowler, J. R. Tesmer, and J. B. Wilhelmy) proach 10s. Heavy methanes (12CDd and ‘3CDd) are now being *National Bureau of Standards, Washington, D.C. used as tracers for atmospheric dynamic studies. They have several characteristics desirable for long-range atmospheric studies:

(1) In air there are essentially no contributions from ,------TERMINAL ------species having mass 21. This suggests the possibility ! of using mass spectroscopic techniques for high-sensitivity studies. IAN DE GRAAFF (2) The heavy methanes are nonradioactive substances and thus free of the environmental objections associated with radioactive materials.

(3) The Los Alamos National Laboratory ICONs pro- I , gram provides reasonably large quantities of stable light isotopes, permitting inexpensive production of heavy methanes. (4) Natural methane has an abundance of -1.5 ppm in the atmosphere and thus should produce no unexpected chemical or physical effects to limit the usefulness of the tracers, as might occur from the Firz. 6. introduction of nonstandard chemicals in a “car- Schematic of proposed e;perirnentaf configuration. rier-free” state. (5) Methane is believed to have a lifetime in the at- atomic constituents ionized. The ions enter art e mosphere of from 2-7 years. The heavy methanes trostatic deflector, which makes an energy/charge se’ will have even longer lifetimes because of isotopic tion. The ions’ paths are deflected and impinge u] effects, enhancing their usefulness for long-range solid-state detectors that record the energies. This dot ghbal studies. analysis should give a unique signal essentially free Current techniques for determining concentration of background. heavy methanes consist of chemically extracting To date we have tested the most critical part of methane from whole air samples and then looking for the proposal, that of ionizing the methane and extractin mass-20 or -21 contribution by mass spectroscopy. with the injection magnet (Fig. 7). For the test a w Sensitivities as great as five parts in 10’2 have been quantity of methane 20 (l*CD,) was mixed v demonstrated for the methane fraction, resulting in a hydrogen carrier gas. The major extracted ions total sensitivity for mass-2 1 methane of -10-17 in the so , , , , , atmosphere. Although quite good, this is still an esti- I I mated two orders of magnitude greater than the antici- a r .lx b.v / a. pated natural background level. We are, therefore, attempting to develop a new technique to improve sensitivities for analytic detection. The use of the vertical Van de Graaff facility at Los Alamos makes possible a double analysis technique consisting of reasonably high resolution mass analysis followed by molecular dissociation of the methane and unique detection of the electrostatic rigidities of the <- dissociated atoms (Fig. 6). A methane sample is in- t troduced into a duoplasmatron ion source in the terminal of the accelerator, which is at a 6 to 8-MV positive potential. A magnet selects the positively charged mass-2 1 fraction and injects the ions into the accelerator. ,~ Following acceleration, the mass-21 fraction is again 30 MASS (amu) selected with an analyzing magnet having a resolution of Fig. 7. -1/104. This fraction then impinges on a 2 lqg/cm2 Mass of ions observed from injection magnet as a function of carbon foil, where the molecule is dissociated and the electromagnet current for an extraction voltage of 15 KV.

6 shown along with their measured currents. The signifi- sufficiently stable chemically in the atmosphere to allow cant deuterium contamination is believed to be from completion of the anticipated applications, without being recent deuterium runs in the source. Nevertheless the so long-lived that it contributes to the overall back- extracted methane was at a very high current and ground. This problem plagues the traditional at- demonstrated the feasibility of the technique for use of a mospheric tracer SFC, which is now limited to transport Van de Graaff facility for ultrasensitive molecular distances of -100 km because of its anthropogenic analysis. background. Furthermore, there should be no extraneous Significant areas remaining for development include sources of the tracer, so that tracer from other sources construction of the detection apparatus, adequate volt- does not confuse the experiment in progress. age regulation in the accelerator, determination of cross In addition to low tracer background, the tracer contamination between samples, and quantitative de- should be detectable at extremely low concentrations. termination of the methane concentration. Typically a tracer maybe diluted with air a trillion fold, so that exceedingly small amounts of the tracer must be measurable. Of course as the distances increase, so do H. ATMOSPHERIC CHEMISTRY AND TRANS- the difficulties with detection. PORT . The tracer materials being studied by Group CNC-7 are methanes that are different in isotopic composition- A. The Heavy Methane Atmospheric Tracer Program from normal methane. The two methanes of interest are (M. M. Fowler) ‘zCD, with a mass of 20 and 13CD4with a mass of 21, whereas normal methane, 12CHd,has a mass of 16. The The large-scale development of energy sources such as two fully deuterated methanes are unique in that they coal or oil shale as alternatives to oil has heightened have no natural sources and no known large-scale aw~eness of associated potential detrimental environ- industrial use, leading to the conclusion that there is mental effects. These effects will not be confined to the virtually no background of these materials in the at- immediate areas containing the developing technology. mosphere. This assumption has been veritied, and with There is a need for assessing the impact of related our current analytical scheme we can say that the efiluents not only nearby but also at a distance. Current- background for 13CDdis less than 1 part in 101sparts of ly there are few numerical models that accurately air by volume as an upper limit. estimate these impacts, and in complex environments The employment of the heavy methanes is unique to there may be none. Los Alamos because the CNC Division ICONs program An atmospheric tracer provides an alternative or provides highly enriched 13Cand depleted 12Cin reason- complementary method for evaluating future or existing ably large quantities and also provides for synthesis of sites. This is not a novel tracer use, but current 12CD4and 13CD4. requirements are for applications at greater transport Currently, the analytical scheme for these tracers distances than previously encountered. Tracers can pro- involves the isolation of a methane fraction from a vide data to calibrate or f~ the parametric variables of sample of atmospheric air followed by mass spec- models, which can, in turn, provide more accurate trometric analysis to determine the abundance of the predictions. tracer relative to normal methane. A tracer concentra- There are a number of additional areas where tion of 1 x 10-18in air by volume corresponds to a ratio long-range atmospheric tracers are in demand, such as of tracer to normal methane of -10-12, about the studies of chemical transformations in the atmosphere minimum measurable ratio for mass-2 1 methane in the and verification of multidimensional transport and dif- mass spectrometer. The detection limit for mass-20 fusion models relating to climatological studies. Al- methane is ~15 times poorer than for mass-21 methane, though there is a recognized need for long-range at- primarily because of background contributions from mospheric tracers, no current system is generally satis- heavy water in the mass spectrometer. These measure- factory. CNC Division of the Los Alamos National ments require -1 cm3 of methane corresponding to Laboratory is developing such a system. 500-1000 t’ of original air sample. In practice, it is not An atmospheric tracer should be nontoxic and should always possible to collect enough air to make the limiting not generate other environmental problems, which vir- measurement and, in these cases, the detection limit is tually eliminates radioactive tracers. It should also be higher. Typically, a 50-t air sample will provide a

7 detection limit of- 10-20 times higher than the case for a methanes has been an important facet of this experim sample of unlimited size. as there are no other long-range tracers against whit Dufing the past year”““a numbe~’ of achievements check the perfluorocarbon tracers. related to this program have been realized. The tracers were released over a period of 3 1 (1) Methods for the preparation of absolute standards of Norman, Oklahoma, during conditions (southerly w CD, at low concentrations in CHA have been that were expected to give a transport trajectory in developed, and based on the standards prepared to desired direction but at a velocity somewhat greater 1 date, the mass spectrometric measurements have a planned. The heavy methanes were premixed in an - relative accuracy of a few percent for concentrations ratio (**CDd:13CDd)in a small cylinder. In this case of 13CD4in CH4 to less than 1 part in 109. two methanes were to be compared with each other (2) The inlet system of the mass spectrometer has been with SF~, which was also released at Norman, Okl/ redesigned to reduce the amount of methane required ma. The release consisted of 84 g of 13CDi and 153 for analysis from 2 cm3 to 1 cm3. The analysis 12CDd, metered out at a constant rate over the system has been improved so that the analysis of period. In addition, 273 kg of SF~ were released. relatively large numbers of samples is now possible. Sampling was carried out both on the surface am (3) Studies using the heavy methanes have been made of aircraft at downwind distances of -100 km and - nocturnal drainage winds in a variety of locations km (see Fig. 8). Sampling along the 100-km “arc wz with transport distances of up to 20 km. intervals of-2.5 0 (-4.5 km) with a total of-20 stat (4) A new cryogenic sampler has been developed and centered on the projected plume trajectory. Collect tested in the field. A series of field experiments have were made by using small pumps to inflate plastic 1 tested new sampling methodology along with experi- over an 8-h period. The aircraft collections were n ments to verify that the tracers are conserved to for periods of -5 min over21 km while the aircraft distances of up to 600 km (See Sec. 11.B.) along the arc -1 km above ground level. Heavy metl (5) Finally, Los Alamos GroupsCNC-11, CNC-7, and sampling at 600 km was made at six locations spacx G-8 participated in the Atmospheric Studies in intervals of -80 km, again centered on the predi Complex Terrain (ASCOT), which took place in the trajectory. Both cryogenically collected samples and geothermal power production area in northern Cali- samples were collected over 2-h periods at each sit fornia in September 1980. Much of next year will be total of five sample pairs was collected at each d spent in the analysis of samples and the interpreta- give some sequential information. The aircraft mm] tion of the resultant data. at 600 km was carried out at -1.2 km above grf

B. A 600-km Atmospheric Tracer Field Test (M. M. Fowler)

A long-range application of the heavy methane tracer system has been carried out using both ‘zCD, and *3CDd.This test had several objectives, including testing a newly developed cryogenic air sampler, testing a newly completed sample-handling apparatus, and demonstrating that the heavy methanes could be used to trace the path of air movement over distances up to 600 km and travel times of- 18 h. This experiment was conceived and planned primarily I I ● -mAwRnwR / I by the Air Resources Laboratories (ARL) of the Na- 9-rf— tional Oceanic and Atmospheric Administration I (NOAA) as a field demonstration of their new auto- Fig. 8. mated sampling system for their perfluorocarbon tracers. Experiment map (600 km). The arrows indicate a typci Los Alamos National Laboratory was invited to partici- plume trajectory, and the relative expected concentrations a pate in thk cooperative experiment. The use of the heavy indicated by contours.

8 level and each sample was collected over -40 km of samples with measurable amounts of 13CDd. The flight path. A total of 19 samples was collected in 2 arrival times of the tracer plume and the peak passes along the 600-km arc. concentrations agree with model predktions. These At this time, about 3/4 of the samples have been results represent the detection and measurement of analyzed and several observations can be made concer- *3CD, at distances of nearly 2500 km from its ningthe data. release. (1) The cryogenic samplers developed by J. Frank and W. Shields worked well, and all of the samples desired were collected. These samples have been C. Project Airstream and Related Efforts in At- analyzed and have shown heavy methane tracer at mospheric Chemical Measurements (E. J. Mroz) two of the sites. (2) The plume position and duration measured at 600 L Project Airstream. Project Airstream provides km agree qualitatively with similar measurements measurements of a number of stable and radioactive made using the perfluorocarbon tracers and agree species (Table 11)in the aerosol and gases that comprise with trajectory predictions. the upper troposphere and lower stratosphere. A (3) The amounts of SF~ observed at both 100 and 600 WB-57F aircraft especially equipped for high-altitude air km agree with those predicted from the heavy sampling is flown for the Department of Energy (DOE) methane results. However, a factor of 2 uncertainty by the National Aeronautics and Space Administration is associated with the SFG measurement at 600 km (NASA) under the direction of the Johnson Space because of the small signal-to-noise ratio. Center. Airstream missions are generally scheduled for (4) The results from the aircrafl samples collected at 100 April, July, and October. Figures 9 and 10 show the km are in agreement with those colJected on the flight paths (altitude, latitude, longitude) flown on each ground. mission. In addition, vertical profdes are flown at (5) The new apparatus that transfers samples from bags Anchorage, Alaska, Houston, Texas, and Panama City, to pressurized cylinders worked as desired and has Panama. been improved for use in the ASCOT experiments. During fiscal year 1980, airstream missions 17, 18, (6) Daily samples were also collected at four other sites: and 19 were flown in October 1979, April 1980, and July Argonne National Laboratory, National Bureau of 1980 as scheduled. Data obtained through Project Standards (Gaithersburg), AIRCO (New Jersey), Airstream are published in Environmental Quarterly, and the Savannah River Plant. These samples have which is prepared by the DOE Environmental Measure- been analyzed and all sites except AIRCO provided ments Laboratory.

TABLE II

CHEMICAL AND PHYSICAL MEASUREMENTS MADE ON THE WB-57F HIGH-ALTITUDE AIR-SAMPLING AIRCRAFT

Gases Particles Project SF6, N20, 14C02, SOT, NO;, NH~, Airstrearn CC1,, CC 13F, CC 12F, ‘Be, %3r, 137CS,‘44Ce$ 9sZr, 239pu,Zlopb HZO, CO, 03 Condensation Nuclei CHAMP Total C 1, Br, I -— Total Halogen Exp HT, HTO -— Tritium Exp

-— Mass and size distribution, QCM Exp particle morphology, chemistry

9 m-m-. 8 9 ● mm Concentration isopleths for 90Srduring July 1978 are ~i I I I I I I I I I ! shown in Fig. 11. In its general features, the dM.ribution of ‘OSr is typical of all species measured by Project Airstream. The contours generally foUow the shape of the tropopause, and at any given altitude the concentration generally increases in the poleward direction. The region of maximum concentration is usually found in the higher latitudes. Figure 12 presents the stratosphere inventory for 90Sr from 1963 to 1978. This figure is generally representative of all the fission products measured as part of Project Airstream. From these data the computed half-residence time for stratospheric air is about 10 months. Measurements of haloca.rbons, SF~, and NZO are being used to vflldate atmospheric circula- 1 I I 1 f .’ -i+ tion and photochemical models. Sulfate measurements -...... ,.... .- \ have shown that volcanic events are important contributors to the stratospheric sulfate inventory,

I I I I I 1 2. Coordinated High-Altitude Measurement 9

—. . . . -. -,. ___ . . Project. The Coordinated High-Altitude Measurement Project (CHAMP) is a NASA-supported effort to aug- ment the measurements made as part of Project Air- -41 I I I stream (Table I) and to interpret jointly the data obtained from all of the on-board experiments discussed here. This project began in April 1980 when instrumentation ar- rived and plans for its installation on the WB-57F were formulated. Although the installation of the CHAMP instrumentation was not completed in time for the

Fig. 9. beginning of Airstream Mission 19 in July 1980, it was A.irstream [atitude coverage. advanced enough to allow extensive flight testing of the

‘1 -i . +“ a - l— I I

● I I T I I T ~ A 1- t ● A +. -i- 1 T 0 I a - .L -r t T I 0 I n . -L -+ + I I t I n. . L + T t I I O* ! I Nm am S % 6 48s * zl * U m t 1 Clmendorf IkclIos’d CllLnqton R0u8ra

LDtitade

Fig. 10. Airstream altitude coverage.

10 CHAMP system. ARer Airstream Mission 19 was accomplished, the remainder of the installation work was completed. Design and construction were begun for a test stand to allow a more convenient means of maintaining, testing, and calibrating the CHAMP instruments. Development of data-processing procedures was also initiated.

3. Total Halogen Experiment. Under a cooperative agreement with the National Center for Atmospheric Research (NCAR), we are making measurements of the total chlorine, bromine, and iodine burdens in the upper troposphere and lower stratosphere, These measurements are crucial to understanding the role that compounds of these elements play in the destruction of ozone in the stratospheres -l X U,GM-ALTITUD[OALLOOMSAU9LCS I ./ ‘.1 --- TnOPOPAusc Initial results show a total chlorine concentration of J’ -3.0 + 1.0 ppbv. This is in good agreement with estimates derived from summing the concentrations of the various halocarbon compounds known to be present I . in the stratosphere. A limited number of total bromine measurements exhibit a range of values between 7 and 40 pptv. Bromine has been shown to be a much more

I.. SIIOmnollmu Ilnno S6mll eflicient catalyst for the destruction of ozone. However, HLMH uhf SI the details of bromine chemistry in the stratosphere are

Fig. 11. still largely unknown. Total iodine values have been Concentration of ‘OSr in stratospheric air (pCl@JO SCM) below our detection limit of -3 pptv. hdy 1978.

,,9 [

LARGE ATMOSPHERIC TCSIS J wTMcnM Mcu,srlwnc ; mnrllcn!l Il[usrllcnc u /.....y .“. 110Oara t

Fig. 12 Stratospheric inventory of 90Sr, northern hemisphere (kCi) 1963-1978.

— 4. Tritium Experiment. Under another cooperative c. Good agreement was found between satellite and agreement with the University of Miami Tritium Labora- WB-57F measurements of the total aeorsol burden in the tory, we are assisting in measurements of HT and HTO. stratosphere. A comparison of tritium and 95Zr data’ has demonstrat- d. As a result of Airstream Mission 19 flights in the ed that both are removed from the stratosphere at about lower stratosphere over the Alaskan panhandle, we the same rate. This implies that gravitational settling is ident~led debris from the 8 August 1980 eruption of an unimportant mechanism for the removal of small Gareloi volcano, located in the Aleutian Islands. (-< l-~m-diam) particles from the lower stratosphere.

5. Quartz Crystal Microbalance Experiment. A III. BIOCHEMISTRY quartz crystal microbalance (QCM) cascade impactor A. Carbon-13 Nuclear Magnetic Resonance Analysis of that was jointly developed by Group CNC-7 and a Metabolic Pathways for Glutamate Biosynthesis by private consultant was installed on the WB-57F in July Microbacterium ammoniaphilum (T. Walker, C. H. Han, 1980. This instrument aerodynamically sizes particles V. Kollman, R. E. London, and N. A. MatwiyofI_) and collects them on oscillating quartz crystals. The change in the frequency of the crystal is proportional to’ We have begun a major new research program the mass of particles collected in each size fraction. The directed toward the in vivo study of major metabolic particles on each stage are then examined with an pathways in microorganisms, the eventual goal being the electron microscope aided by energy-dispersive x-ray efficient large-scale biosynthesis of isotonically labeled analysis. The QCM provided data that aided in the natural products. The initial focus is on the production of identification of the plumes from Mt. St. Helens and those labeled L-amino acids for which there is a need in Gareloi volcanoes. human metabolic and nutritional studies and on the investigation of the structure and dynamics of enzymes 6. Special Projects. The eruption of Mt. St. Helens on enriched with labeled amino acids. Our general approach 18 May 1980 presented the community of atmospheric involves an attempt to produce 13C and *SN labels at scientists with a unique opportunity to study the physics, specitic sites in amino acids using strains of bacteria chemistry, and climatological implications of a volcanic developed by the Japanese that “overproduce” specific eruption plume. DOE elected to borrow two flights tlom amino acid5:9 Airstream Mission 19 in July 1980 to obtain measure- We have been highly successful with the organism ments in the upper tropospheric and lower stratospheric Microbacterium ammoniaphilum, which produces plume of Mt. St. Helens. These two tlights were flown on L-glutamate in a 35-40!40yield from glucose. So far, we 20 and 21 May 1980. The plume passed over Kansas, have labeled glutamate starting with five different sub- Colorado, Wyoming, and northern New Mexico. strates: [15N]ammonium sulphate, sodium [13C]bicar- The results of these two flights together with the bonate, [l-13C]glucose, [1-13C] and [2-13C]acetic acid. sulfate measurements made as part of Airstream Mission These substrates yield [“N]glutamate, [ I-13C] 19 in July and August 1980 were recently presented at a glutamate, [1,2,3,4-13 C]glutamate, [ 1,5-13C] symposium in Washington, D.C.’ The highlights of glutamate, and [2,3,4-13C]glutamate, respectively. We measurements made by the WB-57F are the following. have followed the incorporation of [l-13C]glucose into a. Sulfuric acid aerosol appeared in the stratospheric glutamate, using ‘3C nuclear magnetic resonance (NMR) portions of the volcano plume very early-perhaps on to monitor the intermediates and to quantify the biosyn- the same day as the eruption and certainly within a few thetic pathways involved. Preliminary 13CNMR experi- days. ments have also been performed, using singly labeled b. MOS4if not all, of the mass of volcanic ash injected acetate. The 13CNMR experiments have not been done into the stratosphere appears to have fallen out by in vivo as described by other workersl”” I because of the August 1980. The remaining quantity of sulfuric acid difticuky involved in maintaining the high level of aerosol in the stratosphere was about three times the aeration required by these cells. Instead, we have ex- pre-eruption levels. This represents -0.2 to 0.5 X 109kg amined the growth media as a function of time, observ- of HzSO, added to the stratosphere as a result of the Mt. ing both a series of intermediates and the labeling pattern St. Helens eruption. in the glutamate product.

12 The most interesting biosynthetic intermediate we B. Nuclear Magnetic Resonance Studies of an have observed so far is trehalose, a nonreducing disac- Isotonically Labeled Enzyme: Dihydrofolate Reductase charide produced from glucose. This sugar has previous- (R. E. London, R L. Blakley,* J. P. Groff,” and L. ly been observed by 13C NMR in yeast cellsl”’lz and COCCO*) amoeba’3 although it is not known to occur in bacteria in the free state. 14Trehalose is commonly found in yeasts, Nuclear magnetic resonance (NMR) is the only spec- fungi, and insects, where it has been implicated as a troscopic technique capable of probing indhridual nuclei structural component, as a reserve energy supply, and as of complex molecules or mixtures of molecules in an intermediate in glucose resorption or mobility.14 Its solution. Biochemical applications of this method have presence in Microbacterium ammoniaphilum is a sur- generally been limbed by the enormous complexity of prise, and the significance of its occurrence is under these molecules, as well as by the inherent sensitivity investigation. limitations of the NMR technique. For the past several The labeling patterns observed in the product years, we have undertaken studies of specifically labeled glutamate can be used to predict which metabolic enzymes that are biosynthesized on a medium containing pathways are operative for the synthesis. The product isotonically labeled amino acids. This approach avoids derived from [l-13C]glucose is approximately 40’% en- both technique limitations because it is necessary to deal riched at C-2 and C-4, 10% at C-3, and 6% at C-1. This with only a particular subset of resonances correspond- labeling pattern is extremely useful for 13CNMR experi- ing to the labeled amino acid introduced into the enzyme ments because few 13C-13C multiples are observed. The and because the isotopic labeling greatly enhances the metabolic pathway to glutamate involves the conversion sensitivity of the experiment. For the past several years, of [1-13C]glucose to [3-13C]phosphoenolpyruvate and our interest has focused on the bacterial enzyme [3-’3C]pyruvate by the Embden Myerhoff pathway fol- dihydrofolate reductase. Interest in this enzyme defies lowed by carboxylation to give [3-13C]oxalacetate. The in part from its clinical relevance—it is a target enzyme oxalacetate then reacts with [2-13C]acetyl COA to form of drugs such as methotrexate, which is used in cancer citrate, which is then converted to a-ketoglutarate by the” chemotherapy, as well as drugs such as trimethoprim, fwst third of the Krebs cycle and subsequently to which is used for treating a variety of infectious diseases. glutamate. Carbon-2 of glutamate is labeled from the Labeliig experiments have utilized [metiyl-*3C]meti- [3-’3C]oxalacetate, and C-4 is labeled from the ionine, [guanido-13C]arginine, and [y-13C]tryptophan. [2-’3C]acetyl COA. Carbon-3 is labeled by turns around During the past year, our particular emphasis has the Krebs cycle or the glyoxalate cycle, whereas C-1 is been on the effects of salts both on enzyme activity and labeled either from the HCO~ pool, which is labeled on the NMR spectral parameters. This interest was from C-1 of glucose by way of the pentose phosphate sparked initially by the observation in studying the shunt or from turns around the Krebs cycle. Studies are [y-13C]tryptophan labeled enzyme that one of the tryp- currently in progress to quantify the various pathways tophan residues gives rise to two resonances correspond- involved. ing to a slow conformation equilibrium of the enzyme.ls Microbacterium ammoniaphilum will also grow on The intensity ratio R of the two tryptophan resonances acetic acid, and specifically labeled [13C]glutamate can was subsequently found to depend on the presence of be obtained from [1-13C]and [2-13C]acetic acid. Using KCI in the btier. Up to this time, virtually all NMR [l-’3C]acetic acid, we obtain [1,5-13C]glut~ate, where- studies of this enzyme had been done in high salt buffers as from [2-13C]acetic acid we obtain [2,3,4-13C]glu- because of the stabilizing effect of the salt. We have now tamate. When grown on acetic acid, the glyoxalate found that in the absence of KC1 the R value is low, that pathway must be relatively more important. leading is, the enzyme exists in a nearly pure confirmational predominately to the triply labeled product rather than state. Addition of KC1 results in an increase in R to a the doubly labeled product found when the cells were limiting value of 35Y0.Another more recent result is that grown on glucose. Although we must still fmd optimum the R value is also altered by the addition of Iigands such growth conditions for the cells on acetate, this may turn as the enzyme inhibitor methotrexate. Saturation of the out to be the most economical way to label glutamate. In enzyme with methotrexate in the absence (or presence) of salt results in a limiting R value close to the 35°Afigure. addition, we should be able to follow and quantify the .—— pathways as was done for glucose. University of Iowa School of Medicine.

13 We have recently carried out studies of the effects of KC1 high-order effects whereas others may not. Our recent on the [methyl-’3C]methionine and [guan- studieslg have focused on the behavior of those weakly idine-13C]arginine labeled enzymes as well. In these coupled 13Cspins which appear to be strongly coupled. cases, the limited resolution of the resonances restricts As in the case of virtual coupled spins which are weakly conclusions about the interaction. It was observed, coupled while exhibiting high order spectra, they cannot however, that some of the resonances shift slightly more necessarily be considered fust order. Spectral simulation than others in response to salt, probably reflecting a indicates that this deceptive appearance is a consequence generalized effect on molecular conformation. In parallel of the presence of unresolved splittings which, in turn, with the NMR investigations, we have studied the effect arise from strong coupling interactions elsewhere in the of various salts on enzyme activity, and we found that spectrum. Thus, even a moderately strong interaction, most salts activate the enzyme at low concentrations J/Av ~ 1/4, can significantly perturb the spectra of (4.3 M) and inhibit the enzyme at higher concentra- ‘many of the weakly coupled spins. The conditions under tions. which such effects may be anticipated have been eval- A series of NMR studies dealing with the effects of the uated, based on the formalism developed by Pople and inhibitor trimethoprim and various analogs was also Schaeferzo for a system containing only a single strong undertaken. Trimethoprin has proved one of the most coupling interaction. The observation of spectral asym- interesting Iigands in studies of the [met.hyl- metry for a weakly coupled spin can be used to draw 13Clmethionine labeled enzyme, because very large several general conclusions about the spin system. dowtileld chemical shifts are observed. Of interest also is A second effort has involved the assignment of the ‘3C the different behavior of the [y-13C]tryptophan labeled resonances of the amino acid L-tryptophan based on 13C enzyme resulting from trimethoprim compared with the labeling.2* Isotopic enrichment constitutes the most re- structurally related analog pyrimethamine. We hope to liable basis for making NMR assignments. An optimal deduce a more complete description of the interaction of labeling strategy depends on the relative ease of synthesis these inhibitors with the enzyme on the basis of these of the isotonically labeled species and the information chemical shifts. content of the experiment. Carbon-13 enrichment is particularly favorable on the second basis because the many long-range couplings provide a basis for assigning C. Development of a Data Base for Carbon-13 Enrich- remote nuclei if reasonable expectations exist for the ed Molecules (R. E. London) coupling patterns. In this study, the ‘Jcc scalar coupling constants and chemical shift data have been used to The design of sophisticated biological nuclear magnet- assign the tryptophan *3C resonances. The data have ic resonance (NMR) experiments involving isotopic been supplemented with a Finite Perturbation Theory labeling requires a data base, which includes such Self-Consistent Field Molecular Orbital calculation for parameters as relaxation behavior, coupling constants, comparison of the observed and predicted carbon- 13C assignments, etc. We have collected and published carbon couplings. this data for such systems as carbohydrates and amino Several of our previous studies of 13Clabeled amino acids. Several studies have been carried out during the acids suggested a correlation between the carboxyl past year. carbon shifts and the titration of the carboxyl group. A The extraction of coupling constants from *3C en- recent systematic study of this effectzzdemonstrated that riched molecules is complicated by the presence of a a rough correlation does indeed exist between the distribution of isotopic isomers (for biosynthesized carboxyl pK value and the total shift resulting from molecules), as well as by the possibility of high-order deprotonation of the carboxyl group. Generally, a plot of effects.ie18 Although the latter possibility has generally the shifl in ppm vs pK leads to a curve with a slope close received little attention for 13Cbecause of the large range to 1.0. We expect this behavior to be valid only for of chemical shifts, we have noted a surprising number of carboxyl carbons in an aqueous environment. The such effects in many proton decoupled 13Cspectra of *3C titration behavior of carboxymethyl cyanocobalamin23 enriched molecules, as well as in the proton coupled *3C indicates a dramatic deviation from this predicted behav- spectra of singly enriched or unenriched molecules. ior, presumably reflecting involvement of the carboxyl Additional complications arise because some of the group in an intramolecular hydrogen bond. The observed isotopic isomers present in solution may exhibit

14 correlation may prove useful in characterizing the en- The electrophilic brominating mixture of NCS/Br- vironment of carboxyl side chains in proteins. was chosen for the actual radiobrominations because the 77Br used in tie radiobrominations was in the bromide form when received.29 Both estradiol 1 and IV. BIOMEDICAL RESEARCH 17wA.hynylestradiol V were radiobrominated.30 The radiobrominated components in these reactions were sepa- A. Radioisotopes rated by HPLC using a reverse-phase column, eluting with a 1:1 mixture of acetonitrile and water. Radio- 1. Bromine-77 Labeled Steroids for Detection of brominations of Z and V yielded mixtures of ortho Hormone Associated Tumors (D. S. Wilbur). Radlo- isomers in roughly a 1:2 ratio for 11:111and VI:V..1Z, brominated steroids have potential applications for both respectively. All of the ortho isomers were found to be early diagnosis of hormone-associated tumors and in quite stable in vitro. Unfortunately, the ortho radio- vivo determination of hormone receptor content in cer- brominated isomers accounted for only 50’% of the tain tumors, the latter being important in the choice of activity injected into the HPLC. The largest amount of therapy to be used. However, there are some formidable activity was found to be associated with an unstable problems that must be addressed before these potential species whose exact nature is not presently known. applications can be realized.24 For instance, it is very Radiobrominations using the high specific activity important that the radiolabeled steroids have high specif- 77Br yielded specific activity ranges of 600-1200 ic activities, because there are so few receptor sites Ci/mmol for the 4-bromo isomers 111and V.I. Investiga- (fmol/mg tissue) available that essentially all of the tion of the in vivo stability and biodistribution of these steroid introduced needs to be radiolabeled. It is equally compounds will be conducted in the future. Studies are important that the radiolabeled product should retain its also planned for testing these compounds in rats contain- radiobromine both in vitro and in vivo. ing estrogen-positive and estrogen-negative tumors. Initial studies of radiobrominated steroids have been These studies will be conducted at the University of New conducted with phenolic A-ring steroids (estrogens) Mexico Cancer Research and Treatment Center in because the brominations are relatively easily ac- collaboration with Dr. Fred Mettler. complished and the bromine should be less labile on the The studies of radiobrominated steroids will broaden aromatic nucleus than it would be at other positions in into radiolabeling in other positions in the steroid nucleus the steroid molecules. Prior to radiobromination, meth- in the future but will continue to emphasize synthesizing ods of brominating the phenolic ring of estradiol 1 with radiolabeled steroids with high specific activities. stable bromine were investigated.zs Although there were some previously reported methods of A-ring bromina- 2. Radiohalogenating Fatty Acids in the Omega Posi- tions,26-28none of the investigations described the prod- tion (D. S. Wilbur). The rapid metabolic turnover of uct ratios obtained for the expected ortho regioisomers 11 fatty acids in myocardial tissue3*makes it possible to use and 111 and the dibromo compound W. Bromination of radiolabeled long chain carboxylic acids to study the the phenolic A-ring of estradiol was accomplished using regional distribution of myocardial perfusion. Investiga- a variety of brominating reagents and solvents. Direct tions of radiolabeled fatty acids have shown that the best brominations were carried out with bromine, N-bromo- results are obtained when the radiolabel is in the succinimide (NBS), N-bromoacetamide (NBA), terminal* ((0) position32 rather than within the carbon pyridinium bromide per bromide (PBPB), iodine chain33 or adjacent (a) to the carboxylic acid function.34 monobromide, and a mixture of N-chlorosuccinimide Labeling with radiohalogens in the (o position has been (NCS) and bromide. Organometallic-assisted bromina- accomplished by halogen exchange32 and by mod- tions were attempted with iron dust, mercuric acetate, ification of the fatty acid to contain a terminal phenyl and thallium trifluoroacetate. The results of these reac- substituent,3S which was radiolabeled electrophilically. tions are shown in Table 111.The product ratios were However, these methods are limited by availability of determined by high-performance liquid chromatography appropriate starting materials. (HPLC) on a silica (~-porasil) colum~ eluting with a —— 100:1 mixture of chloroform and acetonitrile and using *Terminalcarbon refersto the carbon that is farthest removed from the carboxylic acid functionality. uv absorbance for detection.

15 TABLE III

BROMINATED ESTRADIOL PRODUCT RATIOS

A-Ring Brominated Products

& R=H v. R=–C-CH II: R=I-I; X=Br; Y=H ~1: R=–C~CH; X=Br,Y=H i: R=H, X=H; Y=Br V~I: R=–C-H, X=H; Y=Br E R=H; X=Br; Y=Br

No. %IJ % III % Ix % Unidentified Reagents/Solvent Equivalents (2-Bromo EJ (4-Bromo E) (2.4-Dibromo EJ (one or more species) .—. . -BrJHOAc 0.5 41 59 trace --- 1.0 40 51 9 --- 2.0 4 4 45 47 NBS/ETOH 0.5 24 67 9 --- 1.0 23 69 8 -— 2.2 —. 100 --- NBA/ETOH 0.5 29 64 trace 7 1.0 25 69 6 --- 2.2 3 8 87 2 PBPB/HOAc 1.0 54 46 trace --- PBPB~HF 1.0 42 51 7 --- PBPB/ETOH 1.0 28 69 3 --- IBr/ETOH 1.0 undefined 13 undefined 87 Fe(dust)/BrjHOAc 1.0/1.0 48 52 —- -— ‘Hg(OAc)JBr#HOAc 1.0/1.0 5 20 25 50 ~I(TFA)#3r~CHjCN 1.0/1.0 23 47 12 8 NCS/Br/ETOH 1.0/1.0 25 61 13 --- ‘VaIuestaken at -50% reaction. Continuation of reaction yieldedmostly unidentifiablecomponents.

A synthetic reagent that may have application to Thus, it may be possible to hydrozirconate unsaturated labeling fatty acids in the m position is Schwartz’s fatty acids and obtain the product that has the zirconium reagent (Cp)zZr(H)C1, which adds readily to double attached to the least hindered carbon in the carboxylic bonds in a process of hydrozirconation.3c The initial acid chain, the w carbon. The loss of the unsaturation in hydrozirconation product is not observed; instead, the fatty acids does not affect the myocardial uptake.32 Once product obtained is the one that has the zirconium metal the zirconium-carbon bond is formed, it can be readily attached to the least hindered carbon atom (reaction 1). cleaved by electrophilic halogens (reaction 2). The 16 zirconium-carbon bond may also be cleaved by other ester functions that may not be cleaved under the aluminum reagents,37 permitting further synthetic trans- highly reducing conditions. formations to be accessible via this route. Because Schwartz’s reagent is a strong reducing agent, 3. Isotopic Exchange Procedures for Labeling Radio- it is not compatible with carboxylic functionalities. pharmaceuticals with Short-Lived Isotopes (P. M. Therefore, the first attempted hydrozirconations were on Wanek). High yield labeling of pharmaceuticals with the methyl ester of oleic acid (reaction 3). Although a short-lived isotopes is difilcult due to decay losses that reaction did occur, it was with the ester portion of the result from transport, labeling chemistry, and quality molecule and not with the double bond. Since the assurance testing. One method to reduce such losses is zirconium reagent is effectively blocked by steric hin- the development of a biomedical radioisotope generator drance, the very large trimethylsilyl and and rapid labeliig chemistries. In the absence of a tert-butyldimethylsilyl esters of oleic acid were syn- suitable generator system, the availability of labeling thesized and reacted. These esters were also reduced. “cold kits” would greatly minimize decay losses. The Two functionalities that are not affected by term “cold kit” means that all the stable reagents hydrozirconation are bulky ethers (e.g., tert-butyl ethers) required in the labeling chemistry are prepackaged as a and oxazolines.* sterile, pyrogen-free unit. When the radiopharmaceutical To utilize ether functions would ultimately require that is needed, the sterilized radioisotope is purchased Ad the these groups be converted to carboxylic acids, a trans- radiopharmaceutical manufactured in accordance with a formation that requires strong oxidizing conditions. Such well-established procedure. Radioiodination cold kits a synthetic path would offset the advantages gained by have been under development for some time in our hydrozirconation. laboratory in anticipation of the widespread availability Meyers 3s has shown that aromatic carboxylic acids of 123 I. may be converted to oxazolines readily and that the Among the numerous radioisotopes of iodine, lnI is oxazolines can be easily removed to yield the starting the most suitable for use in humans. The absence of beta acids. Unfortunately, all attempts to convert the carbox- particle emission together with the relatively short ytic acid in oleic acid to an oxazoline yielded only the half-life (13.3 h) result in low radiation dose to the amide (reaction 4). Attempts to ring close the amide patient, and its major (86%) gamma photon of 159 keV under dehydrating conditions (e.g., cone H2SOd, SOCl~ is in the optimum energy range of the Anger camera.39 were unsuccessful. Previously reported methods for radioiodinating rose Research is continuing with further attempts to pre- bengal, a hepatobiliary diagnostic agent, indicated that pare the oxazoline of oleic acid as well as to explore iodine exchange occurred via radioidine (*12)at elevated temperatures. @-QZWe studied this reaction as a fUnction *This information was furnished by J. Schwartz, Princeton University. of time, solution pH, solvent, reactant concentrations,

(Cp)2Zr(H)Cl (1) CH,(CH~nCH = CH(CH~nCH, CH3(CH~,n+,CH1-Zr(Cp),Cl

X2 or X+ (2) CHJ(CH~YCHZ-Zr(Cp)lCl . > CH3(CHZ)YCH2-X

(Cp),Zr(H)Cl (3) CHJ(CH~7CH = CH(CH~TCOzCH~ Mixture of products - all still contain double bonds

HOC H2C(CHq)2NHz (4) CHj(CHz)7CH = CH(CH~,COzH CH3(CH~7CH = CH(CH~7CONH-C(CH3)2CH20H /0 > CHj(CH2)7CH = CH(CHZ)7C+ (5) CHJ(CH~7CH = CH(CH~,CONH-C(CHJ)2 CH20H or S~&04 CH, 2 N > CH,

17 and temperature. The results demonstrated that 93 to with these procedures include chemical breakdown of the 97% exchange of radioiodine could be achieved in 15 OIH, low labeling yields, and nonadaptability to cold kit mirt at room temperature, and that the final product met preparation. the limit of SIOOA free *1- established by the U. S. Depending on the chemical supplier and the age of the Pharmacopoeia.43 An impurity found in the rose bengaI sample, varying amounts of o-iodobenzoic acid (OIB) starting material reduced the overall labeling yield of the were found as an impurity in the OIH starting material. rose bengal product, The optimum reaction conditions This impurity was more efficiently exchange labeled than include purified rose bengal, a HC1-ethanol solvent OIH, and its presence at the start of the reaction maintained at a pH of <2 (L O M HC1 and ethanol, 1:11 substantially reduced the yield of labeled OIH. Thus, v/v), K103 (0.08 mg/mg of rose bengal) to oxidize *1- to purification of the initial OIH is required. ●IZ, and reductant-free radioactive iodide solution (Fig. The labeling procedure developed in our laboratory 13). The radiochemical purity of the labeled rose bengal consists of placing 5 mg of purified OIH in a stoppered was established using ascending paper radio- and crimp-sealed 1O-CCserum vial and adding 0.3 mt of chromatography, molecular sieve separation, uv spec- reductant-free Na*I (200-600 ~Ci) via syringe through troscopy, and chemical precipitation. Bioloeic confirmat- the rubber septum. The mixture is autoclave for 15 rein, ion of the movement of the labeled product through the cooled to room temperature, diluted with 5.0 mt’of sterile hepatobtiary system was obtained in a rhesus monkey. isotonic phosphate buffer solution, and is then ready for Another agent studied in our laboratory was radio- injection. This procedure consistently yields a product in iodinated o-iodohippuric acid (OH-I), which is a which 999’0of the radioiodine is attached to the OIH, well-established agent for diagnosing kidney dysfunction. while the other 1% is on the OIB. Confirmation tests of Published reportaumelting point determinations. In vivo tests in a rhesus monkey demonstrated the movement of the labeled OIH through the renal system as expected. Both labeling systems described here clearly demonstrate that rapid radioiodination labeling procedures that are adaptable to cold-kit preparations can be developed. 80 - These results have been made available to interested radiopharmaceutical fums for commercial development. I T> -70 - 4. Strontium-82 and Rubidium-82 Biomedical Ship- ~ ments in FY- 1980 (J. W. Barnes, G. E. Bentley, T. P. + NON-PURIFIEO ROSE BENGAL fl 20”C PW?IFIEO ROSE BENGAL AT 20”C DeBusk, M. A. Ott, F. H. Seurer, P. M. Grant, and H. 60 PtJRIFiED ROSE BENGAL AT 5d C A. O’Brien, Jr.). The ‘2Sr-a2Rb generator system is of potential utility in diagnostic nuclear medicine for ! ! 50 cardiovascular studies in conjunction with a high-resolution positron scintigraph device.””g Nonin- vasive perfusion studies of the myocardium, cerebrum, 40 - and kidneys now appear to be the applications with the greatest promise, and Los Alarnos National Laboratory

I I I has been producing and supplying ‘2Sr to quaMed 3 0: I 10 15 30 60 medical investigators since 1978. REACTIONTIME (m-n) The activity is synthesized by irradiating metallic Fig. 13. molybdenum targets with high-intensity medium-energy Chemical yield of ‘2s1rose bengal as a function of time. Curve protons in the Isotope Production Facility at Los A is the average yield of 3 determinations of 20”C and 3 Alamos Meson Physics Facility.’9 Spallogenic ‘2Sr is determinations at 500C using puritied rose bengal. Curve B shows the average yield of 3 determinations at 20”C using recovered and decontaminated by a hot-cell radio- non-puritled rose bengal. chemical procedure,so and shipments of typically s200

18 mCi are made to extramural researchers for animal and B. The National Stable Isotopes Resource (N. human studies with 82Rb. Matwiyofl) Before FY- 1980, 27 different shipments of a total of 1.3 Ci of 82Sr were delivered to 6 medical institutions. The national stable isotopes resource (SIR) is operated The shipments made during FY- 1980 are summarized in as part of the ICONS program, named for the isotopes of Table IV. carbon (lzC, 13C), oxygen (’60, 170, 180), and nitrogen (’4N, ‘sN). The program encompasses the production of 5. Bromine-77 Biomedical Shipments in FY-1980 (J. - large quantities of the separated isotopes by the W. Barnes, G. E. Bentley, T. P. DeBusk, M. A. Ott, F. low-temperature distillation of CO and NO; the develop- H. Seurer, P. M. Grant, and H. A. O’Brien, Jr.). Use of ment of efticient synthetic methods for the incorporation 77Brin nuclear medicine for pharmaceutical and protein of the isotopes into complex molecules; the improvement labeling has been increasing in recent years.sl-s3 In of techniques, especially nuclear magnetic resonance addition to its direct applications in compound labeling, (NMR) and mass spectroscopy, for the analysis of 77Bris also potentially useful indirectly as the generator isotonically labeled compounds; and participation with of its ultrashort-lived 77mSedaughter.s4’s5 extramural investigators in cooperative research and The activity is synthesized by irradiating metallic development programs to develop the utility of stable molybdenum targets with high-intensity, medium-energy isotopes in the biosciences and in environmental studies. protons in the Isotope Production Facility at Los The focus of the SIR, a joint effort of Groups CNC-4 Alamos Meson Physics Facility.sG Spallogenic 77Br is and LS-5, is on developing uses of stable isotopes in the recovered and decontaminated by a hot-cell radio- biosciences by chemical procedures’ and shipments of typically ~200 ● Producing and providing enough separated 13C, mCi are made to extramural and in-house researchers for lSN, and oxygen tO SUppCIrt the Progrm; labeling and biodistribution studies of diverse diagnostic ● synthesizing labeled compounds for accredited in- agents. vestigators when those compounds are not readily Before FY- 1980, 29 different shipments of a total of available from commercial or other sources at 2.2 Ci of 77Br were delivered to 4 medical institutions. acceptable costs; The shipments made during FY- 1980 are summarized in ● Developing an active program of research col- Table V. laboration with investigators in the biosciences

TABLE IV

82sr SHIpMENTS IN FY-1980

Number of Total Activity Institution Shipments (mCi) E. R. Squibb & Sons 4 1700 Hammersmith Hospital, London, England 4 680 Dormer Laboratory, Berkeley 3 580 National Institutes of Health, Bethesda 2 300 Massachusetts General Hospital, Boston 2 240 Mt. Sinai Medical Center, New York 1 99 Johns Hopkins Hospital, Baltimore 1 50 VA Hospital, Madison, Wisconsin 1 25 Oak Ridge National Laboratory 1 2.4 Total 19 3700

19 TABLE V

77BrSHIPMENTS IN FY-1980

Number of Total Activity Institution Shipments (mCi) George Washington University 9 830 Medical Center, Washington, D.C. “ Los Alamos National Laboratory 8 760 Washington University, St. Louis 7 730 Kansas University Medical Center, 8 450 Kansas City Johns Hopkins Hospital, Baltimore 1 100 University of Massachusetts, Amherst 5 62 University of California, Davis 1 5 Total 39 2900

community, providing, as necessary, isotope labeled Nutrition Research Center, Texas Children’s Hospital, compounds and analysis and data interpretation Houston, Texas, have developed a rapid, convenient, with NMR and mass spectrometry; noninvasive test for fat malabsorption based on the oral ● Advising and assisting investigators using isotopes administration of the labeled fat followed by measure- of carbon, oxygen, and nitrogen; ments of its oxidation to 13C02, which rapidly appears in ● Hosting visiting scientists for training in use of the breath. The fats used in the test are the triglycerides, stable isotopes and encouraging exchanges of talks, trioctanoin and triolein, labeled with *3Cin the carboxyl short courses, and extended research opportunities; carbons of the fatty acid portion of the glycerides. When ● Collaborating with other resources in synthesis and these are digested, absorbed, and metabolized, the COZ mass spectrometric and NMR analyses to speed in the breath of the subject is also labeled with 13C.If the development of isotope methodology; and fat is poorly digested and absorbed, most of it passes into ● performing core research designed to keep the the stool, and the breath COZ of the patient with resource at a state-f-the art level. malabsorption is only slightly and slowly labeled with Highlights of several projects supported by the SIR 13C Watkins, Hofman, and Klein have shown that this during the past year are described below. simple breath test compares favorably with the fecal fat test in children with malabsorption caused by pancreatic insutliciency, and it is undergoing further clinical study 1. Diagnosis of Fat Malabsorption by Breath by Dr. Michael Gelfand at the Children’s Hospital Analysis of 13COZafler Oral AdminMration of *3C Medical Center of the University of Cincinnati. Triolein. The fecal test for fat malabsorption in small children frequently requires patient restraint for 3 days to 2. Reaction of the Chemotherapeutic Agent accomplish accurate stool collection. Expensive hospi- Cis-Platinum with Vitamin B,z. Scientists at the national talization may be required even when the patient is able SIR of the Los Alamos National Laboratory are using to cooperate and is a hardship to children and parents. NMR spectroscopy together with specific labeling with Using *3Clabeled fats supplied by the national SIR at the the heavy nonradioactive isotope 13C to study the Los Alamos National Laboratory, J. B. Watkins, M.D., structures and reactions of biologically active molecules. Director, Division of Gastroenterology and Clinical A noteworthy study accomplished recently was the Nutrition, Children’s Hospital of Philadelphia, Philadel- investigation of the interaction of cis-diamine phia, Pennsylvania; A. F. Hofman, University of Califor- platinum complexes with the vitamin B~zderivatives, nia, San Diego, California; and P. D. Klein, Children’s adenosylcobalamin and alkylcobalamins. The antitumor

20 properties of cis-diamine dichloroplatinum(II) have been V. ELEMENT MIGRATION AND FIXATION: well documented, and at present this platinum com- GEOCHEMICAL STUDIES. (E. Bryant) plex alone or in combination with other drugs is used extensively in the treatment of gynecological tumors. This section treats the phenomena of geochemical However, in some cases, the treatment produces severe migration and f~ation of elements, especially minor and side effects, such as hematological and renal toxicity and trace elements, in rocks and pore solutions. We are sometimes neurotoxicity. The peripheral neuropathy studying the source, migration, and f~ation of elements sometimes observed caught our attention because similar of particular interest in relation to geologic disposal of neurological symptons are associated with vitamin B,2 nuclear reactor waste and the extraction of geothermal deficiency. Using 13C NMR spectroscopy and 13C heat. Present basic knowledge about the conditions and labeled cobalamins, we were able to show that mechanisms of migration of elements in the Earth’s crust cis-diamine platinum does indeed react with the is extremely limited, yet the potential application of such cobalamins by detaching the 5,6-dimethy1benzimidazole basic knowledge is very broad. The general questions of moiety from the cobalt(III) of the corrin. This suggests the geochemistry of these elements and, specifically, the that patients treated with platinum complexes can rock types in which they are most abundant; which develop a vitamin B,Z deficiency because the reaction mineral phases incorporate them; under what circum- between the corrinoid and the chemotherapeutic agent stances they are concentrated in the intergranular re- causes inactivation of the corrinoid coenzymes. gions; what processes free them from the source rocks; how and in what chemical form they migrate; how they 3. An Automated Mass Spectrometer for Nitrogen are fixed at a new location; what role thermodynamics Isotope Analysis (B. B. McInteer). The design and has in the solution-solid equilibration; and what are the construction of a unique spectrometer system capable of kinetic controls on release and fixation are being ad- the rapid analysis of the 15N:14N ratios in thousands of dressed in a series of experimental studies presented in samples per year from labeled nitrogen experiments has this section. In addition, a new fundamental research been completed, and the system has been carefully project has been initiated this year to extend these evaluated during the past year. The equipment processes element migration studies beyond their program-oriented several hundred samples per day in a fully automated goals and to treat the above questions in a more general fashion. Small vials of 0.15 mt’ volume are charged with context. 25~g of contained nitrogen in labeled ammonium salt sample solution. The tray of up to 137 samples is dried and then run at a rate of 150 s per sample. The A. Element Migration at the Key Lake Uranium Ore equipment converts the ammonium salt to nitrogen gas Deposit (D. B. Curtis and A. J. Gancarz) using hypobromite reagent, purifies the sample using a cryogenic trap, measures the isotope abundance, prints 1. Introduction. Geologic burial is the favored meth- out the results, and stores the data for the entire tray on od under consideration for the disposal of commercially magnetic tape for future reference. generated radioactive wastes. Efforts to evaluate the Separated *SN and 14N in various chemical com- effectiveness of geologic media in isolating such wastes pounds are used for a wide variety of studies of the from the biosphere are limited by the necessity of nitrogen cycle for agricultural research, forestry, biology, considering periods of time much greater than those range sciences, animal nutrition, environmental studies recorded by human experiences. The Natural Repository of NOX, and other disciplines. Heretofore, a serious Analogue program is a research effort to study the obstacle to the use of these powerful tools has been the retention and migration of elements in the Earth’s crust total isotopic analysis of the large number of samples by examining the geologic record, wtich does extend that are generated in field studies. With this development over appropriate periods of time. Previous efforts in this which is available for commercial exploitation, this regard have been concerned with studies of the natural obstacle is largely removed. With the appropriate mod- fission reactors found at the Oklo mines in the Republic ifications, the instrument will also be useful in the of Gabon, Africa.58-64The work has been extended to the analysis of 13C:12C ratios in breath COZ samples from rich Precambrian uranium deposit discovered at Key clinical studies. Lake in the northwest corner of the Canadian province

21 of Saskatchewan.65 Drill cores, taken as part of the such as apatite, tourmaline, and zircon. A minor quartz exploration program at Key Lake, have provided conglomerate is formed at the base of the sandstone. weU-documented samples from several million cubic There is a highly altered transition zone at the uncon- meters of sandstone, metamorphic rock, and the uranium formity between this basal conglomerate and the ores enclosed in these host rocks. The samples provide crystalline rocks of the basement.’l the opportunity to study elemental retention and migra- Pre- and post-Athabasca faults are important struc- tion in a chemical, physical, and geologic setting quite tural features at Key Lake. They trend north- different from that found at Oklo. east-southwest and dip at 50-70° to the northwest, Uranium and thorium decay through a series of roughly parallel to the stratigraphic dip of the basement radionuclides to form stable isotopes of lead. The relative metasediments. The two Key Lake ore bodies are abundances of actinide parent and stable lead daughter localized in fault zones that appear to impose a structural and the proportions of the four lead isotopes in any control on the mineralization. Ore localized at the natural material are a function of the time that the northeast portion of the zone, the Deilmann orebody, is material has been closed to the loss or gain of parent and the subject of this study. Ores at Deilmann occur at the daughter and the relative concentrations of the ap- unconformity for distances of about 100 m to the propriate nuclides when the system became closed (the southeast of the faulted region. They extend 150 m into initial concentration). In principle, chemical and isotopic the basement along the dip of the fault zone. The analyses of rocks for these three elements provide the Athabasca sandstone that immediately overlays the ores means to understand aspects of the natural history of the is 40-60 m thick. To the northeast, at distances between rocks, that is, when they were formed, the relative 30 and 100 m, the sandstone thins dramatically, occa- abundances of actinide and lead in previous geologic sionally having thicknesses of <5 m. history, the gain or loss of parent or daughter after Uranium and nickel are the major metallic elements in formation, the nature of the physical and chemical the ores, with smaller abundances of lead, zinc, and processes involved in the fractionation, transpor~ and copper. Concentrations of the two major elements oflen redeposition of these elements, and the date of these run into the tens of percent. Three uranium minerals processes. This inform~tion is beiig developed by the have been identified,’1 an oxide called pitchblende I, a analyses of samples from Key Lake. more oxidized variety of pitchblende called sooty pitchblende or pitchblende II, and the silicate mineral 2. Geology of Key Lake. Key Lake is located on the coflinite. southeastern edge of the Athabasca formation, a fluviatile quartz sandstone deposit. The age of this 3. Experiments. Samples representative of the deposit has been determined to be 1350 + 50 million Athabasca sandstone, the transition zone at the uncon- years @yr) by Rb/Sr dating6Gand 1330 + 30 Myr from formity, the crystalline basement, and the ores were lead isotopic data. 67 The Athabasca sandstone Uncon- selected from the cores. Selections were made to provide formably overlays rocks of the Wollaston Domain, a an extensive spatial distribution around the Deilmann ore major structural province of the Canadian shield. The body. Approximately 10 g of rock were removed from highly deformed basement complex consists of sytiorms the interior of core sections and crushed to <0.25 mm; and antiforms with granitoid Archean cores rimmed by l-g aliquots were taken for determination of uranium and Proterozoic metasediments~a Radiometric dating of the thorium concentrations. These two elements were granitoid basement shows it to be at least 2.5 X 109 yr analyzed by neutron activation analysis techniques using old. Multiple periods of metamorphism are observed in the automated analysis system at the Los Alamos the metasediments. The major metamorphic period oc- Omega West Reactor. Lead isotope abundances were curred about 1.7 x 109yr ago with episodes as recent as measured by isotope dilution mass spectrometry on 200 1.57 )( 109 yr ago,‘9S70The entire region is overlaid by to 500-mg aliquots of the powdered samples. Pleistocene glacial debris. The basement is predominately a biotite-feldspar- 4. Summary and Interpretation of Results. With a quartz gneiss interlayered with strata of graphite schist single exception, lead isotopic ratios in non-ore rocks and coarse-grained pegmatoid rocks. Rocks of the from the Athabasca sandstone, from the transition zone Athabasca formation are composed almost entirely of at the unconformity, and from the crystalline basement quartz with traces of clay minerats and resistate minerals define an age of 1.3 x 109 yr, when the sediments were

22 deposited in the Athabasca basin.bl’bs Both geologic media at the Nevada Test Site (NTS) and the potential evidence and radiometric age dates demonstrate that this for movement both on and off the NTS of radioactivity is much later than the last metamorphic and reforma- from underground nucleqr explosions. There was partic- tional event affecting the basement. The time probably ular interest in possible contamination of water supplies, signifies a massive redistribution of lead and uranium in It was also envisioned that the study might provide data the underlying basement rocks associated with the applicable to the. underground disposal of radioactive deposition of the Athabasca sediments. The remarkable waste. This ongoing project is sponsored by the Nevada isotopic homogenization throughout much of this vol- Operations OffIce of the Department of Energy with the ume of rock at a particular time provides a temporal participation of the Los Alarnos National Laboratory, benchmark that can be used to identify subsequent the Lawrence Livermore National Laboratory, the Unit- fractionation and redistribution of uranium, thorium, and ed States Geological Survey, the Desert Research In- lead. stitute, and appropriate support organizations. The majority of samples of all rock types, including The site of the 0.75-kt nuclear test Cambric, which the ores, manifest the fractionation and redistribution of was fired 73 m beneath the water table in tuffaceous lead and the actinide elements in the last 1.3 x 109 yr. alluvium, was chosen for initial studies. It is anticipated Only 20V0of the samples from above the unconformity that eventually tests in o~er geologic media will be and 38% of those from the basement rocks appear to examined. have been chemically stable during this time. The The cavity region was recentered (Hole RNM- 1) using Athabasca sandstone and the transition zone at the standard drilling techniques, and sidewall core sampling unconformity are a repository for lead. All the samples was performed from 34 m below ground surface to 50 m from that region are enriched in lead relative to uranium. below the detonation point to measure the vertical The isotopic systematic cannot distinguish between lead distribution of radionuclides. The hole was cased and the excesses and uranium or thorium deficiencies. However, casing perforated to permit pumping of water from a positive correlation between the absolute abundance of different regions. In this way, variations in the radio- lead and the proportion of radiogenic lead suggests an nuclide content of water from the various intervals were excess of lead. To determine the distances and direction determined. Most of the radioactivity and the highest of transport it is necessary to identify the source of this specitic activities of all radionuclides were still found in excess lead. The two ore samples that have been the region of the original explosion cavity 10 yr after the analyzed are highly deficient in radiogenic lead, which test. No activity above background was found 50 m suggests that ores are a likely source. The quantity below the cavity. Water from the region of highest missing from 1 g of these ores is sufficient to increase the radioactivity at the bottom of the cavity contained only lead concentration in 1 kg of sandstone by an order of tritium and 90Sr at levels higher than the recommended magnitude. Further analysis will attempt to establish if concentration guides for drinking water in uncontrolled the excess lead in the sandstone has an isotopic composi- areas. Most of the radionuclides appear to be retained in tion consistent with lead missing from the ores. If such the fused debris in the cavity region. consistency can be established, it will provide evidence of A satellite well (RNM-2S) was drilled 91 m from the a source-repository relationship between the ore and the Cambric re-entry hole. Pumping of RNM-2S induced sandstone and establish the spatial characteristics of the sufllcient artificial gradient to draw water from the transport processes. It may be possible to defiie the Cambric cavity for study of radionuclide migration extent of such a redistribution in the sandstone by the under field conditions. The appearance of tritiated water absence of excess lead. (HTO) in water from this satellite well signaled the forced breakthrough of water from the Cambric cavity B. Migration from Nuclear Explosion Cavities (D. C. region. By early October 1980, 5 yr after pumping Hoffman and W. R. Daniels) started, 4.77 x 106 m3 of water had been removed from RNM-2S. The only radionucfide other thw tritium - A field study72’73of the distribution of radlonuclides positively identified in this water is 85Kr, a gas that around an underground nuclear explosion cavity was appears to be dissolved in the water, although there is initiated in 1974, about 9 yr afier detonation. The goals some evidence for the possible migration of small ‘= of this Radionuclide Migration (RNM) project were to amounts of 10bRu. Essentially all other radionuclides determine the rates of migration underground in various present in water in the Cambric cavity appear to sorb on

23 the alluvium so that they have not been transported to 12 of these samples have been concentrated to solids and the satellite well. encapsulated in plastic for gamma-spectral analysis. The Nearly 17?40of the tritium.produced in Cambric has background sample used for the gamma-ray assay was been removed in water from the satellite well. The obtained by evaporating 55 gal of water from Well 5B at concentration continues to rise in an essentially linear the NTS. Essentially no radioactivity has been definitely manner (Fig. 14) except for two discontinuities that observed above the Well 5B background sample with the correspond to periods when the pump was. ..- inoperative. exception of a 62 1.8-keV photopeak, presumably from The arrival of tritium at RNM-2S ‘was compared with the 9.75’%branch in the *OsRhdaughter of 368.24 10cRu. the calculations of Sauty74 for an instantaneous tracer Assuming that the 62 1.8-keV photopeak is correctly injection in a radial, converging flow field, similar to the identified as arising from 1°cRu, comparison of the RNM experiment. The shape of the elution curve 10cRu-to-tritium ratios in RNM-2S water with those depends on the Peclet number, which is inversely porpor- observed in RNM- 1 cavity water and those produced in tional to the dispersivity; an excellent fit to the ex- Cambric indicates that essentially all of the 1°dRu perimental data was achieved with Peclet number 10. produced in Cambric remains in the fused debris but that The maximum in the elution curve for Peclet number 10 which entered the cavity water has not been removed or corresponds to a volume of 5.66 X 106 m3 of water delayed during transit to RNM-2S. The latter observa- pumped, indicating that the tritium concentration in tion suggests that any 1°cRupresent in the groundwater RNM-2S water should peak approximately August 1, exista as an anionic species that does not sorb on the 1981 with an uncertainty of 45 d. rock. The concentration of asKr in water from RNM-2S is Nearly 17000 gal (64.35 m3) of water were pumped increasing at approximately the same rate as the tritium. from RNM-I on September 4, 1979 (Re-entry III), and The atom ratio of 6sKr to tritium remains at about water samples were taken at the surface hose bib in one-third that calculated for Cambric, suggesting that plastic bottles, gas-tight bottles, and in 55-gal, krypton travels in the water with the HTO but either at a plastic-lined barrels. In Table VI, data from current and slower rate or with some loss during transit. The relative previous re-entries of RNM- 1 are compared. Although positions of the tritium and krypton peaks should be the current 90Srand 137Csconcentrations maybe slightly informative. lower, the higher ratios to tritium indicate that the tritium Starting in May 1978 a 55-gal sample of RNM-2S concentration is decreasing much more rapidly, presum- water was taken each month in a plastic-lined barrel, and ably because of pumping at RNM-2S. The strontium and cesium results are consistent with the hypothesis that these elements are being replenished from the source 7500- 7000- term owing to their very high retention values.73 6500- In conclusion, during 5 yr (over 1.1 billion gal of 6000- water) of pumping from the satellite well located 91 m = 5500- from the Cambric cavity, only tritium, which is present ( 5ooo - : g 4500 - as HTO and chemically the same as the water, and 8sKr, & 4000 - which seems to be dissolved in the water, have been E 3500 - f positively identified in water removed from this well, ~ 3000 - : 2500 - although there is some evidence for the possible migra- 2000 - tion of minute amounts of 10cRu. These results are 1500 - consistent with laboratory studies that indicate that, in 1000 - 500 - general, sorption is sufficiently high to preclude the Oy I 1 1 migration of most radionuclides from the original cavity 1 1.5 2 2.5 3 3.5 4 4.5 to the satellite well in the near future. Pumping and Volume Pumped ( 106 m3) radioassay of water from the satellite well will be continued to investigate the possible arrival of nonsorb- Fig.” 14. Tritium concentration (corrected to Cambric zero time) in ing species. water pumped from RNM-2S vs volume.

24 TABLE VI REPRESENTATIVE ACTIVITY LEVELS’ IN RNM-1 WATER SAMPLES

(dptimt) Atom Ratios (xIOS) Total Volume Entry Date from RNM-2S ( 106 m3) ‘Sr 137CS ‘OSr/’T 137(ms/T Original-Zone IV 8-8-75 0 N6 -1 1.8 0.31 OriginsI-Zone V 8-14-75 0 -0.25 4.2 0.23 0.18 Re-entry Ib 10-4-77 1.17 1 4.2 14 3.0 Re-entry IIb 11-30-77 1.34 -0.6 4.5 14 12 Re-entry IIIb 9-4-79 3.50 -0.2 4.1 70 40 ‘All activity levels corrected to Cambric zero time. bThe water is believed to come primarily fmm Zone IV.

C. Radionuclide Transport and Retardation in Tuff (E. NTS at Jackass Flats and at Yucca Mountain. Water N. Vine, B. P. Bayhurst, W. R. Daniels, S. J, DeVilliers, from Jackass Flats was pretreated at least 2 wk with B. R. Erdal, F. O. Lawrence, and K. Wolfsberg) crushed tuff from the core being studied before use in the experirnents.7G-sl The suitability of tuff at the Nevada Test Site (NTS) The distribution coefllcient K~ is commonly used to for the isolation of radioactive waste is being investigated describe the partition of a radionuclide between solid and as part of the Nevada Nuclear Waste Storage Investiga- aqueous phases and is defined as the concentration of a tions. Tuff is a geological term applied to pyroclastic species/gram of solid phase divided by its concentra- rocks composed of particles fragmented and ejected tion/milliliter of liquid phase at equilibrium. We prefer to during volcanic eruptions. Such deposits are complex call it “sorption ratio” to avoid the implication of and may exhibit a wide range of properties, depending on equilibrium. In column experiments the relative velocity their cooling and alteration history.’s Related studies of a radionuclide with respect to the groundwater have been performed on other geologic media, especially velocity is measured. This retardation factor R~is related granite and argillite. to the sorption ratio K~ by the simple expression Rf = The migration of radionuclides from a deep geologic (p/E)Kd + 1, where p is the density of the rock column nuclear waste repository would probably be the result of and s is the porosity. transport by groundwater. Retardation because of in- The sorption ratios calculated from flow measure- teractions with the surrounding geologic media should be ments can be compared with data obtained by batch a significant factor in minimizing such transport. Many techniques. Because the batch experiments are simple lithologic types of tuff contain highly sorptive minerals. and fast, it is feasible to measure the influence on K~ of a In addition, long hydrologic flow paths are typical of the large number of parameters. NTS. These are both important reasons for the consideration of tuff as a geologic medium for isolation of 1. Sorption Properties: Batch Measurements. Sever- radioactive waste. al parameters were studied with batch experiments. An understanding of the mechanisms of transport and Particle size had the least effect on K~ values; little or no sorption-desorption is essential for prediction of the variation was obtained among fractions of <106 ~, behavior of radionuclides during the time required for 106-150 ~m, 355-500 ~, and 106-500 ~. Measure- decay to safe levels and, thus, for demonstration of the ments were also made at two temperatures, and sorption effectiveness of tuff, or any potential medium, as a ratios at 70”C were generally greater than at 22° C. migration retardent. Sorptive properties of tuff are being Strontium, cesium, and barium sorption ratios increased studied with both batch measurements and flow experi- by factors of approximately 1.5 to 4, 1 to 2.8, and 2.5 to ments (crushed and solid rock columns). Studies were 5.6, respectively. Americium values changed very little. made on tuff core samples from two drill holes at the

25 Increases in K~ with sorption time were often observed, tion ratios for strontium, cesium, and barium on tuffs although the changes were generally small. containing clinoptilolite or heulandite are at least one to The effects of atmosphere on sorption behavior were two orders of magnitude larger than analcime-containing investigated by comparing the results of studies cores. Cerium and europium sorption, however, does not performed in a pure nitrogen atmosphere having sO.2 seem to be dependent on zeolite content. Ranges of ppm oxygen and ~20 ppm COZ present with similar sorption values obtained on samples containing quartz measurements made under natural atmospheric condi- and feldspar (with and without analcime), samples tions on the same materials. The sorption ratios for containing glass (with and wi~hout clay), and samples technetium were most affected by atmosphere and were containing clinoptilolite (heulandite) are summarized in higher when measured under controlled atmosphere Table VII. Intermediate values for strontium, cesium, conditions, as was the sorption of plutonium. For and barium were obtained on glassy cores. nonzeditized tuff from Yucca Mountain, the sorption ratios of uranium were not affected by atmosphere; 2. Sorption Properties: Column Measurements. however, they were somewhat higher in a nitrogen atmosphere for a zeolitized tuff. As expected, strontium, a. Crushed-Rock Columns. The migration “of radio- cesium, and barium were least afTected by the presence nuclides through crushed-rock-core columns (35-106 or absence of oxygen and COP Although sorption of ~) was measured. Groundwater pretreated with cerium and europium on tuff was also unattested, crushed tuff was used, and the columns were loaded with sorption of both those elements increased by a factor of small volume spikes of the pretreated water containing 10 or more in a nitrogen atmosphere on granite and the tracers. Flow rates generally ranged from 30 to 60 argillite. We have been able to observe apparently m/yr. The free column volumes (used to calculate the negative Eh values on some tuff-water systems but not effective column porosity) were determined with both on granite or argillite systems. HTO and 1311-,which gave identical results. Several Groundwater composition may also influence the kinds of elution behavior were observed: symmetric sorption ratio for many radlonuclides. The two solutions peaks where 50’?40of the activity was eluted at the peak, used were selected to represent extremes for the media asymmetric peaks, and “no peaks,” but instead a slow, beiig studied. The sorption of cesium and barium was usually uniform elution. With one exception the elution relatively insensitive to solution composition, whereas curves of ‘sSr were symmetric, and the column K~ values strontium sorption varied by a factor of 6 and cerium were one to three times lower than the corresponding and europium by greater than a factor of 10. The results batch K~ value. Strontium was eluted from the excep- indicate the importance of the composition of the tional column at a rate of ---0.07%/day for -72 days, solutions. then a small, sharp peak was observed, and then the Batch measurements are also providing relative sorp- slow, uniform “leaking” resumed. This column contained tion data on a wide variety of lithologic types of tuff. a highly vitric tuff, and the slow elution may be due to a Although minor components in a rock sample can gradual dissolution of the glass. This, however, would certainly play a major role in sorption, there is a fairly not explain the weak, sharp peak. Columns of Jackass good correlation between sorption and major phases, as Flats and Yucca Mountain tuff were also loaded with determined by x-ray diffraction, in the tuffs studied to 137Cs.The same slow leaking, without a sharp peak, was date. A devitritied Yucca Mountain tti exhibits some of observed for 137CSon the tuff. The slow elution of ‘sSr the lowest sorption ratios of the samples studied. Sorp- and 137CSmight be the result of exchange of the sorbed

TABLE VII

Major Phases Sr Cs Ba Ce Eu

Quartz, feldspar (+/– analcime) 35-1oo 25012(K) 210-980 140-1400 500-1400 Glass (+/– clay) 270-300 2000-7600 360-1000 24000 1700-20000 Clinoptilolite(heulandite) 1800-28000 8600-17000 1500-130000 550-36400 1200-49700

26 radioactive species with stable isotopes in the water, in a long polycarbonate tube was contacted with which contains -10-9 mol/t’ cesium and -6 x 10-7 groundwater continuously circulated through the mol/t’ strontium. crushed tuff in a closed loop. Results for *sSr, *37CS,and Three columns were loaded with 85Sr and tested at 133Bafrom this circulating system are comparable to higher flow rates. The sorption ratio from one fast-flow those from crushed-rock columns and lower than those column, run with ‘sSr added to the groundwater, was from batch measurements. identical to that obtained from a slow-flow column loaded with a spike. However, an increase of 50?40in K~ 3. Conclusions. Batch measurements provide an un- was obtained on another run at a fast flow rate. Granite derstanding of which experimental variables are impor- columns run at 0.04 ret/h and 4.98 mt’/h also exhibited a tant. For example, sorption ratios vary little with particle considerable increase in K~ at the faster flow rate. One size and surface area. However, groundwater and rock would expect a priori that the K~ might be lower for composition are quite important. A general correlation faster flow if the sorption step is slow. has been identified between mineralogy (major phases) Three Yucca Mountain columns were run at two 137Cs and the degree of sorption for strontium, cesium, and concentrations, 10–bmol/t’ and 10–gmol/t’; the K~ value barium. calculated for cesium was not afYectedby the cesium ion Data from crushed-tuff columns indicate that, except concentration. On a column with tutYfrom Jackass Flats in simple cases where sorption coefficients are relatively there was a gradual elution of 137Cs.In another fast flOW low and ion-exchange equilibria not only exist but are the Yucca Mountain column 50V0 of the total 137CSwas dominant mechanism for removal of radioisotopes from eluted in only 7860 mt, in slowly increasing concentra- solution, the simple relation between the sorption ratio tion; a sharp peak was never observed. A “column K~” K~ and the relative velocity of radionuclides with respect value of 21 900 mt’/g, estimated from the volume to groundwater velocity may be insufficient to permit required to elute 50%. of the activity, is well above that accurate modeling of the retardation of radionuclides. obtained in batch measurements (8600 mt’/g). Additional work on whole-core columns and larger Columns loaded with 133Bashowed peaks, followed in blocks of intact material is required to better understand some cases by a gradual elution of activity. The K~ radionuclide sorption and transport through rock. values are -two to five times lower than the corresponding batch K~ values. A uranium elution peak was quite D. The Leacbiig of Spent Fuel Elements in Water (A. asymmetric, and the concentration slowly decreased. E. Ogard, G. E. Bentley, E. A. Bryant, C. J. DutTy, G. F. Grisham, A. E. Norris, C. J. Orth, and K. W. Thomas) b. Whole-Core Columns. Because studies using crushed rock involve newly exposed mineral surfaces, This project developed from the Oklo natural fission experiments were also undertaken wh.h intact rock cores. reactor studies. It had been determined in the Oklo An “elution” curve was obtained on one tuff core that studies that many fission products and actinides re- was 15.9 mm high and 25.4 mm diameter. Approximate- mained in the reactor site during the periods of their ly 40’% of the ‘sSr loaded was eluted at a fairly constant, radioactive decay following formation in the reactor “peakless/’ rate in 1 year. The estimated sorption ratio zone 2 billion years ago. An explanation for this of -20 m//g is less than the value obtained from batch retention of fission products and actinides uses the measurements and similar to the value obtained on a extreme insolubility of uraninite (UO~ in very reducing crushed rock column of the same material. water environments. One can estimate from available thermodynamic data that the concentration of uranium c. Sorph”on properties: Circdah”ng System kfeasure- in equilibrium with uraninite in pH 7 water that is free of ments. Sorption ratios measured using a batch technique dissolved oxygen is x10-11 mol/t. This low value have frequently been observed to increase slowly with suggests that the reducing conditions that can occur in contact time. Experiments were initiated to determine deep geologic burial would result in a very slow leaching whether thk is the effect of “weathering” and of spent fuel elements in contact with water because self-grinding, which occur during the shaking operation spent fuel elements are largely sintered U02. used in the batch technique. A circulating system was During our studies on the leaching of spent fuel used in which a 355- to 500-Km fraction of crushed tuff elements, we found it difllcult to duplicate readily the

27 reducing conditions of deep geologic burial. This result TABLE VIII we inferred from the relatively high uranium concentrations ihat were found in the leachants rather than the low SOLUBILITIES AT pH 4, DEIONIZED value listed above. However, it was observed that under WATER our reducing condition as well as under an oxidizing (moVt) atmosphere, some of the rare earth fission products and actinides behaved dilTerently from the uranium, a behavior we attribute to a precipitation of the rare earths and Element 25°C 70”C Condition actinides. Eu 23 %8 2 E-9 O&R If the concentration of uranium and the activities of all Ce Z3 E-7 1 E-8 O&R radionuclides in the leachant are dependent only on the Am >5 E-8 2 E-9 O&R dissolution of the matrix UO ~, and all the fission Pu ‘3 E-7 1 E-8 O&R products are homogeneously distributed through the u >5 E-5 >E-4 o UOZ, then the ratio of the fission products to uranium in -2 E-6 R the Ieachant should be comparable to the calculate! radionuclide-to-uranium ratio in the original spent fuel element. Of these ratios the ones for europium, cerium, americium, and plutonium at 70° C under oxidizing conditions and plutonium at 25 ‘C under reducing condi- ogeneous and multicomponent system as a spent fuel tions are very much lower than the calculated ratios in element dissolving in water. the spent fuel element. These large differences in the The fission products 137c5, 9’JSr, ad 125Sb b&ave ratios can occur if europium, cerium, americium, and differently from the other products. Under reducing plutonium are at their volubility limits and precipitate as conditions and at both 25 and 70° C, 137CS,90Sr, and some form of hydrous oxide as the U02 matrix continues 12sSbact similarly to uranium except that the concentra- to dissolve with time. tions of these isotopes in solution are far higher than The data can be used for more quantitative com- expected from the isotope-to-uranium ratio in the spent parisons. The uranium concentrations and activities of fuel element. The ratios to uranium at 25 and 70”C for the radionuclides were used to calculate isotope concen- cesium and strontium are very high, especially the trations. These isotope concentrations were then con- cesium-to-uranium ratios. Katayama et al.8s in leaching verted to elemental concentrations by using the calcu- experiments in air of H. B. Robinson spent fuel elements lated isotopic composition of the H. B. Robinson spent also found a higher fraction of some radionuclides, fuel element.82Based on these data the apparent volubili- especially cesium, in the Ieachant than in the spent fuel ty limits for some of the fission products are listed in element. They interpreted this higher concentration as Table VIII. These numbers assume kinetics did not indicating an absence of congruent dissolution. A higher prevent precipitation at either 25 or 70”C. Also, at 25 “C concentration of radionuclides is not by itself suf?lcient the calculated numbers are largely lower limits because reason to dismiss congruent dissolution. Postirradiation in most cases there was not evidence for precipitation examinations of spent fuel elements have shown that the from differences in the spent fuel-leachant ratios. For radionuclides can be inhomogeneously distributed comparison, we can use the compilations of Baes and through the fuel, especially the more volatile elements, Mesmern3 and the calculated solubilities of Newton et such as cesium and iodine. If the cesium were concen- al.”’ Under oxidizing conditions and p“H 4, uranium trated at the grain boundaries of the fuel and at the oxide would have a volubility of 10–1to 10–2 mol/t and colder exterior of the fuel pellet but were still largely under reducing conditions 10–7to 10–11mol/t’ depending incorporated into the UOZ matrix, its concentration in on which solid, the amorphous or the crystalline, is in the Ieachant could be controlled by the dissolution of the equilibrium with the liquid. Similarly, the volubility of UOZ matrix but at a higher cesium-to-uranium ratio. The plutonium oxide would be 10-3 to 10-7 mol/t’ for behavior of cesium, strontium, and uranium appears to oxidizing and 10–7to 10–*4mol/t’ in reducing conditions. be very similar but at different concentration levels. The volubility is dependent on the crystal form and the We conclude that the solubilities of some radio- actual Eh of the system. These comparisons are proba- nuclides, especially rare earths and actinides, may be bly as good as one could expect from such a heter- important and controlling factors in leaching of waste

28 forms. These solubilities should be measured accurately ing lines of constant volubility as a function of Eh and as a function of pH and not as a part of a multi- pH. Calculations have been made for the +4 oxides and component system. hydrous oxides of uranium, neptunium, and plutonium. Although the amount of data is small, it is interesting The results for PuOz.nHzO are shown in Fig. 15. The to postulate that a negative temperature coetlicient of diagrams were constructed under the assumption that volubility is being exhibited by the actinides and rare conversions of the hydrated oxides to the more stable earths. Individual solubilities should be measured as a crystalline oxides are slow compared with the establish- function of temperature to determine if a kinetic effect is ment of the solubilky equilibria. In spite of the uncertain- being observed in the data. A negative temperature ty in the input data the results are very instructive; they coetlicient of volubility for actinides and rare earths in show that the Eh and pH dependence are certainly quite water would have important consequences for nuclear complex. In addition, these results will be of value in reactor safety and for the management of nuclear wastes. planning volubility experiments and in interpreting the data. The volubility diagram for PuOz.nHzO (Fig. 15) is E. Preliminary Considerations Concerning Actinide divided into two regions by a solid diagonal line; below Solubilities (T. W. Newton, B. P. Bayhurst, W. R. this line the solid phase is the +4 hydrated oxide, while Daniels, B. R. Erdal, and A. E. Ogard) above the line the +6 hydroxide is stable. Abrupt changes in volubility occur when this line is crossed. The The principal practical reason for studying the upper dotted line on the diagram represents the potential near-neutral solution chemistry of the lighter actinides is of the water/oxygen couple, 2HZ0 = Oz + 4H+ + 4e–; to provide quantitative information for input to models systems with apparent Eh values below this line are being developed for prediction of the transport of these thermodynamically unstable in the presence of one elements by groundwater. Information is needed on the atmosphere of oxygen. Reactions involving this couple oxidation states, actual species present, and maximum are usually very slow, so the potential for the more rapid concentration, governed by volubility. Additional impor- HzOz/Oz couple, HZOZ = Oz + 2H+ + 2e-, is also tant uses for this information are the interpretation of the shown. Systems with potentials below this line are results of laboratory and field studies of the sorptive expected to react reasonably rapidly with oxygen. behavior of geologic media and the design of meaningful The diagram shows that the calculated minimum studies of the partitioning of actinides between rock and volubility occurs at the bottom of a basin with approx- groundwater. imately triangular contours. Three distinct principal During the past year, work on fundamental solution volubility equilibria are associated with the regions chemistry pertinent to radioactive waste management showing diagonal, horizontal, and vertical contour lines, has been initiated.sc-sgThus far, work has been confiied respectively. In the lower left of the diagram the contour to preliminary considerations of the problems involved in understanding the precipitation and dissolution behavior of actinide compounds under environmental condhions. For the first step, the considerations have been restricted to equilibrium solubilities in the absence of completing agents for actinide oxides and hydrated oxides, or hydroxides. To get a preliminary idea of the volubility behavior, we attempted to calculate volubility as a function of Eh and pH using the appropriate thermodynamic data. If the volubility products, hydrolysis constants, and oxidation potentials are available, the solubilities can be calculated 2ii567; oloili2 1314 in a direct way. Unfortunately, almost none of the required data have been accurately determined, so Fig. 15. recently published estimatesgo have been used. The Lines for constant log (solubtity) vs Eh snd for plutonium results are presented in terms of “contour maps” show- hydrous oxides.

29 lines show a slope of about -4 x 0.059, and the potentiostat. The requirements for such a moderator in plutonium half-reaction for the principal equilibrium is actinide volubility studies are: ● Formal potentials in the range -0.5 to 0.9 V, PuOz.nHzO + 4H+ + e- = PU3++(2 + n)HzO. (1) approximately. ● Stable for many days with respect to decomposition Farther up on the diagram where the contours are in either the oxidized or reduced forms in the pH horizontal, the half-reaction is range from -2 to -9. ● Relatively rapid redox reactions with actinide spe- PuOz.nHzO = PuOZ+ + nH20 + e-. (2) cies, but no other reactions such as precipitation or complexation. This result is consistent with the observations of Rai and ● Reversible redox reactions at the working electrode coworkers at Battelle Pacitlc Northwest Laboratory, of a potentiostat. who showed that where Pu(V) is the principal solution Bondietti and Lee at Oak Ridge National Laboratory species in contact with PuOZ.nHzO, the volubility de- have used redox indicators as Eh buffers in their work on pends on the Eh but is essentially independent of PH. In technetium. They report that Nile Blue, Thionine, and the lower part of the diagram where the contours are 2,6-dichloroindophenol (DCIP) at concentrations of vertical, the volubility is independent of Eh, and the 10-6 M gave Eh values in agreement with the theoretical principal equilibrium is ones within 10-20 mV at a pH of -8.25. The reported Potentialsgz for Thionine and DCIP are such that they PuOz.nH20 + OH- = Pu(OH)~ - + (n – 2)HZ0. (3) might be useful for PuOZ.nHzO volubility studies in the regions where Eqs. (1) and (2) are the principal This analysis shows that if the input for the calcu- equilibria, and for NpOz. nHzO where equilibria lations is reasonably correct, the only parameters that analogous to Eqs. (2) and (3) are predominant. However, contribute significantly to the solubility of PU02. nH20 DCIP probably would not be suitable for the present are (1) the volubility product, (2) the PU3+ –Pu4+ purposes because it is insoluble in acid solutions, un- standard potential, (3) the PU4+—PUOZ+standard poten- stable in strongly alkaline solutions, and decomposes tial, and (4) thefi~th hydrolysis constant for PU4+. slowly even in neutral solutions.g2 In addition, it forms This discussion indicates that only a limited number of anions that might complex actinide species. Other dyes properly chosen experiments are required to predict the should be considered; for example, Bindschedler’s Green solubility of PUOZOnHzO over the whole range of Eh and forms cations, shows Eh versus pH similar to that for pH. Because there is a fairly reliable value for the DCIP, is useful in the 2 ~ pH ~ 9.5 range, and shows PU+3– PU4+standard potential,gl the volubility product instability only at the extremes of pH. In addition, it could be determined from a set of volubility measure- shows evidence for semiquinone formation, which may ments in the 3 ~ pH ~ 4 and 0.5 S Eh S 0.6 V range facilitate the one-electron steps required in the redox where Eq. (1) is the principal equilibrium. Careful mea- reactions of the actinides. surements in the 3.5 s pH s 6 range where Eq. (2) is the Inorganic couples also should be considered for use as principal equilibrium could be used for an independent redox buffers or moderators. Professor Henry Taube at determination of the volubility product with the diiXculty Stanford University, who has had considerable ex- that the estimated uncertainty in the required potential perience with a wide variety of inorganic complexes, for the PU4+–PU02+ couple is quite Iarge.gl The suggests that although many ruthenium complex couples equilibrium constant for Eq. (3) could be determined in have desirable potentials they are probably not stable any convenient region with pH Z 7 or 8 and Eh ~ 0.5 V. enough. Certain osmium complexes are much more The diagram shows that careful measurement and stable, and Taube suggests that the II-III couples such as control of the Eh will be required for meaningful Os(bipyridyl)~ and Os(bipyridyl)z(CN)z should be tried. volubility determinations in regions where Eqs. (1) and A preliminary list of possible Eh moderators is given (2) are the principal equilibria. A good method probably in Table IX, together with the formal potential at pH 7 is to use Eh moderators or btiers together with a

30 TABLE IX

POSSIBLE Eh MODERATORS

E; (V) pH range 0s(11)-0s(111) couples tris (1, 10-phenanthroline) 0.88 2,2’ -bipyridine 0.88 dicyano-bis-(2,2’ -bipyridine) 0.78 4,7-dhnethylphenanthroline 0.68-0.73 3,4,7,8-tetramethy1phenanthro1ine 0.68-0.73 Co(II)-Co(III) sepulchrate –0.3 Organic couples” Bindschedler’s Green 0.224 2-9.5 Induline Scarlet –0.299 3.0-8.6 Rosinduline 2G –0.281 4.8-11.4 Lissamine Blue BF –0.253 1-11 N,N’ -dhnethyl Viologens –0.446b 8.4-13 Indigo Carmine –o.125 <9’ Pyocyanine –0.034 1-12 ‘Dats taken from Ottaway, 1972. bpotentislsof substitutedViologemare independent of PH Snd foflow the simPIe Nernst . equation Eh = EO+ (RT/F)tn(COJC-). cSemiquinoneis formed above pH 9.

(~) and the PH range under which they can be with basalt-fluid systems. The latter are of interest if such investigated. rocks are to be used as rad-waste repositories. The preliminary conclusions discussed here indicate The rock is reacted in a dynamic (circulation) system some important experimental work that should be done. by flowing fluid over rock disks (or prisms). The rock is Volubility and distribution studies require control of Eh, subjected to temperature (either freed or in a controlled so for this purpose various redox couples should be gradient) up to 310°C and pressures up to 1/3 kbar for tested for stability and for rapidity of reaction with experiments up to 9 months in duration. The rock is actinide species of trace concentrations. examined for etching and secondary mineralization by scanning electron microscopy, electron microprobe, and optical microscopy. Modeling of the system can be done F. Rock-Water Interactions (R. W. Charles and R. J. after the method of Schreinemakers (1915-1925)93 as Vidale) moditied by Korzhinskii (1959),94 Zen ( 1966),9sand Zen (1974).” Work done with this approach follows. 1. Introduction. The experimental rock-water interactions are conducted to model some of the expected 2. Multisystems. A magnetic tape of the program rock-fluid reactions that will be encountered in the REACTION developed by L. W. Finger, Carnegie g Fenton Hill Hot Dry Rock System as the system Institute of Washington, and D. M. Bur~ Arizona State matures, that is, as the system approaches a steady state University, was obtained in FY- 1980. The program is chemically after perturbations caused by initial drilling now running at Los Alamos National Laboratory’s and reservoir establishment have abated. This is a central computing facility (CCF). Although the program granitoid-water system. A small effort has been started was correct as written, 10 fatal errors had to be

31 corrected along with several compilation inconsistencies Note that divariant assemblages, for example, (AST), are because of differences in language between the computer named by absent phases. Holding any two of these for which the program was originally written and the intensive variables constant, the slopes of the generated CCF. X-Y plot may be calculated. Six are possible for this The program is of immediate use in determining all system. Most relevant to the current experiment is the possible reactions between a series of phases, and it case of P and yHzoconstant yielding, prints them in descending order of degeneracy. One must then take these univariant reactions and assemble them dT _ –Ansio, by hand in intensive variable space with possibly ‘kiol AS negative degrees of freedom (Korzhinskii, 1959). This net produces a useful framework of univariant equilibria Exact orientation is not possible because the entropies of which, if properly oriented, will define a series of phase some of the phases are unknown. However, we do know assemblages stable under different A - Uj conditions. the sequence of divariant assemblages with temperature The REACTION program has now been combmed and YS102.The diagram may be oriented as shown in Fig. with a computer plotting routine to place all of the 17 with the reaction path as shown. calculated invarient and univariant equilibria in vl - I+’ The diagram predicts the disappearance of zeolite at space. Systems as large as two negative degrees of higher temperature and does not require additional freedom can be handled at this time. Currently, the divariant assemblages to be found experimentally. In program is in HPL for the HP 9825 calculator with addition, a number of univariant curves separate these 9866B printer and 9872A plotter. We plan to enlarge divariant assemblages, which maybe relevant depending this to handle systems of F = –3 and convert to upon the bulk composition of the experimental system. FORTRAN. Some interesting conclusions were drawn from this. This development relates observed mineral as- Although the experiment is in an open system, for long semblages in intensive variable space, allows identi- periods of time the solution burden is constant, which fication of other assemblages not observed directly, and indicates steady-state equilibrium with secondary materi- defines the univariant equilibria separating the divariant al on the rock surface. To state this another way, for assemblages. An example follows. small changes in bulk composition the system behaves as if it were a closed system. Another point observed is that 3. Biotite Granodiorite + Distilled Water Reacted in a although the system is initially silica supersaturated Temperature Gradient. The complete experiment react- (biotite granodiorite) it becomes silica undersaturated ing biotite granodiorite with distilled water is described in (thomsonite bearing) after reaction. Los Alamos National Laboratory report LA-8566-MS. To summarize: the reacting phases [(thomsonite (T), 4. Sentinel Gap Basalt Reacted in a Temperature stilbite (S), beidellite (B), plagioclase (P), K-spar (K), Gradient. Reaction between water and a basalt reservoir anorthite (A), and sericite (M)] are described by the in a temperature gradient must be defined if basalt is to components NazO-KzO-A1zOq-CaO with HZO and SiOz be used for geothermal energy extraction or radioactive mobile. A connected net for this f = —1 multisystem is waste deposition. Six prisms (2.4 cm by 0.8 cm by 0.8 shown in Fig. 16. The relevant intensive variables for the cm) of Sentinel Gap basalt were reacted along a experiment are P, T, y~io2,and ~~zo. A number of X-Y temperature gradient of 72 to 310°C at 1/3 kbar for 2 plots relate the relevant divariant assemblages months with initially distilled water under flow conditions of 2-3 cc/rein. low T: B+ P+K+M (AST) (to 119°C) , The fresh basalt consists of two pyroxenes, intermediate T: S+ P+K+M (ABT) (161 ‘C) , plagioclase, and Ti-magnetite. The matrix is a micro- high T: T+ P+K+M (ABS) (209°C to 31O”C) , pegmatite with a rhyolite norm. Natural alteration of the and very high T: A+ P+K+M (BST) (above 310”C) , basalt to nontronite is extensive. Under experimental by the method of displaced equilibria: conditions, recrystallization of the basalt is apparent throughout the volume of the sample even though no –AsdT + Avdp – @20dPHzo – AnsiozdPstoz= 0“ attempt is made to flow fluid through the rock. Weight

32 3S1 fn... /’~ 2s1

/ A’/ SPSKST \ ‘ \

\ /.)’””’

Fig. 16. Connected net showing all possible divasiant fields for the biotite granodiorite -I- water system.

loss varies from 5V0at 72 “C to 14?40at 310°C. Surface mineral phases, and intergranular salts ——from a hot. dry and internal assemblages evolve to a smectite-fike clay rock geo~hermal system-. Selected trace and major ele- and an illite, respectively. While the pyroxenes, ment concentrations were determined by neutron activa- plagioclase, and Ti-magnetite are resistant to reaction, tion for (1) 39 water samples taken during the course of a the nontronite and micropegmatite are extensively 75-day experimental run of the Fenton Hill hot dry rock recrystallized at all temperatures. Most of the micro- system, including both the injected cool water and the pegmatite is dissolved at higher temperatures. heated water emerging from the system; (2) a bulk rock core section from 8904 ft (2714 m); (3) each of the seven major phases present in the rock; and (4) a sample of G. The Application of Fluid Chemistry Studies to a Hot intergranular salts obtained by leaching the disag- Dry Rock System: Neutron Activation Studies (R. gregate rock at 25 ‘C. Vidale, L Binder, and A. Gancarz) Sodium, cesium, bromine, and europium continued to increase in the fluid during the 75day test run and were Neutron activation analysis methods were developed added to the circulating fluid almost exclusively by the for determination of element concentrations in deep reservoir. Sudden changes in their concentration geothermal system waters, bulk rock samples, separated may indicate significant events in the system just before

33 300

am o i-

I Ar# U (Si02)

Fig. 17. T vs ~~,m for the observed divariant assemblages. Reaction proe.eeds according to the arrow. Ordy the relevant divariant assemblagesare labeled

days 23, 46, 55. Potassium, calcium, strontium, barium, diiTerent element proportions from those in the working iron, and cobalt also continued to increase and were fluid. Lnited addition of the Jemez deep hot brine will be added both by surface sources and the deep reservoir. considered carefully before further inferences are drawn Many of their concentrations also changed just before about system behavior from solution chemistry. days 23, 46, and 55. Zinc, molybdenum, arsenic, antimony, and tungsten appeared to reach a steady state H. Permeability Measurements (C. Duffy) within 75 days. Plagioclase is the major rock source for sodium and a Matrix permeability (permeability of unfractured rock) major source for calcium. The disproportionately low provides a measure of the minimum permeability of a increase of calcium relative to sodium in the working rock mass. The permeability measurements described fluid suggests dissolution of plagioclase by pore fluid or below are for cylinders, 1 in. (25.4 mm) in diameter by circulating fluid and the formation of a calcium-bearing approximately 1 in. (25.4 mm) long, cut from drill core alteration mineral at depth. This is in agreement with samples from the Fenton Hill hot dry rock site. The laboratory circulating system data. primary importance of the measurements is in under- The major possible sources of elements added to the standing the water loss mechanisms in the hot dry rock working fluid in the deep reservoir are mineral/water system. Water losses above those that can be explained interaction during circulation, local salhe pore solution by matrix permeation would indicate water loss owing to and interstitial salts that have already interacted with the fracture permeation or perhaps the presence of high rock, and the moving deep hot brine of the Jemez permeability rock that was not sampled by coring. system. Mineral/water interaction is known to be signi.ti- Permeability measurements are also important in cnt from experimental work. Local interstitial salts, in understanding mass transfer between fluid and rock the limited rock sample available, seem to occur in because permeability influences the amount of rock that

34 interacts with the fluid. This consideration is of secon- It was noted that for this specimen the permeability did dary importance at Fenton Hill, but in areas such as not increase below -2 MPa. nuclear waste isolation it may be of primary importance. In the remainder of the samples, permeability was The permeabilities of six samples from the EE-2 drill initially measured with increasing P~. These samples hole at Fenton Hill have been measured as a function of showed an irreversible change in permeability with effective confining pressure P, (confting pressure minus increasing P,. After pressurization to a P. of 25-30 MP~ pore pressure) at room temperature (23 ‘C). P. ranges permeabilities measured at low P, were as much as an from -2 to 30 MPa. Permeabilities k in the 2-to 5-MPa order of magnitude lower than observed initially. This range are generally in the 10–17 to 10–ls -mz range, behavior is illustrated by the data for EE-2 13461-2A, whereas those near 30 MPa are in the 10–19-to 1()-20-mz which are shown in Fig. 19. It seems probable that the range. irreversible change in k is due to reduction of porosity, The samples examined were 11743-3, 12854-6, which was created by extraction of the sample from the 13461-2A, 13965-1, 14502-3, and 14964-1. The sample bore hole and subsequent cooling. Apparently the labo- number to the left of the hyphen is the bore hole depth in ratory permeabilities represent only upper bounds on in feet. All of these samples except 12854-6 show some situ matrix permeabilities. foliation. Three cores of 11743-3 cut in orthogonal For these latter specimens k as a function of P, has directions were tested and despite the presence of been fit only to those data obtained after maximum foliation showed no dependence of permeability on pressurization. These relations are: direction. The data for these three cores are shown in Fig. 18. Permeability in all three directions is adequate- for 12854-6, ly described by the relation 8.31 . 10-ls 4.68 . 10-20 2.12. 10-’2 k =(1 + 0.222 P,)10”0s+ (1 + ().fj013~1s0 ‘ k ‘(1 + 447. IPJ’”” ‘ for 13461-2A, where k is in m2 and P~ is in MPa. The permeability of this sample was measured only after P~ had been raised 3.55. 10-16 to -30 MPa. This is also true of sample 13956-1; its k ‘( 1 + 254.7 P~0”94 ‘ permeability can be described by

3.78. 10-18 EE-2 13461-2A k= -17 (1 + 0.327P,) ’40 “

-M . -18 “E X 2E-2 11743-3b-+ A 1 -17 A m -!s A o ● E-2 117433 I&W c “E . -:0 Y

03 0 -1s

Fig. 19. Permeability of EB2 13461-2A 33sa function of effective con- f~ pressure showing reduction of permeability with pressurization of the sample. Higher vzdues of permeability Fig. 18. were obtained upon initial pressurization of the sampl~ lower Permeabdity of EE-2 11743 as a function of effective confin- values upon depreasurization. ing wessue measwd in three orthogonal cores.

35 and for 14502-3,

.6.73. 10-17 k ‘(1 + 251.4P~0”’0 “

Only increasing P, data were collected for 14961-1. It was similar to data for 13461-2A and 14502-3.

i 1. Element Transport in Solids: The Interaction of Water and Fenton Hill Granite (L. A. Blatz and C. E. Honey, Jr.) 275°C MONOMERIC Si02(ppm) vs TIME In connection with the geothermal project at Fenton OF EXTRACTION WITH WATER 240 EXTRACTION No. I Hill we have studied the interaction of water with EXTRACTION No.2 biotite-granodiorite rock (drill cuttings from the 9560- to EXTRACTION No.3 EXTRACTION No.4 I80 9570-tl level of EE- 1 at Fenton Hill) at 198, 235, ancf “ EXTRACTION No.5 275 “C. The rock had an approximate modal composi- SAME ROCK, NEW WATER FOR EACH TIME OF EXTRACTION tion of 26% quartz, 36% plagioclase, 19% microcline, I 20 12% biotite, and 7?40other minerals. I The samples were shaken with varying degrees of 60 vigor in Teflon, titanium, or various steel containers, all encased in steel bombs for 2, 4, 7, 16, 24, 48, and 96 h n L - and more rarely for 8, 16,32, and 65 days. In most cases ‘O 6 12 48 TIME(h) the same rock samples were repeatedly extracted, usually five times, with fresh water for each extraction. The quantities studied in the aqueous phase included Fig. 20. Monomeric silica vs time of extraction with water. the monomeric and total silica concentrations (by both silco-molybdate and atomic absorption analyses), the pH (at room temperature), and, less frequently, the (Nat), (590 ppm and 96 h for the data of Fig. 20), and (SiO~ is (K+), (Al+++), (Cat+), (Mg++), (ZFe), (F-), and (Cl-) the instantaneous silica concentration. The integrated concentrations. form of this rate law is Studies on the solid phase included weight changes afler each extraction, some surface examination of the ~n (si02)sat

36 4.0 I I A rock. If it all came from the quartz, between 15 and 20%

A of the quartz was removed. This decrease in the amount of quartz could itself explain much of the behavior at 48 3.5 - h, although the effect on the surface area is not accurately known. However, at the shorter times the

3.0 – weight loss was much smaller, and the other factors must be involved. The values of (SiO~,,t obtained in the fwst extraction

2.5 – were within 5?40of the values given by Morey, Fournier and Rowe9719sfor the volubility of quartz and were within o 0 -10!4o of the values given by Van Ller, Bruyn, and $2.0 – Oberbeek.99 (Also see Iler.100)

1.5- 275°C J. Amphiboles on the Join Pargasite-Ferropargasite (R. fnQ=-okt W. Charles) ~= (5i0Z)SA7-(SiOZ) (5i0z)sAT The thermodynamic properties of a number of min- I.0 - (slOZ)sAT=590PPIII

A EXTRACTION No. I erals as noted by Robie et al.’”l are at best incomplete. o EXTRACTION No.3 This observation is particularly true for complex, yet 0 EXTRACTION No.5 0.5 common, minerals, such as the amphiboles and micas. We are proposing to grow some of these minerals to

I obtain their enthalpies of formation. Our focus will be the o O 6 12 24 40 fluoro-amphiboles and micas. Both are commonly found TIME(h) in solid solution with their OH end members. This paper

Fig. 21. is based on experimentally grown amphiboles in the Data from Fig. 20 plotted according to the integrated rate series pargasite-ferropargasite and shows our capability equation given in the text. to grow minerals and to determine some of their crystallographic properties.loz which silica dissolves depends in part upon the OH- Amphiboles have been grown across the concentration in the aqueous phase, and this quantity join NaCazMg4AlSib–AlzOz2( OH)z–NaCazFeqAISiG changes with time. (4) The rock surfaces may beat least AI,O,,(OH), on QFM and CCHd oxygen buf- partly coated with insoluble silicates or metal ions during fers to gain insight into the iron-magnesium substitution the course of the reaction and/or coated with mineral in an amphibole without the local charge imbalance alteration products so that the reactive surface area caused by sodium in the M(4) site. Oxygen fugacity was decreases with time. (5) The amountof rock present may found to have no effect upon the unit cell dimensions of decrease. After five 48-h extractions at 275”C, the amphibole. Unit ceU parameters (C 2/m) for amphibole amount of silica removed was 5.4% of the weight of the grown across the series are:

Composition a(A) b(A) c(A) P V(A)3 Mgd 9.892(1Y 17.941(2) 5.277(1) 105°33’(1) “ 902.2(3) MgjFe 9.904( 1) 17.989(5) 5.29 1(2) 105°27’( 1) 908.6(5) Mg~ez 9.915(3) 18.03 1(7) 5.301(3) 105°24’(1) 913.6(1.0) MgFe~ 9.93q5) 18.104(6) 5.320(2) 105° 16’(1) 922.6(9) Fe, 9.953(5) 18.152(3) 5.330(2) 105° 16’(2) 928.8(4) ‘Parenthesized figures represent the estimated deviation (esd) in terrna of least units cited for the value to their immediate left; thus 9.89X 1) indicates an esd of 0.001.

37 No change in cell parameters is observed with tem- As complete exchange occurs, this should approach perature on a given buffer. The essentially linear trend unity. However, because of varying amounts of 170 in an indicates disorder of magnesium and iron in M(l), M(2), enriched *3C0, K’s in excess of 0.9 are not observed. and M(3) sites. In all cases plagioclase and pyroxene Much to our surprise, however, 99V0 y-alumina was were present in the charge. The amount ranged from a found to be an even better catalyst, yielding essentially few percent to >309’0 without atTecting the unit cell complete exchange (K = 0.83) under the same condi- parameters of coexisting amphibole. tions. Analytical data on this alumina did not indicate the presence of substantial amounts of impurities, such as iron and copper oxides that might be expected to VI. INORGANIC CHEMISTRY catalyze the CO exchange. However, to minimize further the possibility that an impurity might be the active A. Small Molecule Chemistry species in the exchange, an ultrapure grade of alumina (99.999%) was examined under the same conditions. 1. AluminaCatalyzedIsotope Exchange in CO (D. Essentially identical results were obtained (K = 0.84). C. Moody, M. Goldblatt, B. B. McInteer, and T. R. For both ruthenium/alumina and alumina some pref- Mills). Carbon- 13 nuclear magnetic resonance spec- erential site exchange between oxygen in the catalyst and troscopy has developed into an extremely powerful tool CO is observed. This phenomenon was observed earlier for the chemist. Thus, the demand for the isotope has in the room temperature studies on alumina. 10s No increased rapidly. Fractional distillation of CO has indication of bulk oxygen exchange with the catalyst has proved to be a convenient method for *3Cenrichment up been observed, however. Likewise, extremely smaU to approximately 94%. Interference by the various amounts of carbon appear to be deposited on the oxygen isotopes prevents dkect enrichment beyond this. catalysts, and exchange with the carbon in the CO Isotope exchange or scrambling is thus an important step occurs. It is unlikely that these two mechanisms would in the ultimate production of >9970 13C0.103 Although a account for all the isotope exchange that we are observ- variety of systems have been reported to promote this ing, and because no appreciable amount of COZ is exchange, the great majority of the work has been formed, we feel that CO/COz exchange is also not a performed with hot metal or metal-carbide fdarnents.l”’ major contribution. These systems are not readily adaptable to flow condi- The exact nature of the exchange process is thus tions where large volumes of gases are involved. unknown. But it is interesting that the exchange occurs Previous studies at room temperature had found only readily on pure y-alumina. Because this is the support of slight activity for y-alumina in the isotope exchange of choice for many metal systems that are active in the CO. High catalytic activity had been observed in the conversion of CO/Hz to hydrocarbons, one has to more easily reduced systems such as the nickel, copper, wonder what role the alumina might be playing in the and ~on o~des. 10sAt higher temperatures, however> we overall reaction scheme, and whether some activation of have found that y-alumina is an excellent catalyst for this the CO might not be coming from the support. Similarly, exchange and because it is not easily reduced, little or no the use of zeolites as supports is becoming more COZ is formed. commonplace, and although not as active as y-alumina, Because ruthenium/alumina has been observed to an molecular sieves have also been found to catalyze this effective Fischer-Tropsch catalyst where the CO is exchange in CO. activated toward reaction with hydrogen, we had ex- The results of this study have been incorporated into pected that this would be a g60d catalyst for the isotope the operation of the Los Alamos ICONs facility and a exchange in CO; and, indeed, we observed K’s between scrambler using y-alumina has been operating con- 0.6 and 0.7 atler 1 hat 500”C in a closed system. This K tinuously for months with no loss of activity. is defined as the following ratio of masses: 2. Catalytic Reduction of SOZ. (D. C. Moody, R. R. Ryan, and K. V. Salazar) Many processes have been K = (28)(31, (28 = lZCl@; 29 = l@O, 13ClCO; used with varying degrees of success for removal of SOZ (29)(30) from flue gases. Quite a few more have been proposed. 30= ‘sCl’o,l*CISO;31 = ‘3C’80). One type of process that seems quite attractive is the reduction of the SOZ to sulfur. Numerous papers and

38 patents pertaining to this subject have appeared. Bauxite- peratures where y-alumina has appreciable activity and alumina-supported systems,’oc in particular, have (300”C, 0.2-0.3 torr/min), 0.5% Ru/Al,O, is almost too received attention. A variety of reducing agents have reactive to get anything but an estimate of the rate been used, the most common of which are Hz, CHd, and (300”C, 0.2-0.3 torr/min), 5% Ru/A120g was the most CO. Operating temperatures between 300 and 600”C active of the catalysts tested and gave a reduction rate are generally required, and substantial amounts of H# -10 times faster than 0.5’%0Ru/AlzOj. Because the rate thus result from reactions of the sulfur produced with increased proportionally to the ruthenium percentage, hydrogen. Thermodynamic and kinetic studies of this 10% Ru/AlzO~ and ruthenium metal were tested. The system suggest that temperatures much lower than surface-impregnated 10% Ru/AlzOJ catalyst showed 400°C should be used to minimize the HJ3 formation.107 only slight activity, whereas ruthenium metal had no In those cases where CO has been used as the reductan~ activity as a catalyst for the reduction of SOZ with HT COS formation often plagues the systems. Surface area ditTerences for these catalysts lirnh the The present work examines the effect of using an accuracy of the comparisons, especially for the extremely active hydrogenation catalyst to promote the ruthenium metal. reduction of SOZ with Hz at temperatures low enough to An important consideration in SOZ reduction experi- minimize H#3 formation. Ruthenium on y-alumina was ments where sulfur is generated is catalyst poisoning. A examined and found to be quite active at temperatures as series of repeated runs using 0.5% Ru/AlzO~ showed a low as 150”C. All experiments were performed under slow decrease in reaction rate. This decrease in rate, we static conditions in an apparatus consisting of a 250-mt feel, is a consequence of our static system, which allowed round bottom flask equipped with a greaseless stopcock sulfur to drop back onto the catalyst and perhaps hinder connected to a manifold (-100 @ with inlets for SOZ, gas contact. This hypothesis is not inconsistent with the Hz, and vacuum. Pressure drop was monitored as a return of 100% of the activity for this catalyst simply by measure of the reaction rate. These conditions are by no heating under vacuum and subliming off sulfur. Under means optimum for this type of reaction, so the extreme flow conditions we do not expect to experience any activity observed for ruthenium/alumina is indeed re- decrease in activity that would necessitate reactivation of markable. This reactivity can be calibrated somewhat by the catalyst. comparison to the reactivity of y-alumina under the same The data presented in Table XI indicate that the conditions. The 0.5% Ru/AlzOJ shows good reactivity at stoichiometry of the reactants (SOZ and HJ need not be 156°C (0.5 torr/rnin) whereas y-alumina is essentially controlled precisely. Clearly, some excess Hz is desirable, unreactive at this temperature (Table X). At tem- but an acceptable rate is observed when stoichiometric

TABLE X

EFFECT OF Ru CONCENTRATIONS IN Ru/y-&O~ CATALYSTS FOR SOZ REDUCTION

S02 H, Temp Pressure Drop (torr) (torr) (“c) Catalyst (torr/min) 200 400 156 0.5% Ru/AlzOJ - zO.5 200 400 200 0.5% Ru/AlzOJ -1.1 160 320 250 0.5% Ru/Al,O~ W3 160 320 300 0.5% Ru/AlzO, -10-12 160 320 300 y-AlzOj 4.2-0.3 200 400 156 5% Ru/AlzO~ -4-5 200 400 156 10% Ru/AlzOq <0.05 200 400 156 99.95% Ru metal No reaction

39 TABLE XI variety of catalysts have been reported.’oc’110However, at 152°C under our experimental conditions, no reaction PERCENT S02 CONVERSION of CH4 with SOZ was observed over 5?4D RU/A1203 ON 0.5% Ru/A120, AT 156°C catalyst. These data suggest that NO, CO, and CH4 will AFTER 5- 1/2 h not hinder the reduction of SOZ with Hz over RU/A1203 under our experimental conditions. The Fischer-Tropsch reaction of CO and Hz, however, does present one SOZ Converted to complication that might arise should this catalyst be used SO, Hz Sul!hr directly in the reduction of SOZ with Hz in flue gas (tord (torr) (%) streams. The increased H2 consumption would probably 50 550 >90% necessitate the removal of the CO from the NO and SOZ 100 500 -3 1% before the reduction step with Hz. 200 400 -20% In summary, Ru/Alz03 is quite active as a catalyst for 400 200 -3% the reduction of S02 with Hz to sulfur and water at temperatures low enough that H# formation is not a problem. The stoichiometry of reactants does not have to be precisely controlled. Poisoning of the catalyst has not proved to be a problem. Nitric oxide reduction occurs amounts of SOZand Hz are available. Because of the low readily under the same conditions with no apparent temperature of operation (156” C), the reaction of sulfur complication arising from the simultaneous reduction of with excess H2 to yield HZS does not occur at an both NO and SO,. These data suggest that this catalyst appreciable extent even where a large excess of Hz is should be examined for possible direct application to available and >90V0 of the SOZ has been consumed. desulfurization of flue gases. Both characteristics would be particularly advantageous should such a system be applied duectly to the removal 3. Novel Reactivity and Structure of of S02 from flue gases. Ru(CO)z(qJIOz. SOJ(PPh3)z (D. C. Moody, R. R. A number of other potentially reactive species are Ryan, and K. V. Salazar). Since our discovery of q2-SOz present in flue gases in additional to S02 Thus, a variety bonding in transition metal complexes,l’1 there has been of experiments were performed to test the effects of such considerable interest in this bonding mode and in the species as NO, CO, and CHd on the reaction under extent to which S-O bond activation actually occurs and study. The reduction of NO with Hz has been examined whether it can be exploited in reaction chemistry studies. extensively, and Ru/AlzO~ not only catalyzes the reac- In this regard, the complex Ru(CO)2(SOJ(PPh3)z tion but promotes Nz formation.los For comparison, this (Ref. 112) appeared quite interesting because a trigonal reduction was examined under our experimental condi- bipyramidal structure with an equatorial q2-S02 was tions using 5?40Ru/AlzO~, and then a mixture of NO, expected by analogy to the known structure of SOZ, and Hz was examined. Reduction of both NO and RuCl(NO)(SOJ(PPh3)2 (Ref. 113). Reinvestigation of SOZwas observed to occur with a total pressure drop of the infrared spectrum of Ru(CO)2(SOJ(PPh3)z revealed 2-3 torr/min. The products obtained were Nz, S8, HZO, u(SO) peaks at 1105 cm-l and 850 cm,-l which shified and a trace of NZO, in addition to unreacted NO and to 1060 cm-l and 815 cm-l when the complex was so,. prepared with S1802 This pattern indicated q2-S02 The reaction of CO and SOZ has also been studied coordination,’ 111114and the extremely low frequency of quite extensively over a variety of catalysts.1°9 Under our the second u@O) peak suggested substantial S-O bond conditions even at 200° C, no appreciable reaction of CO lengthening. These structural features have been veritkd with SOZ was observed over 5?40 Ru/AlzOq. Because through a single crystal x-ray diffraction study. The Ru/AlzO~ catalyzes the conversion of CO and Hz to complex crystallizes in the monoclinic space group P21/n hydrocarbons (Fischer-Tropsch reactions) at moderate with a = 20.276(3), b = 16.158(3), c = 10.69 1(2), ~ = temperatures, the mixture of CO, SOZ, and Hz was not 96.42(1)0 and DC= 1.54 g cm-3 for Z = 4 (T = –60”C). examined. Methane, however, is a major product of this The structure was solved by Patterson and difference Fischer-Tropsch chemistry, so the reaction of CHq with Fourier techniques and refined to R = 0.035 and Rw = SOZ was studied. Again, numerous such studies over a 0.035 for 3976 reflections. As can be seen in Fig. 22, the

40 0 served. The complex slowly reacts with excess S02 in the 9 absence of oxygen to generate the bidentate sulfate complex Ru(SO~)(CO)2(PPhJ)z (Ref. 119), the same complex that is obtained on reaction with molecular oxygen, 112plus PPh# and an unidentilled ruthenium species, which appears to contain bridging carbonyls. The only products obtained in the presence of excess PPh~ are Ru(SOd)(CO)2(PPh~)2 and PPh$. When liquid S02 is used as the solvent, the reaction rate is significant- I Iy enhanced. This is the expected result if coordination of a second S02 to the metal-bound S02 is important in the overall reaction scheme, and because the reaction ultimately involves oxygen transfer from one SOZ to Fig. 22. another, the importance of such an interaction would not Structure of RU(CO)2(qZ–SO,30,)(PPh3)2, be unreasonable. We are currently varying the size and basicity of the phosphine Iigands in an attempt to understand more geometry around the metal is trigonal bipyramidal with completely this unique reaction. This is the first report of an equatorial q2-SOz similar to that reported for electrophilic attack on an q2-S02 and indicates that RuClNO(r12-SO~PPhJ)2 (Ref. 113). The dihedral angle further studies of q2-S02 with Lewis acids may lead to between the S1-04 bond and the S1-RU-03 plane is interesting results. 107.90 as compared to 110.30 in the latter complex. In addition, another SOZ is coordinated to the terminal 4. Coodinatively Unsaturated Mo(O) and W(0) Com- oxygen of the T12-S02 The geometry about the plexes and Their Reactions with Small Molecules (G. J. Iigand-bound S02 is similar to that observed in metal Kubas and R. R. Ryan). The ability of transition metal halide- (and pseudohalide-) bound S02, which character- complexes to achieve coordinative unsaturation nearly istically exhibits rather long S-X distances and pyramidal always plays a vital role in their function as geometry about the sulfur atom.l~s The 2.5-A S-O homogeneous catalysts. Precious metal complexes are distance is approximately midway between the sum of usually suitable in this regard but are, of course, the van der Waals radii (3.25 A) and the sum of the inappropriate for applications where disposable catalysts covalent radii (1.7 ~).’ ‘c The interaction is thus best are desired. We have focused our attention on more described with a bond order less than one, consistent available Group 6 metals and have found the fwst with the extreme lability of this second SOZ molecule. example of a stable coordinatively unsaturated tungsten This lability necessitated the low-temperature structure (0) complex, W(CO),(PCy,)2 (Cy = cyclohexyl), and determination and accounts for the failure to detect only the ‘second example of a 5-coordinate——Mo(O) infrared peaks of the ligand-bound SOZ in room tem- complex, Mo(CO)@Cy3)2 (Ref. 120), These complexes perature nujol mull spectra. can be synthesized quite conveniently and can reversibly The bonding of q-S02 has been suggested to primarily bind small molecules such as dmitrogen, ethylene, and involve n-donation from the metal to the LUMO of SOZ, hydrogen and irreversibly coordinate CO, SOZ, and which is antibonding with respect to the S-O bond and nitrogen donor Iigands (see Table XII). bonding with respect to the O-O Vibration.ll’”ls This type of interaction would be expected to lengthen S-O ether distances and increase the terminal oxygen basicity. It fac-M(CO)3(C,HJ+ 2PCY, ~gon - M(CO),(PCY3)2+ C7H, follows that such an increase in basicity should enhance M=Mo: 16h deeppurpleppt.77% coordination by Lewis acids like S02. The present W: Ih complex exhibits the longest coordinated SO bond and toluenq 2h the lowest u(SO) value of any of the reported q2-SOz L tohxne, argon L=N1,H2,CZH4 complexes.1’8 v 80”C During the synthesis and attempted crystallization of mer-M(CO),(PCyJzL Ru(CO)z(SO~(PPhq)z an unusual reactivity was ob- yellowppt. 60-70%

41 TABLE XII

RESULTS OF ADDITION OF SMALL MOLECULES TO M(CO)JPCYJ2 (M = Mo or W)”

Reversible Irreversible Anomalous No Binding ofi Binding ofi Reactions with:b Reaction with: N2 co 02 NEtJ H, so, NO NHEtz C,H4 NHJ co, C,F4 H,O NHZR CS2 cyclohexene ROH CHjCN CH3N02 propylene acetone pyridme CH2C12 butadiene acetaldehyde pyridme N-oxide CHJ RZOC EtJ formaldehyde HC 1 furful thiophene (M=W) dimethyl- PhSH tetrahydrofuranC formamide PhC=CPh thiophene (M=Mo) ‘In toluene solution at room temperature. boxidative addition, tisproportionation, or mukipleproduct formation Occms. ‘Weak interaction. Unstable complexesformed in ether or THF solutions.

Although these complexes have not yet proven to be TABLE XIII active catalysts, a better understanding of zero-valent IR DATA FOR W(CO)~(PCyJ)zL Group 6 complexes and their potential as catalysts is being achieved. The bulky, mutually tram tricyclohexylphosphine L v(CO)(cm-l) A ligands appear to be unique in stabilizing the 5-coordi- so, 1994 1909 1873 36 cm-l nate species and their adducts. (Many other phosphines Hz 1961 1843 1843 0 of varying size and basicity have been tried without --- 1946 1932 1811 21 success.) Several other aspects of the complexes are also NHZBU” 1936 1811 1788 23 intriguing. Because of steric limitations imposed by the DMF 1925 1801 1775 26 phosphines, M(CO)J(PCyj)z selectively coordinates only PY 1925 1791 1757 34 those lig.ands that “tit.” Thus, NH~ and NHzEt readily EtOH 1941 1806 1744 62 add to the sixth position but NHEtz and NEt~ do not. MeOH 1931 1821 1721 100 (See Table XII for further examples). One can conse- HZ0,HZ*60 1928 1798 1705 93 quently view M(CO)j(PCy~)z as a rather bulky Lewis HDO 1928 1798 1700 98 acid. The complexes obtained with certain energy-related [ DZO 1928 1798 1695 103 small molecules, such as hydrogen, alcohols, and water, 1 are interesting because of their seemingly anomalous infrared absorption. In the complexes containing the reversibly bound hydroxylic ligands, very low carbonyl stretching frequencies are observed, and the value of A DZO). Although the latter phenomenon may be ex- (the dfierence between the second and third listed CO plainable on the basis of mixing of 5(H,0) with u(CO), frequency) is much higher than that observed for non- the possibility that there is a weak interaction between hydroxylic Iigands (Table XIII). Furthermore, the value carbonyl and HZO ligands on the same or neighboring of the lowest u(CO) shifts upon deuteration (L = HZO vs molecules cannot be discounted. The water molecule

42 may also have split on coordination into hydrido and S02 was found in aU previously structurally character- hydroxo ligands, for which there is precedence in certain ized SOZcomplexes of dt metals.123Subsequent work has Pt(0) complexes.lz’ The u(OH) region of the infrared shown that the bonding mode of the S02 in these spectrum of solid Mo(CO)J(PCyJ)z(HzO) contains four octahedral dt systems is quite sensitive to the tyue peaks in the 3300-3660 cm-’ range, further clouding the and arrangement of the ancillary Iigands. For issue. If an unusual bonding situation is occurring, it example, the bonding mode of S02 varies with L in the would be relevant to the water gas shift reaction, ,H20 + complexes cis, frans-Mo(CO)z(PPh~ )2(SOz)L: CO ~ Hz + COZ. for L = pyridine or CHJCN, an ?12-S02 is The infrared spectrum of W(CO)J(PCyq)z(H~ is un- observed; for L = CO or p-tolylisocyanide, an ql-S02 is usual in that I)(W-H) (1568 cm–’) is significantly lower found; and remarkably, for L = alkylisocyanide, than usuaUy observed for metal hydrides, whereas 711-plana and 112-s02 are apparently formed. These 5(W-H) (951 cm-l) is higher than normal. Coupled with observations were quite helpful in deriving bonding the highly reversible nature of the Hz binding, this raises concepts for the q’ vs q2 geometries, which have been set the possibility that the Hz is coordinated in an un- forth in our recent review article on S02 complexes. *24 precedented molecular fashion, rather than as a Further studies have been carri~ out on these dihydride. X-ray crystallography has revealed that the complexes. An x-ray crystal structure of nonhydrogen ligands are arranged in an octahedral Mo(CO)z(PPh3)1(CNCy)(SO~ confirmed the coexistence fashion, but the hydrogens could not be located in the of both q~-planar and T12-S02This is the fwst example of sixth coordination site for either the molybdenum or room-temperature stable S02 linkage isomerism.125 31P tungsten complexes, even at -80° C. Neutron diffraction and ’70 solution NMR studiesl’t were performed on studies in collaboration with Pbillip Vergamini of Los these and related complexes to determine whether or not Alamos Group P-8 are in preliminary stages. separate resonances for the bound and unbound oxygens Finally, attempts were carried out to synthesize com- of q2-S02 could be distinguished. As can be seen from plexes similar to the above but containing two reversibly the data in Table XIV, only one major 31P resonance or weakly bound ligands, that is, Mo(CO)z(PCy3)@~z. was located for Mo(CO)2(PPh3)2(CNCy)(SO~, even If such species could be made, the possibility for down to -50° C. Because infrared studies indicated that catalytic behavior would be increased because of the the ql-planar form predominates in solution, the NMR presence of two potential open coordination sites. How- peak at 44.8 ppm is most likely due either to the ever, this is a very difficult synthetic problem, and so far chemically equivalent trans- PPhJ in this isomer or to an coordinately unsaturated dicarbonyl complexes have not average signal for both isomers. For the CN(p-tolyl) been obtained. analogue, which contains only q 1-S02, a resonance is observed at slightly lower chemical shift (the 24.3-ppm 5. Molybdenum and Tungsten S02 Complexes (G. L signal is apparently due to a decomposition pro- Kubas, G. Jarvinen, and R. R. Ryan). Our work on the duct). The non-S02 containing complexes, coordination chemistry of SOZ contributes significantly Mo(CO)z(PPh3)2(CNR)’, gave resonances at to knowledge of structure and bonding in transition -10 ppm higher field. In regard to the 170 NMR results, metal complexes and has the potential to lead to much in all cases only one resonance was observed for improved methods for controlling this major pollutant. complexes with isotopicaUy enriched S02, even for The q’(side-on) bonding mode of SOZ, f~st deftitively MO(CO)@Y)2(q2-SO~, which may have been expected characterized at Los Ahunos National Laboratory,122 to give separate signals for the bound and unbound has increasingly attracted our attention because t.hk oxygens of the r12-S02.Thus, exchange averaging of the form of coordinated SOZ has shown some intriguing oxygens is apparently occurring, even at —50°C. In- examples of reactivity quite different from that presently terestingly, however, the chemical shift for the q’ com- known for the better studied ql-planar, ql-pyramidal, or plex is much lower than for those with ?11-S02. To bridging S02 coordination modes. Our study of molyb- summarize, it appears that structural changes involving denum and tungsten complexes of S02 began in order to the coordinated S02 occur rapidly on an NMR time show that Mo(CO)q(phen)@Oz) and M~CO)z- scale, and in certain cases little energy difference exists (bipy)(SO~2 contain q2-S02 ligands, whereas q’-planar between the ql and q’ forms of S02 binding.

43 TABLE XIV

31pAND 170NMR DATA

170 Signal Width 6(31P) 6(1’0) at Half Height Compound (ppm)’ (ppm)b (Hz) Mo(CO)2(PPh,),(CNCy)(SOJ +44.8 420 800 Mo(CO),(PPh3)2[ CN(p-tolyl)](S0,) +43.5, +24.3 416 800 MO(CO)j(PY)2(q2-S0,) 234 300 Mo(CO)JPPh3)2(CNCy)2 +54.3 Mo(CO)2(PPhJ2(CNBu’)z +54.2 Mo(CO)2(PPh3)2[CN(p-tolyl)]z +53.3 ‘CH2C1Zsolutions.Reference:MelPO,. bCH,Cl, solutionsof complexeswith isotofiiczdlyenrichedSO,. (33% 170).Reference:H,O. For &-S02, 5 = 512 pp&.

The first example of S02 coordinated to metals by pyridine. Phosphine substitution occurs instead to give way of all three of its atoms, 1Mo(CO)Z(PPh3)(py)- IMo(CO)2(py)2(S0,)]2. Experiments have been carried (SO~]D has been synthesized. It contains bridging out to determine the reactivity of the terminti oxygen of 712-SOZ(Fig. 23) and forms in CH2C12solution from cis, T12-SO*coordinated to Mo(O) and W(0). Use of reagents rrans-Mo(CO)z(PPh3) 2(py)(q2-S02), which apparently such as BF3 and MeSOqF (methylating agent) has thus fiist undergoes rearrangements to a cfs-PPhq isomer and far led to extensive decomposition of the complexes, then loses a phosphine and dimerizes. The basicity of the making it difficult to ascertain the nature of the reac- previously terminal oxygen atom (04) is apparently tions. Experiments involving less reactive Lewis acids are substantial, since the dimer is not readily cleaved by planned. Our attempts to synthesize a phosphine analog of the complexes fac-Mo(CO)3(N-N)(q2-S0,) (N-N = phenan- b-s -2,42 throline and bipyridine) using the bidentate phosphine bis fk2-03-2,19 (l,2-diphenylphosphino)ethane (dppe) yielded the in- kAYI = 2.24 S-03 -1.52 teresting chemistry outlined below. \ s-w -1.50 b-cl -1.89 (? 1) CH3CN reflux, 20h MO-c?-1.99 MO(CO)6 > &-Ho(CO)3(dppn) (CH3CN) 2) add dppe, reflux 20 h + ~2c’2 C52C’2 (n-Su)20 excess S02 excess CU3CN reflux RT, 15 ■ RT, 2 h dppe \\ I

::~gg~’”

C52C’2 (2) excess CH3CN RT, 24 h Fig. 23. L no rxn Molecularstructureof [Mo(CO)1(PPhJ(py)(SOJ]2.(Phenyl dPPe = (C6H5)2PCH2CH2P(C6H5)2 groupshavebeenomittedfor clarity.)

44 The q2-S0, complex Jac-Mo(CO),(dppe)(q2-SO) (~ ) also been developing the chemistry of U(V) fluorides. initially formed from the reaction of excess SOZ with Our entry to fis field was the investig~tion of the @c-Mo(CO)J(dppe)(CH,CN) is gradually converted in thermal reduction reaction:127 solution to the meridional isomer (~ ), where the S02 A adopts an q’-planar bonding mode. This is another UFC+ S02 _ S02F2 + rz-UF5 + U2Fg example of the interconversion of the q ‘-planar and q2-SOz geometries and the first where geometrical + U~FIJ + ----- isomers of a complex show different modes of S02 bonding. The q2-S02 Iigand in (~) is readily displaced At an appropriate temperature it was found that ex- by other Iigands, including CHJCN as shown, to give cellent single crystals of the long known compounds @-Mo(CO),(dppe)L complexes. By contrast, the q’-SO, a-UF~ and U2Fg could be obtained. Single-crystal x-ray ligand in (~) is much less labile. The complex (~) diffraction studies were carried out to verify the struc- presumably represents a more thermodynamically stable tures deduced on the basis of x-ray powder diffraction arrangement of the ligands around the metal atom. The studies. A linear chain of UF6 octahedra with bridging photochemical reaction of Mo(CO)d(dppe) and SO, fluorides forms the basic structure of a-UF5, whereas yields primarily complex (~), but a small amount of U2F9 has a threedimensional bridge structure with the (~) is also present. Because Q ) has been shown to be basic uranium coordination of a tricapped trigonal photochemically converted to (~) at a moderate rate, prism. Microspectrophotometry measurements on U2F9 the initial product of the photochemical reaction of showed the presence of both U(IV) and U(V) and thus Mo(CO)d(dppe) and S02 may also be (~). indicated that U2F9 should not be considered to have a Our previous work on q2-S0, complexes has indicated delocalized, intervalence electronic structure. that the terminal oxygen possesses considerable basicity. We also developed a huge-scale synthesis of ~-UF~ by An attempt to protonate the terminal oxygen of (~) the photolysis of UF6 in the presence of S02 or CO with a slight excess of HC1 led to rapid isomerization to (Refs. 128,129). (~). A similar rapid isomerization occurred upon addition of BF~, another Lewis acid, to Q). The reason for the acid catalysis is not clear. The rate-determining step in the isomerization would not appear to be dissociation of the q2-S02 ligand because substitution of The ready availability of multigram quantities of the q2-S02 by excess CHJCN, which presumably in- ~-UF, allowed us to carry out an extensive investigation volves a rate-determining dissociation of S02, proceeds of the behavior of ~-UF~ in more than 50 nonaqueous much faster than the isomerization. Therefore, the pres- solvent systems. 130It was thus possible to show that ence of the acids must increase the rate of some other &UF5 possesses a fairly extensive chemistry in selected process involved in the isomerization. A variety of coordinating nonaqueous solvents. A predominant reac- mechanisms can be proposed for the isomerization of tion in such systems is autoionization to give UF~ (~) to (~) involving dissociative or nondissociative anions and solvated UFj cations; that is, processes, but there is no basis now for favoring one mechanism over another. It will also be of interest to 2UF~ + xDMF — UF: + UF,(DMF)+X . determine if the Lewis acid catalysis is specific to the SOZ complex (~) or occurs more generally for other The presence of the product species was definitively ligands. shown by near ir-visible and ir spectrophotometry, EPR,. conductivity, and elemental analyses. An example of the identification by near ir-vis spectrophotometry of UFZ B. Actinide Chemistry in solutions of &UF~ in dimethylsulfoxide (DMSO) and dnethylformamide (DMF) is shown in Fig. 24. 1. Uranium(V) Fluoride Chemistry (P. G. Eller, G. The availability of milligram quantities of &UF~ also W. Halstead, and M. P. Eastman*). In connection with allowed an improved synthesis of ura32ium the investigation of organo U(V) compounds, we have pentaethoxidei28’129as well as other desired species, such species _—. _—— as (PPN)(UFG). Ijo.lsl The latter is sigtilcant *Universityof Texas at El Paso, Texas.

45 1 I I I # I I I 1 I I I

plyo.79

Fig. 25. TheEPRspectrumofpolyc~-stalliie[PPN](UF6)at 100”K(v —– 9.049GHz).

that is octahedral within experimental error and suggested that the observed EPR spectrum should be attributed to the low (triclinic) site symmetry and/or very small distortions of the UFZ octahedron.

2. Uranium(V) Alkoxides (P. G. Eller and P. J. Vergamini). An ongoing program is concerned with synthesis and characterization of interesting compounds Na[UF~ IN ACETONITRILE containing pentavalent uranium, one of the less studied valence states of uranium. Uranium(V) alkoxides have been known since the Manhattan Project,132 but recent studies have expanded greatly the knowledge of these interesting compounds. 133U(OCZH)S and U(OCZHS)Sme L&u+&u+ A the only known uranium compounds that are /iqu/d at

WAVELENGTH (rim) ambient conditions. Our investigations 134commenced with the preparation of several new uranium(V) reactions FiR. 24. with uranium pentaethoxide: Thenesuir spectrusnof&Uk, andN@F6]in variousnona- queoussolvents.

U(ORf)@C2HS)5-X(H0c2H5) 9 because we feel that it may be isostructural with the x = 4, & = C4Fg or CH(CF3)2 , unknown protactinium analog. Note that MUFG species have been shown to contain either six or eight coordinate uranium, depending upon the cation, whereas the few MPaFb compounds that have been studied all have a The new compounds were characterized by chemical protactinium coordination of eight. Another unusual reactivity, analyses, variable temperature NMR (13C, aspect of (PPN)(UFJ is that near ir-vis and ir spectra 19F, lH), and, in the Case of U(OC4Fg)@CzH~) indicated the presence of an octahedral UF~ anion with (HOC2H,), single-crystal x-ray diffraction. The new little or no distortion, whereas the EPR spectrum ex- compounds possess moderate thermal stability but are hibited an oct.horhombic g-tensor (Fig. 25) almost un- not unusually volatile. The compounds’ lack of volatility precedented for an actinide compound. 131 A single despite their highly fluorinated nature may be attributed crystal x-ray study verified the existence of a UF: anion to their large molecular weights.

46 A particularly useful result of our investigation was and U(OCGH~)~ are believed to be polynuclear.1321133 the demonstration that high-resolution ‘3C, 19F, and lH However, our single-crystal x-ray study revealed a ntono- NMR can be useful tools for characterizing U(V) meric cis-octahedral structure for U(OC4Fg)4(OCzHS) compounds. Despite the paramagnetism of these & (HOC,H5). Although the “ethanol” proton was not systems, reasonable resonance linewidths are observed located, it is assumed to be hydrogen-bonded between and the spectra are amenable to interpretation. For the cis-ethoxides. Unusual U-O-C angles are presen~ example, consider the *3C NMR spectrum of 1730 for U-O-C(C,Fg) and 158° for U-O-C(C,H,), U(OC&)~, shown in Fig. 26. As expected, at 15“C four consistent with the large steric congestion anticipated for resonances are observed with linewidths clearly reflecting this molecule and the lack of total ethoxide substitution the distances of the particular resonating nuclei from the by the much larger perfluoro-t-butoxy groups. pararnagnetic uranium. As the temperature is lowered, Some reaction chemistry has also been explored for the spectrum becomes more complex because of cluster uranium(V) alkoxides, and an improved synthesis of formation and/or freezing out of geometrically in- uranium pentaethoxide has been developed.13s’13s equivalent phenoxy groups. By *H NMR and “solution molecular weight measure- UF5 + 5 NaOCzH5 ~ 5 NaF + U(OC,H,)~ . ments, nonfluorinated derivatives such as U(OC2H~)~ 3. Interactions of 4f and 5f Cyclopentadienides with o SOZ (P. G. Eller). The objective is to search for novel metal-SOz interactions by using oxophilic 4f and 5f complexes as substrates. Such species might well favor oxygen and side-on binding of the SOZ and perhaps reactions in which S-O bond activation occurs. Thus far we have studied the interactions of several 4f and 5f cyclopentadienides with SOZ (Ref. 137). An example is:

X5S02 cp3ucl b cp3ucl.2 so, ,

where Cp = cyclopentadienyl. 5°C The substrate does, in fact, bind 2 moles of SOZ, but - the product has properties unexpected for a simple --J‘ adduct. The product is nearly air stable, contains irreversibly bound SOZ, is insoluble in common organic - 25°C solvents and thus probably is polymeric, and has an infrared spectrum which suggests a radical change in the bonding of at least some of the Cp groups and the absence of free S-O groups. The compound is formulated as the 0,0’-sulfiiate CpU(CpSO~zCl that results from insertion into M-Cp groups (Fig. 27). Similar results - 45°c _.L,Illwere obtained with Sm, La, and Th cyclopentadienides: 1- Xs S02 Cp3Sm & Cp(CpSO~#m ,

X5SO* ___-J;L?’c Cp3La ● Cp(CpSO~zLa , and 200 ppm 100

Xs S02 Fig. 26. CpdTh > cp(cpsoJ3Th . The C“ NMR spectrumof uraniumpentaphenoxide.

47 been useful in partitioning +3 valent actinides out of highly acidic high-level liquid waste (HLLW) from reprocessing commercial light water reactor (LWR) fuels.139

“\ :2 #\ / \ /OHex c p-OHex t!) ~ IJ Fig. 27. DHDECMP has been reported 139to extract Am(III) as Proposedstructureof “Cp3UC1.2SOfl. Polymericstructures AmL@-H)(NO~)2, where L-H is a deprotonated involvingbridgingsultinategroupsare also Possl%le. DHDECMP with a postulated “acac” type binding to Am (III), that is,

Thus, 4f and 5f cyclopentadienides in general appear to undergo Cp insertion reactions with SOT Possibly the ionic nature of the Cp bonding in the organometallic precursors and/or the oxygen-loving nature of the 4f and 5f metals determine the course of these reactions. Note that among the hundreds of known transition metal cyclopentadienides, Cp insertion has been reported only In conjunction with R. T. Paine and co-workers at the with certain Zr compounds (Table XV). 138 University of New Mexico and N. C. Schroeder at the Idaho Falls National Engineering Laboratory, we have 4. Actinide Extractant Chemistry (S. M. Bowen* attempted to crystallize complexes of DHDECMP (and R. T. Paine*, C. F. Campana*, P. G. Eller, and N. C. similar derivatives), in the belief that structure determina- Schroeder**). The compound dihexyl-N,N-diethyl- tions on such compounds will aid interpretation and carbamylmethylenephosphonate (DHDECMP) has design of improved extraction systems, for which the true —. extracted species are rarely @ ever) known.140 *Universityof New Mexico. We have succeeded in crystallizing and determining **Id~o Fdl.s National EngineeringLaboratory. the single-crystal structure of mercury complexes of the deprotonated DHDECMP ligand Hg- (DHDECMP-H)(NO,) and the diethyl analog TABLE XV Hg(DEDECMP-H)(N03). In contrast to the 0,0 bonded structure proposed for the extracted Am(III) species, REACTIONS OF SO, in the Hg(II) compounds the primary metal-ligand WITH SOME M-cp COMPLEXES interaction is through the methine carbon atom. A primary Hg-O(NOJ) is also present, and secondary interactions to phosphoryl and amide oxygens from a No Reaction with Cp Cp Insertion neighboring molecule lead to formation of dimeric units. CpzFe Cp#m A view of the structure of the diethyl complex, in which cp2Tlc12 CpJLa the central coordination geometry was found to be CPZHKIZ Cp,l% identical to that in the dihexyl compound, is shown in cpTic13 cp3ucl Fig. 28. Very recently, the x-ray crystal structure of a cpw(czHi)(sO,) Cp2Zr(CHJCl Th(IV) complex of DEDECMP was carried out, and CpMn(CO)2(SOJ [Cp#rCl],O 0,0’ binding, as proposed for the extracted AM(III) (c,H,)cr(cO)@OJ cp,zr(cHJ, species mentioned above, was formed.t Thus, these CpdZr ‘This information was provided by R. T. Paine.

48 C(4) plicated oxygen polyhedra are packed around cavities

c (3) that can accommodate ions of various sizes and charges. 8 The ions of neptunium, plutonium, and americium have different valences and, hence, difTerent sizes. It is C(sj extremely important in regard to these elements to 0(4) consider the effects of valence, size, and concomitant oxygen coordination number requirements (cavity size O(2I and geometry). The reasons are several. c(s)

0[6) (1) Alpha radiation and recoils can cause metamic- tization of the host material, C(7) (2) reduction of the actinide guest ion by radiation effects will cause lattice expansion, C(9I (3) oxidation of the actinide guest ion by radiation Cllol effects will cause lattice contraction, and (4) there can be changes in leachability of the actinide Fig. 28. as consequences. The structureof the UF,- anionin [PPN](UF,). Because actinide ions are the largest for their charge types in the periodic system of elements, it is useful to start with this consideration. phosphonate ligands indeed possess an unanticipated In Fig. 29 are shown dz~ferences in radii (for example, degree of binding complexity, and further structural Th4+ is 0.24 ~ larger than Zr4+).142Even though the work is mandated. radius of the higher actinides decreases by way of the 5f contraction, the Bk4+ ion (Bk is one past the series 5. Valence, Size, and Coordination Demands of Ac- midpoint) is still 0.06 A larger in radius than its tinides as Applicable to Storage in Synthetic Materials Ianthanide (rare earth) counterpart, terbium. (R. A. Penneman). Actinides, and especially americium, Indeed, when people focus solely on electronic con- are the major long-term contributors to nuclear waste figuration to select the Ianthanide congener of an actinide hazards. From about 500 years to 50000 years, 241Am (say europium for americium), they ofien fail to notice and 243Amlead all other elements.1” Actti~de ions are the size discrepancy. For the early part of the two series, Chatt-Ahrland Class A cations and strongly attract hard it is appropriate to displace the lighter 4f series -3 anions such as F- and O=. There is no doubt that the elements to the right to approximate ion-size equality. actinide 3+ and 4+ ions can be incorporated into Figure 30 shows this point and compares La3+ with U3+ cavities of the right (large) size, which can provide oxide ~d pr4+ with PU4+. Even SO, the oxidation chemistries of coordination of eight or greater. It still must be de- the two elements will differ widely; for example, Pr4+ is a termined whether radiation effects on the actinide far more powerful oxidant than PU4+ or Am4+ and is valences and on the surrounding lattice will affect about equal to Cm’+. actinide retention in a nonteachable state. There are many suggested matrices that can act as bosh for actinide storage: glass, cement, various syn- & thetic minerals, etc. All of these share a common basis; a zr that is, the actinide is always coordinated by oxygen. The I I .0.01 A nearest neighbors surrounding, for example, an Am’+ ion +O16k 1 I are oxygens, usually derived from a regular polygon. c~.lo rb— -0.07 qf Extremes range from simple oxide ions, as those in I I I ThOz, to oxygens primarily bound to representative +0.06 +0.06 +0;03, 0.04 8 elements such as silicon (silicate) and phosphorous 1 I (phosphate) and include oxygens shared with small, nl~ .Olt Be__.______+ &~* highly charged transition elements such as titanium (titanates) or molybdenum (molybdates). In all but the Fig. 29. simplest structures, tetrahedral, octahedra, or more com- Trendsin sizedifferencesof tetravalentelements.

49 .~ l_a3+Ce P#+ Nd ------4f TABLE XVI ------5f AMERICIUM-OXYGEN BOND A A DISTANCES ‘CT’P8{NPPU47L#t-F8 = 2.42 Pr’v-08 = 232 U“’-FB =2.42 IPU’V-08 = 2.34 Bond Distances Fig. 30. Coordination (A) For approximatesizeqtdvalenc~4V5fiStide4fseries-3 ele- mentsto right. Number Trivalent Tetravalent

8 2.47 2.33 Most of the host structures proposed to accommodate 10 2.55 2.40 12 2.47 guest actinides have not been studied with actinides 2.62 actually present, and all are deficient in that no studies have been conducted with the actinide in different valence states, for example, +3, 4, 5, or 6. In the absence of data we can calculate the effect of could well be disruptive, encouraging ion migration and valence changes by using the equations of W. H. expulsion from the host.1” Zachariasen, which relate bond to bond strength and are In the case of a simple structure such as ThOz, oxygen based on well-established structural data.143Thus, while loss can allow accommodation. However, when the one intuitively feels that a valence change of +3 to +4 in oxygens are bound to other elements (as in silicate and the same oxygen coordination, say 8, would cause bond phosphate), such oxygen migration and loss are not shortening, Zachariasen’s formulas provide quantitative possible. Thus, reduction of M’+ to M3+ must be figures. accompanied by a localized internal pressure in the Zachariasen’s equations are of the form lattice, trying to expand it to S.I1OWfor attainment of the now-longer equilibrium M3+ -O bond distance de- D(s) = D, – B in(s) , manded by the lowered bond strength. When equilibrium bond distances can be attained, where D1 is the bond length normalized to unit bond oxygen coordination increases the stability of the strength and (s) is the bond strength at bond length tetravalent state over the trivalent. Information on stabi- D(s).’42 For a simple example, in Th02 there is cubic lization of the actinide tetravalent states over their coordination and Th4+ is bound to eight equivalent trivalent states can be derived from the formation of oxygens. For Th4+ — OS,s = 4/8 = 0.5; for Th, DI = heteropolytungstates and molybdates,l” whose struc- 2.181. B = 0.35 A fors S 1. Thus, tures provide cavities in the oxide matrix that can accommodate M3+ and M’+ ions. Studies have shown D(s) = 2,181 – 0.35 ln(O.5) = 2.42 A. that Pu(III) and Pu(IV) are both complexed in solution by heteropolytungstates 14Sbut that Pu(IV) is much more If we put La3+ in place of Th4+ and remove oxygens stable*4b (as would be expected from the knbwn statistically to allow just six oxygens per La3+ vs the chemistry of plutonium). Another studyl” has shown eight for Th4+, the La3+-Oc distance is 2.43 ~, nearly that Cm(IV) in aqueous polytungstate solution is com- identical to that of Th4+-0~ [obtained from D(s)= 2.20 – pletely reduced in a zero-order reaction to Cm(III) in 0.339 ln(0.5)].143 1.5h when the alpha-emitter 244Cmis used. The studies of In the case of americium, the effect of valence and polytungstates and polymolybdates were conducted in oxygen coordination number is demonstrated in Table the presence of water and suggest an increased stabiliza- XVI. tion of M’+ over M3+ of -1 V. Because the Pu3+/Pu4+ The major fact to be observed from the table is that, at couple is -1 V, it is clear that PU4+ will be greatly the same coordination, there is a major increase of stabilized. The comparable americium couple is -—2.4 -0.15 A in the M-O bond distance on reduction of a V, so that stabilizing tetravalent americium by IV will tetravalent actinide to the trivalent state. Such a change still leave it unstable towards reduction to Am3+. It must

50 be determined whether Am3+ or Am4+ will be the stable Our recent successful attempt in this arealsl produced form, especially where radiation is present to eject a “lbw-temperature” phase of uranium molybdate, electrons into different lattices. We predict that PU4+will U(M004)Z, by the following reaction: be very stable and Am’+ metastable, but that Cm’+ will 1200”C be unstable. There is one catch: little is known about the UOZ + 2MoOq — U(M004)2 . relative stabilities of the various oxidation states of neptunium, plutonium, americium, and curium, when A single crystal selected from the solidified melt was incorporated in anhydrous minerals in the presence of examined by single-crystal x-ray diffraction and shown ionizing radiation. Their stabilities will be strongly in- to possess a structure (Fig. 32) with sheets containing fluenced by specific site size and also the presence or uranium, molybdenum, and oxygen connected by short, absence of other reducible transition elements, for exam- nearly linear U-O-U linkages (U-O = 2.059 A). ple, molybdenum, iron, etc. Uranium-oxygen bond lengths in the sheets are 2.39 (1)~, 2.32 (2)1$ and 2.20 (2)~. Molybdenum-oxygen 6. Actinide Molybdates (P. G. Eller, T. Cremers, R. bond lengths range from 1.869 to 2.002 A within the A. Penneman, and C. Herrick). The dissolution of plane and are 1.674 and 2.438 A between the sheets. zirconium-clad nuclear fuel rods in high-acid media can Space Group: Orthorhombic Pban, a = 20.069(4), b = lead to varying amounts of plutonium-containing in- 7.328(l), c = 4.1148(7)~ and R = 0.058 for 954 soluble residues (up to several percent plutonium con- reflections with I > 2@). This structure diiTers radically tent).14a’i49The possibilityy has been considered that from the high-temperature a form of UMOZOB,in which fission product molybdenum can allow formation of M004 tetrahedral (Mo-O = 1.62-1.96 ~) bridge between heteropolymolybdates that can incorporate plutonium UOC octahedra (U-O = 2.12-2.64 ~).1s2 The relatively into large heteropoly cages (see Fig. 3 l).lsO Some large difference in volume/formula unit, 177.0 fi3 for the structural and synthetic information is available on actinide-molybdates, but for the most part the area is chaotic. Our objective is to prepare and structurally b characterize selected actinide molybdate phases, with the > hope of gaining better insight into the formation of the I insoluble plutonium-containing phases mentioned above.

[U(M0,2042)]8- [U(M0,00Ml]8-

12-COORDINATE 8-COORDINATE

Fig. 31. Sketches of the heteropoly uranium molybdates [U(M0,,04J]’”,whichcontains12coordinateuranium~)and Fig. 32. [U(M0,00,,)]8-,whichcontains8 coordinateuranium\b)The Thestructureof the low-temperature(orthorhombic)formof octahedralunitsrepresentoctahedral(MoOJ polyhedra. UMozO~. a form and 151.3 A3 for the ~ form, also is consistent of fluorine and oxygen in PuOF, which resulted in a with the lower coordination numbers for the a form. reversal of the positions formerly assigned, provided a A few other phases, both synthetic and naturally striking demonstration of their utility. In the compounds occurring, are listed in Table XVII. A number of other of the class MOF (M = Pu, La, etc.), the x-ray data can uranium-molybdenum oxide phases are also known. be fit equally well, with either the Pu-O or the Pu-F An interesting aspect that the ~-UMozOg struc- distance Ming the shorter of the two. In Table XVIII ture shares with many seemingly dissimilar oxo- each choice is assessed. uranium structures is the occurrence of sheets separated The bond strengths can be calculated from the known by short, nearly linear U-O-U linkage with an interplanar bond distances in the structure. The formula D(s) = DI distance of 4.1 A. Some other structures in which this —B In(s) is solved for bond strength (s) and summed for feature occurs are: “ the elements. In Set 1, the bond strength sums to ridiculous values, in contrast to Set 2 where the values sum nicely to the expected valences in PU3+,02-, F1-. u-o (A) d (A) Ref. Thus, the Pu-O distance is the smaller of the two, whereas the free ion 02- is larger than F- and this size a-U30~ 2.073 155 order was used as the basis for the original assignment. p-u308 2.080 156 The shortening is a direct consequence of the bond UOzBr 2.054 157 strength. That is, each oxygen and fluorine ion is shared UV05 2.05 158 by 4-plutonium ions so that the bond strength of the Pu-O bond is 2/4 = 0.5 (VS0.4997 talc) and each Pu-F bond is 1/4= 0.25 (VS0.2363 talc from the formulas of W. H. Zachariasen1s9’ls‘? 7. Bond Lengths and Bond Strengths in Actinide In a similar manner all known actinide fluoride Fluorides (R. A. Penneman). In this section compounds were tested, resulting in some atom position Zachariasen’s formulas for actinide fluorides are tested reassignments. 1s9 Some representative compounds are and applied.ls9’ls0 The decision between atom positions listed in Table XIX.

TABLE XVII

SOME PREVIOUSLY REPORTED PHASES RELATED TO ~-URANIUM MOLYBDATE

Metal Formula Crystal System a b c Ref. Coord. No.

U(M004), Monoclinicor 3.36(6) 11.08(3) 6.42(5) 153 Unknown Sedovite orthorhomlic a-U(Mo04)2 TrigonaJ 17.30(1) 6.145(1) 154 Mo tetrahedral, U octahedra a-Th(MoO,Jz Trigonal 17.61(2) 6.259(5) 154 Mo tetrahedral, Th octahedra PU(M004)2 Orthorhombic 3.34 10.97 6.32 148,149 Unknown

52 TABLE XVIII 8. Actinide Oxo Chemistry (P. G. Eller, R. A. Penneman, and T. L. Cremers). In parallel with our PuOF studies on oxide phases (actinide molybdates) pertinent to Purex process problems (Sec. VI.B.6), we are also ● Locating the light atoms in oxy-fluorides, LaOF, PuOF. investigating unusual complexes of “yl” or “OXO”cations ● X-ray diffraction studies. such as UO~ and PaO~. In particular, we wish to ● Cannot distinguish between O and F. crystallize complexes of such species and to determine W. H. Zach_tiase~ Acts. Cryst. 4,231 (195 1). whether the linear geometry (as in aIl uranyl and known ● Ionic radii O > F-; is M-O > M_F? MO;+ species) or the angular geometry (as in nearly all transition metal “yl” species such as MoO:+) results. Use Bond Length — Bond Strengths This point is particularly significant for pentavalent protactinium, which possesses certain chemical proper- Set 1: PU-40 Pu-4F ties (such as hydrolysis/polymerization in acid media 2.569 ~ 2.385 ~ and propensity for binding “soft” donor Iigands) more S = 0.2952 s = 0.3745 akin to d-block than to f-block metals. Additionally, studies of such species are signMcant because protac- Pu = 2.68; O = 1.18; F = 1.50 x x z tinium is by far the least studied of the early actinides and because oxo favoring conditions are encountered in Interchange O and F Positions virtualy all nuclear waste cycles. We have begun to investigate the reduction of uranyl” Set 2: PU-40 Pu-4F ion with reductants such as Cr(II) and Ti(III) in non- 2.385 ~ 2.569 A aqueous solvents as a possible route to stable U@z s = 0.4997 S = 0.2363 species. Unlike the reported situation in water,lcl in a variety of nonaqueous systems such as DMF and z pu = 2.94; z o = 200; z F = 0.95 DMSO the resulting U@, (identified spectroscopically) seems to be quite stable (weeks, in some cases), and we are optimistic that crystalline U@2 complexes may be isolated and studied crystallographically. We have also TABLE XIX repeated French work, which claimed that UOZC1can be prepared by the hot tube reaction of UCld and U~O~at Dobsd Dcalc 590”C (Ref. 162). This reaction, indeed, appears to work Compound Coordinate (A) (A) as described, and we have collected an x-ray data set on single crystals resulting from this reaction. A complete Pu-4F 2.58 2.55 yPuOF structure determination is in progress. Attempts thus far PU-40 2.39 2.39 ( to dissolve this material in strongly coordinating solvents Li~ThF7 Th-9F 2.377 2.37 in order to prepare a complex containing a discrete, Th-3F 2.32 2.33 mononuclear U@z complex have been unsuccessful, but KTh,F,3 Th-4F 2.35 2.36 work continues. Similar chemical studies are being { Th-2F 2.51 2.49 carried out for the reported UOzBr compound.lc2)*c3 Electrochemical reduction of nonaqueous uranyl solu- K~ThFg Th-8F 2.33 2.33 tions will also be used. Subsequently, we will proceed to CsUFb u-m 2.057 2.06 prepare and characterize analogous PaOzX systems by similar means. Structural parameters for the MO; (NH4),UF, U-8F 2.28 2.28 moiety will be compared with those of other known NH4UF~ U-9F 2.33 2.33 M@z+ species and correlated with theoretical studies U-20 1.74 1.76 of such species. U0,F2 {U-6F 2.429 2.42 Properties of actinide monoxo species are also being investigated. For example, we have discovered that

53 UOF4 forms stable, soluble complexes with a variety of were included. The results of Hasek et al.1c7on the use of strongly coordinating organic molecules including SF, as a fluoridating agent were used for comparison. nitriles, sulfoxides, amides, and alcohols. The preliminary Olah’s studieslcs of UF6 as a fluoridating agent were re.wdts indicate that for UOF4 an extensive chemistry focused only on the organic part of the reaction, and his may exist, similar to that observed with UF~ (Ref. 164). suggestions as to the fate of the UF6 were incorrect; we These results suggest that other acdnide fluorides and therefore carried out our own examinations with UF& oxo species may also be solubilized and complexed, thus Because very little data concerning fluoridations by WF6 providing synthetic routes to new, unusual, and perhaps exist, we investigated these reactions also. volatile actinide compounds. Crystal structure studies Both inorganic and organic compounds formed in the are planned for several key mixed-donor compounds. fluorination reactions were identified when possible. We are also attempting to engage the aid of theo- Powder x-ray and analytical methods, as well as some ir reticians in understanding the reasons for the geometric spectroscopy, were used on solids. Spectroscopic meth- difference between f-block (linear) and d-block (angular) ods used included ‘9F and lH NMR, ir, mass spec- “yl” species. Despite many theoretical studies on the trometry, and visible UV. Gases, liquids, and solids uranyl ion, the fundamental reasons for the strong resulting from the reaction were examined. stabilization of the linear geometry remain unclear. This point is borne out by controversy over a recent paper a. Expen”ments. Unless otherwise noted, WF6 and which ascribes uranyl linearity to a cooperative interac- UF6 were diluted with CFCl~ (Freon 11) in order to tion between ftied 6p and empty 7s orbitals, a type of moderate reactions, some of which are quite violent. interaction not possible with d-block metals.lss Reactions where 19F and lH NMR were used for characterization were carried out in polyfluoroethylene 9. Fluorination Reactions of UFC with Organic Com- (PFE) plastic tubes resistant to both fluorination and pounds (L. B. Asprey and P. G. Eller). Numerous oxidation. A Varian 390 NMR spectrometer was used. inorganic fluorides have been used to introduce fluorine Large-scale reactions where ir was used for analysis were into an organic compound or to rupture the compound carried out in 30 mt’ Kel-F tubes. Metal ir cells with into various smaller organic fragments containing a AgCl windows were used for the u measurements on a fluorine atom. Several classification schemes have been Pekin-Elmer Model 180 spectrometer. Solids were ex- proposed to describe the behavior of these fluoridating amined by Debye-Scherrer powder methods. All solids agents. Probably the best known is that of Meshri and were loaded into capillaries in an inert atmosphere box. White,lce which divides these agents into hard, moderate, A Cary Model 14 spectrometer was used for visible-uv and sotl. Under this scheme, strong oxidizing agents spectra. For mass spectrometry, a Bendix Time-of-Flight containing fluorine, such as CIF, CIFJ, OFZ, KzNiF6, machine was used. and UF6, are hard agents. Moderates include HgFz, All compounds employed were of reagent grade and SbF3, SbFj/SbCl~, and AsFq among others; these are for dried thoroughly before use. WF6 and UF6 were purified the most part nonoxidative or slightly so. The soft class by trap-to-trap distillation to remove HF. includes alkali fluorides AgF, HF, SF,, COF2, and A typical experiment consisted of loading the desired others, which are strictly metathetical in their fluorina- organic compound, usuaUy 1-2 mmols, in a plastic NMR tion behavior. The distinctions between the several tube, distilling in 3-5 mmols of Freon 11 followed by the classes are blurred, and several well-known fluorinators desired amount of WFb or UF6. The tube was sealed off such as WFb are omitted. and placed in a standard glass 5-mm-o.d. NMR tube for Because we have worked extensively with UFb for examination. A similar procedure was followed for ir some years, we decided to study reactions of this hard study except that the amounts were increased to 5-10 agent and compare it to the behavior of nonclass~led mmols of organic compound, the amounts of other WF6 and to the soft SF@An extensive study of SFd as a reagents increased correspondingly, and the reactions fluoridating agent by Hasek et al.ls’ and a study of UF6 were carried out in a 19-mm-o.d. Kel-F tube. The by Olah et al.lcs have been reported. resulting gases were then expanded into an ir cell for Our work has been on the reaction of UFC and WF6 measurement. After removal of the volatiles, the tube with a number of simple organic molecules. Alcohols, containing solids was transferred to an inert atmosphere ethers, ketones, and acids, both aliphatic and aromatic, box for loading of x-ray capillaries.

54 b. Results and Discussion. Alcohols: Methyl alcohol c. Summary. From the above results, it can be seen in Freon 11 solution reacts cleanly with SFd to give that the fluoridating behavior of WFb is like that of SFq CHJF, SOFZ, and HF. UFC also gives CH~F, solid in most cases. It tends to react gently with functional ~-UF,, and an unidentified material. However, using oxygen groups to substitute fluorines for the oxygen, CHjOH as the solvent leads to reduction of U(VI) with with WOF4 the inorganic product. It is also unreactive in formation of a solution of UF~ in CHJOH and formation many cases where there are no organic functional of HF. WFC behaves very differently, with methoxy groups, as with alkanes and with aromatics such as groups replacing the fluorides in WFb one by one, which benzene. results in a whole series of WFX(CHjO)G_Xcompounds. The behavior of UF6 is very different from both SFq SFq plus ethyl alcohol in Freon 11 yields CzH~F and and WF& UFC is a strong oxidizing agent and tends to SOFZ cleanly, whereas UFC gives CzH~F, CH~F, and break C-C bonds, forming fluorinated fragments from CO, which shows C-C bond breakage. As with methyl the original compound and being itself reduced to U(V) alcohol, WFC forms an entire series of ethoxy- as UF~. Occasionally, it remains as U(W) and replaces fluoro-tungsten(VI) compounds. an oxygen, forming UOFd in a manner analogous to Ketones: Acetone reacts smoothly with SFd to give WF6. the ditluoroalkane CHjCFzCHJ and SOF2. In this case, WFb behaves similarly, with WOFd being the solid product. However, UFb oxidizes acetone to give a VII. ISOTOPE SEPARATION AND ANALYSIS considerable amount of tar and some CH3CFzCH~, UOF~, CO, and HF; all of the latter could be identified. A. Separation of Stable Isotopes (Carbon, Nitrogen, and Benzophenone reacts with SF, to give @CFz-$ in the Oxygen) and Production of Labeled Compounds (T. R. presence of a catalyst and heat. 167WFC in Freon 11 does Mills, M. Goldblatt, and R. C. Vandervoort) not appear to react. However, UFC in Freon 11 reacts smoothly to give +- CFZ-+and the orange solid, UOFd. The stable isotope separation program has the objec- Acids: Acetic acid does not appear to react with SFd tives of providing separated stable isotopes of carbon, or WF6 under the mild conditions used. However, UF~ oxygen, and nitrogen (ICONS) for research purposes and does react with glacial acetic acid to yield U02F, and also of developing new or improved techniques for other unidentitled products that contain UOF4 and incorporating the separated isotopes into commonly UOZFZ, probably UOZFZ.UOFA, UOZFZ,2UOF~, etc. desired chemical forms. As part of the stable isotopes Other organic products were not identified. resource (SIR) at Los Alamos, the isotope separation Trifluoroacetic acid reacts with UF6 by two paths. program distributes isotopic materials to SIR- approved One is light-catalyzed and yields UOFd, CFJCOF, and researchers. The remainder of isotopic materials are sold HF. In the dark, however, the predominant products are at cost to Los Alamos investigators or to the general UF~, CFd, and CO1, which shows breakage of a C-C research community through Mound Facility. The value bond. of isotopic materials produced for sales during FY- 1980 Ethers: Tetrahydrofuran’s behavior with SFAwas not was $585K. studied and did not appear in the literature. WF6 in The isotopes are separated by cryogenic distillation of Freon 1f reacts smoothly to open the ring and give CO for carbon isotopes and of NO for both nitrogen and CHZF-CHZ-CHZ-CHZF and solid WOFd. UFb in Freon oxygen isotopes. During FY- 1980, the quantities of 11 added to tetrahydrofuran resulted in a very violent isotopes separated were 5.6 kg 13C at 90°A enrichmen~ reaction, almost an explosion, and was not further 4.3 kg 13C(99%), 1.2 kg 15N(60+%), 0.7 kg lSN (98%), investigated. 58.2 kg *60 (99.98%), 0.1 kg ’70 (20%), 0.1 kg *70 Aromatics: Benzene does not react with either SFd or (50%), and 0.7 kg 180(10%). WFb at room temperature. However, a violent reaction The distillation columns, which are up to 225m occurs with UF6 with the production of tar. No further long, are of unique design.ls9 Several significant im- study was made. provements were made in the separation plant in AIkanes: SFh and WFG do not react with heptane at FY- 1980. As part of the 13C enrichment system it is room temperature. Addition of UFC to a large excess of necessary to promote isotopic exchange of CO spe- heptane results in the formation of tar. cies. A new CO exchanger was built, using the new

55 alumina-catalyzed exchange method (see Section Because this capacity limits the use of nitrogen isotopes VI.A. 1). The exchanger works at exchange rates up to 15 for tracer experiments, we have developed automatic mole/day with complete exchange and without losses equipment capable of handling several hundred samples caused by dkproportionation. Also, the process control per day, unattended. CEC-621 mass spectrometer was automated for in- The basic instrument is an isotope-ratio mass spec- creased speed and improved reliability. In early FY- 1981 trometer* whose inlet system has been completely re- the spectrometer wiUbe fully automated to permit totally placed by the new equipment. The circuitry has been unattended analyses. slightly moditled to permit automatic data monitoring Most of the isotonically enriched CO or NO is and tine automatic adjustment to the analyzer magnet converted to other labeled compounds for use by re- current for mass peaking. Samples containing 0.25 mg searchers. A variety of forms were prepared in FY-1980 nitrogen are pipetted into smail p[astic vials with 0. 15mt in batches ranging from several grams to several kilo- vol. After drying by flowing gas stream, they are grams of compound. Some products were made using mounted in a movable sample tray holding up to 137 precursors produced in previous years. Table XX sum- vials. The samples are then processed one after another marizes these conversions. and results are printed out and also stored on magnetic tape for later listing of the complete tray. The procedure used for sample processing is similar B. Automatic Nitrogen Analysis ( B. B. McInteer and J. to that developed manually since the f~st use of sodium G. Montoya) hypobromite by Rittenburg.*70 The reagent solution is only half as concentrated and is squirted through ..— Nitrogen isotopes are used globally as tracers for field capillary ~ubing 0.05 mt per sample. The greatest novelty and laboratory experiments directed toward clarification of the basic procedure is the use of a condensable purge of the nitrogen cycle. Thousands of sampfes requiring gas, Freon- 12, to displace the air above the sample isotope ratio determinations result from these studies. instead of evacuating the sample. This permits most Heretofore these samples in the form of ammonium salts ————— have been processed using a routine laboratory pro- *Model 3-60, manufactured by Nuclide, Inc., 62 E. ColIege cedure capable of handling 20-50 samples per day. Ave., State CoUege,Pennsylvania.

TABLE XX

Quantity Product Reactions (mol)

13C02 13C0 + (JUO + 13C02 + Cu 346 13CHqOH 13COZ+ 3HZ ~ CHZOH + H20 15 12c180 12C+ 1/21802 + 12C180 0.1 13CF4 13COZ+ SF, ~ 13CF4+ 2SOF2 0.02 12c1601E() Cu + 1/21S02+ CU180 CU’80 + 12C160+ 12C160180 5.6 12C180180 lZC + 215N1S0~ lZCISOISO+ lSN2 1.6 14NZ 214NH3+ 3CU0 ~ 3CU + 14N2+ 3H20 0.5 15NH3 lSNO + Hz ~ 1SNH3+ H20 59 H15N03 215N0 + H20 + 3/20z - 2H1SN03 19 K15N03 H1SN03 + KOH ~ K*SN03 + H20 17 (“NH4)2S04 15NH3+ HZS04 ~ (*SNH4)2S04 38 l~N2 21SNH3+ 3CU0 ~ 3CU + *5N2+ 3H20 16

H2170, H2*80 N*O + H 2*‘t H2*0 + NH3 50 1802 H2180 ‘l’@rO1ys*sF H2 + 1/21802 3.6

56 sample processing to be at ambient pressure. After the The necessary conditions for successful isotope sepa- reagent has caused the sample to release Nz gas, the ration are a high transmission of rare species and the resulting gas mixture flows to a small U-trap of stainless lowest possible cross contamination of the steel capillary tubing, which is chilled with liquid nitro- low-abundance isotopes with the nearby high activity of gen. This freezes out the Freon- 12 as well as trace an n,y isotope. This phenomena, called taihg, is present- impurities of the evolved gas, and the resulting purified ly at the 5 x 10-4 level at the M-1 position, where M is Nz flows to the mass spectrometer for isotope ratio the most abundant isotope. In many cases this is still one measurement. Tiny pneumatic valves were specially or two orders too high for good, rapid measurement of designed for this machine. The total volume occupied by the n,2n species. State-of-the-art separators are two to the sample gas is -0.5 cm3. three orders better than ours at present. Many of the procedures necessary for accurate, A modernization program has been in progress for the reproducible results are like those of a manual procedure past year to retrofit these separators with new electronic, for good mass spectrometry. A reference gas is run vacuum, and magnetic components to improve their regularly, and a record is maintained and checked in performance. In addition, new ion sources develop a computer memory for stable results. Similarly, the capability to measure isotopes of elements not previously background peaks at Mass-29 and -28 are monitored. In available to this method. Gold, iodine (as a positive ion), addhion, sets of standard samples of NH$30d of various the platinum group, and other rare earths in addition to isotopic compositions have been prepared for routine europium, thulium, and lutetium are under active de- checking of the machine. Incidentally, enough interest velopment. The goal of the ion sourcery effort is to have has been generated in other laboratories for these sources with sufficient versatility to produce a useful ion standards to be distributed internationally throughout beam from any element of interest. the scientitlc community. The ion optics of these separators are far from Certain sources of error are distinctive to this auto- optimum. The aberrations caused by both electrostatic matic machine. The Freon gas available commercially and magnetic imperfections are under study, using has an unacceptable level of nitrogen impurity, and we available computer codes. Some lens redesign has re- have designed and built a small distillation column, sulted in much less electrical breakdown in our lens operating at ambient temperature, to purify the purge system. The magnet optics are quite poor in view of gas. The seal between the polyethylene vial and the today’s technology. A study has begun to determine if holder has also proved unreliable, and a neoprene O-ring quadrapole and sextupole coils in the magnet gap will is now used for a more reliable seal. The pressurization improve magnet performance. of the reagent reservoir with gas causes some gas A large program is under way to provide ion beam solubilky and subsequent evolution in the sample vial, so diagnostic techniques that can guide the development we have used purified Freon there, too. Fresh reagent is and improvement of the separators. Present tools for this prepared for each tray, and it is degassed under vacuum purpose are rudimentary. before use. The twin needs of high transmission of material loaded The result of this development has been a capability of into the ion source and small tailing effects are the running a tray of samples at 120-150 s per sample. Our proximate goals. Their accomplishment will give the laboratory has processed about 4000 samples in its fwst weapons diagnosticians many more elements to use. year of operation and has capacity for many more.

VIII. ATOMIC AND MOLECULAR COLLISIONS C. Modernization of Isotope Separators (J. P. Balagna) A. Molecular Dynamics of the NO and Ozone The isotope separators that are presently in use are 16 Chemical Reaction (J. J. Valentini, J. B. Cross, and G. and 10 years old, and the designs are even older. These H. Kwei) separators have become a necessary tool in the weapons diagnostic program of the group. The ability to measure The chemical reaction between NO and ozone to an isotope produced by an n,2n or n,3n reaction after produce NOZ and oxygen is important and familiar to separation from a high-abundance n,y product has made chemists and atmospheric scientists. It is one step in the it possible to improve weapons diagnostic techniques. NOX catalyzed destruction of “odd” oxygen (oxygen

57 atoms and ozone) in the stratosphere and is central to the photochemistry of the polluted troposphere. It is also one of the most extensively studied of all chemical reactions, there beiig more than 20 papers in the literature dealing with it. Despite its familiarity, the dynamics of the NO/ozone reaction have not been clearly elucidated, because the reaction is quite complicated. The five reactant and product electronic states that are accessible in the reaction give rise to several possible reaction potential energy surfaces. We have completed a crossed molecular beam study of this reaction, the results of which show one striking new feature of the dynamics and clarify others. Figure 33 shows the angular distribution of the N02 product of the / reaction at two collision energies. A slight but unam- 0% \ biguous bimodality is evident. This results from the 1/ . ‘;? \ existence of two reaction channels, one leading to *B1,2 ‘ 00 electronically excited NOZ, the other to ground state *AI N02 This bimodality is more clearly evident in the Fig. 34. Center-of-massrecoilangleand velocityfluxcontourmapof center-of-mass recoil angle and velocity distribution of the NOZproductfrom the NO + 03 reactionat a relative Fig. 34, obtained by transforming the scattering data translationalenergy of 14.2 kcsl/mole. Contour map is from the space-f~ed laboratory coordinate system to a superimposedon the “Newtondiagram”showingthe most coordinate system in which the center-of-mass motion probableNO (0,,~= 0°) andO,(O,ti= 90°)velocityvectors.

has been removed. Here we see a very narrow, strongly No+03— N02 + 02 backward N02 peak and a broad sideways NOZ peak. i 1 J 1 1 ! 1 I I 1’ I Iq Conservation of energy considerations require that the 11 Q: 14.2 kcal/mole backward peak be assigned to ‘Al, N02 and the 16 sideways peak to 2B~,zNOZ. 14 Although it is admittedly diflicult to draw conclusions 12 about the character of the reaction potential energy

10 surface from the angle-velocity distributions for such a

I complex system, we can find no other explanation for the strongly backward peaked ground state N02 than that it 6 A 1 I \ comes about because the NO abstracts the central 4 - \ \ oxygen atom of ozone, with consequent strong product 2 — \ m. repulsive interaction. Such a mechanism, whale not 1 1 1 ! 1 I 1 I 1 0 1 I without precedent, is a surprising feature of the

10 — E,,: 1.6 kcal/ mole dynamics. T Our results also seem to contradict previous observations of an anamolously strong dependence of the reaction yield on collision energy. Over the energy range of 5 kcal/mol to 14 kcal/mol, we find that the overall yield of both 2BI,2 N02 and ‘Al N02 approximately quadruples. Previous measurements based on measure- LAB SCATTERING ANGLE ment of the chemiluminescence from the ‘B1,2products, as compared to our mass spectrometric measurements, Fig. 33. indicated an increase of more than a factor of 50.171We Angulardistributionof the NO, productfromthe NO + 0, reaction at relativetranslationalenergiesof 8.6 and 14.2 believe that there are features of the chemiluminescence kcal/mole.Oj besrnat 90°, NO beamat OO. from this reaction, such as an energy-dependent spectral

58 “blue” shift or a slightly energy-dependent branching source is in operation; no physical adjustments are ratio between states of widely varying radiative lifetime, required. that seriously affect the chemiluminescence yields and Comparisons of the mechanical temporal profile of the lead to overestimating the energy dependence of the valve, measured by optical techniques, and the gas beam reaction. temporal profde, measured by laser-induced fluorescence of Iz expanded in helium carrier gas, show excellent agreement, with the gas pulse being 5-10’XOshorter than B. High-Repetition-Rate Pulsed Gas Beam Source (J. B. the mechanical pulse. The pulse-to-pulse stability is very Cross and J. J. Valentini) high, fluctuations in gas pulse intensity being less than 594. Major advances in molecular collision dynamics and This pulsed gas beam source produces a nearly ideal spectroscopy have been made possible through exploit- supersonic gas expansion. Extensive measurements of ing the unique properties of molecular beams produced the temperature of the molecules in the beam, made by by the supersonic expansion of gas through a smaU inverse Raman spectroscopy, show close agreement with orifice. These properties, low temperatures (1-10 K) and continuum mechanics predictions for ideal isentropic high number densities (1013-1016molecules/cm3), aUow flow. For a pure methane expansion with a 0,50-mm high signal-to-noise experiments to be performed with a orifice and 50 psi backing pressure, we have observed a very nearly state selected group of molecules; that is, the rotational temperature of 9 K at a distance 32 mm partition function of the system is nearly unity. Con- downstream, where the pressure is 0.040 torr. The tinuously operating supersonic nozzles have been most predicted temperature here is 10 K. otlen used to produce these beams because of their The valve can be employed in a variety of molecular simplicity and high reliability. However, these gas beam beam spectroscopy experiments and because of its high sources generally require high pumping speed vacuum repetition rate should even prove useful in crossed systems, which are bulky and expensive. Because of this, molecular beam dynamics experiments. pulsed nozzle sources have been developed, in which the gas flow through the nozzle orifice is rapidly switched on and off by some type of valve. Such pulsed sources C. Coupling of Chemical Reaction with Ambipolar require only modest vacuum systems, because the gas Diffusion in a Flowing Afterglow Experiment: Applica- flow is reduced by the duty factor of the valve, that is, tion to Ion-Molecule Reactions of Uranium Hexatluoride the product of “on” time and the repetition rate, and at (G. E. Streit and T. W. Newton) low duty cycle the reduced flow can permit the use of peak nozzle throughputs 10 to 1000 times greater than is The flowing afterglow technique yields rate constants possible with cw nozzles. for ion-molecule reactions that are generally in good These pulsed sources are well suited to spectroscopic agreement with the results of other methods, such as or other experiments in which the intermittent nature of merged beams, high-pressure mass spectrometry, and the beam is not a hindrance. The pulsed sources ion cyclotron resonance spectrometry; it is thus well currently ?vailable, however, generally require complex accepted for measuring the rates of such reactions.l’z and expensive electronic driving circuits, have low repeti- An accurate determination of rate constants from tion rates and a limited range of pulse widths, and are flowing afterglow experiments requires the solution of the often somewhat unreliable. We have developed an inex- transport equation pensive, reliable, simple, high-repetition-rate pulsed gas beam source. The source was constructed by modifying ~ C?[A-] + 82[A-] ~(r) ~ [A-1= @A-) a commercial piezoelectric leak valve and is driven by a 8Z [ r Zk ~rz small signal generator whose square wave output is (1) amplified by a simple one-transistor amp~ler. t32[A-] + – k[A-][B] , The valve is highly reliable; we have obtained nearly az2 1 107 pulses without failure. It is also very flexible, producing pulse widths from 50 us to several ms at where V(r) is the radial velocity distribution, [A-] and repetition rates of more than 500 S.-l Significantly, the [B] are the reactant ion and neutral molecule concentra- pulse width and repetition rate can be varied while the tions, D~_ is the ambipolar diffusion coefficient, and k is

59 the second-order rate constant for the reaction between SCM I I A- and B. The negative charge on A was chosen only to A“ A-. B -c- be specific; it could as well be positive. Several groups D“ IS COUNTER ION have solved this equation by either analytical or numer- =s00 - ical techniques173-17cusing various simplifying assump- g tions. One of these is that loss of A- by diffusion is “E ~ccm - governed by a diffusion coeilicient that is independent of a the extent of reaction. For many reactions of interest this Ow assumption is not valid, and in our workl” we have c- m - made DA_ a function of the ion composition and solved Eq. (1) numerically. We consider a three-ion system in -.-1 which a reactant ion is converted to a product ion in the ([&]*[:)/[Al presence of a nonreacting ion of the opposite sign. The ion concentrations are such that the diffusion is am- Fig. 35. bipolar. Equations for the required ambipolar diffusion f Ambipolsrdiffu8ioncoetlicientsfor a three-ionsystemas a functionofcounter-ion-to-reactant-ionratioor 1+ (C-)/(A-). coefficients have been derived by Oskam*78 and for a positive ion and two negative ions are:

D,+ = 2D+~ estimate for the free diffusion coefficient for UF6 is D++D ‘ considerably smaller than for the reactant ions. For all the reactions, however, the experimental curvature was (2) greater than the curvature calculated with the diffusion coefficient of the reactant ion as a function of extent of reaction. This is illustrated in Fig. 36 for the Cl- + UF6 reaction. The best calculated lines through the first and

I I i i I I where D = (qlDl + IIz + Dh/(ql + IIz), D+, Dl, ad Dz Cl-+ UF6 are the ambipolar diffusion coefficients, D+, D ~,and Dz i are the free diffusion coefficients, q, and qz are the number densities, the subscript + indicates the positive ion and the subscripts 1 and 2 indicate the two negative ions. If the free diffusion coefficients DI and Dz difler significantly, all three ambipolar diffusion coefficients will depend on the relative concentrations of the two negative ions. This is illustrated in Fig. 35. k.s2 , lo”~ Our numerical solutions of Eq. (1) show that when the \ cA molecubis+ two free dill’usion coefficients are equal, a plot of the logarithm of the reactant ion concentration versus the h. 1.35 a 10-9 neutral reactant concentration is essentially linear, in clAnOJec”lo~ S* agreement with previous solutions of the equation. A However, when the free diffusion coetlicient of the \ product ion is less than that of the reactant ion, I I ! 1 I I significantly greater curvature is observed. M 7CI 105 MO 175 210 These results ha;e been applied to our experimental FLOW UF6 (i0.301m-em3s’) study of charge transfer from the negative ions F–, Cl–, Br-, 1-, and SFC- to UF6 (Ref. 179). In all cases, plots of Fig. 36. the logarithm of the reactant ion signal versus the UFb DataforthereactionCl- + UFC= C1+ UFC-plottedaslog ion signalvs UFt flow.A indicatesexperimentaldata. Solid flow were curved, like the calculated plot mentioned linesindicatecomputedIit8withtheindicatedratecoet?icients above. This is consistent with the fact that our best in cm3molecule#ls-i.

60 last portions of the data give rate constants that differ 1P(B). The second method is measuring the equilibrium from the mean by about 25Y0. constant for a reaction, thus yielding the free energy of Our results for charge transfer reactions to UFG are reaction. This may be accomplished only if the reaction summarized in Table XXI and show that all the rate is thermoneutral within a few tenths of an electron volt constants are slightly lower than for ion-induced dipole and if the neutral product is not a labile species. orbiting collisions, the Langevin limit; the rate constants We have investigated some ion-molecule chemistry of depend on the square root of the reduced masses of the SFC and SF~ and, in addition to several rate constant reactants; and the rates appear to be independent of the measurements (Table XXII), have determined values for energy of reaction. Our value of SFb– lies between the IP(SF~), AP(SF~+/SF~, the appearance potential of SF~+ previous two values. from SFC, and DOz,,(F#-F).’82 An examination of charge exchange reactions of SF5+ with the neutral molecules NO1 (IP = 9.75 eV), NHq(lO. 17 eV), D. Ion-Molecule Reactions by the Flowing Afierglow HZS(10.43 eV), Brz(10.51 eV), and Clz(l 1.48 eV) leads Technique: A New Technique: A New Determination to the establishment of the ionization potential of SF~ at of D~g8(F$$-F) and of the Ionization Potential of SF~ 10.5 + 0.1 eV. We have also determined an equilibrium (L. M. Babcock and G. E. Streit) constant for the reaction system CF3+ + SF6 ~ CF4 + SF~+.The equilibrium constant, K = (5.9 X 103)+ 50V0, In addition to using the flowing afterglow technique in yields a AGO~g~= -0.22 + 0.01 eV, and by using stan- determining rate constants of ion-molecule reactions, it dard entropies we obtain AH02g~= -0.17 + 0.02 eV. may be used to obtain thermodynamic information, such The appearance potential AP(SF~’/SF6) is obtained as ionization potentials (1P) and heats of reaction. from the following thermochemical cycle. Thermochemical information can be obtained from the two types of flowing afterglow measurement. The SFG~SF~++F+e AP(SF~+/SF6) frst is a “yes/no” method by which limits for the CF3+ + e ~ CF3 –9.17 k 0.08 eV ionization potential of A may be set based on whether it undergoes a charge exchange reaction with B, for which CF3+ + F ~ CF4 –5.42 + 0.17 eV the ionization potential is known. That is, if the reaction A’ + B ~ A + B+ occurs, then 1P(A) > 1P(B). Conversely, if the reaction does not occur, then 1P(A) < CF~+ + SF6 ~ CFd + SF~+ AH,gS = -0.17 i 0.02 eV

TABLE XXI NEGATIVE ION-UF, ELECTRON TRANSFER REACTIONS

Rate Constant (cm3 molecule-l S-l) [E.A. (UF,) - E.A. (X)]’ Reaction eV This Workb Langevin Prior Work -. .-— .—. -—. -

Cl- + UFC ~ Cl + UF; 1.5 1.1 x 10-9 1.5 x 10-9 6.5 X 10-10+_15wm%c Br- + UF6 ~ Br + UF; 1.7 9.3 x 10-’0 1.0 x 10-9 I-+ UF6~I+UF; 2.0 7.7 X 10-10 8.5 X 10-10

SF; + UF~ ~ SF6 + UF; 4.6 6.9 X 10-10 8.1 X 10-10 2.4 X 10-10+~5NW%C 1.5 x 10-9 *20%d ‘Based on E.A. (UFJ = 5.1 eV. b+ 50%0 CRef.180. ‘Ref. 181.

— TABLE XXII

ION-MOLECULE REACTIONS INVOLVING SFb OR SF~

k Reaction (cm3molecule-ls-’)

SF~+ + F + He SFC+ He+ -+ SFd+ + 2F + He 2.0 x 10-9 SFJ+ + 3F + He SFb + Nz+ ~ SF~+ + F + Nz 1.3 )( 10-9 SFG + N+ ~ SFf+ + NF 1.4 x 10-9 SF~ + C02+ ~ SF~+ + COZF 1.4 x 10-11 SFb + SOZ+~ SF~+ + SOZF 2.8 x 10-10 SFC + SO+ ~ SF~+ + SOF 4.5 )( 10-’0 SF~ + HjO+ # <5 x 10-12 SFC + NO,+ # <5 x 10-12 SFC + NO+ # <5 x 10-12 SF~+ + N02 ~ NOZ+ + SF~ 2.3 )( 10-1’ SF~+ + NHJ ~ NHg+ + SF~ 1.2 )( 10-9 SF~+ + H# ~ HZS+ + SF3 5.6 x 10-11 SF~+ + Brz ~ Br2+ + SF~ <4 x 10-12 SF~+ + Clz ~ Clz+ + SF~ <4 )( 10-12

Thus the appearance potential of SF~+ from SFb is 14.42 IX. MOLECULAR SPECTROSCOPY + 0.27 eV. Combining this with the ionization potential of SF~ yields D ;g8(F@-F) = 3.9 eV. A. Ultrahigh-Resolution Coherent Raman Spectroscopy Early work on the energy of the SF~-F bond placed it in Molecular Beams (J. J. Valentini, P. Esherick,* and A. at 3.29 + 0.17 eV based on shock tube studies1s3and at Owyoung*) 3.38 eV based on thermodynamic studies.184 More recently, chemiluminescence experiments done by Kiang Supersonic molecular beams provide a unique en- et al.’ss yield a somewhat higher value: 3.87 + at 0.15 vironment for molecular spectroscopic studies. By vari- eV. Our work is in excellent agreement with t.hk and ation of the beam operating conditions, specifically the represents the only other experimental determination of nozzle orifice size, the pressure behind the nozzle, and DO–zg~(F~S-F)that corroborates the theoretical value of the distance downstream of the nozzle where the spectra 3.99 ev calculated by Lyman 186 using are recorded, it is possible to select the temperature (300 Rice-Ramsperger-Kassel-Marcus unimolecular rate the- to “<10 K) of the molecules in the beam. This selectivity ory. Because SF6 has been used as a model compound allows the spectroscopist to control the distribution of for the study of laser induced chemistry and also because the molecules over rotational and vibrational states and the u multiphoton dissociation of SF6 has received much hence simplifies the analysis of complex molecular attention, an accurate knowledge of its thermodynamic spectra. Significantly, this temperature control can be parameters is of importance. effected while maintaining pressures in the beam that are — ●Sandia National Laboratories, Albuquerque.

62 orders of magnitude greater than equilibrium vapor We are presently applying this technique to the study pressures, allowing otherwise unresolvable or unin- of the high-resolution spectra of moderately large terpretable Raman spectra to be simplified and analyzed, polyatomic molecules, such as sulfur hexafluoride and even for relatively involatile compounds. ethane, as well as to the study of weakly bound We have recently completed the first experiments to molecules, such as tie argon dimer, which can be studied use coherent Raman techniques, specifically quasi-cw only in molecular beams. inverse Raman spectroscopy, in obtaining ultrahigh resolution (0.002 cm-l) Raman spectra in pulsed as well as cw molecular beams.167 Figure 37 shows typical B. Remote Detection of Ionizing Radiation by Raman spectra obtained for the v, vibration of methane in both Scattering from N,+ (A. H. Zeltmann) static gas and cw molecular beam. The substantial Doppler width reduction and controlled cooling possible We have investigated the feasibility of remotely detect- in the beam are evident here. ing covert radiation sources by Raman scattering from

A T=300K Ia

z o

T=50K

c -t I T-13K

RAMAN SHIFT (cm-l)

Fig. 37. Inverse Raman spectra of v, Q-branch of ‘ZCH4.Bandbead at 2916.472 cm-l, with higherJ transitions extending to higher frequency. (a) Static g% 1 torr, 300 L =Ideg optical crossing angle; (b) molecularjet, 350+M nozzle, 4.8 psi backing pressure+ 1.8 mm downstream, estimated density (cf. Ref. 188) 1.5 x 10’6 cm-3, z5deg optical crossing angle; (c) molecular je~ 100-w nozzle, 55 psi backing pressure, 4.5 mm downstream, estimated density (cf, Ref. 188) 2.2 X 10U cm-3, =5deg optical crossingangle.

63 ions (specifically N2+) that are produced in air by the background noise, which must be considered for a real radiation. The air above the source is probed by a laser system. Even with optimistic parameters our calculations and tht! Raman scattered light then collected by a large indicate that the signal strength would be too low for telescope and focused through a narrow-band light filter reliable detection by at least two orders of magnitude. onto a photomultiplier detector. N2+ ions are the chosen The basic limitations of the method are threefold: indicator ions because of the predominance of Nz in the ● Laser power and stability; 1 j/pulse; drift, 0.05 atmosphere. A’/h. We have conducted laboratory experiments in which ● The time that can be devoted to scanning a portion Nz+ ions in air and in pure Nz were produced by x of an area, - l/rein. radiation at levels of 4 x 105 R/h. To detect these ions ● The level of radiation, 1 R/h. we used resonant Raman scattering from the most It is a fair generalization that increasing laser power abundant rovibrational states of Nz+ in the P-branch tends to decrease stability and increases bandwidth. Both near K = 8, with the exciting wavelength at 3914 A.169 are detrimental. Without a major breakthrough, no The Raman scattered light was observed at 4278 ~ with improvements can be expected. a photomultiplier detector. Because the width of the dye The laboratory ion-producing and Raman detection laser line is 4.13 ~ and the absorbing line widthat3914 system we have constructed can, however, be profitably A is estimated to be 4.02 A, much of the dye laser employed to study ionic processes in gases by laser power is off resonance under the best conditions. The spectroscopy. dye laser wavelength cannot be controlled more closely than 0.05 A over a l-h period, and the drifl over the long periods necessary for measurement increases the ex- C. Optogalvanic Double-Resonance Spectroscopy: Ex- perimental uncertainty. perimental Observations 192(R. Engleman, Jr., and R. A. Calculations indicated that the rapid charge exchange Keller) process The optogalvanic effect (laser-induced impedance Nz+ + 02 ~ Nz + Oz+ changes in gaseous discharges) has become an important spectroscopic tool. When two lasers with wavelengths would reduce greatly the steady-state concentration of corresponding to different optical transitions are used to Nz+. However, the Nz+ fwst negative band fluorescence induce impedance changes in a discharge, a conjunctive etliciency in air and in pure Nz is roughly the same.190 signal is present when there is a common intermediate Nitrogen bands involving neutral species have their energy level involved in the two transitions. fluorescence reduced by a factor of 20 in air. Thus, it The elements studied were neon, uranium, and sodi- appears possible to make measurements equally well in um. The energy levels irradiated in uranium and sodium air as in pure nitrogen. are shown in Fig. 38 and the data are summarized in Solomon and Silva191have made a preliminary study Table XXIII. It is apparent that large effects are of Nz+ produced by x rays. Much of our effort was observed: optogalvanic signals associated with laser B concerned with duplicating their Raman cross-section can be tripled when laser A irradiates a transition measurements. We have observed the x-ray fluorescence terminating in a common intermediate level. spectrum reported in the literature190 and have detected Inspection of Fig. 38 and the data in Table XXIII Raman scattering from Nz+ at 4278 A. The cross-section shows that, in sodium, energy transfer can occur to a estimate from our measurements agrees with those nearby level, which is not common to both laser reported by Solomon and Silva. irradiations, and can result in a conjunctive signal. Calculations based on this cross-section for Raman Similar effects occur in uranium. Energy transfer will scattering indicate that this method for detection of always be a problem when this technique is used to covert radiation sources is not feasible. Our most determine a common intermediate energy level involving optimistic estimate of the signal at 250 m is 0.05 photons these two transitions. On the other hand, this effect can detected per second. This signal cannot be reliably lead to interesting information concerning energy- detected unless the observation time is intolerably long in transfer processes in atoms and molecules. a system whose time stability is measured in fractions of Finally, it should be noted that, although this method an hour in he laboratory. We have not assumed any can be used to discern connecting energy levels and help

64 17361 an-l A’

/ 16SKI0 cm-l //////// ///// “h T I

5972 & -5915 ~ 7632 A- ~7639 a

4275 cm-’

3600 cm-’

SODIUM URANIUM 620 cm-’

Fig. 38. P Energy levels and irradiated transitions in sodium and uranium for optogalvanic double-resonance spectroscopy. Laser A tuned off resonance (A’) had no effect on OGE@). Fig. 39. Energy levels and irradiatedtransitions in uranium for laser- enhanced emission studies. The wavy line denotes the oc- in spectral assignments, it is no more sensitive than currence of energy transfer but does not imply a spccitic mechanism for this transfer. measuring changes in emission intensity, and it is significantly more complicated. An example of finding connecting levels in uranium by inducing changes in uranium atlas. Note that the 7639-A emission is from the emission intensities is shown in Figs. 39 and 40. The energy level at 17 361 cm–’. The intensity of this spectral assignments shown in Fig. 40 were obtained emission is doubled (Fig. 40a and c) when the laser is from the data in the Los Alamos National Laboratory’s tuned to irradiate the 5972-A transition that terminates

TABLE XXIII

CONJUNCTIVE EFFECTS FOR DUAL-LASER IRRADIATION OF A HOLLOW-CATHODE DISCHARGE

OGE Power A Power B OGE (B) (B + A) :) f) (mW) (mW) (mV) (mV~ Sodium 5895 6154 120 140 5 10 5889 6154 140 140 5 6b 5889 6161 140 130 7 10 5895 6161 140 150 10 1lb Uranium 5915 6067 120 50 25 70 ‘Laser A, dc. Signalis B ac signalenhanced by A. bNocommon energy levels.(SeeFig. 38.)

- 65 D. Locking of cw Dye Laser Emission onto the 1 Wavelength of Molecular Fluorescence by Intracavity Gain: Example 12193(K. A. Truesdell, R. A. Keller, and E. F. Zalewski”)

Locking of laser emission to wavelengths of molecular fluorescence is potentially useful for wavelength standards, molecular excitation for photochemical reactions or fluorescence analysis, gain measurements, and state selection by stimulation emission. In a few cases, that is, Iz, Naz, Liz, Biz, and Tez, cw dirner lasers have been developed for these purposes, but we believe that the technique using the gain present in the dye medium will be more generaUy applicable. For state selection by stimulated emission there is c considerable advantage to placing the sample inside the cavity of the dye laser. State selection by stimulated emission involves the use of a pump laser to excite a molecule to a specitlc v’, J’ level of an excited electronic state and then stimulation of emission from this state to a specific v“~” level of the ground electronic state. It is J_JLldifiicult to use two independent lasers for this purpose because the wavelengths of each laser must be controlled m. 40. to within a few MHz so that the same portion of the Uranium-emission .mectrssfr~m a hollow-cathode dkehame. Doppler distribution is addressed by each laser. Placing The verticalaxis is&e same for all spectra. a. No laserirrad~a- the sample inside the dye laser cavity automatically pulls tion; b. 240 mW of laser irradiationat 5915 ~; c. 270 mW of the dye laser emission onto the desired fluorescence laser irradiation at 5972 A. wavelength. An additional advantage of this technique for some applications is the high circulating power available inside the dye cavity. _@the 17 36 l*m-l level. Similar results were obtained The introduction of small optical losses inside the with emission at 7632 A when the laser was tuned to cavity of a broadband dye laser decreases the laser 5915 ~. Energy transfer is also apparent in Fig. 40 by power at wavelengths corresponding to the absorption the increase in the 7632-A emission when the laser is losses. The laser output is extremely sensitive to these tuned to 5972 A, or by the increase in 7939-A emission losses, and this phenomenon forms the basis for in- when the laser is tuned to 5915 A. The emission line at tracavity absorption spectroscopy. In a similar fashion it 7635 A is from an energy level at 20420 cm-l, which is has been demonstrated that introduction of small optical too far removed from 17 361 cm-l for appreciable gains into the laser cavity results in the laser locking onto energy transfer to occur. wavelengths corresponding to these gains. For example, Optogalvanic double-resonance spectroscopy would gains as small as 0.0003 were sufllcient to lock a dye be useful for laser-wavelength control in experiments laser to emission wavelengths from a helium-selenium requiring sequential photoexcitation involving a common discharge placed within the laser cavity. The small intermediate level. There may also be some cases in optical gain required for laser locking means that this which emission cannot be readily observed because of technique should be applicable for many molecular small quantum yields or highly luminous backgrounds; systems in addition to those that exhibit sufficient gain to in those cases, the double-resonance technique ‘would act as lasers by themselves. present distinct advantages for discerning common in- ——— termediate-energy levels. *NationalBureau of Standards, Washington, D. C.

66 In the present work a single mode Ar+ laser is tuned to Ar”.006W excite the P(13) and/or R(15), 43’ - O“, B3110U+ DL *O09W XIZO~ transition in molecular iodine. The Ar+ laser radiation is then passed through the dichroic end mirror of the dye laser cavity and into a sample cell of iodine. Iodine fluorescencehas been detected on transitions v’ = 43, J’ = 12 and/or 16 to J“= 11, 13 and/or 15, 17, v”= L AI”.012W DL .OIOW Oto 86. This fluorescence introduces gain into the optical cavity at the corresponding wavelengths; when the dye laser is tuned near to one of the fluorescence wavelengths, locking occurs, with the result that a L substantial amount of the dye laser output is at a Ar”. O wavelength corresponding to a particular iodine DL=OIOW fluorescence (Fig. 41). The major conclusions from this work are: (1) An organic dye laser is sensitive to small optical

gains as low as 0.0001 are sufficient to lock a portion of J_ used effectively to lock a large portion of the laser output Ar” .0 onto wavelengths corresponding to molecular DL.009W

fluorescence. We have demonstrated that single-pass @ gains as low as 0.001 are sufficient to lock a portion of the dye laser output onto 12fluorescence frequencies. (2) The intracavity gain-probing technique requires J_ R(15) 43’-13” wavelength control of the pump-down laser of only +6 A. In contrast, if a single-frequency extracavity method were used for gain detection, the pump-down frequency c would have to be controlled to within a few MHz. 5%7 5%3 59s9 (3) The dye-laser-assisted 12 laser should be useful for WAVELENGTH (~) state selection and photochemical applications. These Fig. 41. experiments could be performed either extracavity or Dye laser assisted Iz laser spectra for 43’ – 13” transitions. intracavity, and the efficiency of the system can be Ar+ = Ar+ – Izpump laser power, DL = dye laser circulating maximized by judicious choice of the transmission power, 19 cm 11cell. (a) Dye laserwith Izinside the cavity and characteristics of the output coupler. the.Ar+ – 12pumplaser tunedoffthe43’– O“absorption,P12 = 0.3 tom.(b) Dye laser with 11inside the cavity, P,2 = 0.3 torr. Ar+ – Iz laser is tuned to R( 15)43’ – O“absorption. (c) Dye laser with 12inside the cavity (no Ar+laser),P,2 = 0.3 E. Photoionization of Polymers of Hydrogen Sullide torr. (d)DyelaserwithoutIzinsidethecavity(noAr+laser), and of C~bonyl Sulfide (N. C. Blais and E. Walters*) P,2 = O. (c) Iz tluoreseence, P12= 0.3 torr, Ar+= 0.11We, Ar+ – Iz laser tuned as indicated in (b). The intensity scale is the same for a-d. The photoionization work currently being conducted in Group CNC-2 is directed at obtaining properties of ions of van der Waals molecules and, where possible, the The apparatus consists of a monochromatic photon properties of the neutral molecules.194’19sBy comparing source, a free jet expansion molecular beam source,. and the variation of some of the measured properties, such as a moderate resolution mass spectrometer. 194 Besides the ionization potential, with the size of the molecular cooling the beam molecules sufficiently to produce cluster, we can begin to obtain values for bulk properties measurable concentrations of molecular clusters, the free from those of the individual molecules. We report here jet expansion also collapses the distribution of initial on the photoionization yields of carbonyl sulflde and its rotational states of the molecules to that characteristic of dimer and of hydrogen sulfide and several of its a temperature of less than 100 K. As a result, the polymers. .—— ——— resolution of the photoion yield curves approaches the *Universityof New Mexico. optical resolution of the monochromator. For the

67 monomeric species the optical resolution is about 12 Born-Haber cycle gives a value of 0.45 + 0.01 eV for the meV (1.5 ~), whereas for the polymers the optical van der Waals bond energy of (OCS)Z+. Table XXIV resolution is 32 meV (3.7 ~) because wider slits are used. summarizes some of the transitions of the OCS molecule Figures 42 and 43 show the photoion yield per photon that we have identified in the photoion spectrum of the for the carbonyl sulfide (OCS) system. Figure 42 is for monomer. the monomer OCS+ and Fig. 43 is for the dimer Figures 44 and 45 show the photoion yields of the H# (OCS),+. “The energy threshold is clearly lower for the molecule and its dimer, respectively. Autoionization dimer than for the monomer. The autoionization peak at makes the monomer spectrum of HZS more complicated about 1010 A is sharp and narrow for the monomer and centered at 1017 A. For the dimer it is broadened considerably and shifted slightly upward in energy. Both TABLE XXIV changes are the result of the presence of the other moiety, the neutral OCS partner. Application of the IONIZATION THRESHOLDS AND SPECTRAL ASSIGNMENTS FOR OCS+ AND (OCS); E(eV) 10.332 10.781 11.271 II .808 12.399 13.051 1 1 1 1 Ionization G Ion Threshold Wavelength OCS hv-OCS++ e- .=C 3 + 98619 cm-l n L J o 0CS+(T13,J 11.179 1109.1 1 J * ocs+(’l-rl,J 11.213 1105.7 ~ - ● (Ocs); 10.74 1154.2 : - 9* e AE Spectral F - . g Wavelength (cm-’, +50) Assignment = !-l

z~ I 1100.7 688 3/2 + VI 1200 1150 I100 [050 1000 950 z~ 1097.4 684 1/2 + V1 WAVELENGTH(~) z~ 1093.5 1286 3/2 + 2V1 2~ F~. 42 1090.1 1294 1/2 + 2VI 2~ The photoion yield per photon for OCS+. Errorbars are less 1085.2 1986 3/2 + v3 or svl then the size of the circled points. 1081.7 2007 2rI~lz+ v3or 3V1

E (eV) [0.332 10.781 11.271 11.808 12.398 13.051 I I I I E(eV) (OCS)2+hv-(OCS~ + e- 10332 I Q78 I II Ileo . ,9 51 s . . .- % H2S + hv +H2S*+e . . C --- “. 3 .“. . -t + s .“.” “ .. .. 98619 cm-l ?? . ..’”.. 0 . ..-. “.. & ...... “.o .“. . a ‘. - & . ,...... - . . ~ - 4* ‘IP.1186.5 X -z -10.449 tOD06aV . . “ “ )+ I ~ ..> .. ; . . fl+@## % z t s \ “ ~ .Y.e’< ;;: g IP=I154.2 ~ ,...*. .-: .W = %:? ‘pw’w’w~ x *e I-4 :1 ‘ ‘7”8: @ L’.’, I ,~,,,,,,,,1 .@ 1200 1150 Ilcm ICXX 9s0 1 WAVELENGT; ?( ! 1200 1150 1100 1050 1000 950 WAVELENGTH (A) Fii. 44. The photoion yield pcr photon for HzS+. Typical error bars Fig.43. are shown. Near threshold, the statistical errorsare less then The photoionyieldper photonfor the diner, (OCS),+. the circled points.

68 E (eV) hydrogen bonding, which should occur as with H20, is i37 9.918 10.332 10.781 11.271 11.80s 12.398’ 13.051 responsible for the departure from a straight line, but

. O+2S)2● hv-(H#~ ● e virial coefilcient data indicate an unexceptional bond ,-25x strength for the neutral dimer, 0.028 eV.’98’1ggThe dimer J ion is bound by 0.74 + 0.01 eV. Bonding of each 1P-1273.11 :“ “. . additional HZS unit in the ion can be obtained from Fig. . w * 0.0I # I OV* 46 with additional assumptions about the small nuetral ● bond strengths. ✎☛✎ ✎

✎☛✃☛✎ ✎ ✎ ☛ d. ..O” . @d-””d F. Evaluation of the Vibrational Transition Moment for *“ the UzBands of 14NDJand ‘5NDJ (L. H. Jones and B. J. , 1 t Krohn) m 1250 1200 1150 1100 1050 Iwo 950 WAVELENGTH (~) In connection with the development of lasers for F~. 45. irradiation in certain regions of the infrared, we desired The photoion yield per photon for (H$)Z+. The insert is the region near threshold and has the same wavelength scale. to know the vibrational transition moment for the Uz bands of “NDj and *SNDJ. These vibration-rotation bands had been previously observed and analyzed by than the spectra of CSZ or OCS within the same energy one of US2Wat relatively high resolution (0.04 cm–l, full range. As was the case with OCS, considerable broad- width half maximum). The best approach is to measure ening of the autoionization peaks occurs in the (HZS)Z+ the true integrated intensities of a number of individual spectrum. Much of the analysis of the HZS+ spectrum lines of known vibration-rotation transition. To resolve remains to be done, but several very interesting proper- individual lines this requires a pressure of 10 torr or less. ties of the polymers are quickly obtained. Figure 46 The true line widths are then narrower than our resolu- shows the variation of the ionization threshold energy tion. This required development of a computer program with the number of HZS units comprising the van der for deconvolution of the true line intensity from the Waals molecule. In contrast to results for other observed width and peak absorbance. The line shape polymers,194’19c’197a straight line does not fit these data assumed was a Voigt function, which combines because the relative strengths of the bonds as monomeric Gaussian character because of Doppler broadening and units are added to the polymer. One can conjecture that Lorenzian character because of pressure broadening.

105 1 I i I 0 1 Applying this treatment led to a transition moment of 0.179 + 0.010 Debye for both 14ND4and lSNDJ. These lead to a derivative of the dipole moment, Ii3K/~Q,l = 93 cm’” s.- 1 A manuscript describing these studies is now in press.zol

G. Low-Temperature Impurity-Doped Solids

1. High-Resolution Infrared Absorption Studies of SF6 and SeF~ Trapped in Noble Gas Solids (L. H. Jones, B. I. Swanson, and S. A. Ekberg). Matrix isolation spectroscopy has become widely used to study molecular structure, isotope shifts, free radicals, V-V energy transfer and other effects for which lack of rotational and I/n collisional complications is desirable. A premixed gas is Fig. 46. deposited onto a sample plate at cryogenic temperature. The ionization potential in electron volts of H2S polymers, (H,S)”, where n is the number of H,S units in the polymer, The guest, or impurity, is generally quite dilute (mole plotted as a function of I/n. fraction 10-3 or less) in the host matrix to minimize

69 aggregation and resonance interactions. The host is commonly a noble gas (neon, argon, krypton, xenon) or nitrogen because the~e are relatively inert species and will not tiect significantly the structure or vibrational energy levels of the guest molecules. Although it is RESOLUTION generally recognized that there is always some host-guest \ interaction, the nature of such matrix effects is not well understood, and they are generally ignored. However, for such little understood phenomena as energy transfer and molecular dynamics in matrices, it is important to understand the matrix-molecule interactions. For example, it has been reported that CH3F does not rotate in a low-temperature argon matrix;zoz yet recent V-V energy 0.04CM‘1 transfer studies of CH3F in argon matrices203 indicate that relaxation occurs by transfer of a quantum of the RESOLUTION C-F stretching vibration to a rotational level of high quantum number (14- 18). We hope to resolve such ‘-- contradictory results by detailed studies of JI I I matrix-molecule interactions using high resolution. 936.0 _, 940.0 In the past, and even today, most infrared matrix cm-’ studies are carried out at fairly low resolution (- 1 cm-l), Fu.47. leading to concealment of many of the enlightening Speetrum of SFC in argon a; 10 K at a ratio of 1/10000. details of the absorption spectra. With the use of Resolutionis as indicated high-resolution infrared studies (0.035 cm-l), we have resolved structure revealing new and important matrix effects. Much of this work has been carried out with SFG in noble gas matrices. As an example of the value of high 21 K resolution, we present Fig. 47, which shows the v~ absorption band of SFC in argon at both 0.5- and 0.035-cm-’ resolution. SFS is anoctahedral molecule for which V3, the antisymmetric S-F stretching mode, is triply degenerate for the truly unperturbed molecule. The 0.5-cm-i spectrum shows little detail; however, the 16 K high-resolution spectrum, as reported earlier,204 shows o al much sharp, fine structure, which indicates multiple . trapping sites and site symmetry splittings. In Fig. 48 we show the effect of temperature variation on the observed vibrational spectrum. Note that in IOK heating from 10-16 K, peak H disappears (actually it A merges with I). This temperature effect is completely reversible, although in some cases spectral changes with I $E ,0 93b. o 93’?.0 9313. O 93!4) .0 9d3. o temperature indicate irreversible phenomena, such as l/cll aggregation, change in site structure, or change in crystallite size. We attribute this temperature reversible Fig. 48. v, absorption, Ar/SF6 = 10 000 annealed at 30 K. Tem- coalescence to dynamic site exchange induced by vibra- peratures as indicated. tional dephasingms and will discuss it further in Sec. IX.G.2. We believe that peaks H and I are site symmetry for SFGin an argon matrix under the conditions of Fig, split components from one site and that E and F are 48. from another site, Including the other peaks observed, we SF6 in a krypton matrix shows rather different struc- conclude that there are at least six different trapping sites ture. Of particular interest is a striking difference for

70 34SFCand 32SF6as shown in Fig. 49. This compares the a C02 laser falls on the low-frequency wing of the strong spectrum of the two isotopic species in a matrix contain- peak whereas 10P32 (933.00 cm-l) lies in the middle of ing equal amounts of 32SFCand 34SF& In particular, note the high-frequency coalescing doublet. that the strong 34SF6 peak is sharper and more sym- We have also studied the spectra of SeF6 isolated in metrical than the analogous peak for 32SFb,which has a noble gas matrices. It is somewhat larger than SFb and side-band structure. The only explanation that occurs at thus gives us a probe into the effect of change in size of present is that the vibrational amplitudes differ, particu- the guest within a given matrix host. In Fig. 50 we see a larly in the excited state. The greater amplitude for V3of rich display of absorption peaks because five isotope 32SF6may lead to greater interaction with the phonons, species contribute significantly, each one giving rise to leading to phonon side bands. This requires further seven peaks. Fortunately, the isotope shift for a mass investigation. One other point to notice is that the two change of two is greater than the spread of peaks for one high-frequency doublets coalesce with increase in tem- isotope. Thus it is not dKtlcuh to assign peaks to a given perature, another example of dynamic site exchange.20b isotope. The fimestructure is duplicated for each isotope Temperature dependent studies of SF6 in a xenon with the appropriate intensity. By comparison of lattice matrix show that a high-frequency doublet of V3exhibits constants of the matrix and molecular sizes, we might dynamic site exchange and amazingly shows a kinetic expect SeF6 in krypton to have a spectrum similar in isotope effect (see Sec. IX. G.2)207. Other groups are structure to SFC in argon. Although the spectra are not studying V-V energy transfer of SF6 in noble gas duplicates, there is some correspondence. In particular matrices by pumping the V3mode with a C02 laser and we note that the doublet slightly above 772.0 cm–’ shows studying the relaxation from excited vibrational states.* dynamic site exchange and coalescence in the same To interpret such results satisfactorily, it is important to temperature range as does SF~ in argon.208 This is understand what transitions are being pumped. For discussed further in Sec. IX.G.2. example, for SF6 in argon at 10 K there are only two SeFc in xenon shows structure and dynamics similar near coincidences of C02 laser lines with SFb absorption to SF6 in xenon. In an argon matrix, however, SeFd does lines— IOP26 (936.83) is slightly below peak B. (Fig. not resemble any of the SFCmatrices and does not show 48). We note that the absorption lines shift slightly, in an evidence of dynamic site exchange.209 unpredictable fashion, as temperature is changed. Thus, with a knowledge of the high-resolution spectrum and the frequency shifts with temperature, one can hope to optimize the pumping etlciency. For a krypton matrix at 10 K, the only near coincidence is from IOP30 (934.92 cm- ‘), which hits on the low-frequency side of the strong peak. For SFC in xenon at 10K, 20P34 (931.05 cm-l) of S9K — *This information was provided by L. Abouaf-Marguin, Universityde Paris-Sud. --J@’J’

9K -1

,“ 93 .0 n9Li.0 ask .O Ai; mmk.o sA.o sak.o sA. o wb.o ,0 76b. Q 77j. o 773.0 i’7k. cI 77’?.0 779.0 .7BI. Q 1/m

Fig. 49. Fig. 50. v, absorption for 32SF6and “SF. at 10 K. Krp2SF/4SFe = v absorption for SeFc, naturatabundance Kr/SeF6 = 10 000; 10 000/0.5/0.5, A = ‘2SFb; B = “SFt. Frequency scale is annealed at 39 K. Numbers over bracketed regions indicate shfied by -17 cm-’ for “SF& selenium isotopic maw.

71 We have not yet discussed the trapping cages we XXV. Using the gas phase frequencies 211for V3 and expect ,for these octahedral molecules in noble gas VA(778.5 + 2 cm–l and 436.0 t 5 cm-l), we have matrices, which have a face-centered cubic structure. In calculated the potential constants for SeF6. The com- Ref. 206, we conclude that in argon, krypton, and xenon, puter program was altered to refine on the isotope shit?.s SFCand SeFt are too small to tit satisfactorily in place of as well as on the frequencies of the main isotope, using six host atoms. However, they will fit rather snugly in a weights in accord with the above estimated error limits. four-atom substitutional site in Td (tetrahedral) sym- The results are listed in Table XXVI along with earlier metry. Therefore, the relevant spectroscopic point values of Abramowitz and Levin211estimated with the groups for these molecules are Td (a subgroup of 0~ aid of the Coriolis constant ~ calculated from band and the subgroups of Td. This tells us, for example, that contour analysis of Vd. Within experimental error our SFCcould reside on a site of symmetry Cqvor C, or any results are in agreement with those of Ref. 211; however, of the other subgroups of Td within a Td trapping cage ours are determined with greater precision. This is resulting in splitting of the v~ mode. We have not yet another demonstration that accurate isotope shifts meas- been able to sort out the symmetries of the various ured in a neon matrix are quite useful for estimation of observed sites. potential constants. FinaUy we would like to discuss results for both SF~ and SeFt in a neon matrix. From the size we conclude 2. Dynamic Site Exchange and Vibrational Dephas- that these molecules must replace six neon atoms and ing on a Picosecond Time Scale (B. I. Swanson and L. may thus maintain octahedral symmetry.zos Because of H. Jones). Matrix isolated molecules are expected to distortions, however, the V3mode could be split into two exhibit rich dynamics ranging from rigid structural or three absorption peaks. We note that the major arrangements at low temperature (T <10 K) to diffusion absorption in each case consists of three peaks, suggest- at temperatures well below the melting point ing low symmetry because of distortion from Oh sym- of the host matrix. Surprisingly, the only dynamic metry. If it were possible to follow these absorption to process that has been studied in any detail for high enough temperature, we might observe coalescence low-temperature matrices is hindered molecular rotation from dynamic averaging. The absorption in neon are of diatomics and other small molecules.zlz These earlier fairly close to the gas phase values for v~ [-947.7 for studies were carried out at relatively low resolution (-0.5 SF6 (Ref. 210) and 778.5 for SeF6 (Ref. 21 l)]. Also the cm-l). In an effort to further clarify dynamics in isotope shifts can be measured quite accurately. These low-temperature matrices, we have studied the facts indicate that an accurate potential function can be high-resolution (0.035 cm-l) ir spectra of trapped species calculated from the spectra. The Vq frequencies for as a function of temperature, where irreversible spectral ‘0SeF6 and the various isotope shiils are given in Table

TABLE XXV

FREQUENCIES FOR V, OF 80SeFcAND ISOTOPE SHIFTS FOR 1SeF6IN A NEON MATRIXa

v Av(cm-l) Peak 80SeF6 80-82 80-78 80-77 80-76 80-74

A 775.986 2.955 –3. 105 -4.720 –6.382 –9.840 B 776.069 2.951 –3. 108 -4.723 –6.385 –9.843 c 776.186 2.947 –3. 108 –4.720 –6.384 --- D 776.543 2.955 –3. 108 ------E 776.751 2.951 –3.112 ------– Ave Av 2.952 –3. 108 –4.721 –6.384 –9.841 “Neon/SeF6= 10 000/1; T = 4,2 K.

72 TABLE XXVI

POTENTIAL CONSTANTS FOR Flu MODES OF SeF~

Aa,b B

c ,3 0.2176(3) --- Ca 0.584(3) --- C34 –0.0907(5) —- Fg,c 4.916 (6) 4.88 + 0.10 F44 1.823 (13) 1.817 + 0.03 F34 0.765 (6) 0.74 * 0.04 *A (gas phase, uncorrected for anharmonicity); B (calculated by Abramowitz and Levin, Ref. 207). bNumbers“mparentheses are least squares standard deviationsin units of last decimal place. ‘Symmetry force constants are as defined in Ref. 211. Units are millidynes A-l for FjJ, millidyne . rad-’ for Fj4, and rnillidynes. A rad-z for F44.UNta for compliance constants, CU,are inverseof those for Fu. changes have been eliminated by prior annealing of the matrix (see Sec. IX.G. 1). Noble gas (neon, argon, krypton, and xenon) matrices ,OIJ of SFb and SeFc exhibit substantial spectral changes with I/cm temperature that are completely reversible. The most striking result is the broadening and coalescence of site Pig. 51. symmetry split components of degenerate modes to give Temperature dependence of portion of Vj region of SFC in argon matrix. Argon/SF~ = 10 000; deposited at 9 K and an- single peaks as temperature is raised; the results obtained nealed at 30 K. for VJof SFC in an argon matrix, which are typical, are shown in Fig, 51. Similar studies for ‘OSeF~are shown in the two fundamentals. It is stressed that several systems Fig. 52. We have been able to show that the motional studied to date exhibit motional collapse of vibrational collapse of site symmetry split components results from bands, indicating that dynamic site exchange is a general rapid exchange among equivalent low symmetry trap- phenomenon for matrix isolated species and, no doub~ is ping sites on the ir time scale, much like motional important for other impurity doped solids. averaging of NMR, which is often observed for nonrigid We have used a modifed Bloch equation to estimate molec~es.213 Our results represent the first observation the activation energies for site exchange where the of motional averaging on the vibrational time scale and frequency spectrum is given by can be treated using modern theories of vibrational dephasing. 214-216EssentiWy, tie two high-frequencY fun- it[I+(a_~ + 1) + L-(a+T + 1) + WJ-)1’21 I(v) = Im damentals of the trapped species undergo phase relaxa- (a+~ + l)(a_~ + 1) – 1 tion through enharmonic coupling of both modes to a low-frequency site local phonon mode. Excitation and and a+ = l/T* + 2ni(v —VO~ 5v/2). Here T*, I*, and tlv de-excitation of the site phonon mode through coupling are the pure dephasing times, the intensities, and the peak to the phonon bath modulates phase exchange between separations in the low-temperature zero exchange limit. the two fundamentals. As temperature is raised, the rate The spectral changes as a function of temperature have of excitation and de-excitation of the low-energy dephas- been used with the above equation to evaluate the ing mode increases, resulting in exchange averaging of activation energies for exchange, E,, and the

73 TABLE XXVII

BARRIERS AND HIGH- TEMPERATURE EXCHANGE TIMES FOR DYNAMIC SITE EXCHANGE FOR SFC AND SeFb IN NOBLE GAS 39K MATRICES ~c:.l) ;

SFC/Ar 21 11 SF~/Kr 9 65 32SFC/Xe 17 54 34SFC/Xe 17 45 1SK SeFb /Kr 31 4 SeFb /Xe 23 65

dephasing modes correspond to resonances in the phonon structure induced by the impurity molecules. Although theories of vibrational dephasing provide a model for interpretation of the matrix results, current 1ZK observations point to the need for further development of current theories. First, we observe asymmetric line shapes for the fundamentals undergoing phase exchange, whereas current theories predict Lorentzian lines. Sur- prisingly, we observe an inverse kinetic isotope effect for the site exchange process in the case of SFt in xenon. Essentially, the 34SFGspecies shows motional collapse at a significantly lower temperature than 32SFt. It is difticult at present to rationalize a kinetic isotope effect for such a subtle mass change. The theory for vibrational dephasing must be modifkd to explain adequately the matrix results. In addition to vibrational dephasing, the temperature 1 1 I 1 .0 771.0 772.0 773.0 779.0 dependence studies show unusual relative intensity and l/crl line-width changes for monomer trapping sites. Results obtained for SeF~Kr are presented in Fig. 52, where the Fig. 52. VJpeaks for several sites are shown to lose intensity and v, region for ‘SeF~ in a krypton matrixdeposited at 20 K and broaden as temperature is raised. The relative intensity annealed at 39 K; 1:10000. changes do not result from changes in equilibrium among the various monomer sites because none of these grow in intensity. Rather, the intensity appears to go high-temperature exchange rates; these are presented in reversibly to a broad absorption underlying the sharp Table XXVII for several systems. This is essentially an monomer peaks. This broad band is consistent with that Orbach type activation process, where E, gives the expected for a trapped molecule that is undergoing rapid energy of the dephasing mode.214*21SThe frequencies of (on the vibrational time scale) pseudo-rotation to give an the dephasing modes calculated using the above procedure all fall within the broad phonon bands217 of the averaged external environment for the molecule. The fact host matrix materials. Thus, it is reasonable that the that the relative intensity changes are accompanied by a

74 concomitant line broadening points to dynamics as the 3. Estimation of True Line Shapes, Widths, and source of the spectral changes. Note, however, that Intensities for Sharp Absorption Peaks in current theories for dynamics perturbations to vibra- Low-Temperature Matrices (L. H. Jones). In our tional structure do not allow for intensity changes. low-temperature matrix experiments, we have observed a Additional experimental and theoretical work is needed number of sharp absorption lines using our to understand fully the rich and unusual dynamics high-resolution ir Fourier transform spectrometer. To exhibited by matrix isolation species. understand the matrix-molecule interactions and Dynamics of molecules trapped in low-temperature dynamics, it is important to be able to estimate the matrices plays an important role in both V-V energy integrated intensities, widths, and shapes of these lines. transfer processes and energy relaxation. It has been Our spectrometer can resolve lines having a full width at shown21s*219that the e!llciency of V-V energy transfer is half maximum (FWHM) of -0.035 cm-l. Even so, we strongly dependent on the mismatch in energies of the find some lines in low-temperature matrices that are vibrational states involved and is, therefore, assisted by considerably narrower than the available resolution. To low-energy modes, which provide and receive excess estimate the true intensity and width of such lines, one energy. In energy relaxation, a quantum of vibrational must deconvolute this information from the observed energy is transferred directly to several quanta of spectrum and the known instrumental line shape (ILS). rotational, resonance phonon, or bulk phonon modes.219 This has been carried out satisfactorily for lines that are Much of the early work with V-V energy transfer and only slightly narrower than the ILS; however, for lines energy relaxation phenomena focused on diatomic that are considerably narrower (by a factor of 1/4 or molecules trapped in inert gas matrices where rotation of less) significant discrepancies appear, as evidenced in the diatomic was known to play a dominant role,219 studies of N20 and CO vapor, for which transition Spectroscopic studies of the fundamental stretch of moments are known. several dlatomics clearly exhibited rovibrational struc- We record our highest resolution spectra without ture consistent with the diatomics acting as free or anodization. This results in a sin x/x function for the ILS. hindered rotors in the matrices.212 For the narrower lines this leads to undulations on either More recently, interest in V-V energy transfer and side of the peak, One can remove these undulations by relaxation in condensed phase materials has shifted to applying an anodization function to the interferogram larger molecules such as CHqF and SFC. The tendency before transforming it; however, it degrades the resolu- has been to attribute the dominant low-energy mode in tion, which is undesirable for our purposes. Figure 53 energy transfer processes to free or hindered rotational presents calculated spectra for Lorentzian lines of dif- motion by analogy to the earlier work on diatomics. It is ferent true widths but the same integrated intensity quite clear from our work on SFGin a variety of matrices convoluted with our instrumental line shape. We see that and C HjF in argon that these molecules do not undergo if the true line width is equal to or larger than the rotation. Accordingly, we believe that for these systems instrumental Iine width, the undulations disappear. How- the dominant receiver modes for energy relaxation and ever, as we go to narrower lines, the undulations become phonon assisted V-V energy transfer must involve local more pronounced. It appears that the amplitude of these site phonop modes and not rotational modes. The fact undulations will be a useful measure of the true line that we observe vibrational dephasing for site symmetry width-more so than the observed width. The in- split components of degenerate vibrations of trapped strumental line shape is primarily determined from the molecules is prima facie evidence for substantial mirror travel and the aperture of the source. It appears enharmonic coupling between these modes and a that another experimental factor may be affecting our low-energy dephasing mode. Thus, the mechanism for results to some extent, and we are trying to pin this down energy relaxation to such dephasing modes is present in for better accuracy. these systems and, no doubt, provides the dominant Note, in Fig. 53, how the observed peak area decreas- pathway for energy transfer and relaxation. It is our es dramatically as the true line width becomes much contention that local site phonon modes will dominate smaller than the instrumental line width (resolution). V-V energy transfer and relaxation for most large Thus, the apparent intensities of narrow lines can be molecules trapped in a host crystal. quite deceiving without thorough analysis.

75 R=I.O R =0.5 The Q branch maximum of the symmetric PF stretch lies at 984.8 cm-’ for 32SPF3and at 982.8 cm-* for 34SPFY The SPF3 molecule is remarkably stable in that so many pulses are required to decompose it to S and PF3. The fraction of 32SPFg decomposed was about 0.36 as estimated from the ir spectrum. Mass spectra of the gas before and after irradiation gave for the 34/32 ratio 0.920 + 0.005 and 0.998 + 0.021, respectively. Using these numbers with the fraction decomposed yields an a34 of 0.84, which represents the ratio of the probability of decomposing 34SPF3to that of decomposing 3%PF3. R=O.I R=O.01 A similar experiment with RZO(975.9 cm-l) showed 0.8 very little isotopic separation, if any, which is as expected w because it falls in the P branch of both isotopes. Using v 30000 shots of R3s, which is to the blue of the Q branch z of 3%PF3, gave an even better selectivity than R34, ~ namely, a3d x 0.68. The results are tabulated in Table m a XXVIII. 0.0 Though the values of a34 for SPF3 do not appear to be competitive with those for SFG (O.1 to 0.2),220 the B Bilill separation of products should be simple as the reaction yields solid sulfur.

Convolution of Lorerrtzianlines of freedintegratedabsorbance (0.037 n) but varying width, y, with instrumental line shape of SPF3 (gas) g S (solid)+ PF3 (gas). width yw R = y/yWScale is the same for alt four carves. y and y. are half widths at half maximum. The vibrational mode being pumped with the COZ laser is the symmetric PF stretch. This leads to fracture H. Laser and Photo-Chemistry of the weakest bond (PS). Though the selectivity is not great, it is remarkable that it is as significant as observed, 1. Isotonically Selective Dissociation of SPF~ Using a inasmuch as the isotope shift is only 2 cm-* and the two High-Energy Pulsed COZ Laser (L. B. Asprey, L. H. isotopic vibration-rotation bands badly overlap. Jones, and S. A. Ekberg). This experiment was designed to investigate the dissociation, and accompanying isotopic selectivity induced in SPFj by irradiation with a high-energy pulsed COZ laser. The analyses were carried TABLE XXVIII out with infrared absorption spectroscopy for extent of reaction and mass spectroscopy for 32S/34S isotopic ISOTOPIC SELECTIVITY FOR ratio. For greater sensitivity we required SPFq enriched DISSOCIATION OF SPF3 USING to about 50V0 in 34s0 Both 32SPF3 and 34SPFJ were A COZ LASER prepared by the reactions Liie a34a

AIC13 10R3s (986.64 cm-’) 0.68 * 0.04 s + Pc13~ SPC13; 10R34(984.43 cm-’)b 0.84 + 0.04 SPCL3 + 3 KF ~ SPF3 +3 KCI . 10 R,. (975.94 cm-’) -1.0 ‘a,, is the ratio of the probability of decomposing 34SPFJ to that of decomposing We have irradiated a O.l-torr sample of SPF3 (about 32SPF3. 50% 34S)with 28000 shots of a sharply focused C02 bThe Q branch for 32SPF3peaks at 984,8 laser beam of R34 (001-100) at 984.4 cm-’, -1 J/pulse. cm-’; that for 34SPFJpeaks at 982.8 cm-’.

76 2. Photoreduction of UFcat 10 K(L. H. Jones and and variation in total series intensities that serve as S. A. Ekberg). As part of our continuing effort to measures of atomic capture probabilities. Modern ex- understand photolytic reactions of UFb in the condensed perimental programs are involved in eliciting the correla- phase, we have studied the photoreduction of UFC tions between these variations and known structural dimers, trimers, etc., in argon matrices at 10 K. The idea features. An important goal is a theory of meson capture was to investigate the possibility that UF~ combines with and cascade that adequately explains these effects and UFCto form UZF,,. Although we do not find evidence for that might then be employed, in conjunction with formation of UZF,1, we do find, as described below, that experimental measurements, to provide chemicid struc- aggregates of UFb are more readily reduced to UF~ than ture information not easily available by other means. are UFC monomers in low-temperature argon matrices. As part of our study of muonic x-ray spectra of This result is of importance to separation of uranium gaseous target systems, we have obtained experimental isotopes using laser excitation of UFb. data on NO that provide evidence for the dipole In a typical experiment we deposited a matrix at 10 K orientation of this molecule, Our experiment involved with the ratio argon/UF~ = 60/1. Before irradiation, we measurement of Coulomb capture ratios for negative see the usual UFC monomer VJabsorption at 619 cm-’ muons stopped in three targets: 5 atm Nz + 5 atm Oz, 10 with considerable absorption because of dimer and atm NO, and 10 atm CO. The target gases were higher aggregates on either side of the monomer peak. contained in an aluminum~ressure_—— vessel exposed—._ .——.to a Upon irradiation with an unfocused mercury arc, the beam of negative muo& (p. = 82 MeV/c) from the Los aggregation UFb peaks diminish much more readily than Alarnos Meson Physics Facility Stopped Muon Channel, the monomer peak; broad peaks attributable to UF~ and the muonic x rays were detected with an intrinsic aggregates are seen to grow in at a much faster rate than germanium detector suitably shielded to minimize UF~ monomer peaks appear. Though UZFI~cannot be muonic x rays originating from stops in the container. ruled out, the resulting spectra can be explained without Areas of the peaks of interest in the muonic x-ray invoking its existence. The conclusion is that aggregated spectrum were .determined with the peak-fitting program UF~ is more readily photolyzed than UFGmonomer in an SAMPO; analysis of the data took into account absorp- argon matrix, perhaps because when a UF bond is tion and distributed source effects, backgrounds, and in excited, the fluorine can readily attach itself to another the case of the Nz + Oz target, the uncertainty in the nearby fluorine, forming an Fz molecule and leaving composition of the mixture. behind (UF,),, thus inhibiting the recombination UF~ + The results are shown in Table XXIX where the F -~ UFC. uncertainties indicated are ~ la. The column “Z Law” refers to the original treatment of Fermi and Teller,221in which they predicted that for low-gap materials like X. MUONIC X RAYS metal solid solutions the relative captures of mesons in the individual elements of a compound should be propor- A. Muonic X-Ray Evidence for the Molecular Dipole Orientation ‘NO+ (J. D. Knight, C. J. Orth, M. E. Schillaci, R. A. Naumann,* F. J. Hartmann,** J. J. TABLE XXIX Reidy*, and H. Schneuwlytt) MUON CAPTURE RATIOS The Coulomb capture of stopped negative mesons or muons and the subsequent de-excitation of the resulting Z Law mesonic or muonic atoms are known to be sigfilcantly Target Ratio Experhnent (Ref. 221) afTected by the chemical structure of the stopping ——— . . material. The effect is usually observed as a variation in 5 atm N, ~ the mesonic x-ray intensities with structure: variation in + N/O 0.834 + 0.031 0.875 relative intensities of the individual members of a series 5 atm Oz 1 10 atm NO N/O 0.959 + 0.030 0.875 *Princeton University, Princeton, New Jersey. **Technical university of Munich, D-8C146 Gsrching, 10 atm CO C/O 0.766 + 0.030 0.750

Germany. (Nmnl%tum ‘University of Mississippi,University,Mississippi. 0.870 + 0.032 1.000 ‘tUniversity of Fribourg, CH-1700 Fribourg, Switzerland. (N/O)..

77 tional to Z; the law is commonly cited as a reference tion of the t substates of one n level, say nu = 14. llte mark for all substances. subsequent de-excitation cascade is computed with the The most striking’ feature of these data is that the model code, finally yielding predicted intensity patterns fraction of muons captured by the nitrogen in the NO for the members of the muonic Lyman, Balmer, etc., target is clearly greater than that for the Nz + Oz mixture x-ray series. Fitting of theoretical to experimental pat- of the same atomic composition. There is at present no terns is attempted by adjustment of the original t realistic theoretical model by which this result can be distribution. Apart from experiments done with interpreted in terms of the electronic structure of the hydrogen gas, almost all measurements done so far have molecules involved. It is commonly accepted, however, been carried out on condensed materials, where Auger that meson capture should be related to electron density, electrons lost from muonic atoms are believed to be and there has recently appeared a semi-empirical for- replaced so rapidly that electron depletion has no m~ation222 that takes into account the ionicity of the significant effect on the Auger widths in the cascade. N-O bond in computing the N/O capture. ratio. In this We have been examining the electron depletion effect formulation, muon capture occurs through Auger ejec- by measuring muonic x-ray spectra in a series of gas tion of loosely bound electrons, and the probability of targets at various pressures. Our main sequence of capture by an atom is related to the number of such targets consisted of N2, argon, and SF~, measured in the electrons near it. Applying the computation to the NO condensed phase (liquid or solid) and in the gas phase at with the valence structure :N~O: , we fmd that the pressures Up to 20 atm. Muonic x-ray intensity patterns experimental capture ratio can be reproduced only if the for argon in liquid and gas states are shown in Figs. 54 bond ionicity is such as to give the polarity ‘NO+. and 55, where the experimental data are represented by Similarly, for the valence form :C-0: , the experimental the points and the predicted values are represented by the data can be fitted only by assigning the polarity ‘CO+; junctions of the straight line segments. We used the cas- t.lis dipole orientation for the CO molecule is in accord cade of Akylas and Vogel,22Swith the initial t distribu- with the one inferred from microwave spectroscopy.223 tion given by the function P(t) = ea~(2t+ 1), where a is an We are not aware of a corresponding assignment for adjustable constant. Taking initial n~ = 14, setting the K NO, but an ab initfo generalized valence bond calcu- electron refilling width at 0.1 eV, and adjusting a for best lation of the electronic structure224 has led to the tit to the observed Lyman intensities for the liquid argon, theoretical assignment ‘NO+ for the molecular ground we obtained the results shown in Fig. 54. Using the same state. Thus, although the muon capture data cannot yet n and a, bu~ adjusting the code parameters to give zero be interpreted as fum proof for the NO polarity, in refilling rate for all electrons, we obtained the muonic K cmjunction with the correct prediction for CO they can and L intensity patterns shown in Fig. 55. The tits for be considered as experimental support. both the liquid and gaseous argon data are reasonably good, although it is evident that theory overestimates the higher muonic Balmer members for liquid argon. The fit B. Target Density Effects in Muonic Atom Cascades (J. D. Knight, C. J. Orth, M. E. Schillaci, R. A. Naumann, F. J. Hartmann, J. J. Reidy, and H. Schneuwly)

Our principal source of experimental information on the processes involved in Coulomb capture of stopped negative mesons or muons is the mesonic or muonic “ x-ray spectrum generated as the captured particle cascades from its initial capture state down to its atomic ground state. Because only the last few steps of the cascade produce x rays at detectable levels (the preced- ing steps are dominated by Auger election transitions, which practically we cannot measure), we need a model to help us bridge the gap between observation and phenomenon. In employing current muonic atom

cascade models, we usually start with the assumption Fig. 54. that the muons are captured into some arbitrary distribu- Muonic Lyman and Balmer intensity patterns, liquid argon.

78 TABLE XXX

MUON CAPTURE RATIOS IN SFCTARGETS

Target F captures/S captures L, A(. SFC solid 6.37 + 0.30 SF~ gas 5 atm 5.96 + 0.50 [\ SFb gas 20 atm 6.54 + 0.45 Z Law 3.38

#,1. .-_lXI. NUCLEAR COSMOCHEMISTRY Fig. 55. Muonic Lyman and Balmer intensity pattemsj gaseoos argon. A. Variations of Average Solar-Proton Fluxes During the Last 10 Million Years (R. C. Reedy) of the zero-refiil calculation to the data for argon at 20 The sun once was believed to be perfect. The invention atm is not as strange as it may appear. For monatomic of the telescope led to the discovery that dark spots often gases such as argon, whose muonic atoms start out and appear on the sun’s surface. Over a century ago, the travel at near thermal energies, the time to fwst collision numbers of these sunspots were found to vary regularly at 20 atm is of the order of 10-11 s, whereas the with an 11-yr cycle. Each sunspot cycle starts at the time de-excitation cascade should have run its course, on the of fewest sunspots, called solar minimum, and the average, in <10-12 s; the average cascade proceeds number of sunspots then increases roughly sinusoidally under approximately zero-refill conditions. For until the peak in sunspot number, solar maximum. molecules such as Nz and SFC, on the other hand, the Although the total radiative output of the sun does not muonic atom should be starting out with a kinetic energy appear to change during a sunspot cycle, many other of the order of several eV and thus should have a high outputs of the sun, especially particles and magnetic probability of colliding with a potential electron donor in fields, are known to vary over these 1l-yr solar-activity time to intluence the course of the de-excitation cascade. cycles.22s Our data on N2 and SFb show a prominent pressure Until recently, these many forms of solar activity were effect, as expected, but thus far we have not succeeded in believed to have always varied regularly with 1l-yr finding a simple set of initial model parameters that yield cycles. However, in 1976, Eddy227showed that there was a tit to the experimental data. a prolonged period of very few sunspots from 1645 to In studies of the relative muon capture probabilities of 1715, the “Maunder Minimum.” Data for aurorae, solar the individual elements in a compound, the so-called corona during eclipses, and activities of cosmic- “muon capture ratio,” the question arises: “Does the ray-produced 14C in dated tree rings showed the capture ratio depend on the pressure (of a gas) or on the same trend of greatly reduced solar activity throughout state of aggregation?” For relatively covalent molecules this period. The 7000-yr record of 14Cin dated tree rings the effect is expected to be small, because the slowing showed that other long periods of either very low or very down and capture of the muon are determined by the high solar activity have occurred. For longer time spans, electronic structure, and the electronic structure should the only data for studying solar variations are the record not be significantly affected by the presence of neighbor- of the exposure of solar-system matter to cosmic-ray ing molecules. We have had an opportunity to test this particles or the paleoclimate of the Earth. However, conclusion in our studies with SFb. Results are shown in terrestrial climatic changes could have may causes. Table XXX, where the indicated uncertainties are + 10. Variations in solar activity change the fluxes of We note that the F/S capture ratios are constant within cosmic-ray particles,zzs with decreased solar activity experimental error. increasing the intensities of the galactic cosmic rays

— (GCR) and decreasing the numbers of solar-cosmic-ray 11 and 12 samples, Finkel et al.230and others concluded (SCR) particles. These cosmic-ray flux variations are that the intensity and spectral shape of solar protons recorded by the radioactive and stable nuclides that these averaged over the last million years were similar to those particles produce in solar-system matter.228Almost all of observed recently. However, the great similarity of the the cosmic-ray-produced nuclides in the Earth or 22Na and 2SA1 SCR-produced activities was largely meteorites are made by GCR particles. The flux vari- accidental, as about 80V0 of the SCR-produced 22Na ations of GCR particles also can be caused by changes activities in Apollo 11, 12, and 14 samples were made by in their sources or in their transport to the solar system. solar protons emitted during a number of intense flares Cosmogonic nuclides in lunar samples have recorded the about a decade (four half-lives) before the Apollo past variations of SCR particles. Although this lunar missions.231 Adopting satellite-measured solar-proton data set is not very complete, it does extend back fluxes for 1965-1972 (sunspot cycle 20), lunar millions of years and is the best record of solar activity depth-activity profiles for 22Naand 2.7-yr 5SFewere used over such an extended period. to determine the fluxes for solar protons during In the moon, the depth-activity profdes of nuclides 1954-1965 (sunspot cycle 19).231The fluxes adopted for made by GCR and SCR particles are very different,2u solar cycle 20 and determined for solar cycle 19 are slowly varying to depths of meters for GCR reactions included in Table XXXI. and steep protles in the top few centimeters for SCR The radioactivity data for 2SAIand 3.7 x 10s-yr ‘3Mn reactions. Thus, the experimental depth-activity profdes in a number of lunar samples have shown that the can be readily divided into the parts made by each type solar-proton fluxes over the last 0.5-10 million yr have of cosmic rays. Fluxes of SCR particles can be de- varied little230’232and are similar to the average fluxes for termined from cosmogonic nuclide data if the sample’s sunspot cycle 20 (see Table XxXI). This sunspot cycle chemical composition and the cross sections for the had sunspot numbers that were like the average of those nuclear reactions making the nuclide are known.229 observed during the last two centuries, whereas sunspot Lunar radioactivity data for fairly short-lived nuclides, cycle 19 had about twice this number of sunspots,231the like 78day ‘sCo, were in good agreement with the most ever seen over a sunspot cycle. Thus, sunspot cycle pro ffles expected for the solar-proton fluxes measured by 20 seems typical of long-term averages in both solar- detectors on satellites.230$231The low-energy-proton reac- proton fluxes and sunspot numbers. However, as noted tions that produce 2.6-yr 22Na and 7.3 x 105-yr 2dAlin in Table XxXI, most of the solar protons during this lunar rocks are similar. 2mBecause sindar depth-activity period were from two very large sfohu-flare events in profdes were measured for these radionuclides in Apollo August 1972.

TABLE XXXI

AVERAGE SOLAR-PROTON FLUXES OVER VARIOUS PERIODS AS DETERMINED FROM LUNAR RADIOACTIVITY MEASUREMENTS

Fluxes (protons/cm2 s) Period (Data) E>lOMeV E>30MeV E>60MeV E>100MeV

1965-1975 (SPME’) (Ref. 231) 89 28 8.0 -— 1965-7/72b (SPME’) (Ref. 231) 25 4.2 0.9 -— 1954-1964(22N&‘sFe) (Ref.231) 378 136 59 26 -5 X ld y (TL) (Ref. 235) -60 -14 ~6 -3 104 y (“C) (Ref. 233) g200 72 26 9 3 X 10s y (ulKr) (Ref. 229) -- -— =18 E9 106y (“Al) (Ref. 232) 70 25 9 3 5 X 106y (s3Mn) (Ref. 232) 70 25 9 3 ‘SPME is the Solar Proton Monitor Experiment (Ref. 231). bAveragedover 11 yr. so , , The only other lunar radionuclide that had been used O.IOL , , 1 r I , 1 I I 4 to study ancient solar-proton fluxes is 5730-yr *4C,made “Kr ROCK 12002 I ! J mainly by the 1‘O(P,3P)14C reaction. The solar-proton 0.050 - fluxes determined from its depth-activity profdes (Table ToTAL XXXI) are much higher than those for the last million — — years, 233These “Cdeduced solar-proton fluxes have ~ 0.020 - “ been questioned because of three reasons: (1) the possi- o- GCR { bility of solar-wind-implanted 14Cin lunar samples;n4 (2) ~ considerable uncertainties in the cross sections for the e SCR X lsO@,3p)14C reaction;229 and (3) the much lower s&r- 0.005 - proton fluxes determined for a similar period using J6W (E>IO MeVl thermoluminescence FL) data for a lunar rock23s (see = 70 PROTONS/cm2s Table XxXI). However, the presence of solar- 0.002 wind-irnplanted 14C does not atTect the solar-proton t fluxes, because the same flux is obtained when one o.ooA~m excludes the data for the surface layer (where all the solar-wind 14C is implanted). The mean-tie for radi- DEPTH (g /cmz) ation-damage-produced trapped electrons (the source of Fig. 56. TL) is not well determined, and the solar-proton prod- The measured and calculated activity of 2.1 x 103-Y*lKr is uction rate of such radiation damage is not well known. shownas a function of depth in lunar rock 12002. “TOTAL” Mainly because of these reasons and uncertainties, the is the observed da@ “OCR” is the estimated eontriiution of gaIactic-cosmic-rayreactions, arrd“SCR” is the solar-proton- large differences between the solar-proton fluxes de- produced part [both inferred and (solid line) calculate]. The termined from data for 14Cand the other radionuclides solid triangles arethe calculated production rates of ‘k using often have been ignored. An independent determination the average solar-proton flurres over a million years aa determined from 26AIand ‘3Mn radioactivities. of ancient variations in solar-photon fluxes would help to confirm the 14C-deduced results. Concentrations of 2.1 x 10s-yr 81Kr have been meas- these target elements; most of the cross sections are ured in lunar rocks, but, until recently, the data have estimated on the basis of nuclear systematics.23s If never been analyzed for solar-proton fluxes. Using the earlier, estimated “Kr-production cross sections237 are unpublished data for 61Krin lunar rock 12002* shown in used, the solar-proton fluxes obtained are about 0.75 of Fig. 56 and the krypton-production cross sections of thoge given here. Another large source of uncertainty in Regnier et al.23sthe solar-proton fluxes given in Table these solar-proton fluxes is the GCR-production nor- XXXI were obtained. The total-less-GCR component of malization factor used to correct for GCR production of Fig. 56 gives a good SCR depth-activity protle that is ‘lKr (Ref. 229). The deepest sample in which 81Kr was considerably higher than that calculated using the solar- measured in rock 12C02 (2-6 cm) appears to have proton fluxes for the last 10s yr. No fluxes are given in considerable SCR-produced activity of’] Kr. Regnier et Table XXXI for energies below 60 MeV because the SI.236compared the observed and calculated krypton main reactions producing 81Kr in lunar samples have isotopic abundances in 10 samples (none of which was threshold energies about 60 MeV.23s deeper than 6 cm), and the average value of ob- There are several factors contributing to the uncertain- served-to-calculated 81Kr activities in the deeper samples ties of the solar-proton fluxes determined from this 81Kr was 0.97, the value adapted here, but with a 25°A data. Chemical abundances of the target elements standard deviation. The ‘lKr activity in the O- to 1-mm (rubidium, strontium, yttrium, and zirconium) were not layer of rock is 1.7 times that in the 2- to 6-cm layer, so measured in the samples used for krypton measurements. variations in the GCR normalization factor should not Measurements made with other samples of rock 12002 greatly change the solar-proton fluxes. An uncertainty of and similar rocks show that these elements are fairly +25?40 in this normalization factor affects the solar- homogeneous, and the uncertainties of the elemental proton flux by about +20Y0. New cross-section data abundances used here are about A10’Yo.Only a few cross and additional lunar-rock analyses for ‘lKr are being sections have been measured for 81Kr production from made to reduce the uncertainty (-+409’0) for the solar- —— *This information was furnished by K. Marti. proton fluxes given here.

81 Yaniv and Marti recently measured noble-gas concen- very small experimental uncertainties. The few excep- trations in samples of lunar rock 68815, which was tions generally are produced by isotopic fractionation shielded from cosmic rays until only 2 million yr ago while changing chemical or physical states or, as in when it was placed in the position it was found by the meteorites, by cosmic-ray-induced reactions. Recently, Apollo 16 astronauts. Comparisons of 81Kr, made some unusual isotopic anomalies have been measured in mainly over the last 3 x 105 yr, and stable krypton some inclusions found in meteorites. For example, ex- isotopes, made over the last 2 x 10s yr, allow the ratio of cesses of 2sMg in several meteoritic inclusions with high solar-proton fluxes over these two periods to be fairly aluminum/magnesium ratios have been ascribed to the well determined almost independently of the uncertahty decay of 7.3 x 105-yr 2SAIafler the inclusion solidified. sources listed above (because these nuclides are made The presence of excess 1°7Ag in samples of iron from the same target elements and because only relative meteorites with large (-104) palladium/silver ratios, production ratios need to be known). Preliminary eval- initially reported by Kelly and Wasserburg,239 has been uation of the krypton data for rock 68815238is consistent confiimed by Kaiser et al.240The new work showed that with the solar-proton flux variations previously de- most of the silver previously measured in meteorites was termined from lunar radionuclide activities (Table surface contamination. Kaiser et al, found that the XXXI). central pieces of two different iron meteorites (Piiion and A1though the similarity of solar-proton fluxes aver- Santa Clara) has 107Ag/109Agratios of up to 2.8, whereas aged over the last few million years and observed normal silver has a 1°7Ag/109Agratio of 1.08. Ratios of recently is noteworthy, the evidence for considerably the two silver isotopes and of the excess 1°7Ag(denoted larger fluxes over the last 104 and 105 yr is intriguing. 107Ag*)to palladium isotopes are given in Table XXXIL Although I believe the results given in Table XXXI are The source of the 107Ag*was ascribed by Kelly and generally correct, much work could be done to improve Wasserburg to the decay of 1°7Pd(half-life of 6.5 x 10s the accuracies of the fluxes given there and to add results yr) in the meteorite shortly after it formed. However, for additional radionuclides or periods. Additional cross Kaiser et al. felt that other factors, such as irradiation by sections for protons producing certain radionuclides, energetic particles or in situ fission, could be possible especially 14Cand 81Kr, need to be measured. Concen- sources of the small amounts of silver found in these trations of alKr and other noble-gas isotopes should be meteorites. measured in more lunar samples and at depths where The isotope 1°7Agcan be produced by nuclear reac- SCR production is negligible, in addition to the surface tions with 1°aPd (atom abundance of 26.79’0)and llOPd layers where SCR effects prevail. Measurements of (1 1.8% abundance), but 1°9Agcan be made only from SCR-produced nuclides in rocks with known exposure llOPd. Thus, a high fluence of energetic cosmic-ray ages would provide fluxes for periods other than particles would produce an excess of 107Agrelative to mean-fives of radionuclides and help to convert average 109Ag by nuclear reactions with palladium isotopes. integral fluxes into fluxes for “differential” periods in the Cross sections for the production of 107Agand 109Ag past., from 1°aPd and llOPd were evaluated or estimated and Cosmogonic nuclides provide good evidence that the used to determine the production rates of these silver ancient sun was not constant but had variations in its isotopes to see if the observed excesses could be of activity. It is to be hoped that the fluctuations observed cosmogonic origin. in cosmic-ray fluxes can be combined with other fossil There are several measured and theoretical cross llopd(n,2n)lwpd reactions241’242that records in the moon, meteorites, and the Earth to sections for the improve our knowledge of the ancient sun. were evaluated to provide an excitation function for the production of 109Ag(produced by the decay of 109Pd)by GCR-produced neutrons. Cross sections for the reac- B. Silver Isotopic AnomaIies in Iron Meteorites: Cos- tions 110Pd(p,pn)109Pdand 11°Pd(p,2n)109Agby high- mic-Ray Production and Other Possible Sources (R. C. energy protons were estimated from cross sections for Reedy) similar reactions with other nuclei. Because of the long half-life for *07Pd, no *06Pd(n,2n)107Pd or When different solid samples of the Earth, moon, or 108pd@,pn)107Pdcross sections have been measured. meteorites are analyzed, the relative abundances of the Cross sections for (n,p), (n,a), (n,np), and other reactions isotopes for each element usually are identical to within of 14-MeV neutrons with 108Pdare very low and similar

82 TABLE XXXII

COMPARISONS OF THE RATIOS OF SILVER ISOTOPES AND EXCESS ‘07Ag(DENOTED 1°7Ag*)TO PALLADIUM ISOTOPES AS MEASURED IN CENTRAL PIECES FROM TWO IRON METEORITES (REF. 240) WITH THOSE CALCULATED FOR COSMIC-RAY-INDUCED SPALLATION AND NEUTRON-CAPTURE REACTIONS WITH PALLADIUM OVER THE LAST 109 YEARS

Sample or Source 107A#08pd l’TAg*/106pd 10gA~ll’pd

Piiion #D 3.3 x 10-s 1.3 )( 10-5 4.3 x 10-5 Piilon #2B 2.6 X 10-5 1.5 x 10-5 2.4 )( 10-5 Santa Clara #106. 1 2.3 )( 10-5 0.9 x 10-5 2.9 X 10-5 Santa Clara #9 2.7 X 10-s 1.0 x 10-5 3.5 x 10-5 Spallation’ 2.4 X 10-7 1.4 x 10-7 2.1 )( 10-7 Neutron captureb -4 x 10-9 -– -4 x 10-7 ‘Upper limits.(Typicalvaluesare expectedto be ~0.35 of thesevalues.) bOrderof magnitudeestimates.(Such rates are highly variable in meteorites.)

to the cross sections for the same reactions. with lloPd, so oms/min/kg-Fe)= 0.45 (+29Yo), and lo7Ag/lo9Ag= 2.60 it seemed safe to assume that the cross sections for the (+3%). The calculated ratios of the production rates for lospd(n,2n)lmpd reaction tie essentially the same as the silver isotopes from palladium to those of 3CCIfrom those for the ll”Pd(n,2n)lo9Pd reaction. Measured and iron (made only by high-energy particles) had standard theoretical cross sections 243 for (n,xn) reactions with deviations of over 100%, showing the need to compare 1°7Agwere used to help construct the excitation function silver production with a low-energy product from iron, for the 110Pd(n,4n)107Pdreaction. like 53Mn. The radionuclide ‘3Mn is made by low-energy reac- In iron meteorites, ‘3Mn activities up to 600 tions with iron similar to the reactions that make ‘07Ag dis/min/kg have been measured, with typical values and 1°9Ag from palladium, so using calculated prod- -200-300 dis/min/kg. Assuming 600 atoms/min/kg as uction ratios for these silver isotopes from palladium and the upper limit for ‘3Mn production rates, upper limits for 53Mn from iron and using measured 53Mn activities for *07Agand 109Agproduction rates are 690 and 270 seemed the best way to estimate the production rates of atoms/min/kg-Pd, respectively. The production rate of silver isotopes. The cross sections used for the prod- excess ‘07Agwould be 690 – 270 x (0.5 183/0.4817) = uction of 53Mn from iron were estimated onesm for 400 (atoms/minlkg-Pd) (where 0.5183 and 0.4817 are energies below 35 MeV and experimental proton-induced atom abundances of natural ~07Agand 109Ag,respective- cross sections24s above 45 MeV. The measured ‘3Mn ly). Assuming 109 years as an upper limit for the time activities in lunar samples are about 1.4 times those iron meteorites were exposed to cosmic rays,z’b the ratio calculated using these 53Mnproduction cross sections.244 of excess 107Agto losPd is 1.4 x 10-7 (see Table XxXII). This 53Mn normalization factor of 1.4 will be ignored This is only - 19foof the excess observed in the iron below because the production ratios *07Ag/53Mnand meteorites. Thus, cosmic-ray-induced spallation reac- 109Ag/53Mnare calculated and we want upper limits for tions during the last several billion years could not production of silver isotopes. produce the observed excess lo7Ag. Various extremes in flux shapes for GCR particles in Neutron-capture reactions with mass 106 and 108 meteorites and lunar samples were used with the above isotopes also could produce silver isotopes. The neu- cross sections to get the following average production tron-capture cross sections for locCd and losCd are x 1 b, ratios: lo7Ag (atoms/min/kg-Pd)/53Mn (atoms/min/kg- and the abundance of cadmium in iron meteorites is very Fe) = 1.15 (+27%), *09Ag(atoms/min/kg-Pd)/s3Mn(at- low, so reactions with cadmium could not produce much

t?3 silver. Palladium is fairly abundant (-10 ppm) in iron ratio. Alpha-particle-induced reactions [for example, meteorites. However, the neutron-capture cross sections 23Na(a,n)2cAl and 104Ru(r@07Pd] or a harder proton for 106Pd are much larger than those for 1°sPdj so spectrum (for example, E‘305)would change the prod- neutron-capture reactions with palladium would produce uction ratios but would produce isotopic anomalies in silver with a 109Ag/107Agratio of about 40. Rates for other elements, which have not been found. Variable neutron-capture reactions in iron meteorites are highly proton fluxes in different parts of the irradiated region variable and not well known. I used cOCo activities would yield different production rates. Other tests, such measured in iron meteorites to estimate the orders of as those proposed by Lee,249would be needed to check magnitude of the rates for neutron-capture reactions with his hypothesis for an early proton irradiation, as the palladium isotopes. The estimated rate for the excess 107Agobserved in iron meteorites is compatible lonp n,Y)109pd reactionS is . d( -500 (atoms/min/kg-Pd). with such a model. Because the rate for producing excess ‘07Agby spallation The excess 107Agobserved in iron meteorites cannot reactions is ’400 (atoms/min/kg-Pd), neutron-capture be produced by a long exposure to cosmic-ray particles, reactions with palladium in iron meteorites would lower and its production by in situ fission seems very unlikely. or cancel entirely the production of cosmogonic 1°7Ag*. Thus, there is good evidence for the existence of 1°7Pdin The production of silver isotopes by neutron-capture the early solar system. It is hard to make the amount of reactions could not account for the silver seen in these 107Pd observed in these iron meteorites by an early meteorites (see Table XXXH). intense proton irradiation, so the excess 1°7Agis proba- Libby, Libby, and Runcorn 247 have proposed that bly due to the decay of nucleosynthetic 107Pdin these many elements in iron meteorites, like silver, are pro- iron meteorites. duced in situ by the spontaneous fission of a siderophilic super heavy element (SHE). The normal palladium C. Gamma-Ray Spectroscopy of Comets (R. C. Reedy) isotopic composition in Santa Clara239showed that such a fission source is not likely. The mode by which an SHE Comets can be spectacular objects in the night sky, would fission is not known. If an SHE undergoes binary but very little is known about them. ScientificaUy, they fission, trends for product yields from the fission of are among the most interesting objects in the solar transuranic elements248 indicate that more 109Agthan system, probably being the most primitive and pristine 1°7Agwould be produced because, for elements heavier bodies accessible to direct study. Their chemical com- than fermium, the lowest yield peak would have A z positions are more like that of the sun than most other 110. objects in the inner solar system,zso having considerably Lee*’g has proposed that an early intense proton more volatile elements (hydrogen, carbon, and nitrogen) irradiation of a small part of the solar system produced than even the most primitive meteorites, the CI chon- the isotopic anomalies observed in some meteoritic drites. Comets that pass near the sun are believed to samples. The protons had an energy spectrum of the originate from the Oort cloud, a large reservoir of comets shape E–4.s. Lee proposed that the excess 2cMg that is at the outer edges of the solar system. 2s1The giant, outer found in such samples, believed to be made by the in situ planets like Jupiter possibly accumulated from many decay of 7 x 10s-yr 2CA1,is made by these protons by comet-like planetesimals. A comet probably is a dirty way of the 2sMg@,n)2cAlreaction. The 2cAlfsMg ratios snowball, the nucleus, a few kilometers in diameter in meteorites, inferred from 2cMg anomalies and cosmic which, when heated by the sun, produces a coma, a abundances, were ~ 4 x 10-s, about three times the spherical cloud of dimension -104- 10s km, and both ion 107Pd/10aPd ratios inferred from 1°7Ag* in iron and dust tails up to -106 km long.2s1Various groups that meteorites. The major reaction for making *07Pd by advise the National Aeronautics and Space Adminis- protons is 1°6pd(p,pn)107pd. Cross sections for this tration (NASA) have urged detailed studies, especially reaction were estimated and used with measured with spacecraft, of comets. The Comet Working Group 26M g(p,n)2cAl cross sections244 and an E-405 proton concluded that the most important objective of a comet spectrum to calculate a (2cA1/2cMg)/(107Pd/10*Pd)prod- mission is the characterization of the chemical and uction ratio of 9, which is much bigger than the observed physical nature of the nucleus. ratio. This production ratio would be lower if small Gamma-ray spectroscopy is an excellent method to grains (r - 0.1 g/cm2) were irradiated. Radioactive determine the chemical composition of a comet’s nucle- decay afler the irradiation terminated would lower this us. Atomic nuclei that are excited by radioactive decay

84 or cosmic-ray-induced reactions emit y-rays that usually The fluxes of the energetic neutrons (1 S Es 15 MeV) have unique energies characteristic of that nucleus. were calculated by the neutron-transport codes to be Among the strongest y-ray lines emitted from a lower than those for the case of no water by about a planetary body with their sourcea,~z are those at 2.614 factor of 3, a trend consistent with that previously MeV, 208Tldaughter of 232Th;6.129 MeV, lbO(n,ny); a c~culatedo2sS These lower fluxes for energetic neutrons doublet at 7.64 MeV, ‘bFe(n,y); and 0.847 MeV, mean that the fluxes of the inelastic-scattering (n,ny) y ‘bFe(n,ny). The Apollo 15 and 16 spacecraft carried rays in a medurn with 42V0water are about 1/3 of those NaI(Tl) detectors, which measured these and other y for a similar composition with no water. The net effect of rays and which allowed about 20V0of the moon’s surface the presence of 42’% water compared to a medium with to be geochemically mapped. 2S3To help plan for future no water is to increase the ratio of neuton-capture y rays missions to the moon with high-resolution germanium to inelastic-scattering y rays by a factor of-9. The great spectrometers, a large catalogue of expected fluxes of change in this ratio for neutron-capture to in- y-ray lines was compiled.zs’ These y-ray fluxes can be elastic-scattering reactions means that hydrogen can be used for other planetary bodies that do not contain much detected both by its 2.22-MeV y ray and by changes in hydrogen. However, because hydrogen can greatly mod- the flux ratio. ify the energy spectrum of y-ray-producing cosmic-ray The greater fluxes of neutron-capture y rays compared particles,zss new calculations were done to predict the to those for nonelastic-scattering y rays make the fluxes of y rays emitted from a comet. calculation of y-ray line fluxes, especially relative vah2es, A chemical model for a comet’s nucleus was adopted much easier for a comet than for a lunar-like composi- that consisted of 47?A0CI chondrite, 42’% water, 8% tion. Nonelastic-scattering (n,xy) reactions occur over a COZ, 2V0 hydrocarbons, and 1’% sulfur.* Many years wide range of energies, so both particle fluxes for several ago, neutron-transport calculations had been made for a depths and cross sections are needed for many energies. chondritic composition with 6% water,2s5and the energy Both these particle fluxes and cross sections can have spectrum and the depth-flux profde of neutrons were appreciable uncertainties. Neutron-capture (n,y) reac- considerably difTerent from those for the same medium tions are induced mainly by thermal neutrons, and (n,y) without water. These calculations showed that new cross sections and y-ray yields usually are known quite neutron transport calculations were needed for the well. model-comet composition. Neutron fluxes in a comet An important advantage of (n,y) reactions compared were calculated independently by groups at NASA’s to (n,ny) reactions is that the former usually produce Goddard Space Flight Center** and at the Brookhaven y-ray lines unique to that elemen4 whereas the excited National Laboratory.t I used these neutron fluxes to levels made by (n,ny) reactions also can be made by calculate the fluxes of y-ray lines escaping from the (n,xy) or (p,xy) reactions with heavier nuclei. These comet. multiple sources for certain y rays are a serious problem The fluxes for neutron-capture y-ray lines are about for low-abundance elements just before elements in the three times those of an average lunar composition.2S4 periodic table that are present in high abundances. For Because the CI-plus-H20 chemical composition has a example, the 1.434-MeV y-ray line from excited 52Crcan high macroscopic thermal-neutron cross section, which be made both by ‘2Cr(n,ny)52Cr and ‘6Fe(n,nay)s2Cr would have depressed lunar neutron-capture y-ray fluxes reactions, with the latter reaction producing a larger flux by a factor of 2 (Ref. 254), the effect of such a large of this y ray than the former one.zs’ However, the concentration of water was to make the flux of neu- ‘3Cr(n,y) reaction produces y rays, such as one of 8.884 tron-capture y-ray lines about six times that of a similar MeV, that essentially are not made by any other medium with no water. The cause of this enhancement is reactions. the much higher flux of low-energy neutrons near the Because the flux of a y-ray line escaping from an surface when water is present (peak thermal-neutron flux object depends on the absorber half-thickness for that y being at depth of-30 g/cm2) compared to when water is ray, the absorber half-thicknesses for silicate media like absent (peak at -150 g/cm2). that of the moon (which has no water or carbon) were compared with those for water and carbon. For most *This information was provided by A. Delsemme. energies, carbon and water have slightly larger and **~is information was provided by J. Lapides. smaller, respectively, half-thicknesses than do silicates. ~Tlis information was provided by M. Spergel. The net effects of carbon and water on half-thicknesses, and hence on y-ray-line fluxes, were usually less than 5% example, ‘2B) y rays, and these same nuclei would be and never more than about 10% when compared to a made in large yields by cosmic-ray reactions with pure lunar medium. For the calculation of y-ray fluxes oxygen. from a comet, these small changes in absorber The 12C(n,y)13Creaction produces several y rays that half-thicknesses can be ignored, because the presence of are not produced by any reactions with other nuclei, but water greatly changes the source strengths for neu- the cross section for this reaction with thermal neutrons tron-capture and nonelastic-scattering y rays. is small (only 3.4 rob), so the fluxes of these neu- The ~-ray spectrometers that have been proposed for tron-capture y rays are low. The most intense line future missions would use high-purity germanium produced by the 12C(n,y) reaction has an energy of crystals and have resolutions for y rays of a few keV. 4.9455 MeV. The only possible interference with this line However, some y-ray lines have large energy spreads in a planetary y-ray spectrum is a weak lcO(n,ny) line at because of Doppler broadening.~c This broadening of 4.95 + 0.03 MeV. The energy of this 4.95-MeV line from line energy is worst for light nuclei (which get larger *COneeds to be determined better. If the energy of this recoil velocities immediately following the nuclear reac- line from lCO is within a few keV of 4.9455 MeV, its tion producing the y ray) and for excited levels with very intensity in a planetary spectrum can be determined short mean-lives (where the y ray is emitted while the because the excited level in lCO (11.08 MeV) that excited nucleus is still recoiling). Most excited levels that produces the 4.95-MeV line also produces a similar produce major y-ray lines have mean-lives of- 10-11s or number of 4. 16-MeV y rays. However, the calculated Ionger,zscwhich is long enough that the recoiling excited flux of the 4.9455-MeV neutron-capture y-ray line is so nucleus has stopped moving in a solid before it emits its ~ low that the best line for detecting carbon is the ray; therefore, there is no line broadening. However, the Doppler-broadened y ray at 4.438 MeV. The fwst excited level of 12C,which emits the 4.438-MeV y 4.9455-MeV y ray would only be observed for long ray, has a mean-life of 5 x 10-14 s. The recoil velocity of counting times and would be detected best from an 12c(n,n72c* reaction is a ‘2C nucleus excited by a object with large quantities of hydrogen to moderate the relatively large and produces a full-width at half max- neutrons to thermal energies. imum (FWHM) of >60 keV for the 4.438-MeV y-ray Except for carbon, the other elements that should be line.zs’ For the spectrum of neutrons producing the present in cometary nuclei in appreciable quantities emit 4.438-MeV y ray in a planetary body, the FWHM of this relatively strong fluxes of narrow y-ray lines. Most line would be s100 keV. This line broadening makes the elements emit fairly intense fluxes of (n,y) lines. A few detection of the 4.438-MeV y ray from 12Cmuch harder elements (for example, magnesium and oxygen) have low than if the line was not Doppler broadened. or very weak fluxes of (n,y) lines but have strong (n,xy) The Doppler broadening of the 4.438-MeV y of 12C lines. Several elements, especially iron and silicon, have makes detection of carbon difficult because there are no fairly intense y-ray lines made by both types of reactions, other good y rays from carbon for use in planetary y-ray so relative elemental abundances determined by either spectroscopy. Most excited levels of 12C decay by (n,y) or (n,xy) y-ray lines can be normalized. So, alpha-particle emission. The only other 12Clevel (besides although absolute fluxes of emitted y rays cannot be the 4.438-MeV one) that emits a high yield of y rays is calculated very well, almost all of the most abundant the one at 15.11 MeV. This level has an exceedingly elements can be measured, and the relative concentra- short mean-life of 1 x 10-17 s, so its ~-ray line will be tions can be normalized to sum to 100Yo. Besides Doppler broadened with a FWHM of =300 keV (be- determining almost all of the major elements, including cause of its higher recoil velocity). In a y-ray spec- volatile hydrogen and nonvolatile elements like iron and trometer the background around 15 MeV would be silicon, y-ray spectroscopy also can determine the abun- much lower than that at 4.4 MeV, but the cross section dances of certain key minor elements, such as potassium, for exciting this 15-MeV level is much lower.~8 The flux titanium, and nickel. Thus, a y-ray spectrometer near a of the 15.1l-MeV y-ray line probably would be E1 % of comet’s nucleus would provide valuable chemical abun-.. .. that for the 4.438-MeV line. Spallation reactions with dances that would help in understanding the nature of carbon produce other radioactive or excited nuclei, but these interesting objects. these nuclei emit no (for example, llC) or few (for

86 D. Boron Abundances in the Early Solar System (D. B. overabundant in meteorites relative to estimates of its Curtis) cosmic abundance.’ There are many similarly under- abundant elements in chondritic meteorites and many” 1. Introduction. Meteorites are extraterrestrial objects hypothetical processes in the early solar system that that have fallen to the Earth’s surface. Since this was might produce such deficiencies.2e0-2e3However, boron recognized, they have been objects of considerable was one of the few elements that appeared to manifest scient~lc research. Perhaps the most profound reason for processes of chemical enrichment in chondrites. As such, the study of meteorites is their antiquity. With very few it could provide a unique clue to one aspect of the exceptions, the chronometers provided by the decay of physical and chemical history of the early solar system. radioactive nuclides show that these objects were formed The elements lithium, beryllium, and boron cannot be as solid bodies 4.5 billion yr ago and have remained formed in stellar interiors because of the instabtity of largely unaltered since that time. Meteorites represent 0.5 their isotopes at stellar temperatures. Fowler et S.I.*e’ x 109to 1.0 x 109yr of solar system history that has been suggested that these elements could be formed at stellar largely obliterated on the Earth and the Earth’s moon, surfaces. However, Ryter et al.2e5demonstrated that the the only other objects available for direct laboratory energetic required for production at stellar surfaces study. In addition, recent measurements have shown that were unrealistic. Reeves et al.2ee proposed a plausible some of the meteoritic material solidfled almost instan- method of producing %, 9Be, ‘OB,and *lB in intergalac- taneously (within a few million years) after the end of tic space by spallation of carbon, nitrogen, and oxygen stellar nucleosynthesis. The study of meteorites bears isotopes with high-energy galactic cosmic rays (GCR). directly on physical and chemical processes before, Because these theories of nucleosynthesis attempt to during, and shortly after the formation of this solar explain the formation of only four nuclides, two of which system. are isotopes of boron, an accurate measure of the Meteorites represent a broad spectrum of material unfractionated abundance of boron relative-to lithium types. MarIy of them are highly differentiated chemically and beryllium is one of the few tests of such hypotheses. relative to what is believed to be the average composition Because boron abundances in meteorites may man- of the solar system. Others have compositions that are, ifest unusual physical and chemical processes in the early in most aspects, similar to the composition of the sun and presolar system, an experiment was initiated to (99% of the mass in the solar system) and thus are measure boron abundances in a large number of thought to be relatively undifferentiated. Meteorites of meteorites and meteoritic material. the latter type are called chondrites. Within the broad chondrite classification there are subtle chemical, min- 2. Experiments. Boron abundances were determined eralogical, and metrological differences that have resulted using a neutron activation analysis technique in which y in many subclass~lcations. For our purposes only two rays emitted “instantaneously” after neutron capture are broad subgroups will be identified, ordinary chondrites measured.ze’ The isotope 1°Bhas an exceptionally huge and carbonaceous chondrites. The latter are thought to thermal neutron capture cross section of 3838 b.2e8 be the least differentiated of all meteorites and as such Neutron capture produces the nuclear reaction * their composition has been used to define the average 10B(n,a)TL1“*. The excited state 7LI* de-excites with a abundance of many elements in the solar system (the half-life of Z10-*3 s by the emission of a 478-keV y “cosmic abundance”). In this sense, these meteorites ray.266Because the y ray is emitted from a recoiling ‘Li represent a kind of compositional benchmark in the nucleus, it is Doppler broadened and produces a unique history of the solar system. Chemical differences be- rectangular peak in the prompt y-ray energy spectrum. tween carbonaceous chondrites and other objects are Samples are encapsulated in polyethylene containers used to infer the nature of processes of differentation in and irradiated in a f~ed position in the thermal column the solar system. Because carbonaceous chondrites are of the Los Alamos National Laboratory Omega West considered to be a relatively unfractionated sampling of Reactor. During the irradiation a eollirnated beam of y the processes of nucleosynthesis, their composition rep- rays from the sample is analyzed by a Ge(Li) detector resents an important constraint on theories of the coupled in anticoincidenee with a NaI annulus to a 4096 formation of the elements. channel pulse height analyzer. The neutron fluence in the Before the work of Curtis et al.259boron was thought thermal column is monitored by a gas flow f~sion to be one of the few elements that is significantly

87 counter during data accumulation. All data are nor- samples. The median boron abundance in unknown malized to this fluence. Boron abundances are calculated carbonaceous chondrites is four times greater than it is in by direkt comparison with the National Bureau of interior pieces of the same type of meteorite. Even more Standards certified standard orchard leaves dramatically, 80% of the results on unknown pieces (53 (NBS-SRM- 1571) and with various quantities of grav- analyses) are greater than the maximum abundance imetrically prepared boric acid solution that were dried measured in an interior piece. in standard counting vials at room temperature. The median abundance in unknown samples of ordinary chondrites is 40?40greater than it is in interior 3. Discussion of Results. A blank is a measured pieces of the same type of meteorite. Twenty-five percent quantity of boron that is not indigenous to the sample. of the reported abundances in unknown samples (12 We have identified three general sources of blank in our analyses) are greater than the maximum abundance procedure and have tried to evaluate the effect of each on measured in an interior sample. the results of the experiment. We conclude that there is a significant probability that The most direct source of blank is the components of measured boron abundances in chondritic meteorites are the irradiation facility. Because the measurements were adversely influenced by terrestrial contamination. Conse- made “on Iine/’ boron-containing components that re- quently, only a few tenths of a gram of recently prepared side in the neutron flux and emit y rays that encounter interior pieces are considered to be representative of the Ge(Li) detector are indistinguishable from boron in uncontaminated chondritic material. Results from the sample. The magnitude of such a source was samples of this type will be considered in the conclusions. evaluated by regularly analyzing empty polyethylene containers (the system blank). All results have had the 4. Conclusions, appropriate system blank subtracted. Uncertainties for the results reflect the uncertainty in this blank correction. a. % Cosmic Abundznce of Boron. When there are Another potential source of blank is boro~ i~roduc=d significant compositional differences between ordinary into the sample during sample preparation at this and carbonaceous chondrites, the carbonaceous chon- laborato~. To monitor boron introduced into the drites are used to evaluate the cosmic abundance of the samples, a piece of reactor-grade graphite was routinely differentiated elements. Because the data show no basis prepared and analyzed. The results showed that boron for identifying a generalized fractionation pattern be- that may have been introduced to the sample during tween chondritic subgroups, the results from analyses of preparation was indistinguishable from the system blank. all 10 meteorites of different chondritic types have been The final consideration of blanks addresses the prob- used to evaluate the cosmic abundance of boron. The lem of boron introduced into samples before arrival at logarithmicaverage is 6.6~f:~ B/10’%i; uncertainties rep- our laboratory. Initial measurements were made on 70 resent 1 standard deviation of the 10 results. The result is meteorites of all varieties obtained from 6 institutions in a factor of 6.7 less than the previous low estimate based Europe and the United States. Most of these samples upon measured meteoritic abundances. - were encapsulated at the curatorial facility, shipped, and Assuming (Si/H)~,tm,lt,, = (Si/H),O1,, = 4.5 X 10-’ analayzed dhectly with no further processing. It was (Ref. 269), the newly evaluated atomic ratio in meteorites required that samples be from material that was ob- is 3.Oj~:~B/lOIOH. The comparisons in Table XXXIII served to fall, but otherwise the terrestrial histories of the show that this new meteoritic value is in excellent rocks were not known. For convenience these 70 will be agreement with the solar limit established by Engvold270 referred to as “unknown” samples. Highly variable and with the (B/H)~Ol~rbased upon the only positive boron concentrations were obtained from difTerent un- spectroscopic observation of a boron species in the known pieces of the same meteorite and from different sun,z’l The meteoritic value is higher than the limit unknown chondrites from the same subgroup. To at- established by Hall and Engvold.272 It is likely that the tempt to determine whether these variable results reflect previous discrepancy between meteoritic and solar boron boron contamination or truly represent heterogeneity of abundances was an artifact of terrestrial boron con- indigenous boron, samples were taken speciilcally “for tamination in carbonaceous chondrites. It is no longer this work from the interiors of meteorites. necessary to consider processes that enrich boron in Surprisingly, boron abundances in unknown samples carbonaceous chondrites273or deplete boron in the solar of meteorites are systematically higher than in interior

88 TABLE XXXIII galactic cosmic rays (GCR). Meneguzzi et al.z’b used this theory to predict the relative production rates of the ESTIMATES OF THE COSMIC light isotopes. They assumed an energy spgctrum for the ABUNDANCE OF BORON GCR that was proportional to (EO+ E)-’”b, where EO= 0.931 GeV and E is the kinetic energy of the particle. B/lO’OH This energy spectrum predcted a 10B/’lB ratio that was Meteoritic 160 (Ref. 283) significantly outside the uncertainty of measured values. Meteoritic 65 (Ref. 273) To compensate for this failure, several authors have Meteoritic 20 (Ref. 274) introduced a contribution of low-energy particles. This Meteoritic 3.05:: additional component to the GCR energy spectrum is Solar ~ 1.2 (Ref. 272) added to the standard energy spectrum by an exponen- Solar <3.2 (Ref. 270) tial term of the form E-? where y typically falls between solar 4 (Ref. 271) 1.5 and 5 (Refs. 266, 277). Moyle et al.’” suggest that this low-energy contribution to the GCR spectrum is attributable to stellar flares. Table XXXIV278-2E2contains element and isotope photosphere 274to account for differences between the ratios of the light elements using our newly calculated two. value for the cosmic abundance of boron. When the data b. Constraints on the Nuckosynthesis of Light Ele- were available, element ratios have been calculated for ments. The isotopes 7Li, ‘Be, 10B, and 1‘B cannot be individual meteorites. The ratios in individual rocks fall made by thermonuclear reactions in stars. Reeves et within reasonable limits of the average values. Also aL27ssuggested that the light isotopes were produced in included in Table XXXIV are relative element and intergalactic space by spallation reactions of nuclei of isotope production model-predicted rates of light ele- carbon, nitrogen, and oxygen induced by high-energy ments production by spallation reactions induced by

TABLE XXXIV

COMPARISON BETWEEN THEORETICAL LIGHT ISOTOPE PRODUCTION AND RELATIVE METEORITIC ABUNDANCES

Source B/Be B/bIJ’ llB/10B

Measured Chondritic Average 9.3 (Ref. 278) 2.1 (Ref. 279) 4.03 + 0.01 (Ref. 280) Murchison 11.4 (Ref. 281) —- -— 15.1 (Ref. 282) , AUende 4.5 (Ref. 282) 1.1 (Ref. 279) --- 3.4 (Ref. 282) Richardson 1.2 (Ref. 279) Saratov --- 2.0 (Ref. 279) -— Bruderheim 16.8 (Ref. 278) 2.3 (Ref. 279) 4.05 Leedey --- 0.62 (Ref. 279) .—

Calculated (Ref. 276) +(E) a (E. + E)-’*6 3.75 2.4 (Ref. 277) $(E) a (E. + E)-’”’ + E-3 j; 2.5 4.1 (Ref. 266) $(E) a (EO+ E)-’*6 -I-E-’ 21 2.3 4.05 (Ref. 266) $(E) a (E. + E)-’b + E-7 24 4.8 =4.05 ‘Assumes 7Li/’Li = 12.5.

89 GCR with different particle energy spectra. The model 82.6-day 86Zr(n,2n)87Zr that enhances the low-energy portion of the GCR 82.6day 88Zr(n,np)87m18Y. spectrum with the form E–s most closely matches the The lutetium and zirconium measurements are directly elemental and isotopic abudances in meteorites. Given applicable to weapons test results, whereas the the spread in the dat% the model predictions are in gadolinium numbers are a test of nuclear model calcu- reasonable agreement with the meteoritic composition. lations for neutron deficient isotopes in the rare-earth region. Mass spectroscopy on the gadolinium target material enabled us to determine the correct half-life XII. NUCLEAR STRUCTURE AND REACTIONS given above for the 148Gd target isotope, and this supporting work was crucial to the accurate determina- A. Measurement of 14-MeV Neutron Cross Sections on tion of the above cross sections. Radioactive Nuclides (R. J. Prestwood and K. W. We are presently evaluating the possibility for (n,2n) Thomas) cross section measurements on 148,149EU~d/or 167T16hM isotopes. The feasibility of these measurements will The measurement of fast neuton (-14 MeV) cross depend upon a complex evaluation of the schedule and sections on radionuclides that have been produced at the facilities requisite to the experiments. Los Alamos Meson Physics Facility (LAMPF) is an ● Irradiation of a tantalum target at the LAMPF ongoing program in CNC -11. These experiments, con- beam stop. ducted in collaboration with members of the Lawrence ● Hot cell separations at CNC-3 and 11. Livermore National Laboratory (LLNL) radiochemistry ● Target purification and preparation possibly requir- group, are unique as they are the only published work of ing isotope enrichment on the Los Alamos or this kind. They have had significant impact on the LLNL radiochemistry machines. nuclear model calculations upon which we partially ● Mass spectroscopy measurement of isotopic consti- depend for our radiochemical test diagnostics. tuency of the final target material. In this program, we make sophisticated measurements ● Irradiation with 14.8-MeV neutrons at the LLNL of the interaction processes of fast neutrons with radio- ICT facility. active isotopes on the neutron deficient side of nuclear ● Measurement of the reaction products by counting stability. The results provide a rigorous test of complex techniques; this may require an additional post- nuclear model calculations of these reaction probabili- irradiation isotope enrichment to enhance the sig- ties. In the broadest sense, the program contributes nal/noise ratio, which is a severe restriction in these significantly to our basic knowledge of atomic nuclei, experiments utilizing such highly radioactive and in addition, the specific elements we choose for these targets. studies have direct application to our current weapons Because the half-lives of the proposed target isotopes test diagnostics. Thus, two important aspects of the Los range from 9 days to 93 days, timing and coordination of Alarnos National Laboratory mission are served. the various steps described above is clearly crucial to a The fust measurement in this program was the successful experiment. 14.8-MeV cross section for the reaction 106d All these vanguard experiments have had sigtilcant ‘8Y(n,2n)87m1*Yconducted in September 1975. The impact on the nuclear model calculations upon which we measurement of 8718*Yisotopes produced in nuclear partially depend for radiochemical test diagnostics. explosions provides the keystone of the Laboratory’s Hence an important adjunct to this work is the continu- determination of thermonuclear yields. ing comparison of our experimental cross sections with Since that time a number of additional -mesurements those calculated by Los Alamos Group T-2. using 14.8-MeV neutrons available at the LLNL ICT In summary, this continuing program in CNC- 11 facility have been made: combines the unique facilities for radionuclide prod- 533day 173Lu(n,2n)172Lu uction at LAMPF and 14-MeV neutron production at 74.6-yr 148Gd(n,2n+ n,np)]47Eu the LLNL ICT facility in concert with our joint radio- 74.6-yr 146Gd(n,p)148Eu chemical expertise to measure hitherto unknown neutron 1.8 x 10c-yr ls0Gd(n,2n + n,np)149Eu cross sections relevant to our test diagnostic program. 3.3day ‘9Zr(n,2n)6sZr

● B. Determination of the Half-Lives of a7Zr, *’MY,and of the branching to the “MY and 876Ystates from the ’78Y(R. J. Prestwood) decay of 87Zr. The counting data from the Trochoidal analyzer, As part of a continuing program for the measurement when treated with a least squares program, gave a of the 14-MeV-neutron cross sections of radioactive half-life of 1.684 + 0.001 h for *7Zr. An independent isotopes, it was necessary to have accurate values for the determination of the half-life from the GAMANAL half-lives of ‘7Zr, 87mY,and ‘7gY.Although half-lives for analysis of the following gamma rays—511 .0, 793.8, these species have been reported in the literature, n4-287 1023.9, and 1209.8 keV—gave a value of 1.667 + 0.006 recent improvements in counting techniques and com- h. From these results, a final value of 1.68 + 0.01 h was puter analyses warranted the redetermination of these chosen. Among previously reported values for the values. half-life are 1.57 hm’ and 1.6 + 0.1 h.ns A computer program was developed for the calcu- 1. The Determination of the Half-Life of ‘7Zr and the lation of the disintegrations of the 391.3- and 484-keV Branching to ““Y and 87EY. The target for the gamma rays as a function of the branching. The 86Sr(3He,2n)87zr reaction was strontium oxide enriched observed counting data and the best fit corresponded to sssr, g50720/o; ‘J4sr, 0.020/o; “sr, 1.240%; in 8%r (analysis: a branching of 0.98 + 0.006 to 87mY. *8Sr, 3.01 VO).The oxide was vacuum-evaporated to a thickness of -300 ~g/cm2 on a 1-roil beryllium foil. The 2. The Determination of the Half-Lives of “MY and target foil was bombarded with 16-MeV 3He2+ ions on 8’8Y0me t~getfor tie 88&(p,2n)87mY-87gYreaction was the Los Alamos Tandem Van de Graaff accelerator for strontium oxide enriched in strontium-88 (analysis: 88Sr, -100 min at_350 nA. 99.84VO;87Sr,0.11 ‘?40;8%r, 0.05?40;a4Sr, <0.1 Yo).Target Following bombardment, the target was dissolved in 6 preparation and dimensions were identical to those for M HC 1, about 20 mg of zirconium carrier was added, the 8%r target. Two target foils were bombarded, one for and the solution was saturated with HC 1 gas. The about 5 min and the other for 1 h and 20 rein, at -7 MA solution was then placed on a Bio-Rad AG l-X8 anion with 17.O-MeVprotons on the Van de Graaff accelerator exchange resin column (50- 100 mesh; 0.8 x 10 cm). The noted above. zirconium was adsorbed on the column, and beryllium, The latter sample was counted immediately in a LEPS yttrium, and strontium passed through quantitatively. G~Li) counter, 16 x 4.75 mm, with a resolution of 800 The column was washed two or three times with ev at 380 keV. The sample that had been irradiated for 5 concentrated HCI and the time of the last wash was min was counted on another Ge(Li) counter, 52 by 47 recorded. The zirconium was eluted with 3 M HC 1 and mm (-95 cm3), with an efficiency of 18.5Vo. the column was then washed with 0.2 M HC 1. The The decay of the 380.82-keV gamma ray from “MY eluates containing the zirconium were combined. The was followed on both counters for many days. The data combined eluate was divided into two parts and a were processed with the GAMANAL computer pro- zirconium mandelate was precipitated from each by the gram, and a least squares analysis of the information addition of 15?40aqueous mandelic acid. gave a half-life of 13.38 + 0.01 h from the huge Ge(Li) One sample of zirconium mandelate was mounted for counter and 13.36 + 0.01 h from the LEPS counter. The counting in the Trochoidal analyzer (positron counter), value of 13.37 + 0.03 h was taken as the half-life of the and positron decay was followed over a 3day period. A isotope. Other values in the literature are 13.2 + 0.2 hzss small number of positrons from ‘9Zr arising from the and 12.5 + 0.2 h.zs’ 88&(3He,2n)89Zr reaction gave a small tail that was The decay of the 484.4-keV gamma ray from 87gY removed by means of a least squares analysis of the plus that of the 388.4-keV gamma from 87mSr, in counting data. For the second zirconium mandelate equilibrium with the 484.4-keV gamma, was followed for sample, the 381.3- and 484.4-keV gamma rays from the about 70 days on a 3- by 3-in. NaI crystal and a least decay of 87Zr were carefully counted at early times in a squares program was run on the data to remove the Ge(Li) counter. The ratio of the disintegration rate for small background of 88Ypresent. A detailed analysis of the 38 1.3-keV gamma process to that for the 484.4-keV the data gave a half-life of 79.6 # 0.2 h for 87gYin close gamma process at early times is a very sensitive measure agreement with the previously reported value of 80.3 + 0.3 h.us C. Determination of the Half-Liie of 148Gd(R. J. Prest- 50 mt’ of high-purity hydrochloric acid (source: NBS, wood, D. B. Curtis, and J. H. Cappis) batch #4028), and the solution made up to a weighed mass of -1 kg with water from the Millipore Mini-Q In experiments designed to obtain the (n,2n) cross water puritlcation system. Each standard solution was section of 148Gd~aa a measurement of considerable cross calibrated by titration with standard EDTA solu- interest because of the neutron-deficiency of that alpha tion. The results obtained by titration were biased by -0.4 emitter, an accurate value of the half-life was needed. and -0.2% relative to the gravimetrically determined A tantalum target was irradiated with 800-MeV values. Standard results obtained by titration were used protons for 56.3 milliamphours at the Los Alamos for the final determination of isotopic concentrations. Meson Physics Facility (LAMPF). The target was The relative gadolinium isotopic abundances in the dissolved in a mixture of concentrated nitric and standard and the sample solution are shown in Table hydrofluoric acids, and lanthanum carrier was added to XXXV. The isotopic composition of the standard solu- precipitate Ianthanide fluorides. Gadolinium was sepa- tion was assumed to be that measured by Russ.290The rated from the other lanthanides by selective elution with isotopes of primary interes~ the alpha

TABLE XXXV

ISOTOPIC COMPOSITION OF GADOLINIUM

At.% ‘ 148 150 152 154 155 156 157 158 160

Sample 19.59 17.45 22.44 1.65 37.29 0.64 0.50 0.24 0.20 Standard 0.20 2.18 14.80 20.47 15.65 24.83 21.86

92 be ascribed to interferences by other species with mass TABLE XXXVI numbers 155, 156, and 157. Only the results calculated from masses 158 and 160 were used. The concentrations CONCENTRATIONS OF 14%3(1AND of 146Gd and 150Gd (calculated from the 148Gd/’s0Gd lsOGdIN DILUTION atomic ratio) are presented in Table XxXVI. Each value OF GADOLINIUM FROM shown is the average of seven mass spectrometric LAMPF-IRRADIATED TANTALUM measurements on five different spiked solutions using each of the two calibrated standards. The uncertainties Isotopic Abundance are 1 std dev of the seven results. Isotope (nmole/g of sample solution) Several aliquots of the original sample solution were ‘48Gd 0.5254 + 0.0018 carefully weighed and transferred to platinum lSOGd 0.4680 + 0.0019 alpha-counting plates. The plates were &led, ignited over an open flame to give a virtually weightless sample, and alpha-counted. The result was 2.806 + 0.005 x 106 counts/rein/g of original sample solution. Gadolinium- 150 has a half-life so long, 1.78 x 106 yr, active target ‘48Gd (t,,2 = 75 yr) and performed the that it offers no interference in the counting of 148Gd 148Gd(p,t)14bGdreaction. The alpha energy of 14sGdis low (3. 18 MeV). Because The target material was produced by spallation reac- the back-scattering of an alpha particle of low energy is tions on tantalum with high-intensity protons from the less than that of one of higher energy, it was necessary to 800-MeV beam at the Los Alamos Meson Physics determine the counting efficiency for the I’sGd alpha. Facility (LAMPF). The target was 22 g/cm2 and ex- Using the Low Geometry Alpha Counter, J. Balagna posed to -5.6 x 104 ~A/h primary proton beam. The determined the efilciency to be 0.5023 A 0.0025. There- tantalum was dissolved with an HF/HN03 mixture, and fore, the number of alpha counts per minute per gram of the rare earth group was isolated from the bulk solution original sample solution corresponds to 5.587 x 106 by adding a lanthanum carrier and precipitating the rare disintegrations/min/g of sample solution. From the disin- earth fluorides. The rare earths were separated from each tegration rate and the isotopic abundance in nanomoles other by using standard cation exchange chromato- per gram of sample solution, the half-life of *’EGdwas graphy with a-hydroxyisobutyric acid as the column found to be 74.6 + 3.0 yr. Work reported by previous ehmnt. These procedures have been adapted to remote investigators gave a value of 97.5 + 6.5 yr.291 operation in the CNC hot cells. The chemically extracted gadolinium fraction was assayed to contain 9.8 ~g of 148Gd.A l-mg carrier of natural gadolinium was added D. The (p,t) Reaction on the Exotic Target *’sGd (R. E. to the solution and then precipitated as a wet hydroxide. Brown, E. R. Flynn, J. Van der Plicht, G. E. Bentley, J. The precipitate was shipped to Lawrence Livermore B. Wdhelmy, L. G. Mann,* and G. L. Struble*) National Laboratory where it was converted to an oxide and isotonically separated. The 148Gdwas collected on a The nucleus 14bGdhas received considerable attention 40 @cm2 carbon foil onto a nominal spot size of 2 by 2 recently because of its supposed “doubly closed” shell mm2. The target was returned to Los Alamos where a character. Its first excited state is thought to be a 3- and thickness determination was performed using 14Celastic lies relatively high in excitation energy and, therefore, scattering which gave a limit of <16 @cm2. apparently resembles 208Pb. Because *4bGdlies too far The (p,t) experiment was performed using the from the line of stability to be examined by normal three-stage capability of the Los Alamos Van de Graaff light-ion particle transfer, it has been studied only facility and the Q3D spectrometer. Assuming the ground through xn reactions and heavy-ion two-proton transfer state cross section of the (p,t) reaction to be similar to reactions. The nuclear structure of the levels is difXcult to previously measured 142Ce(p,t),a thickness of 6 ~g/cm2 extract with the xn measurements, and the heavy-ion was obtained. Even with this very thin target an angular reactions are subject intrinsically to poor resolution. To distribution on all states below 2.5 MeV was obtained, overcome these difficulties we have obtained the radio- consisting of nine angles with adequate statistics to identify most final spin values. Initial results are shown in *LawrenceLivermore National Laboratory.

93 Fig. 57. These will be complemented in a future experi- 146&J ment involving a study of higher excitation energy in the (P,tl 14GGdnucleus. Prililw%us ASlf$:D The results presented in Fig. 57 establish that no 2.653 excited states lie below the 1.575-MeV state given in the (5-) literature. The results indicate a 2+ spin to the 1.980-MeV state and a 0+ spin to the 2.173-MeV state. 2.173 This latter state is not the 0+ pairing vibration, however, (0+) o+ as it contains less than 10’%of the ground state strength. 1.980 ~+ The 3- spin of the 1.575-MeV state is not confirmed by the present data. ~- 1.575 The results of the present experiment establish that useful nuclear reaction results may be obtained on targets as thin as -10 ~~cmz using the Q3D spectrometer system. This gives rise to a large variety of possible targets from the LAMPF beam stop with a significant number of experiments possible of high physics interest.

E. Search for Neutron-Deficient Light Nuclei near the 0 Proton Drip Line (G. W. Butler, D. J. Vieira, D. G. 0+ Perry, A. M. Poskanzer,* L. P. Remsberg,** and J. L. Clark) Fig. 57. Low-1yinglevels in ‘46Gd. Defining the limits of particle stability in the light mass region provides a challenge to both the experimentalist drip line for the elements magnesium through argon. and the theorist. The surprising discoveries of the particle These measurements were done in the thin target area, stability of the neutron-rich nuclei 1*Li, I’Be, *9C, and which consists of a scattering chamber with several 32134Na,which were predicted to be unstable with respect 5-m-long flight tubes. This facility fully utilizes the to one or two neutron emission, pointed out significant unique high instantaneous beam intensity and excellent deficiencies in. the understanding of the nuclear mass time structure of the main proton beam, allowing TOF surface for light nuclei far from the valley of ~-stability. experiments such as these to be undertaken. Today such measurements of very neutron rich or very The observed energy distributions of the spallation neutron deficient nuclei remain one of the most critical residues from such light and medhzm mass targets were tests of current nuclear mass theories. found to decrease rapidly with increasing kinetic energy, Tne-of-tlight (TOF) techniques have been employed with very low yields for nuclei with energies greater than in ongoing experiments at the Clinton P. Anderson 2 MeV/amu. Therefore a detection system capable of Meson Physics Facility (LAMPF) in search of neutron characterizing reaction products to as low an energy as rich292or very neutron deficient nuclei near the limits of possible was necessary. This system consisted of two particle stability. In the present experimen~ spallation fast-timing, secondary-emission channel plate residues produced by the intense (500-@ average cur- detectors293 and a standard AE-E, gas-Si telescope.294A rent) 800-MeV proton beam with targets of ‘atCaFz, schematic layout of the experimental arrangement is “tNI, and 92M0 (thickness 4.5 mg/cm2) were detected shown in Fig. 58. For each event nine parameters were at an angle of450 in an attempt to establish the proton recorded, from which the following quantities were ————— determined: (1) the long flight path TOF between the *Nuclear Science Division, Lawrence BerkeleyLaboratory, target and CP 1 (TIOns),(2) the total kinetic energy EtOt~l, Berkeley,California. **Chemis@ Dep~ent, Brookhaven National Laboratory, (3) the mass A, and (4) the atomic number Z of the Upton, New York. spallation residue. In this experiment the long fight path

94 Beam energy threshold of 26 MeV was used, resulting in a mass and charge resolution (FWHM) of 0.4 amu and 0.4 > charge units, respectively, for a typical spallation prod- CPI CP2 AE(gas) E(Si) uct like ‘CAL > Target I About 10 million events of the elements nitrogen / d through calcium were collected from a nickel target hi 1 ‘LONG-1- I month. The data were analyzed in the fashion previously Tb+l ~ FTC~ described, and Fig. 59 shows two of the observed mass ~ spectra. All of the known neutron-deficient isotopes of ~ ~TW= 5 ns (FWHM-250 PS) aluminum and phosphorus are seen out to the currently known limits of particle stability, 23A1and 27P. Beyond E~o~~~=AE +E + ~D.L!s+ PHD these points we fmd some evidence that 22A1and 26Pmay be stable; however, the statistics are not sufficient to be Mass IX 2 E707AL (TLONG/DLONG)2 convincing. Furthermore, the aluminum spectrum is confused by five potentially spurious events observed Fig. 58. below mass 22. Current predictions using Schematic layout of the experimental srrsngement, the LAMPF besm microstructure and the important experimental Kelson-Garvey mass relationships predict 22Al to be parameters. marginally bound by 250 keV, whereas 26Pis predicted to be proton unbound by 90 keV.29cFurther experiments to define the neutrondeficient limits of particle stability TOF was determined to high precision by combining a and, in particular, the possible stability of 22A1and 26P coarse time measurement, TS, which was used to de- have been performed, and the data analysis is currently termine the long flight time to the nearest rf period, and a in progress. fine time measurement, T~, which measured the time of the event to a fraction of an rf period. Atler correcting TS and T~ for time walk with respect to CP 1 and CP2 F. Production of Nuclides Far From Stahiity (R. amplitudes, a time resolution of 0.25 ns (FWHM) was Brandt,* W. Faubel, D. C. Hoffman, J. Van der Plicht, obtained over a short flight path (CP 1-CP2) of 50 cm, and J. B. Wilhelxny) whereas the long flight path (target —CP 1 = 4.3 m) time resolution was found to be 1.2 ns. We are initiating a long-range program with the goal The total kinetic energy of the reaction product was of production and identification of the fission decay obtained by adding the pressure and tem- properties of heavy actinide nuclei. Recent experiments perature-normalized AE-E detector telescope energies. on difi3cult to produce fermium and mendelevium Dead layer corrections for energy losses in the thin isotopes have resulted in the frst dramatic deviations carbon foil (20 ~g/cm2) of the channel plate detectors from the well-established fission systematic observed in and the polypropylene gas isolation window (60 @cm2) lighter actinide fission. We wish to explore t.hk area more on the detector telescope were made using the dE/dx extensively, but efforts to reach the region are hampered table lookup method. Owing to the lack of an existing by the ditXculty of access with conventional techniques dE/dx table of sufficient accuracy in this energy region, and production of many short-Lived spontaneous fission we generated our own table from the data. Finally, an activities without adequate methods for spec~lc isotopic estimate of the pu[se height defect (PHD) using the assignment. To cope with these problems we are study- method of Kaufman et al.295was added to give the total ing the possibility of using neutron rich transfer reactions kinetic energy, EtOt~PThe Z of each spallation residue to produce the isotopes and the development of modem was determined by using the AE-E table lookup ap- gas counter techniques to enable assignment of the proach, which was then followed by a mass correction to observed fission decay to specific isotopes. remove the mass dependence of the Z determinations. Our initial efforts in studying transfer reactions have Stringent requirements were used to avoid any am- been to produce xenon isotopes using ~4Cand lsO beams biguity in the final mass determination and to reduce ————. —— background events due to random coincidences and *LOSAlamos National Laboratory Vkiting Staff Member. other spurious effects. In this analysis a total kinetic

9s 1.3 . WV ~ ~ 102 -

I 1 Il”llil I I I I 1 ! I INIIIII n, mfi- 20 22 24 26 28 30 32 34 36 Moss Number

I 1 I I 1 I I 1 [ I 1 1 I 1 I I

1’ ,~4 - (b) p+ Ni-P

103 -

,.2 .

I I I 1111n mn nl ‘. 24 26 28 30 32 34 36 38 40 Mass Number

Fig. 59. Mess spectra observed in 800-McV proton bombardment of ‘“tNIfor the elements (a) aluminum and (b) phosphorus.

on targets of tin, antimony, tellurium, and iodine. We aluminum layer on top of the KI. The available beam have chosen these specific reactions for the following currents of high-energy *SOwere limited because of the reasons: requirement of stripping the ion to the 7+ or 8+ charge ● Use of neutron excess projectiles (iicluding 14C, state. For the 8+ lsO, a beam of 83.0 MeV was used at which is uniquely available in the US at Los an average current of-2 pnA, For the 7+ lsO the energy Alamos). was 74.5 MeV with an intensity of -40 pnA. The ● Ease of radiochemical isolation of the xenon prod- irradiated targets were dissolved in HC1 and the xenon uct from the bulk of the elements produced in the isotopes were cryogenically trapped onto charcoal beads reaction. in liquid nitrogen. The beads were y-ray counted using a ● Use of the Los Alamos Van de GraafT facility since high-dliciency well detector. The chemical yield of the the Coulomb barriers are sutliciently low to enable xenon trapping was not established in this experiment, on-site reaction mechanism studies. and the only detected xenon isotopes were 127Xeand ● High sensitivity for detection of y-ray decays from 129Xe.With an assumption of a 10VOchemical yield, the the xenon isotopes. 129Xeproduction was 1 mb for the 7+ irradiation and 3 ● Production of a variety of detectable radioactive mb for the 8+irradiation. In the 8+ irradiation, 127Xewas xenon isotopes from 122Xe-135Xeto permit study of produced with a cross section of -100 ~b. whereas 133Xe transfer trends. was not observed within the detection sensitivity of- 10 The fwst bombardments were with lEO on KI targets. pb. The targets were prepared by evaporating 3-5 mg/cm2 The second Los Alamos experiment used a 14Cbeam KI onto a 1.5 mg/cm2 aluminum foil and then en- on targets between tin and iodine and is summarized in capsulating the target by evaporation of an wO.5 mg/cm2 Table XXXVII. The xenon fractions were extracted by

96 TABLE XXXVII

*4CBOMBARDMENTS

E Run Target (MeV) Fluence Chemistry Chemical Yield

1 w 66. 9.08 x 1015 HC1 5.5% 2KI 57.5 10.04 )( 1015 HCI >3.8% 3 Te 66. 7.71 x 101’ HC1 + H,O, -60% 4 We 66. 8.36 X 10’s HC1 + HZOZ 29.3% 5 Te 57.4 7.92 X 101s HC1 + H;O; 21.6% 6 Sb 66. 8.44 x 10’5 H#04 8.6% 7 Sb 57.4 6.54 X 101s H$04 15.7% 8 Sn 66. 6.82 X 10]5 HC1 11.3%

chemically dissolving the target material in the indicated tially possible. Even at our current sensitivity, we are acids and then cryogenically trapping the xenon through able to detect a “lOLi” transfer which would yield the a gas vacuum system onto an activated charcoal bead very exotic isotope ‘b’No with an irradiation of an ~4Es submerged in liquid nitrogen. The beads were counted in target. We plan to continue these studies and extend a Ge(Li) well counter and the spectra analyzed to extract them to production of neutron rich bismuth isotopes the yields of the xenon isotopes. Results of the analysis using reactions are presented in Table XXXVIII. With a general sensi- zos~, Zospb) + lSO ~ 21’-214Bi+ residuals tivity on the order of 1 Lb, the neutron excess transfer (204Hg, products seen include “4H” transfer to make 131mXefrom 1271.“sHe” transfer to produce 13sXe from *30Te;and The ’80 reactions on these heavier Z targets will “ ‘“~i” transfer to produce 133Xe from 123Sb. With require higher beam energies than can be obtained at the improved beam intensities and target irradiation develop- Los Alamos Van de Graa.fTand w-illbe performed at an ment, sensitivities on the order of nanobarns are poten- outside facility. Detection methods of high sensitivity

TABLE XXXVIII

PRODUCTION CROSS SECTIONS (IN Lb) FOR XENON ISOTOPES WITH 14CBEAMS

Xe Isotope Run Target 122 125 127 129m 131m 133m 133 135

1 Kl 9.2 940. 40.5 <0.75 2 m <5. <150. <23. <1.2 3 Te 3.8 46.5 112. 215. 973. 694. 147. 4 13rqe 19.7 4700. 2790. 693. 5 Te 3.4 58.0 129. 298. 1390. 1120. 459. 6 Sb 2100 1970. 10000 230. <4.1 2.2 7 Sb 112. 1140. 313. <%0 8 Sn 1880. 13800. 94300. 985. 9120. <230. <44. <30.

97 should also be available for these neutron rich bismuth the mechanism by which these processes take place is isotopes. The half-lives for zlz-zlfBitie ~ the 20 rein-I h not well understood, in that theoretical calculations range and can be radiochemically isolated from the bulk cannot explain the observed excitation functions. (Most reaction products. These isotopes (1–decay to very short theoretical models predict a minimum at the (3,3) lived polonium isotopes, which in turn decay by emission pion-nucleon resonance.) of uinique, easily identified high-energy alphas. The Pion single-charge-exchange reactions, which can be majority of the reaction cross section goes into prompt studied by radiochemical methods, populate many final fission decay and the surviving part of the compound states in the product nuclei. Within the limit of many cross section results in short-lived a activities that decay final states, the nuclear structure effects may average to long-lived a emitters that have substantially lower out, leaving only the gross features involved in the charge energy emissions than the desired bismuth daughters to exchange process. In this case, we wish to show how the be measured. absolute cross sections and excitation function shapes In pursuit of the ultimate goal of producing and change as a function of A and/or number of bound levels detecting exotic heavy fissioning isotopes, we have begun available for population. development work on detection techniques. We envision The excitation functions for the pion single-charge- a system that consists of a recoil-collecting foil for exchange reactions 27Al(n–,z0) 27Mg (9.4 rein), reaction products, a very thin (-60 ~g/cm2) avalanche 4sSc(n+,#)45Ti (3.1 h), and c5Cu(n-,n0)c5Ni (2.5 h) were counter for a start signal, a position-sensitive parallel determined for incident pion energies ranging from 80 to plate avalanche counter some 20 cm away to provide 400 MeV. The results of these experiments will be fragment velocity information, and finally an ionization compared with the Fermi gas model calculations of counter for residual fragment energy measurement. Pro- Kaufman and Hower,297and we hope they will stimulate totypes of the position-sensitive avalanche counter are further theoretical work on single-charge-exchange reac- being currently constructed. Realistic detector responses tions leading to many final states. have been simulated, using a Monte Carlo method to Targets were irradiated in the LEP and P3 pion select fission distributions. The detector responses were channels of Los Alamos Meson Physics Facility then unfolded, using calculated range-energy rela- (LAMPF), and the resulting activities were determined tionships to establish fission fragment charge and mass radiochemically. Exposures ranged in duration from one assignments. Wk.h as few as 10 fission events, the to two half-lives of the reaction products, and the l.xam standard deviation of the charge distribution of the intensity was monitored using aluminum monitor foils composite fission system was N 1 Z unit, and the mass attached to the target (the aluminum target did not distribution was -2 A units. The standard deviation will require an additional monitor foil). The pion intensity become narrower as the square root of the number of was determined by measuring the l*F ( 110-min) or ‘Na observations. The final resolution will undoubtedly be (15-h) activity in the monitor foil and using the known limited by systematic errors, but the simulation is cross sections for the spallation reactions “Al(n*, encouraging for the possibility of using such detector Spa.ll)**F and “Al(n*, Spall)24Na.298 The aluminum arrays for assignment of fission events to specific charge exchange experiment required no chemical sepa- isotopes. ration, and the 27Mg (9.45-rein) activity was simply determined by counting the 843.8-keV y ray using a G. Pion-Nucleus Reactions Ge(Li) spectrometer. The 4’Ti was chemically separated from the scandium target, and the 3.078-h ~+ activity 1. Pion Single-Charge-Exchange in Complex Nuclei was determined using y-y annihilation counters. The csNi (R. S. Rundberg, G. W. Butler, B. J. Dropesky, G. C. was also chemically separated from the copper target, GiesIer, S. B. Kaufman,* and E. P. Steinberg*). In their and the 2.52-h ~– activity was measured in interactions with nuclei, pions of both positive and low-background ~ counters. negative charge may undergo charge exchange. Both Because nucleon-charge-exchange reactions, that is, single-charge exchange, that is, Az(z+,nO)Az+l and (n,P) or (P,n) reactions, yield the same products as pion A~n-,zO)Az-l and double-charge exchange, that is, charge exchange, it was necessary to determine the effect Az(n+,n-)Az+2 and Az(z–,n+)Az-2 can occur. However, of secondary nucleons resulting from primary pion ● — reactions. The secondary effect was determined by *Argonne National Laboratory Chemistry Department. measuring the cross section as a function of target

98 thickness. (In the limit of very thin targets, the apparent reduction factors, as defined by T. Ericson et al.299and cross section owing to secondary reactions should scale are similar to the distorted wave impulse approximation. with the target thickness.) The measured aluminum The reduction factor is the probability of-.-.an—incident pion reaction cross sections, which showed significant con- traveling through the nucleus without interacting to ‘a” tributions from secondary effects, were extrapolated to given position in the nucleus, where single-charge ex- zero target thickness. The secondary effect was larger in change takes place, times the probability of the exciting the aluminum cross section for two reasons: (1) the pion traveling out of the nucleus without interacting. targets used were thicker because the counting etliciency The reduction factor becomes smaller near the (3,3) was low; (2) the (n,p) cross section is larger in aluminum resonance because the mean free path of the pion because the Coulomb barrier is smaller than, for exam- becomes shorter. When this energy dependence of the ple, in copper. The secondary effect for scandium and reduction factor is removed, the excitation function has a copper targets was shown to be small relative to the maximum near the (3,3) resonance. The shape of the experimental uncertainty in the measurements. The re- excitation function was shown not to depend on the sulting excitation functions are shown in Fig. 60. Fermi momentum used in the calculation. The magnitude The Fermi gas model calculations 297show a strong of the cross section, however, was shown to be strongly influence of the (3,3) pion-nucleus resonance. The calcu- dependent on the Fermi momentum. lated excitation function has, a deep minimum near the The results of our measurements show no signitlcant (3,3) resonance. These calculation; involve the use of structure at all in the excitation tinction (that is, there is no minimum or maximum near 150 MeV). The lack of structure was common to all the target nuclei used. This 2.2 I I I I I I . I lack of structure may be due to broadening of the resonance in the total cross section, resulting in a + 27Al(?z-,K0)27M9 washout of the minimum in the reduction factor. Al- though the Fermi gas model failed to predict the correct shape for the excitation function, the relative magnitudes of the cross sections of the various nuclei seem to fit 1.6 - reasonably well with this model (Fig. 61). The single-charge-exchange cross section is predicted to have a I.4 - Z/A(E0)2 dependence for- incident n-, or N/A(E0)2 for z+, where EO is the energy required to evaporate a 1.2 - z nucleon and Z, N, and A are the proton, neutron, and E mass numbers, respectively. x 1.0 - In summary, the excitation function for single-charge exchange in complex nuclei does not have a minimum, in 0.8 - contrast to the prediction of the Fermi gas model. The excitation functions are smooth functions decreasing 06 - with increasing pion kinetic energy and suggest a l/k2 function (k is the momentum of the incident pion). The 0.4 - dependence of the magnitude of the single-charge-exchange cross section on target nucleus, however, can be 02 - explained using the simple relation predicted by the

o~ Fermi gas model. We are continuing this study with Zm 230 303 350 403 139La(n+, ~0)139ce reaction cross measurements of the PION KINETIC ENERGY ( MeV) section as a function of pion kinetic energy. We hope these studies will stimulate more theoretical efforts to Fig. 60. Measured excitation functions for the reactions understand single-charge exchange in complex nuclei 17Al(n-,rc0)27Mg,4%c(rr+,z0)4sTi,and CsCu(rr-,rr”)csNI. and to calculate new excitation functions for this process.

99 2.C

n E K 1.0

9 t , , 1 0.0 10.0 20.0 30s3 4Q0

Fig. 61. The dependenceof the single-chargeexchangecross section at selectedenergieson Z(N)/A (E”)2as predictedby the Fermi gas model.

2. A Covariant Coupled-Channel Theory for exchange reactions leading to isobaric analog states Pion-Nucleus Single-Charge-Exchange Reactions. (L. C. (IAS).303 [The theory is currently being expanded to CIU)It has long been known that single-charge exchange include the study of pion-nucleus double-charge ex- scattering of hadrons from nuclei with a neutron excess change (DCE) reactions.] The novel features of our can shed light on the main features of the isovector approach can be summarized as follows: component of the nuclear force. Because the basic (1) The underlying dynamical equations of the theory pion-nucleon scattering amplitude is much better de- are fully relativistic. termined than the nucleon-nucleon scattering amplitude, (2) The pion-nucleus effective interaction used in the pion-nucleus single-charge-exchange (SCE) reactions theory is covariant and is not based on FSA. At each have received considerable attention in recent years.300 order, the effective interaction can be evaluated from Most of the published theoretical work3w’30i made use corresponding reaction diagrams with unambiguous of the distorted-wave impulse approximation (DWIA) relativistic kinematics, as well as well- and assumed a one-step reaction mechanism, where the defined nuclear dynamics. Fermi motion and the charge exchange takes place between the projectile pion binding effect of the target nucleons are treated from and a single target nucleon. Some researchers also first principles. calculated the contribution to SCE arising from two-step (3) Making use of a new nonperturbative expansion of processes. However, only the conventional two-step effective interactions for strongly interacting parti- processes related to the scattering of projectiles by cles,304we construct the second-order effective in- correlated nucleon pairs were considered. 302The ques- teraction, which can be related to observable reaction of contributions to SCE due to true pion absorption tion processes through unitarity considerations. by two nucleons has not been addressed. Finally, almost (4) We propose a new two-nucleon reaction mechanism all calculations reported in the literature were based on for SCE, which involves the true pion absorption by f~ed-scatterer approximation (FSA), a calculational a pair of target nucleons and the subsequent creation scheme that contains many theoretical uncertainties and of a pion by the same pair. The foundations of our introduces serious numerical errors into the study of the proposition are the concept of reactive contents of an pion-nucleus interaction at pion energies near and below effective interaction outlined in (3) and the ex- the (3,3) resonance. perimental fact that true pion absorption by a We have developed a covariant coupled-channel theory suitable for the study of pion-nucleus single-charge

100 nucleus exhausts more than one-third of the total pion-nucleus reaction cross section in the (3,3) resonance region. Both true pion absorption by two nucleons and pion scattering from correlated nucleon l\ T I pairs are included in our theory. (5) We develop an isospin scaling model, which allows the calculation of the second-order SCE interaction from the second-order optical potentials determined in the analysis of the elastic scattering of pions from neighboring nuclei. (6) Finally, we introduce a momentum-space, coupled-channel, Coulomb-nuclear matching method to take fully into account macroscopic isospin symmetry-breaking that is due to the pion-nucleous Coulomb interaction, as well as the mass difference between analog nuclei caused by the Coulomb force between the constituent nucleons. As an application of our theory, we studied the excitation function of the ‘3C(n+,n 0)13N (g.s.) reaction and elastic scattering of charged pions from 13C,making use of our knowledge of the pion-12C optical potential. In Fig. 62, we show theoretical and experimental differential cross sections for X*-13Celastic scattering at 180 MeV. The good agreement between the theoretical results and the data30s is encouraging, in that no adjustable parameters have been used in the present calculation. ,o+~ On the other hand, calculated excitation functions of o 20 40 60 80 100 120 140 the SCE reaction exhibit a strong dependence on the type 81ab (deg) of the two-nucleon processes being considered (see Fig. 63). Our study indicates therefore that SCE reactions Fig. 62. leading to IAS may offer a useful tool for probing Calculated differentialcross sections for n+ *3Cand n- *3C elastic scattering at 180MeV.Data arc taken from Ref. 6, The pion-nucleus dynamics.303 In this respect, comparison of solid curves correspond to the situation in which ordythe true our calculated excitation functions with the forthcoming pion absorption processes contribute to the second-orderSCE nuclear chemistry measurements of this SCE reaction at potentiat V(z).Results calculated with the assumption that V(z) Los Alamos Meson Physics Facility will provide useful is due to pion scattering from correlated pairs are represented by the dot-dash curves. The dashed curves represent information as to the composition of the second-order theoretical results calculated in the limit that the contributions processes.303 from these two two-nucleon prcesses to V(2)cancel each other. 3. Yields of Two-Nucleon-Out Pr6ducts from Stop- ped Negative Pion Reactions (C. J. Orth, B. J. Drop- esky, G. C. Glesler, L. C. Liu, and R. S. Rundberg). The recoil from each other at 180° in the center of mass absorption of a negative pion by the nucleus of an atom system with about 70 MeV each. The counter telescope into which it has been Coulomb captured is a poorly experiment of Nordberg, Kinsey, and Burman30s in understood process. To conserve momentum the absorp- which coincident nn and np pairs were observed at 1800 tion cannot take place on a single proton, but rather confirmed this absorption mechanism. occurs, most likely, on a proton-neutron (p) or pro- An interesting and important question concerning ton-proton (pp) pair. In the process of absorption of a pion absorption is the relative probability of absorption pion on a nucleon pair, a proton is converted to a on a pn pair versus a pp pair. In the Nordberg et al. neutron and the rest mass of the pion (140 MeV) is experiment the ratio R(nn/np) was determined for a converted to kinetic energy of the nucleons so that they series of N = Z nuclei to be 3 + 1 and for 20sPbto be 4.7

101 I I I I I I I’.lyb

0.2

T=(MeV) t F%. 63. l’beoreticrd excitation functions for the SCE reaction 13C ~+,n0)13N(~o~o). cue A corr~ponds to the situationin ~ ( I which only the true absorption processes contribute to V[z). N/Z OF TARGET Results calculated with the assumption that V(z)is due solely to pion scattering tlom correlated pairs are represented by Curve B. The dashed curve represents the excitation function Fig. 64. calculated in the limit that the contributions of these two two- Ratios of nn-out to rip-outresidual product yieldsversus N/Z nuckm processes to @*) cancel each other. The dotdash of the target nucleus for stopped rr- reactions. The results for curve indicates theoretical results when ordy the fust-order in- “MO are prelindiary. teraction is used.

* 4.7. These ratios may well differ from the primary In Fig. 64 we show a semilogarithmic plot of the ratio ratios because of charge exchange scattering of the of the yields of the nn-out and rip-out products versus outgoing nucleons. N/Z of the target. Extrapolation of the straight line to To provide further information about this process, we N/Z = 1 gives a value of 4.2, and for 20sPb we would have measured yields of residual two-nucleon-out prod- predict a ratio of 20, compared with R(nn/np) = 3 A 1 ucts from stopped n- reactions in 2eMg, 74Ge, “Mo, and 4.7 + 4.7, respectively, from Nordberg et al.306 114Cd,14~e, and 174Ybusing activation techniques. After Whether or not our data correspond directly to the irradiation the targets were counted with a initial ratios of absorption on np and pp pairs is not now high-resolution Ge@) detector system to determine known. The large ratios that we have observed may be y-ray intensities of the radioactive products. With 114Cd due to selective sampling of those absorption that occur it was necessary to do radiochemical separations for on the surface of the nucleus where the ratio of neutrons silver and palladium products, Although the AA = 2 to protons may be greater than the average for the products were our primary interest, we also measured nucleus. This possibility suggests that these measure- the yields of the other radioactive products to establish ments may be a sensitive method for studying the tie shapes of the yield distributions of the (n-,xn) and existence of a “neutron skin” in nuclei. (n-,pxn) products. The existence of AA = 2 residual We are attempting to gain further understanding of products requires that the recoiling nucleons escape the our measured ratios by comparing them with yields nucleus without depositing more than about 6 MeV of calculated from a model that includes a pionic atom excitation energy, otherwise nucleon evaporation would cascade routine followed by intranuclear cascade/evapo- occur, resulting in residual products with .0A 5 3. ration codes (ISOBAR/DFF). The latter codes are being Therefore, these measured yield ratios should correlate mod~led to include diflerent nuclear density distributions closely with the original ratios of absorption on np and for the neutrons and the protons. pp pairs.

102 XIII. RADIOCHEMICAL SEPARATIONS TABLE XXXIX

A. The Chemical Isolation of Spallogenic c8Ge From ACTIVITIES IDENTIFIED IN RbBr RbBr. (D. A. Miller,? P. M. Grant, J. W. Barnes, G. E. TARGETS AFTER IRRADIATION Bentley, and H. A. O’Brien, Jr.) WITH 800-MeV PROTONS

Radiogallium, particularly C7G%is useful in nuclear Element Nuclide — —. —— medicine for tumor localization and for the detection of ... . Y 88 inflammatory disease.30TBecause of the i31CreaSir3gin- Sr 82, 83,85 terest in positron emission tomography and the existence Rb 81, 82m, 83,84,86 of its long-lived c8Ge parent, c8Ga from a biomedical Br 75, 76, 77, 80m, 82,83 generator is predicted to have numerous important Se 72, 73, 75 applications in positron scintigraphy.308 The present high As 71, 72,73,74,76,77,78 cost of b8Geis a deterrent to extensive research in ‘aGa Ge 68, 69 Iabelling chemistry, however, and the exploration of the Ga 66, 67,72 production capabilities of Los Alamos Meson Physics Zn 62, 65, 69m Facility (LAMPF) for this system has been initiated. Cu 61,64,67 Experiments have been conducted at the laboratory Ni 57 scale on the synthesis of c8Ge from the spallation of co 56, 57,58,60 RbBr pressed-salt targets by 800-MeV protons. The Fe 59 activities induced in the target by such an irradiation are Mn 52, 54,56 given in Table XxXIX. The irradiated pellet is dissolved Cr 51 in 6 &f HC1, and distillation into a cooled receiver v 48 containing a few m? of HZOZis effected. The distillate is Sc 44, 44m, 46,47 then adjusted to 8.4 M HC1 and extracted with CCld. A Be 7 final back-extraction with distilled water completes the separation procedure as it has been developed thus far. As expected from a previous study of the distillation of NCA309 radiogermanium from 6 M HCl~10 *Ge quan- RbBr by 800-MeV protons has been measured to be 19 titatively volatilized and was trapped in the receiver. mb (Ref. 311). When this datum is factored with Moreover, under these conditions, only isotopes of LAMPF target thicknesses and proton intensities, it arsenic and selenium codisti with the germanium. The translates to Ci-level capabilities for c8Gesynthesis in the overall chemical yields of these three elements in the Isotope Production Facility. The utilization of LAMPF separation procedure, from eight independent experi- for the supply of c8Ge to the research and medical ments, are given in Table XL. Following the distillation, communities should provide abundant quantities of this the CC14solvent extraction effectively separated german- material more reliably and economically than was pre- ium from arsenic and selenium and the back-extraction viously possible. with distill;d water returned *Ge to an aqueous environment. Although this final solution often contained a small fraction of *Se impurity, the *Ge may be suitable B. A 172Hf-172LuIsotope Generator for Preclinical Nu- for medical use in this medium because it will be used in clear Medicine (P. M. Grant, R J. Daniels,* W. J. a b8Ge-c8Gagenerator system. Daniels,** G. E. Bentley, and H. A. O’Brien, Jr.) A reasonably quantitative recovery of *Ge from irradiated RbBr targets has been demonstrated at the Recent work at Los Alamos has resulted in a practical research level, and excellent decontamination from at method for the synthesis, quantitative recovery, and least 17 neighboring radioelements has been ac- purification of Ci quantities of NCA312 172Hf. This complished. The cross section for c8Ge production in long-lived (1.87-yr half-life) nuclide decays to 6.70d ———— — TDepartment of Chemistry, California State University, *Indian MedicalCenter, Phoenix, Arizona. Northridge. **ShellOil Compmy, Houston, Texas.

103 TABLE XL

RADIOCHEMICAL SEPARATION OF 6sGe FROM PROTON-IRRADIATED RbBr TARGETS

Overall Chemical Yield (%)., Analytical Chemical Stev Fraction Ge As Se

Original Solution -— 100 100 100 Residue 0 4+2 14*4 Distillation Distillate 98+2 91+2 59*7 Aqueous 0.5 * 0.2 90 * 3 51 + 20 CCld Extraction Organic 87*3 o 7*3

Organic 2*1 o 9*4 HZO Back-Extraction Aaueous 87*2 o 1.3 * 0.3

172Lu, a neutrondeficient isotope of the heaviest were an anion exchange column eluted with 12 M HC1 rare-earth element. Heavy lanthandies, particularly (Ref. 314), solvent extraction utilizing TTA/2 Al HC1 1C9W,have found increasing use in nuclear medicine for (Refs. 315,3 16), and solvent extraction with HDEHP/9 cistemography, tumor localization, and other diagnostic M HC1 (Ref. 317). Initial experiments employed 10-50 procedures, Although 172Ludecays to stable 172~ by ~Ci of 172Hfper run, and each separation system was electron capture, it produces a number of abundant, studied in duplicate. Experimental solutions were highaergy gamma rays that would prohibit its use in analyzed for 172Luyield and (after the reattainment of patient imaging with present instrumentation. It has been equilibrium) 172Hfbreakthrough by Ge(Li) gamma-ray proposed/*3 however, that I’zLu would be useful for spectrometry. Comparisons with a primary external compound-labelling investigations and animal standard were made for activity-balance determinations, biodistribution studies, and its availability would spur and agreements to within +5- 10OAwere obtained. increased preclinical research with rare-earth com- The anion columns loaded with 172Hfwere milked with pounds. Following successful preclinical studies, another cone HCI, and average 172Luyields of 0.92 and 172Hf radiolanthanide with better nuclear properties for breakthroughs of 9.6 x 10-s were measured. The average diagnostic imaging could be interchanged for 172Lu.The separation factor for this system was therefore convenience of generator availability and the very long (0.92/9.6 E-5) = 9600. The TTA extraction systems shelf-life of the 172Hf-172Lusystem could make it an proved to be decidely inferior and resulted in an average attractive research tool for medical investigators. separation factor of39, primarily due to increased 172Hf The production of 172Hfis accomplished by irradiating breakthroughs. Moreover, appreciable radiation damage metallic tantalum targets with medium-energy protons at to the TTA with but wCi quantities of 172Hfwas observed the Los Alamos Meson Physics Facility (LAMPF). The over the 3-month duration of this study. Results with the targets are then remotely processed in a hot cell to HDEHP generators were 0.95 *’zLu yield and a separa- radiochemically isolate a pure radiohafnium fraction, tion factor of 8300. The HDEHP/9 M HC1 extraction and significant quantities of 172Hfare thus made avail- system and the anion exchange column were therefore able for use in isotopic generators. comparable in generator performance at yCi activity A preliminary literature search uncovered a number of levels. potentially useful analytical procedures for the chemical For reasons of convenience and resistance to radio- separation of lutetium from hafnium, of which three were lysis effects, it was decided to implement the HDEHP selected for evaluation as 172Hf-172Lugenerators. These generator in the Laboratory’s radiochemistry hot cells

104 for the processing of LAMPF-irradiated targets. A test In 1977, Chauncey et al.318reported that “Mn uptake of this system under actual hot cell conditions was then in canine myocardium was nearly twice that of 201Tl,the performed. A total of 430 mCi of I’zHf was extracted most widely used radioactive agent in cardiovascular into a 50°A HDEHP (by volume) in toluene solution, and nuclear medicine today. They also noted that the quanti- 172Luwas then back-extracted from the organic phase ty of “Mn in the area of myocardial infarction was with four sequential washings of 9 M HC1 [multiple markedly decreased. Both Chauncey et al. and Atcher et extractions are required for quantitative lutetium real 319 have observed very rapid blood clearances of covery because the yield from a single step is only -0.5] Mn(II) and large heart-to-blood ratios, as shown in Table (Ref. 3 17). The HCI fractions were combined, and XLI. These rapid blood clearances, increased aliquots of the organic and inorganic phases were myocardial uptake over 201T1,ad lage heart-to-blood assayed for 17*Lu and 172Hf. The separation factor ratios at short times all point to the potential usefulness obtained in this experiment was 1.7 x 104,in reasonable of ‘2mMnin the diagnosis and study of cardiac diseases. agreement with the results of the laboratory-scale work. Sodd, Scholz, and Blue320reported in 1974 a cross A generator for the separation of 172Lufrom 172Hfhas section of 1.35 + 0.30 mb for the formation of ‘2Fe from thus been developed. Quantitative ~72Luyields are ob- 588-MeV proton spallation of nickel, whereas corre- tainable with a separation factor of 104, and the gener- sponding cross sections for targets of cobal~ copper, and ator has been found to be effective at loadings up to manganese were shown to be -10 times smaller. Our about 0.5 Ci, The HDEHP medium in the hot cell has group reported a cross section of 1.54 + 0.13 mb for been very resistant to radiolytic perturbations for nearly ‘2Fe from nickel bombarded with 800-MeV protons.321 2 yr, with no novel chemical phenomena observed over More recently, Ku et al. reported that the yield from the that period. ‘sMn@,4n)s2Fe reaction is somewhat greater than that The performance parameters of the HDEHP gener- from 200-MeV proton spa.llation of nickel.322However, it ator should be satisfactory for the proposed preclinical should be noted that their reported overall 52Fe yield of uses of 172Lu.Investigators that are interested in obtain- 120 mCi at the end of bombardment (15-h irradiation) is ing research quantities of *72Hf-*72Lu(or the separated not sufficient for widespread distribution. daughter alone) should contact this laboratory. Dissolution of the nickel metal is accomplished with 10 M HN03 and gentle heat. The solution is then made 6 M in HCI by the addition of 12 M HC1. The extraction C. Chemical Recovery of 52Fe From Nickel (H. A. procedure is based on the work of Pinajian,323 in which O’Brien, P. M. Grant, G. E. Bentley, J. W. Barnes, and he demonstrated a K~ of greater than 103for Fe+3 using H. M. Zacharis) pre-equilibrated MIBK (methylisobutylketone) from 6 M HC1. We observed a significant increase in the organic In cancer therapy there is a need for an agent to volume (about 30?40)at the conclusion of this step. measure radiation effects on bone marrow and to After phase separation, the organic is washed twice determine the rate of recovery of the red- with equal volumes of 6 M HC1 plus 39’0HZOT The blood-cell-forming segment of the marrow, that is, the remaining contaminants are thus removed, and the iron erythropoietic marrow, following radiation therapy. If is stripped from the organic with distilled water. insufficient active marrow remains, initiation of The chemical yields measured for this radiochemical chemotherapy must be delayed for a period sufficient to procedure are shown in Table XLIL Note that allow the marrow to recover. chromium, manganese, and nickel are completely Iridium-III labeled transferring, as used today, local- eliminated after the first extraction, and that sodium, izes in the reticuloendothelial (RE) system of the marrow scandium, vanadium, and cobalt me removed during the and cannot accurately measure erythropoietic marrow acid-peroxide washes. In three separate experiments, activity as can 52Fe. Previous work indicates that at low long counts were performed on the final product solu- doses of radiation the erythropoietic marrow is severely tions to look for radio-nuclidic contaminants. The results affected, whereas the RE portion shows little, if any, are shown in Table XLIII. The 48Vseen in targets 1 and effect. At higher doses of radiation andlor drugs, both 2 is absent from target 3. This arises from a slight portions appear to be similarly affected. Thus, 52Fe modflcation in the procedure. For the fust two targets, should prove useful in following the course of radi- the original solution, containing 10 M HNOq and 6 M ationlchemotherapy involving the skeletal system. HC1, was made 3V0in H202 before the MIBK extraction.

105 TABLE XLI

TISSUE CONCENTRATION OF “Mn IN MICE (Percent of Total Dose/Gram of Tissue’)

Time Post Injection 5Min 10Min 20Min 2H Organ Blood 0.18 0.13 0.06 000.04 Myocardium 17.34 16.53 13.00 12.85 Liver 14.82 11.38 11.60 13.18 Kidney 40.57 37.89 34.90 33.57 Lung 8.25 7.03 4.67 6.07 Myocardiurr@ood 97.5 123.5 236. 328.9 Myocardium/Liver 1.17 1.47 1.12 0.97 Mymrdium/Lung 2.12 2.36 2.78 2.12 Myocardium/Kidney 0.43 0.44 0.37 0.38 ‘R. W. Atcher, et al., J. Nucl. Med. 19(6),689 (1978).

TABLE XLII

CHEMICAL YIELDS MEASURED FOR SPALLOGENIC IRON RADIOCHEMICAL PROCEDURE (RESULTS AVERAGE OF 4 EXPERIMENTS)

Overall Chemical Meld (%) Na’ Sc v Cr Mn Fe Co Ni Original solution 100 100 100 100 100 100 100 100 Aqueous after MIBK 93 98+1 96*4 100 100 0.30 * 0.5 99 i 0.2 100 MIBK 1 6.6 2.0 k 0.8 4.0*4 o 0 100 + 0.6 1.1 + 0.2 0 6 M HC1 wash 6.6 2.0 + 0.8 4.0*4 o 0 0.66 * 0.5 1.1 * 0.2 0 M1~K 2 0 0 0 00 99+1 o 0 MIBK 3 0 0 0 00 0 0 0 HZO Sttip o 0 0 00 99*1 o 0 (Final solution) ‘Results of one expexirnent only.

106 TABLE XLIII

RADIOCONTAMINANTS IN ‘2Fe PRODUCTS (Proton irradiation conditions: 800 MeV, -1 @,20 rein)

Target 1 [TC= tO+ 6.5676 D] 4EVAO= 2.0987 E4 DPM (0.049% of V activity in original solution) ‘2Mn AO= 1.1950 E5 DPM (“Fe daughter) ‘9Fe AO= 2.2579 E5 DPM (“Fe/”Fe at t, = 0.0018)

Target 2 [tC= t, + -10.56 D] 48VAO= 2.566 E4 DPM (0.056% of V activity in original solution) 51MnAO= 1.4082 E5 DPM (“Fe daughter) 59Fe AO= 1.9412 E5 DPM (s9Fe/’2Fe at t, = 0.0016)

Target 3 [tC= tO+ 6.0504 D] ‘*SC AO= 9.5669 E3 DPM (0.0060% of Sc activity in original solution) ‘2Mn AO= 2.0969 E5 DPM (“Fe daughter) 59FeAO= 3.8281 E5 DPM (’9Fe/’2Fe at to = 0.0018)

- For target 3, the peroxide addhion was omitted before the mechanism for cluster growth. Our treatment, usual- extraction and a much cleaner product resulted. The ly called the chemical dynamics approach, provides overall chemical yield of ‘2Fe using this procedure is 99 fundamental information on the details of the dynamics * IYO. of cluster growth. These studies show that the cluster growth process consists of the making and breaking of “bonds” in the XIV. THEORETICAL CHEMISTRY same manner as chemical reactions. This suggests that much of the extensive knowledge of chemical reactions A. Theoretical Chemical Dynamics can be validly applied to nucleation. For example, our results demonstrate that chemical theories, such as the 1. The Dynamics of Cluster Growth (J. W. Brady, J. RRKM unirnolecular theory, are duect.ly applicable to D. Doll, imd D. L. Thompson). A series of classical dissociation of quasi-bound clusters. The study also trajectory studies has been completed that examines the shows that cross sections and rate constants are well dynamics of the elementary steps of the early stages of behaved functions of angular momentum, total energy, nucleation.324-327Specifically, the formation and dissocia- and the number of atoms, thus allowing extrapolations to tion of quasi-bound clusters of four, five, and six argon be made and suggesting that with a reasonable number atoms have been investigated and microscopic rate of calculations a complete description of microcluster constants computed. This work represents a unique growth could be obtained. Furthermore, the insight into treatment of the nucleation problem, which is usually the fundamental nature of the cluster growth mechanism studied using macroscopic theories or one of two micro- gained by this study should allow more realistic and scopic simulation methods—Monte Carlo simulation or accurate macroscopic theories to be formulated. All molecular dynamics calculations. Neither of these meth- calculations were performed using CNC-2’S Digital ods provides information about the individual steps in Equipment VAX 11/780 minicomputer.

107

— 2. Unimolecular Dissociation of Van der Waals workers have employed much the same methods, these Molecules (S. B. Woodruff and D. L. earlier studies have assumed that the ion dynamics is Thompson). Chemical and physical processes involving influenced exclusively by isolated two-body collisions Van der Waals molecules are related to many traditional with the solid atoms, an assumption that seems physi- areas of research, such as energy transfer, bimolecular cally unrealistic. We have, in contrast, explicitly summed and termolecular reactions, unimolecular decay, and all two-body interactions at each step in the trajectory to spectroscopy. We have made a quasi-classical trajectory include the longer range potential effects which our study of the dissociation of the Van der Waals molecule calculations indicate are nonnegligible.) These trajec- He.. .Iz to He + Iz for collinear geometries as a function tories are easily generated by direct integration of of Iz vibrational state. 3U The agreement between these Hamilton’s equations, although the present problem is classical results and those of a quantum mechanical somewhat more difficult than conventional atom-diatom calculation is excellen~ showing the validity of trajectory scattering problems because the interaction of the ion treatments in this important area of chemical dynamics. with the electron gas of the metal creates an effective This is the first trajectory study of a highly frictional drag on the particle’s motion, thereby destroy- mode-selective molecular decomposition process. The ing energy conservation. This velocitydependent friction results show that the system undergoes exponential is the classical analog (unquantized, of course) of decay, demonstrating that this nonergodic system has plasmon excitations. Because the energy-loss mechanism random lifetimes. Furthermore, a new method of treating causes the ions to come to rest within the crystal, one the results was introduced in this work to show that can generate theoretically a depth profde of ions scat- trajectory-computed decay rates can be obtained much tered into the metal and can subsequently compare this more accurately than by previous methods. An impor- prediction with the recent experiments. All calculations tant aspect of this research is that the system studied is were performed using CNC-2’S Digital Equipment VAX similar to many models that have been used to study the 11/780 minicomputer. fundamental behavior of unimolecular dynamics and At present we are able to make the following general thus has attracted considerable interest among theo- comments concerning the channeling simulations. Firs4 retical chemists. one can obtain fair qualitative agreement between theory and experiment even for the case (the only one that we “ 3. Low-Energy Ion Channeling (J. E. Adams and J. have examined so far) in which the solid atoms are held D. Doll). It has been known for a number of years that if f~ed in their equilibrium positions. Second, ion pene- an ion beam impinging upon the face of a crystal is tration proffles are quite sensitive to the screening length oriented so that the ions are incident along one of the of the ion-atom elastic potential, whereas the major crystallographic axes, then the observed ion back-scattered ion energy spectra are particularly sensi- penetration depths are much greater than would be tive to the magnitude of the effective frictional forces. expected if the beam were randomly oriented or if the (we have suggested that these two observations might solid were amorphous. Such an effect, known as channel- permit experimentalists to obtain more accurate de- ing, is fairly well characterized both experimentally and terminations of the interatomic forces involved.) Third, theoretically in the high-energy (keV-MeV) regime. How- small rotations of the angle of incidence of the ions away ever, a recent experiment 329[D+ on W( 110)] performed from the surface normal do not alter the gross structure at ion energies of 80 eV has yielded a penetration depth of the penetration depth distributions, even though such profde that is qualitatively ditYerent from that predicted rotations can significantly tiect the back-scattered by an extrapolation of the high-energy results. Because energy spectra. Finally, we can say that one should not the structure of the depth profde is intimately linked not ignore the analytic uses of low-energy ion channeling, at only to the structure of the solid surface but also to that least at present; the phenomenon may well provide an of any adsorbed overlayers that may block otherwise independent means for obtaining surface and adsorbate available channels, ion channeling at low energies would structures. seem to have a great potential as a surface diagnostic tool if a better understanding of the dynamics of the 4. Adsorption/Desorption Kinetics (J. E. Adams and process could be obtained. J. D. Doll). Descriptions of adsorption/desorption Our approach to this problem3301331has involved the phenomena represent important components in a general use of classicaf trajectory techniques. (Although other theoretical characterization of heterogeneous catalysis,

108 but no work has appeared that adequately treats the 5. Energy Transfer, Reaction, and Dissociation as a whole range of kinetic detail that is just now being Function of Initial State for H + Hz on an Accurate ab observed experimentally, We have, however, recently initio Potential Energy Surface (N. C. Blais and D. G. proposed a method for calculating such information that Truhlar*). We present results of trajectory calculations is both uniquely versatile, in that it does indeed permit for the following reactions. one to investigate arbitrarily complex real systems, and also quite accurate, with the quality of the calculations HA + H~H~v, j) ~ HA + H~Hc(v’, j’) (RI) being comparable to that obtained in the best of the recent experiments. JJZIJJJIn paficular, we are able tO ~ H~HB(v’,j’) + Hc or HAHC(V’,j’) + HB (R2) evaluate such nonnegligible effects on the rates as adsorbate concentration, system temperature, and con- ~H~+HB+Hc (R3) current dtiusion parallel to the substrate surface. No other work to date has been able to incorporate such a We have examined the dependence of these reactions degree of dynamical complexity. (energy transfer, atom exchange, and dissociation) on the The actual formalism employed in the present study initial internal state of the Hz molecule, including states involves a relatively straightforward, two-step procedure. at high energy. For the high-energy states the transition FirsL a generalization of Slater’s theory of unimolecular probabilities are reasonably high and the concern with reaction kinetics334is used to generate what is essentially zero-point energy is minimized, thereby justifying our just a transition state theory approximation. (Physically, use of quasi-classical trajectories for the dynamical this is equivalent to calculating the equilibrium vapor calculations.33s’337We also have used an accurate ab pressure of the adsorbed species.) One then applies the initio potential energy surface, the LSTH potential,338$339 dynamical corrections suggested by Chandler33s to the so that the results are the best predictions that can be transition state results, thereby obtaining “exact” rate made presently about the real system. constants. Nowhere in the development does one need to We were especially interested in how several reaction restrict the dynamical description to only harmonic attributes changed over the manifold of initial bound interactions or to highly idealized surface models. states. In Fig. 65 we have plotted values of the rate Initial studies have examined thermal resorption of the constant for (R2) for each initial state investigated. Both ligher rare gases from solid xenon. Below are listed a few axis scales are linear in energy so that the energy of the more important conclusions of this work. All dependence is evident. However, because vibration and calculations were performed using CNC-2’S Digital rotation energies are not additive, the correspondence Equipment VAX 11/780 minicomputer. between the state and energy is strictly true only on the . The inclusion of adatom-adatom interactions may axes. The dependence of the rate constant on the initial increase resorption rates by as much as 1000A. vibrational quantum number and on the initial rotational . At suftlciently high temperatures the motion of the quantum number is evident. From the change in rate surface atoms may be ignored, inasmuch as the coefficients for the states along the axes it is clear tha~ resorption depends only upon the average potential with equal amounts of initial internal energy in the interaction of an adatom with a surface unit cell. molecule, vibration is much more effective than rotation ● Resorption rates depend on the atomic density of in promoting atom exchange. In fact, vibration is at least the crystal face and are larger for crystal faces with 10 times as effective as rotation. However, if vibration lower atomic densities. and rotation are both present in the molecule in roughly . For some systems one can see a marked decrease equal amounts (as near the center of the plot), then in the rates for finite adsorbate coverages with rotation is almost as effective as vibration in promoting respect to the analogous infinite dilution results at atom exchange. temperatures just above x~-l, where & is the Figure 66 is a similar plot but with the average final adatom-adatom potential well depth. Such an effect vibrational quantum number indicated at each initial should be of particular importance ifs is substan- —— tially larger than the adatom-solid atom interaction. *Universityof Minncsota.

109 REACTION RATE kr AVERAGE FINAL VIBRATION (v’) (cm3 molecule-t s-1 ) BOTH AXES LINEAR IN ENERGY BOTH AXES LINEAR IN ENERGY v v 01 3 6 9 12 o 3 6 9 12 I 1 I I I I ! I , I I 1 ! 2 ..09 .57 22 4.6 7. I 10. 2- i.5 6.5 3. I (-17) (-14) & ?i!) (-lo) Yo) .14 4.6 10 .32 2.e 5.1 ’16) e4 II. lo- L. I 5.1 8.8 [-[6) (’-ii (:i~l (-lo) .“10) { 14 .53 3B 6.7 9.5 14- 1.7 4.0 5.8 :-w (-l 1) ~i~) (-lo) i Ie 1.3 3.s 7.5 j j ,4 [8-2.4 9.4 7.8 (-la (-II) ~i~) 7.7 22 4.8 R3 L 7.3 (-12) ~ i:) 22- 1.4 :-II) ~j~) (: i:) 26 2.5 5.5 ~i$ 26- 2.6 \ ;-II) ~i~) 30

30- 5.8 (-lI) Fig. 66. 1 t I I I 1 1 1 1 I I I r The average final vibrational quantum number for the exchange product of reaction (R2) for various initirdstates for a 300 K distribution of relative translational energy. The quen- Fig. 65. tity given is , where (v’ + l/2)h = J\ whereJr is the final The rate constant (ii cm3 ~okcule-’ s-’) for the exchange viirationsd radial action variable.The axes are as in Fig. 65. reaction (R2) for various initial states for a 300 K distribution of relative translational energy. Numbers in parentheses are powers of 10. Tire initial vl%rationtdend rotational quantum AVERAGE FINAL ROTATION numbers are indicated on the abscissa end ordinate, respec- (j’) tively. The abscissa is chosen to be linear in energy for (v,O) BOTH AXES LI NEAR IN ENERGY states, and the ordinate scale is chosen to be linear in energy for (OJ) states. state. There is a clear trend for vibration to be adiabatic during exchange. In fact, along the coordinate j = 10, the vibrational quantum number changes very little from 14 72 6.2 7.4 ao reactant to product. But, as might be expected, there is 1 1 significant transfer of rotational to vibrational energy at 1816.4 I0.2 8.4 -1 high initial j and, conversely, vibrational to rotational J .1 0.3 energy at low initial j. 22 8. I I 0.9 11.6 In marked contrast to the adiabaticity for vibrational ! I 12.5 energy, the average final rotational quantum number differs considerably from its initial value, as shown in 26 10.1 12.8 Fig. 67. Only at very low j is j’ nearly the same as j. For j >8 there is a net energy loss from rotation. Because 30112.e t 1 1 1 , t t I , 1 vibration does not change much during exchange, the net energy loss from rotation appears as translation. There- Fig. 67. fore exchange when reactants have high internal energies The averagefmsdrotationrdquantum number for the exchange causes the products to be translationally hotter than the product of reaction (R2) for various initisdstates for a 300 K reagents. distributionof relativetranslational energy.The quantity given is q’>, where (j’ + l/2)h = 2rrJ’ = J&whereJo’is tie fmsl Energy transfer from the higher energy states of a rotational action variable and J’ is the tlnai rotational angular molecule are of particular importance because, in the momentum. The axes are es in Fi. 65.

110 laboratory, studies on dissociation and recombination vibration or rotation apparently have no systematic always involve a competition between the dissociation correlation with the initial state. It is also significant that process to higher unbound states and the energy transfer these large multiple quantum transitions are not nearly to lower nondissociative states. In Fig. 68 are sum- as unlikely as has been predicted before. (See references marized the results of energy transfer from six initial in Ref. 340.) The systematic of energy transfer in the H states at a f~ed collision energy of 0.5 eV. The contour + Hz system are similar to those in a completely dfierent lines connect points of equal transition cross section and collision system, Ar + Hz (Ref. 340). are spaced at the values 9.0, 3.0, 1.0, 0.36, 0.12, 0.045, In Fig. 69 the contour plots are for the transfer of 0.015, and 0.005 a02, with the interior contours around energy with mechanism (R 1), nonexchanging collisions, the initial state having the highest value. The “flow” of and for (R2), with atom exchange for two of the states transition probability is a complex function of the initial presented in Fig. 68. In this figure the contours have the state. If the initial state has a high j then, for those values of 3.75, 1.25, 0.417, 0.139, 0.046, 0.015, and collisions that change the state, the transition probability 0.005. The two distributions differ considerably. The is largest for final states of about equal energy. For inkial distribution for the case of no exchange is generally states with low j, transitions to other states are pre- concave, whereas that for the case with exchange is dominantly along constant v’, with v = O,j = 6 being an convex. This implies an even higher probability for large extreme case. Transitions involving large changes in multiple quantum transitions if thermoneutral atom exchange produces the energy transfer. v’ v’ Figure 70 shows the cross section for dissociation of 02468101214 02466101214 Hz molecules on collision with hydrogen atoms and with 2 2 argon atoms. The results from a calculation using a line 6 6 10 10 of centers (LOC) model, a model often used to describe

j, ~ j( ~

22 22 NoN EXCHANCSD

28 26 30 30 m v=2 j= 18 v’ v’ O24661O O 2 4 6 610

v’ v’ 2 2 02468101214 02466101214 6 6 2 2 o 10 10 6 6, j’ 14 10 10 j’ 14 18 18 j,: ~ j! ~ 22 22 v=2 j= 18

22 22 m 28 26 26 30 v=6 j=O 30 v=O j= 18 m D I 34 NON EKNANCSD EXCNANCSD v’ v’ 02466101214 02466101214 v’ v’ 0246810 O 2 4 6 610 2 6 2 2 10 6 6 j, : 10 10 22 T 224 r 14 j’ 14 26 16 18 v=4 j=6 30“i v=O j=6 I z? 22 34 I 26 l%. 68. Contour plots of equat cro;s section for molecular energy Fig. 69. transfer, process (R1), initial molecular states. Each plot is Contour plots of equal cross sections for the state-to-state labeled by the inkial state, and the axes indicate the tlnal processes (Rl) and (lU). Tbe relative translational energy is states. The relative translational energy was 0.5 eV and the 0.5 eV and the contours have the values 3.75, 1.25, 0.417, contours have the values 9.0, 3.0, LO,0.36, 0.12, 0.045, and 0.139, 0.046, 0.015, and 0.005 a02.The innermost contours 0.015 aoz.The contour of 9.0 a02is the one nearest to the in- have the largest vatue and the values dimiish monotonically itial molecular state. (within statistical error) to the edges.

111 DISSOCIATION CROSS SECTION Em= 1.0eV dissociation, is also shown for the hydrogen atom ● H+H2 AAr+H2 0 LOC collision. The model is clearly inappropriate. The difference in the interatomic forces when a hydrogen atom or an argon atom collides with the Hz molecule leads to a higher efficiency for dissociation by the hydrogen atom. We have also calculated the thermal rate constants and activation energies (Table XLIV)3411342for (R2) at 10’ three different temperatures, 444 K, 875 K, and 2400 K. At the lowest temperatures we compare our results with r< ---u the most reliable experimental values, and at each b temperature we list the best transition state calculation (with tunneling corrections). 100 Our calculations are among the very few completely ab initio calculations of the rate constant and activation energy for any chemical reaction. Of particular interest is the trend for the activation to increase with increasing temperature. An Arrhenius plot of the logarithm of the ,,lo#—LuJJd rate constant versus (I/T) would not be a straight line 2 4 6 8 10 12 14 . 30 26 24 20 “ 16 12 8 0 but would be concave upward. I 1 Fig. 70. The dissociationcross section (in AZ)plotted against the initial B. Monte Carlo Based Electronic Structure Techniques molccutar state quantum numbers. AUthe states have approx- (J. D. Doll) imately the same internal energy. Three sets of points are plotted. Filled circlescorrtxpond to H + Hz, fticd triangIesto Ar + Hz, and open circles are values calculated from a Traditional quantum-chemical approaches to studies line-of~errters(LOC) mcdel. of electronic structure are based on the use of the

TABLE XLIV

THE RATE CONSTANT AND THE ACTIVATION ENERGY FOR ATOM EXCHANGE (R2)

(cm3mol~ule-’s-’) T(K) Trajectories Ref. 341 Ref. 342 Tramition State

444 6.7 + .8(–15) 7.7(–15) 1.0(–14) 9.49(-15) 875 8.0 + .7(–13) [4.4(–13)]’ [9.9(–13)]* 8.99(– 13) 2400 3.5 + .3(–11) “ 4.63(–1 1)

Activation energy (eV)

444 0.34 * .01 0.350 0.382 0.33 875 0.38 ~ .01 [0.414]’ 0.39 2400 0.60 A .09 0.62

“Square brackets indicate extrapolation from a lower temperature range using the Arrhem”us constants.

112 “variational principle.” This principle assures that, given behaves as (1EAEI /N)l’2, where E is the true electronic proper symmetry constraints, the energy associated with energy, AE is the difference in the true and approximate a trail wave function will always exceed that of the true energies, and N is the number of MC points used in the electronic ground state, Trail functions are, thus op- calculation. timized by varying adjustable parameters to minimize The result shows that the convergence is more rapid than the computed energy. Historically this procedure has might have been assumed. One might initially have evolved in the direction of using trial functions of guessed, for example, that the convergence would be as sufficiently simple functional form that the basic inte- IEl /@. Such a convergence would have been pro- grals that arise can be calculated essentially analytically. hibitively slow because the total energy, E, is often quite Such simplicity is gained at the expense of using trial large. Because the actual result involves AE, which is functions that are intrinsically inefficient. That is, by often quite small, convergence is acceptable. As a related virtue of their special functional form (chosen for point we note that the MC method becomes easier to convenience), these trial functions are often quite un- apply as the quality of the trial function increases (AE physical and, as a consequence, must contain many becomes smaller). The known convergence of the meth- (102-10s) adjustable parameters if chemical accuracy is od permits one to develop extrapolation estimates of the desired. true energy. The computational feasibility of the method From the earliest days of quantum chemistry one has was checked by performing benchmark calculations for known that compact and extremely accurate wave a simple (but nontrivial) model system, the HJ+ functions can be developed provided one is williig to molecular ion. Using an extremely simple correlated trial build into these functions an explicit dependence on the function involving only three adjustable para- electron-electron separation distances. Such “correlated” meters, we reproduced the results obtained by previous functions were used in the 1930s by James and Coolidge investigators3M using wave functions with over 300 such and by Hylleraas to treat simple systems with spec- parameters. This hundredfold decrease in the number of troscopic accuracy. Unfortunately, the functional form parameters graphically illustrates the potentially in- of such correlated trial functions makes it very difXcult creased efficiency of correlated trial functions. All calcu- to use them to treat m&e complex systems within a lations were performed using CNC-2’S Digital Equip- traditional framework. The basic integrals involved are ment VAX 11/780 minicomputer. analytically intractable. Recently we have examined the use of Monte Carlo (MC) based techniques in conjunction with correlated XV. UNCLASSIFIED WEAPONS RESEARCH trial functions.343 In this approach one foregoes any attempt to perform analytically the basic integrals which A. Bismuth: A New Weapons Radiochemical Detector arise. Rather all integrations are performed using a (K. W. Thomas, W. R. Shields, D. J. Rokop, J. S. modified form of the well-known Metropolis Monte Gdmore, A. J. Gancarz, G. W. Butler, and D. W. Barr) Carlo method, which is especially suited to this application because the method’s intrinsic complexity is inde- One of the primary functions within the pendent of the dimensionality of the integrations in- Chemistry-Nuclear Chemistry Division is the radio- volved. This implies that the method will be applicable to chemical diagnosis of nuclear devices detoqated under- systems with significantly larger numbers of electrons ground at the Nevada Test Site. For the evaluation of the than can be treated conventionally. A second important performance of the fission portion of the devices, it is point is that the present method serves to unify the only necessary to measure residual uranium, plutonium, treatment of finite and extended systems, which will and selected fission products. Assessment of the prove especially important for applications such as performance of the fusion parts is less straightforward, chemisorption that have both aspects. and two general approaches are used. One is to measure Our results thus far involve both formal and computa- the amount of 4He produced in the principal tional aspects. On the formal side we have succeeded in thermonuclear reactions (shown below) and other sub- establishing a quantitative estimate of the numerical sidiary reactions. accuracy of the MC method when applied to this problem. The estimate shows that the statistical uncer- A. cLi+n~a+T+4.77MeV tainty (the standard deviation for the computed energy) B. D+ T-+a+nl~+17.6MeV

113 The alternative approach is to measure the fluence of bismuth from lead because 208Pband 207Pbinterfere with 14-MeV neutrons produced in reaction B by the use of their respective bismuth isobars in the mass spec- radiochemical detector elements. These elements, which trometric analysis. The chemical procedure meeting are idealy monoisotopic, are doped into or placed these requirements as well as the necessity for extreme between different parts or regions of the device. The radiochemical purity is an operation capable of process- resultant (n,2n), multiple (n,2n) and (n,y) products are ing 25 g of postshot debris and isolating 1-20 pg of measured and interpreted for the thence of neutrons. bismuth. The reaction products are radioactive and are measured The major steps include (1) extraction of bismuth into by conventional radiochemical methods. There are 11 of tri-n-octylamine from a medium 0.1 it-f in each HzSO, these detector elements now in use at the Los Alamos and KBr; (2) back-extraction with 0.5 M HC104; (3) National Laboratory. This number permits detailed adsorption of the element on a cation exchange resin examination of device performance. Such detailed column; (4) elution from the resin by means of 1 M analyses are crucial in understanding the physics of HC 1; (5) adsorption as a chloro-complex on an anion thermonuclear burn and are instrumental in suggesting exchange resin column; and (6) elution with 2 M HF. design modifications and developing new designs. As a After a portion of the eluate is taken for radiochemical result of the interest in detailed diagnoses, we are in the analysis, the remainder is prepared for mass spec- process of trying to develop the class of potential new trometric analysis by converting the bismuth to the detectors whose reaction products are too long-lived to nitrate and electroplating the metal onto a rhenium be measured by radiochemical techniques, but which, in cathode and the residual lead onto a platinum anode. principle, can be measured mass-spectrometrically. The mass spectrometric analysis is done by thermally During this past year we have successfully im- ionizing bismuth, effecting the mass separation by using plemented bismuth as one of these new detectors and two magnet sectors in tandem, and detecting the ions by here briefly summarize recent results. an electron multiplier operated in the pulse-counting The stable bismuth isotope has A = 209. The tirst- mode. The two main mass spectrometric problems are and second-order (n,2n) products, A = 208 and A = hydrocarbon interferences and lead isobaric interferences 207, are long-lived species that can be detected at the mass 207 and 208 positions. These problems, mass-spectrometrically, although in some cases A = 207 however, can be solved by careful and clean chemical also can be detected radiochemically. In these cases, the techniques and the use of a tandem-magnet mass spec- values of 207Bimeasured by the two techniques are in trometer. good agreemen4 and we have determined a half-life for Bismuth has been used as a detector on three recent 207Biof 32.3 a. The higher order (n,2n) products, A = tests and will be on an upcoming test. On one test it was 206 and A = 205, and the (n,y) produc~ A = 210, are used with other detectors to provide a cross-calibration relatively short-lived and are measured radiochemically. at a high specific thermonuclear yield; it will be placed The ability to detect higher order reaction products is on an upcoming test to provide a cross-calibration at a important, because they are sensitive measures of both low specific yield. In another test, it was placed remote neutron fluence gradients and/or a mixture of small from a thermonuclear fuel. Using the previous calibra- amounts of the doped portion of the device into high-flux tion data, the results from this experiment are in quite regions. Ordy two other detectors, lutetium and euro- reasonable agreement with other detectors and theo- pium, in addition to the new detector bismuth, can be retical calculations. This will be confirmed by the used to measure fourth-order (n,2n) reaction products. additional calibration to be completed shortly. The implementation of bismuth as a detector has involved development of chemical and radiochemical separation procedures, mass spectrometry procedures B. Vibrational Spectra and Normal Coordinates of High for analysis of ‘9Bi, 208Bi, and 207Bi, and counting Explosives under Ambient Conditions (B. L Swanson procedures for samples with low specific activities. and Scott A. Ekberg) The chemistry needs (1) to be relatively rapid because of the 6.2-day half-life of 20cBi;(2) to be carrier-free Very little is known about the behavior for shock because the addition of bismuth carrier would make the initiation of high explosives (HE) at a microscopic level value of 2ogBi/2°sBitoo Itigefor mass spectrometric despite the extensive work that has been carried out at determination; and (3) to effect a 10s separation of Los Alarnos National Laboratory and other research

114 institutions. A shock wave produces ahighpressurea;d quadratic potential constants. Accordingly, ir and temperature front that dominantly perturbs the phonon Rarnan spectra of normal and isotonically substituted modes (translational and vibrational motions of the samples of pentaerythritol tetranitrate (PETN) and molecules). A portion of the energy induced in the TATB are being obtained. TATB is well suited for such a phonon bath by the shock wave must be transferred to detailed vibrational analysis because the molecule is higher energy molecular vibrations before decomposition constrained to a high symmetry arrangement (D3~ in the can take place. One view is that the hydrodynamic solid state.351Raman spectra of TATB labeled with 15N heating by shock compression is enough to raise the in both the nitro and amino groups, as well as deuterated temperature of a homogeneous explosive to the point samples, have been observed. The results show extensive where thermal decomposition can take place.34s’34GIn mixing of N-O stretching modes with NHZ deformations, nonuniform explosives the argument is modiiied by as well as large spectral changes upon deuteration. postulating that thermal decomposition occurs only in Several partially deuterated samples have been studied local regions (hot spots) and that these sites then initiate and their spectra (Fig. 71) give evidence for H-D detonation.347v348Another view is that the shock forces scrambling in the solid, as no discrete modes involving result in bond breakage by multiphonon energy transfer either hydrogen or deuteriurn motion are found. Surpris- to selected molecular vibrations.349’350The distinction ingly, the incorporation of small amounts of deuterium in here is whether or not the shock wave results in rapid an otherwise hydrogenated sample, and vice versa, thermalization of the energy among all the vibrational results in completely new modes in the 1000-1600 cm–l states as opposed to a nonequilibrium situation in which region where —NHZ deformation and N-O stretch are certain modes are selectively excited. In the event of expected. These results support the notion that –HNZ selective mode excitation, the energy deposited in partic- and N-O motions are strongly mixed and point to the ular molecular vibrations may undergo vibra- importance of intermolecular interactions in determining tional-vibrational (V-V) energy transfer to other the makeup and energy of molecular modes in the molecular modes to build up sufficient energy in the 1000-1600 cm-l region. The implication here is that bonds that are initially broken. To understand better the these same modes are strongly coupled to the phonon transfer of energy from the phonon bath to molecular modes, which are dependent on intermolecular interac- vibration and V-V energy transfer, a vibrational spec- tions. troscopic study of HEs has been initiated. The principal goals are to characterize the molecular C. Raman Spectra of High Explosives Under Extreme vibrations in HEs under ambient conditions and to Pressure and Temperature Conditions (B. I. Swanson monitor the vibrational spectra under extreme pressure and D. Schtierl) and temperature conditions that simulate the shock wave. We hope to be able to differentiate between The motivation for studying vibrational spectra for equilibrium versus nonequilibrium excitation by de- high explosives (HEs) under extreme pressure and tem- termining whether or not particular molecular vibrations perature conditions is to simulate the effect that a shock are strongly coupled to the phonon bath. If only certain wave would have on the HEs’ vibrational modes. One modes are coupled to the phonon bath, it is likely that goal is to follow the dependence of the phonon modes (ii they can act as receiver modes in a multiphonon energy both frequency and line shape) on pressure and tem- transfer process. The identity of such receiver modes will perature. Equally important, experiments of this type then help clarify which bonds are initially broken. should help identify those molecular vibrations that are Studies of both sensitive and insensitive HEs may also responsive to pressure and temperature and, therefore, help clarify what makes systems such as triaminotrinitro are strongly coupled to the lower energy phonon modes. benzene (TATB) insensitive. A multiphonon energy transfer process, where several The fwst step in a vibrational spectroscopic study of quanta of a low-energy phonon mode are transferred to a HEs is to characterize the molecular vibrations in terms high-energy internal vibration, requires strong of the internal coordinates (bond stretching and angle enharmonic coupling between the phonon modes and the deformation). Essentially, the eigenvectors of the fun- high-energy receiving mode. Finally, spectroscopic stud- damental modes of vibration will be evaluated using ies as a function of pressure may help identify structural normal mode analysis where the observed frequencies of phase transformations that occur under the extreme vibration and isotopic frequency shifts are used to tit the conditions of a shock wave.

11s 100% D TATB

Qg%g 161P.

~%D TATQ

40%0 lATQ

20% 0 TAT2

0% D TATB

Fig. 71. Raman spectra of TATB as a function of deuteration.

Typically, the pressures involved in a shock-initiated were able to observe several of the lattice and molecular detonation of HEs are less than 100 kbar. Recent modes. The frequencies of several modes are given in advances in high-pressure technology have made it Table XLV. The frequency positions of the phonon possible to observe Raman spectra Upto 100 kb~.3521353 modes were all observed to increase substantially with The high-pressure diamond anvil cells required for such a pressure. Surprisingly, several of the higher energy study are convenient for laser excitation of the sample molecular combinations were also observed to shift to and will allow investigation of both the low-energy higher frequencies with pressure. The results lend sup- phonon region and the higher energy molecular modes. port to a muhiphonon process involving selected internal Infrared measurements are less useful here because the modes. The substantial frequency increase observed for diamond windows amd and the pressurizing mediums are the phonon modes is significant in that the etXciency of a strong ir absorbers, effectively eliminating much of the ir multiphonon energy transfer is strongly dependent on the region for study. Nonetheless, it should be possible to frequency separation of the phonon and receiving modes. carry out k measurements within the window region of Low-temperature (10 K) Raman spectra have been the diamond anvil cells, which include the important N-O obtained for several isotopes of TATB and the normal stretch region. For the above reasons the work will focus isotopic species of PETN and tetryl. In general, we on Raman measurements. observe significant sharpening of the modes for all of the Preliminary Raman measurements of PETN at -9 samples, resulting in the resolution of a great deal of kbar have been made. Although the spectral quality was structure in the phonon region. The frequencies of the poor by virtue of the low sensitivity of the Cary 82 phonon modes are observed to increase as temperature is spectrometer and the absence of signal averaging, we lowered. In the case of TATB, the frequencies of several

116 TABLE XLV 4. B. A. Palmer, R. A. Keller, F. V. Kawolski, and J. L. Hall, “Accurate Wave Number Measurements PRESSURE DEPENDENCE OF of Uranium Spectral Lines;’ submitted to J, Opt. SELECTED RAMAN MODES Sot. OF PETN 5. E. F. Zalewski, R. A. Keller, and C. T. Apel, “The kbar 9 kbar Optogalvganic Effect as a Detector for Intracavity Atomic Absorption in a cw Dye Laser7 accepted 41 90 by Appl. Opt. (LA-UR-80-2733). 51 72 74 92 6. W. W. Berg, P. J. Crutzen, H. E. Grahek, S. N. 108 Phonon Modes Gitlin, and W. A. Sedlacek, “First Measurements 96 114 of Total Chlorine and Bromine in the Lower 277 290 Stratosphere,” Geophys. Res. L&., in press 871 879 Internal Modes (1980). 1291 1297 2984 2997 7. A. Mason, G. Hut, and K. Telegadas, “Com- 3023 3043 parison of Stratospheric Tritium (as HTO) and Zirconium-95 Burdens from the High- Yield Chi- nese Nuclear Tests of June 27, 1973 and Novem- ber 17, 1976,” Environmental Quarterly, USDOE of the internal modes also exhibit temperature depen- Report EML-371 (April 1980). dence. Surprisingly, the -14NOz,-lsNOz isotopic shifts for three modes known to involve -NOZ motion are observed 8. W. A. Sedlacek, E. J. Mroz, E. S. Gladney, G. H. to change significantly upon cooling, indicating that the Heiken, R. Leifer, and R. Chuan, “Physical and mode mixture changing with temperature. These results Chemical Characteristics of Mt. St. Helens Air- point to the strong coupling of certain molecular modes borne Debris:—.. Symposium on Mt. St.--—Helens to the phonon modes that are most perturbed by Eruption: Its ‘At.&osphenc Effects a-d Potential temperature. Climatic Impacq Washington, D.C., November 18-19, 1980.

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274. M. R. Weller, M. Furst, T. A. Tombrello, and D. S. 284. F. D. S. Butement and G. B. Briscoe, J. Inorg. Burnett, “Boron Concentrations in Carbonaceous Nucl. Chem., 25, 151 (1963). Chondrites,” Geochim. Cosmochim. Acts 42, 999-1010 (1978). 285. E. K. Hyde and G. D. O’Kelley, Phys. Rev., 82, 944 (1944). 275. H. Reeves, W. A. Fowler, and F. Hoyle, “Galactic 286. W. H. Zoner, W. B. Walters, and C. D. Coryell, Cosmic Ray Origin of Li, Be, and B in Stars:’ Phys. Rev., 185, 1537(1969). Nature 226,727-729 (1970). 287. M. Kazumasha, J. Phys. Sot. Japan, 23, 1191 276. M. Meneguzzi, J. Andouze, and H. Reeves, “The (1967). Production of the Elements Li, Be, and B by Galactic Cosmic Rays in Space and its Relation 288. R. J. Prestwood, D. R. Nethaway, and N. L. with Stellar Observations,” Astron. Atrophys. 15, Smith, to be published. 337-356 (1971). 289. K. Wolfsberg, “Collected Radiochemical Pro- 277. R. A. Moyle, B. G. Glagola, G. J. Mathews, and V. cedures,” Los Alamos National Laboratory report E. Viola, Jr., “Nucleosynthesis of Li, Be, and B: LA-1721, 4th Ed. (1976), p. 73. Contributions from the p + lCOReaction at 50-90 MeV” Phys. Rev. C 19,631-640 (1979). 290. G. P. Russ HI, Earth Planet. Sci. Lett. 19, 275 (1973). 278. C. W. Sill and C. P. Willis, “The Beryllium Content of Some Meteorites;’ Geochim. Cosmochim. Acts 291. A. M. Freeman, J. Milsted, D. Metta, D. Hen- 26, 1209-1214 (1962). derson, J. Lerner, A. L. Harkness, and D. J. Rokop, Radiochim. Acts. 5, 192 (1966). 279. W. Nichiporuk and C. B. Moore, “Lithium in Chondritic Meteorites,” Earth Plant. Sci. Lett. 9, 292. G. W. Butler, D. G. Perry, L. P. Remsberg, A. M. 280-286 (1970). Poskanzer, J. B. Natowitz, and F. Plasil, Phys. Rev. Lett. 38, 1380 (1977). 280. E. K. Agyei and C. C. McMullen, “Determination of the Isotopic Abundance of Boron in Meteorites 293. A.M. Zebelman, W. G. Meyer, K. Halbach, A. M. and Tektites,” Short Papers of the Fourth Interna- Poskanzer, R. G. Sextro, G. Gabor, and D. A. tional Conference, Geochronology, Cos- Landis, Nucl. Instrum. Methods 141,439 (1977). mochronology, Isotope Geology, R. Zartman, Ed., Geol. Surv. Open-File Report 78-701 (1978), pp. 294. M. M. Fowler and R. C. Jared, Nucl. Instrum. 3-6. Methods 124, 341 (1975).

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130 323. J. J. Pinajian, Oak Ridge National Laboratory 334. N. B. Slater, Theory of Unimolecular Reactions report ORNL-TM- 1481 (April 1966). (Cornell University, Ithaca, 1959).

324. J. W. Brady, J. D. Doll, and D. L. Thompson, 335. David Chandler, J. Chem. Phys. 68,2959 (1978). “Cluster Dynamics: A Classical Trajectory Study of A + An ss A;+,,” J. Chem. Phys. 71, 2467 336. D. L. Bunker and N. C. Blais, “Monte Carlo (1979). Calculations. V. Three-Dimensional Study of a General Bimolecular Interaction Potential:’ J. 325. J. W. Brady, J. D. Doll, and D. L. Thompson, Chem. Phys. 41, 2377 (1964). “Cluster Dynamics: Further Classical Trajectory Studies of A + An ~ A~+l,” J. Chem. Phys. 73, 337. N. C. Blais and D. G. Truhlar, “Monte Carlo 2767 (1980). Trajectory Study of Ar + H2 Collisions, I. Poten- tial Energy Surface and Cross Sections for Dis- 326. J. W. Brady, J. D. Doll, and D. L. Thompson, sociation, Recombination, and Inelastic Scatter- “Cluster Dynamics: A Classical Trajectory Study ing:’ J. Chem. Phys. 65; 5335 (1976). of A; ~ A~_l + A;’ J. Chem. Phys. 74, 1026 (1981). 338. P. Sieglbahn and B. Liu, “An Accurate Three-Dimensional Potential Energy Surface for 327. J. W. Brady, J. D. Doll, and D. L. Thompson, Hq~’ J. Chem. Phys. 68,2457 (1978). “Classical Trajectory Studies of Homogeneous Nucleation of a Rare Gas; to appear in Potential 339. D, G. Truhlar and C. J. Horowitz, “Functional Energy Su#aces and Dynamics Calculations, D. Representation of Liu and Siegbahn’s Accurate ab G. Truhlar, Ed. (Plenum Press, New York, 1981). initio Potential Energy Calculations for H + Hz;’ J. Chem. Phys. 68,2466 (1978). 328. S. B. Woodruff and D. L. Thompson, “A Quasi-Classical Trajectory Study of Vibrational 340. J. W. Duff, N. C. Blais and D. G. Truhlar, “Monte Predissocation of Van der Waals Molecules:’ J. Carlo Trajectory Study of Ar + Hz Collisions: Chem. Phys. 71,376-380 (1979). Thermally Averaged Vibrational Transition Rates at 4500 ~’ J. Chem. Phys. 71,4304 (1979). 329. J. A. Panitz, “Deuterium Depth Profdes in Metals using Imaging Field Desorption,” J. Vat. Sci. 341. W. R. Schulz and D. J. LeRoy, “Kinetics of the Technol. 14,502 (1977). Reaction H + p – Hz ~ O – Hz + H;’ Can. J. Chem. 42,3869 (1965). 330. J. E. Adams and J. D. Doll, “Dynamics of Ion Channeling at Low Energies: Preliminary Trajec- 342. K. A. Quickert and D. J. LeRoy, “Test of Transi- tory Studies,” J. Chem. Phys. 73,2137 (1980). tion-State Theory using the Experimentally De- termined Rate Constant Ratio for the Reactions H 331. J. E. Adams and J. D. Doll, “Dynamics of Ion + Hz and H + DZJ’ J. Chem. Phys. 53, 1325 Chameling at Low Energies: Non-Normal In- (1970) and “Erratum: ..,” J. Chem. Phys. 54,5444 cidence,” J. Chem. Phys., accepted for publication. (1971), combined with A. A. Westenburg and N. (LA-UR-80-2706). de Haas, “Atom-Molecule Kinetics using ESR Detection. II. Results for D + Hz ~ HD + H and 332. J. E. Adams and J. D. Doll, “Resorption from H + Dz a HD + D;’ J. Chem. Phys. 47, 1393 Solid Surfaces via Generalized Slater Theory:’ J. (1967). Chem. Phys. 74, 1467 (1981). 343. J. D. Doll, J. Chem. Phys. submitted. 333. J. E. Adams and J. D. Doll, “Dynamical Correc- tions to Transition State Theory Adsorption Rates: 344. G. D. Carney and R. N. Porter, J. Chem. Phys. 60, Effect of a Precursor State,” submitted to Surface 4251 (1974). Science (LA-UR-80-208 1).

131 345. A. W. Campbell, W. C. Davis, and J. R. Travis, 350. A. M. Karo, J. R. Hardy, and F. E. Walker, Acts Phys. Fluids 4,498, (1961). Astronaut. 5, 1041 (1970).

346. C. L. Mader, Phys. Fluids 6,375 (1963). 351. H. C. Cady and A. C. Larson, Acts Cryst. 18,485 (1965). 347. A. W. Campbell, W. C. Davis, J. B. Ramsey, and J. R. Travis, Phys, Fluids 4,511 (1961). 352. L. Merrill and W. A. Bassett, Rev. Sci, Instrum. 45, 290 (1974), 348. C. L. Mader, Phys. Fluids 8, 1811 (1965). 353. R. LeSar, S. A. Ekberg, L. H. Jones, R. L. Mills, L. 349. F. Owens, Army Armament Research and De- A. Schwalbe, and D. Schiferl, Solid State Com- velopment Command Large Caliber Weapons Sys- mun. 32, 131 (1979). tems Laboratory, Technical Report ARLCD-TR-79037 (1979).

132 e APPENDIX A

PUBLICATIONS

CNC-2 J. M. Bunch, J. G. Hoffman, and A. H. Zeltmann, “On PUBLICATIONS 1978-80 the Nature of Features Seen by TEM in Fast Neutron Irradiated Al,OJ,” J. Nuclear Mater. 73, (1978) 65-69. J. E. Adams and J. D. Doll, “Dynamics of Ion Channel- ing at Low Energies: Preliminary Trajectory Studies,” J. R. W. Charles, C. E. Honey, Jr., J. W. Tester, L. A. Chem. Phys. 73,2137 (1980). Blatz, and C. O. Grigsby, “Experimentally Determined Rock-Fluid Interactions Applicable to a Natural Hot N. C. Blais and D. G. Truhlar, “Monte Carlo Trajectory Dry Rock Geotherm~ System:’ The Metallurgical Soci- Study of Ar+Hz: Vibrational Selectivity of Dissociative ety of AIME, TMS Paper Selection A80-8 (1980). Collisions at 4500 K and the Characteristics of Dissocia- tion under Equilibrium Conditions,” J. Chem. Phys. 70, J. D. Doll, “A Unified Theory of Dissociation,” J. Chem. 2962 (1979). Phys. 73, 2760( 1980).

N. C. Blais and D. G. Truhlar, “Ab initio Calculation of J. D. Doll, “Enharmonic Corrections in Unimolecular the Vibrational Energy Transfer Rate of H2 in Ar using Theory: A Monte Carlo Approach;’ Chem. Phys. Lett. Monte Carlo Classical Trajectories and the Forced 72, 139 (1980). Quantum Oscillator Model; J. Chem. Phys. 69, 846 (1978). J. D. Doti, “Generalized Langevin Theory of Gas/Solid-Surface Dynamics: A Formulation for J. W. Brady, J. D. Doll, and D. L. Thompson, “Cluster Thermal DesorptionV J. Chem. Phys. 68,3158 (1978). Dynamics: Further Classical Trajectories Studies of A+A~~A~~l;’ J. Chem. Phys. 73, 2767 (1980). J. W. Duff, N. C. Blais, and D. G. Truhkr, “Monte Carlo Trajectory Study of Ar+Hz Collisions: Thermally J. W. Brady, J. D. Doll, and D. L. Thompson, “A Averaged Vibrational Transition Rates at 4500 K,” J. Classical Trajectory Study of Xenon Atom-Chlorine Chem. Phys. 71,4304 (1979). Dimer Collisions,” J. Chem. Phys. 73,292 (1980). J. W. Duff and P. Brumer, “Statistical Behavior and the J. W. Brady, J. D. Doll, and D. L. Thompson, “Cluster Detailed Dynamics of Collinear F+H2. Trajectories J. Dynamics: A ClassicaI Trajectory Study of Chem. Phys. 71,3895 (1979). A+ AnqA~+l~’ J. Chem. Phys. 71, 2467 (1979). T. H. Dunning, Jr., and P. J. Hay, “The Covalent and J. W. Brady, J. D. Doll, and D. L. Thompson, “Angular Ionic States of the Rare Gas Monofluorides/’ J. Chem. Dependence of Velocity Distributions in Phys. 69, 134 (1978). Gas/Solid-Surface Collisions: Relationship to the In- teraction Potential:’ J. Chem. Phys. 69, 3458 (1978). T. H. Dunning, Jr., M. Valley, and H. S. Taylor, “Theoretical Studies of the Low-Lying Electronic States I. J. Brink and C. E. Honey, “The Enthalpy of For- of GaKr, Including Extrapolation to InKr and T Ikr:’ J. mation of Strontium Monoxide,” J. Chem. Thermodyn. Chem. Phys. 69,2672 (1978). 1978, 10, 259-266. R. Engleman, Jr., R. A. Keller, and B. A. Palmer, J. C. Brown, H. E. Bass, and D. L. Thompson, “A “Hyperfme Structure and Isotope Shift of the 1.3 Vm Quasi-Classical Trajectory Stud& of the Four-Center Transition of ‘2’17 Appl. Opt. 19, 2767(1980). Reactions: HBr+Cl, and HBr~BrC1/’ J. Chem. Phys. 70, 2326 (1979). C. E. Honey, Jr., and E. J. Huber, Jr., Combustion Calorimetry, V.1. Experimental Chemical Thermo-

133 dynamics, S. Sunner and M. Mansson, E&., “Combus- W. B. Lewis and A. H. Zeltmann, “Opto-Acoustic tion Calorimetry of Metals and Simple Metallic Com- Spectroscopy and the Energy of Photodissociation of pounds:’ (Pergarnon Press, Inc., 1979), Chap. 10, pp. Uranium Hexafluoride~’ J. Photochem. 12,51 (1980). 211-237. D. R. McLaughlin and D. L. Thompson, “Ground- and C. E. Honey, Jr., “Funding of Research in Lower Excited-State Discrete ab initio Electronic Poten- Thermodynamics: TRC Current Data News 7, No. 2 tial-Energy Surfaces for Doublet HeH2/’ J. Chem. Phys. (1979). 70, 2748 (1979).

C. E. Honey, Jr., “Funding of Research in R. K. Preston, D. L. Thompson, and D. R. McLaughlin, Thermcxdynamics:’ Editorial J. Chem. Engr. Data 23, “A Theoretical Prediction of Vibrational Enhancement No. 4,4A (1978). for Dissociative Charge Transfer in the HeHz+ System:’ J. Chem. Phys. 68, 13 (1978). R. A. Keller, R. Engleman, Jr., and B. A. Palmer, “Atlas for Optogalvanic Wavelength Calibration: Appl. Opt. J. A. Silver, N. C. Blais, and G. H. Kwei, “Crossed 19,836 (1980). Beam Studies of the Na(3p2P~~ Atoms by Nz, Oz, CO, and NO Molecules:’ J. Chem. Phys. 71 3412(1979). R. A. Keller and E. F. Zalewski, “Noise Considerations, Signal Magnitudes and Detection Limits in a Hollow K. C. Smyth, R. A. Keller, and F. F. Crim, Cathode Discharge by Optogalvanic Spectroscopy:’ “Photon-Induced Ionization Changes in a Neon Dis- Appl. Opt. 19,3301 (1980). charge: Chem. Phys. Lett. 55,473 (1978).

R. A. Keller, R. Engleman, Jr., and E. F. Zalewski, G. E. Streit and T. W. Newton, “Negative Ion-Uranium “Optogalvanic Spectroscopy in a Uranium Hollow Hexafluoride Charge Transfer Reactions,” J. Chem. Cathode Discharge: J. Opt. SW. Am. 69,738 (1979). Phys. 73,3178 (1980).

P. M. Kroger, S. J. Riley, and G. H. Kwei, “Polyhalide H. H. Suzukaw~ M. Wolfsberg, and D. L. Thompson, Photofragment Spectra. II. Ultraviolet Photodissociation “A Quasi-Classical Trajectory Study of the Energy Dynamics of UF~~ J. Chem. Phys. 68,4195 (1978). Transfer in COz-Rare Gas Systems,” J. Chem. Phys. 68, 455 (1978). G. H. Kwei and V, W. S. Lo, “Crossed Beam Studies of the Hydrogen Exchange Reaction: The Reaction of H D. L. Thompson, “On the Rate and Activation Energy and D Atoms with Tz Molecules;’ J. Chem. Phys. 72, of the Br+Brz Atom-Exchange Reaction:’ Chem. Phys. 6265 (1980). Lett. 55,424 (1978).

G. H. Kwei and D. R, Herschbach, “Optical Model W. M. Trott, N. C. Blais, and E. A. Walters, Analysis of H+H2 Reactive Scattering;’ J. Phys. Chem. “Photoionization of Carbon Disultide Monomers and 83, 1550 (1979). Dimers in a Supersonic Molecular Beam;’ J. Chem. Phys. 71, 1692 (1979). G. H. Kwei, “Classical Trajectory Studies of Alkali Halide Collision Dynamics,” Chap. 14 in Alkali Halide W. M. Trott, “Photoionization Mass Spectrometric Vapors: Structure, Spectra, and Reaction ‘Dynamics, P. Studies of Selected Compounds in a Molecular Beam: Davidovits and D. L. McFadden, Eds. (Academic Press, Los Alamos National Laboratory report LA-7727-T New York, 1979), pp. 441-477. (March 1979).

G. H. Kwei, Book review of Molecular Scattering: W. M. Trott, N. C. Blais, and E. A. Walters, “Molecular Physical and Chemical Applications, K. P. Lawley, Ed., Beam PhotoionizatiW Study of Acetone and J. Am. Chem. SW. 100,3268 (1978). Acetonedc,” J. Chem. Phys. 69,3150 (1978).

134 K. A. Truesdell, R. A. Keller, and E. F. Zalewski, J. W. Brady, J. D. Doll, and D. L. Thompson, “Classical “Locking of cw Dye Laser Emission onto the Trajectory Studies of Homogeneous Nucleation of a Wavelength of Molecukw Fluorescence by Intracavity Rare Gas: to appear in Potential Energy Surjfaces and Gain: Example I,:’ J. Chem. Phys. 73, 1117 (1980). Dynamics Calculations, D. G. Truhlar, Ed. (Plenum Press, New York, 198 1). D. G. Truhlar, N. C. Blais, J.-C. J. Hajduk, and J. H. Kiefer, “Monte Carlo Trajectory Study of Ar+Hz Col- J. D. Doll, “Monte Carlo Sampling Techniques and the lisions: Master-Equation Simulation of a 4500 K Shock Evaluation of Unimolecular Rate Constants,” J. Chem. Wave Experiment with Thermal Rotation/’ Chem. Phys. Phys. Lett. 63, 337 (1979). R. Engleman, Jr., and R. A. Keller, “Optoga.lvanic S. P. Walch and T. H. Duming, Jr., “Calculated Barrier Double Resonance Spectroscopy: Experimental Ob- to Hydrogen Atom Abstraction from Methane by Triplet servations,” Opt. Lett. P Oxygen Atoms/’ J. Chem. Phys. 72,3221 (1980). C. E. Hol.ley, Jr., M. H. Rand, and E. K. Storms, “The S. B. Woodruff and D. L. Thompson, “A Actinide Carbides: book chapter in The Chemical Quasi-Classical Trajectory Study of Vibrational Pre- Thermodynamics of Actinide Elements and Compounds dissociation of Van der Waals Molecules: Collinear (IAEA). He.. .12(B31_I),”J. Chem. Phys. 71,376 (1979). G. H. Kwei, “Crossed Beam Studies of Chemical E. F. Zalewski, R. A. Keller, and R. Engleman, Jr., Kinetics Using Radiotracer Techniques; to be published “Laser Induced Impedance Changes in a Neon Hollow in book form in the American Chemical Society’s Cathode Discharge. A Mechanistic Study,” J. Chem. ADVANCES IN CHEMISTRY series. Phys. 70, 1015 (1979). G. E. Streit and T. W. Newton, “The Effect of Chemical Reaction on Diffusive Ion Loss Processes in a Flowing PAPERS ACCEPTED FOR PUBLICATION IN Afterglow,” Int. J. Mass Spectrom. Ion Phys. FY 1980

J. E. Adams and J. D. Doll, “Dynamics of Ion Channel- J. J. Valentini, P. Esherick, and A. Owyoung, “Use of a ing at Low Energies: Non-Normal Incidence,” J. Chem. Free-Expansion Jet in Ultra-High Resolution Inverse Phys. Raman Spectroscopy;’ Chem. Phys. Lett.

J. E. Adams and J. D. Doll, “Resorption from Solid Surfaces via Generalized Slater Theory:’ J. Chem. Phys. LA REPORT

J. E. Adams and J. D. Doll, “Dynamical Corrections to B. A. Palmer, R. Engleman, and R. Keller, “An Atlas of Transition State Theory Adsorption Rates: Effect of a Uranium Emission Intensities in a Hollow Cathode Precursor State:’ Surf. Sci. Discharge:’ LA-825 l-MS (July 1980).

N. C. Blais and D. G. Truhlar, “Reaction, Dissociation, and Energy Transfer as a Function of Initial State for PAPERS AND TALKS PRESENTED AT SCIEN- H+HZ on an Accurate Ab Znitio Potential Energy TIFIC MEETINGS IN FY 1980 Surface;’ to appear in Potential Energy Swfaces and Dynamics Calculations, D. G. Truhlar, Ed. (Plenum G. E. Streit, “Flowing Afterglow Studies of Negative Press, New York, 1981). Ion-UFb Electron Transfer Reactions: 32nd Annual Gaseous Electronics Conference, Pittsburgh, Pennsylva- J. W. Brady, J. D. Doll, and D. L. Thompson, “Cluster nia%October 9-12, 1979. Dynamics: A Classical Trajectory Study of A*n*lA .+I,+A,” J. Chem. Phys.

135 G. E. Streit, “Negative Ion-UFb Electron Transfer Reac- R. A. Keller, “Tunable Lasers in Analytical Chemistry:’ tions: Detailed Modelling of Rate and Diffusion Coeffi- ACS Meeting, Kansas City, Missouri, April 17-18, cients in the Flowing Afterglow;’ 32nd Annual Gaseous 1980. Electronics Conference, Pittsburgh, Pennsylvania, Octo- ber 9-12, 1979. *R. A. Keller, “Analytical and Spectroscopic Applica- tions of Optogalvanic Spectroscopy;’ the University of D. L. Thompson, “EiYects of Vibrational Energy on Nebraska April 15-16, 1980; the University of Missouri, Rotational Relaxation: He + HZ: Southwest Region~ April 17-18, 1980; and the University of Arkansas, April ACS Meeting, Austin, Texas, December 6-7, 1979. 19, 1980.

*J. J. Valentini, “Crossed Molecular Beam Study of the J. E. Adams, “Resorption from Solid Surfaces via NO+OJ~NOz+Oz,” University of California, Berkeley. Generalized Slater Theory:’ poster session, National ACS Meeting, Las Vegas, Nevada, August 25-29, 1980. *J. D. Doll, “Review of Long Range Force Problems in Gas/Solid Surface Scattering:’ National Resource in L. Babcock, “Study of Reactions of Small Positive Ions Computational Chemistry workshop on Long Range with Selected Metal Hexaltluorides,” poster session, Forces, Menlo Park, California, January 8-11, 1980. National ACS Meeting, Las Vegas, Nevada, August 25-29, 1980. *N. C. Blais, “Energy Transfer, Reaction and Dissocia- tion as a Function of Initial State for H+HZ on an L. A. Blatz, “The Interaction of Water and Accurate ab fnitio Potential Energy Surface:’ ACS Biotite-Granodiorite Rock at 198”C, 235 “C and Meeting, Las Vegas, Nevada, August 25-29, 1980. 275 “C; 3rd International Symp. Water-Rock Interac- tions, Edmonton, Albert% Canad& July 14-24, 1980. J. E. Adams, “Dynamics of Ion Channeling at Low Energies: Preliminary Trajectory Studies: 2nd West *D. L. Thompson, “Classical Trajectory Studies of Coast Theoretical Chemistry Conference, California Homogeneous Nucleation of a Rae Gas:’ Potential Institute of Technology, Pasaden% California, April Energy Surfaces and Dynamics Calculations at the 9-11, 1980. National ACS Meeting, Las Vegas, Nevada, August 25-29, 1980. J. D. Doll, “Utiled Theory of Dissociation:’ 2nd West Coast Theoretical Chemistry Conference, California C. E. Honey, “Interaction of Water with Crystalline Institute of Technology, Pasadena, Califomi~ April Basement Rock in Fractured Hot Dry Rock Geothermal 9-11, 1980. Reservoirs,” 3rd International Symp. Water-Rock In- teractions, Edmonton, Alberta, Canada, July 14-24, C. E. Honey, “Geothermal Energy from Hot Dry 1980. Rock:’ Southwestern and Rocky Mountain Division, AAAS, 56th Annual Meeting, Las Vegas, Nevadaj April 9-12, 1980. CNC-3 J. D. Doll, “Nucleation Dynamics; Theoretical PUBLICATIONS 1978-80 Chemistry Conference, Banff, Canada, June 15-20, 1980. R. J. Daniels, P. M. Grant, and H. A. O’Brien, Jr., “The Production, Recovery, and Purification of Hf- 172 for J. D. Valentini, “Ultra-High Resolution Inverse Raman Utilization in Nuclear Medicine as the Generator of Spectroscopy of Methane in a cw Free-Expansion Je4° Lu-172~’ Int. J. Nucl. Med. Biol. 5, 11-17 (1978). 1lth International Quantum Electronics Conference, —. Boston, Massachusetts, June 23-27, 1980. *Invited talk. —.—.——— ●Invited talk.

136 P. M. Grant, B. R. Erdal, R. E. Whipple, R. J. Daniels, D. A. Miller, P. M. Grant, J. W. Barnes, G. E. Bentley, and H. A. O’Brien, Jr., “The Half-Lives of Sr-82 and and H. A. O’Brien, “Research Scale Experimentation on Rb-82,” Phys. Rev. C 18(6), 2799-2800 (1978). the Production and Purification of Spallogenic %3e at Los Alamos for Nuclear Medicine Applications; P. M. Grant, H. A. O’Brien, Jr., S. Mirzadeh, and R. E. Pergamon Press. Whipple, (Letter to Editor) “Premature Evaluation of a 6SGe/68Ga Dist~atiOn Genemm9 “ J. Nucl. Med. 21, H. A. O’Brien, Jr., and P. M. Grant, “Biomedical 702-703 (1980). Positron Generators;’ Pergamon Press.

P. M. Grant, R. E. Whipple, H. A. O’Brien, Jr., and S. D. S. Wilbur and H. A. O’Brien, Jr., “A-Ring Bromina- Kulprathipanja, “The Influence of Carrier Strontium tions of Estradiol. An Investigation of the Product Level and Eluant Volume on the Performance of Ratios,” J. Label. Cmpds. Radiopharm. Sr-82/Rb-82 Biomedical Generators,” J. Nucl. Med. 19 1250-1255 (1978). PAPERS AND TALKS PRESENTED AT SCIENTIFIC MEETINGS IN FY 1980 H. B. Hupf, P. M. Wanek, and H. A. O’Brien, Jr., “Rapid Radioiodination of Rose Bengal at Room Tem- R. E. Gibson, A. Mazaitis, B. Francis, R. PatL W. C. perature,” J. Nucl. Med. 19,525-529 (1978). Eckelman, R. C. Reba, and H. A. O’Brien, “In Vivo Receptor Binding of Radiolabeled Estrogens/’ J. Nucl. S. Mirzadeh, M. Kahn, P. M. Grant, and H. A. O’Brien, Med. 21,36 (1980). Jr., “A Procedure for the Preparation of Chloride-Free Solutions of Carrier-Free Germanium-68/’ Rad~ochem. P. M. Grant, P. M. Wanek, R. E. Whipple, G. E. Radioanal. Letters 42(6),361-364 (1980). Bentley, J. W. Barnes, and H. A. O’Brien, “Novel Research Radioisotopes from the Los Alamos Meson H. A. O’Brien, Jr., “Accelerator Preparation of Radio- Physics Facility;’ Abstracts of Papers, 146th Nat. Mtg., isotopesfor Medical Applications,” Trans. Amer. Nucl. AAAS, A. Herschman, Ed. 126 (1980).

SOC. 33, 222-224 (1979). C. Haydock, K. S. Sastry, H. A. O’Brien, P. Grant, J. H. A. O’Brien, Jr., A. E. Ogard, and P. M. Grant, “The W. Barnes, and G. E. Bentley, “Bromine-77: A Promis- LASL Medical Radioisotope Research Program: An ing New Probe for Bimolecular Research Through Overview of LAMPF and the Isotope Production Facil- PAC,” Proc. Int. Conf. Nucl. Phys. ( 1980). ity;’ Prog. Nucl. Med. 4, 16-22 (1978). D. A. Miller, P. M. Gran4 J. W. Barnes, G. E. Bentley, . H. A. O’Brien, Jr., P. M. Grant, and A. E. Ogard, “The and H. A. O’Brien, “Radionuclides from Proton-Induced LASL Medical Radioisotope Research Program: Radio- Spallation Reactions for Biomedical Applications. V. chemistry Problems and New Developments,” Prog. Ge-68 Recovery from RbBr Targets;’ Abstracts of Nucl. Med. 4,93-99 (1978). Papers, 2nd Chem. Cong. No. Amer. Cont. Amer. Chem. Sot., Part 1, NUCL No. 45, (August 1980). Y. Yano, T. F. Budinger, H. A. O’Brien, Jr., and P. M. Grant, “Evaluation and Application of Alumina Column H. A. O’Brien, Jr., “A Review of Biomedical Generators Rb-82 Generators;’ J. Nucl. Med. 20,961-966 (1979). Yielding Positron Emitters of Interest in Medcine: Abstracts of Papers, 2nd Chem. Cong. No. Amer. Cont. Amer. Chem. Sot., Part 1, NUCL No. 42, (August PAPERS ACCEPTED FOR PUBLICATION IN FY 1980). 1980 L. Rosen, D. C. Hoffman, B. J. Dropesky, and H. A. P. M. Grant, R. J. Daniels, W. J. Daniels, G. E. Bentley, O’Brien, Jr., “Nuclear and Radiochemistry Facilities at and H. A. O’Brien, “A Heavy Rare Earth Nuclide LAMPF,” Abstracts of Papers, 2nd Chem. Cong. No. Generator: J. Label. Cmpds. Radiopharm. Amer. Cont. Amer. Chem. Sot., Part 1, NUCL No. 62, (August 1980).

137 CNC-4 D. L. Anton, H. P. C. Hogenkamp, T. E. Walker, and N. PUBLICATIONS 1978-80 A. Matwiyoff, “Carbon-13 Nuclear Magnetic Resonan- ce Studies of the Monocarboxylic Acids of M. Alei, Jr., “Rapid Synthesis of Isotonically Labelled Cyanocobalamin. Assignments of the b-, d-, and Methanes: J. Labelled Compd. & Radiopharm. e-Monocarboxylic Acids,” J. Am. Chem. Sot. 102, XVII(l), 115-19 (1980). 2215-19 (1980).

M. Alei, Jr., L. O. Morgan, and W. E. Wageman, “lSN L. B. Asprey and R. T. Paine, “Metal Pentafluorides/’ Magnetic Resonance of Aqueous Imidazole and in Znorgatzic Sythesis XIX, D. F. Shriver, Ed. Zn(II)-Imidazole Complexes. Evidence for Hex- (Wiley-Interscience, New York, 1979), pp. 137-40. acoordmation~ Inorg. Chem. 17, 2288-93 (1978). J. E. Barefield, L. H. Jones, and R. Liepens, “Vibra- M. Alei, Jr., L. O. Morgan, W. E. Wageman, and T. W. tion-Rotation Analysis of Deuterium Tritide~’ J. Mol. Whaley, “pH Dependence of *SN NMR Shifts and Spectrosc. 80,233-236 (1980). Coupling Constants in Aqueous Imidazole and l-Methylirnidazole. Comments on Estimation of R. Barker and T. E. Walker, “*3C NMR Spectroscopy Tautomeric Equilibrium Constants for Aqueous His- of IsotopicaUy Enriched Carboh ydrates~’ in Methods in tidine~ J. Am. Chem. Sot. 102(9), 2881-2887 (1980). Carbohydrate Chemistry (Academic Press, 1980), Vol. VIII, Chap. 21, pp. 151-165. M. Alei, Jr., and William E. Wageman, “15NNMR Shifts for Imidazole and l-Methyl Imidazole in CHZC12Rela- R. L. Blakley, L. Cocco, R. E. London, T. E. Walker, tive to Aqueous Solution,” Tetrahedron Let. 8, 667-70 and N. A. Matwiyoff, “Nuclear Magnetic Resonance (1979). Studies on Bacterial Dihydrofolate Reductase Contain- ing [tnethyL13C]-Methionine,” Biochemistry 17, 2284-93 M. Alei, Jr., and W. E. Wageman, “Gas Phase 13C (1978). Chemical Shifts and Coupling Constants in the Deu- teromethanes: J. Chem. Phys. 68,783-84 (1978). J. R. Carm, R. E. London, J. M. Stewart, and N. A. Matwiyoff, “Effect of Temperature upon the Circular M. Alei, Jr., W. E. Wageman, and L. O. Morgan, Dichroism of BradykininJ’ Int. J. Pept. Protein Res. “Nitrogen- 15 Chemical Shifta for Imidazole in Aqueous 14(5), 388-92 (1979). CD2+ Solutionsfl Inorg. Chem. 17,3314-15 (1978). L. Cocco, R. L. Blakley, R. E. London, J. P. Groff, T. E. M. Alei, Jr., P. J. Vergamini, and William E. Wageman, Walker, and N. A. Matwiyoff, “NMR Studies of 13C “lSN NMR of cis-Diamine-Platinum(II) Complexes in Labeled Dihydrofolate Reductase,” in ChendstV and Aqueous Solution:’ J. Am. Chem. Sot. 101(18),5415-17 Biology of Pteridines, Proc. Sixth Int. Symposium, La (1979). Jolla, California, Sept. 25-28, 1978, R. L. Kisliuk and G. M. Brown, Eds. (Developments in Biochemistry, Vol. 4) D. E. Armstrong, B. B. McInteer, T. R. Mills, and J. G. (Elsevier/North-Holland, New York, 1979) pp. 383-388. Montoya, “Isotopic Enrichment of 15N,170, and 160%in Stable Isotopes, Proc. 3rd Int. Conf., May 23-26, 1978, L. Cocco, R. L. Blakley, T. E. Walker, R. E. London, Oak Brook, Illinois, E. R. Klein and P. D. Klein, Eds. and N. A. Matwiyoff, “Nuclear Magnetic Resonance (Academic Press, New York, 1979) p. 175. Studies on Bacterial Dihydrofolate Reductase Contain- ing [Guanidino-13C]-labeled Arginine~’ Biochemistry 17, D. E. Armstrong, T. R. Mills, B. B. McInteer, J. G. 4285-4290 (1978). Montoya, C. A. Lehman, R. C. Vandervoofi and M. Goldblatt, “The COLA Column for 13CProduction:’ in P. G. Eller, book review of Structure and Bonding, Stable Isotopes, Proc. 3rd Int. Con f., May 23-26, 1978, Volume 28, Electrons in Oxygen- and SUl- Oak Brook, Illinois, E. Roseland Klein and Peter D. phur-Containing Ligands, (Springer-Verlag, New York, Klein, Eds. (Academic Press, New York, 1979) p. 177. 1976), in J. Am. Chem. Sot. 100(9), 2938(1978).

138 P. G. Eller and G. J. Kubas, “Synthesis, Properties, and C. T. Gregg, J. Rudnick, B. B. McInteer, T. W. Whaley, Structure of Iodosulfiiate Salts,” Inorg. Chem. 17, and W. W. Shreeve, “The Effect of Ethanol on Galactose 894-97 (1978). Tolerance in Man,” in Stable Isotopes, Proc. 3rd Int. Conf. May 23-26, 1978, Oak Brook, Illinois, E. R. Klein P. G. Eller, A. C. Larson, J. R. Peterson, D. D. Ensor, and P. D. Klein, E&. (Academic Press, New York, and J. P. Young, “Crystal Structures of a-UF~ and UzFg 1979), pp. 515-25. and Spectral Characterization of UzFg~’ Inorg. Chem. Acts 37, 129-133 (1979). G. W. Halstead, P. G. Eller, L. B. Asprey, and K. V. Salazar, “Convenient Multigram Syntheses of Uranium P. G. Eller and R. R. Ryan, “Crystal and Molecular Pentafluoride and Uranium Pentaethoxide,” Inorg. Structures of Two Square-Pyramidal Rhodium(I)-Sulfur Chem. 17,2967-69 (1978). Dioxide Complexes. Bonding Effects in Pyramidal-SOz Complexes~’ Inorg. Chem. 19(l), 142-47 (1980). G. W. Halstead, P. G. Eller, and M. P. Eastman, “Nonaqueous Chemistry of Uranium Pentatluoride,” H. Flicker and L. H. Jones, “Integration of Absorption Inorg. Chem. 18(10), 2867-72 (1979). Lines Using the Nicolet FT-IR Spectrometer: Nicolet Instr. Corp. Newslet., IW-IR Spectral Lines II No. 1, H. P. C. Hogenkamp, N. A. Kohlmiller, R. Howsinger, (March 1980) p. 6. T. E. Walker, and N. A. Matwiyoff, “Interaction of cfs-Diamminediaquoplatinum(II) with (Adenosyl-) E. Fukushima, book review of Magnetic Resonance of cobalamin and Alkylcobalarninq” J. Chem. Sot., Dalton Phase Transitions, F. J. Owens, C. P. Poole, Jr., and H. Trans. 9, 1668-1673 (1980), A. Farach, Eds. (Academic Press, New York, 1979), in J. Magn. Resonan. 40,409-412 (1980). L. H. Jones, “Measurement and Analysis of the V2Bands of 14NDJ and lsNDj~ J. Mol. Spectrosc. 73(3), 409-22 E. Fukushirna, A. A. V. Gibson, and T. A. Scot4 (1979). “Carbon- 13 NMR of Carbon Monoxide. II. Molecular DifTusion and Spin-rotation Interaction in Liquid CO,” J. L. H. Jones and S. A. Ekberg, “Vibrational Spectrum Chem. Phys. 71(4), 1531-36 (1979). and Potential Constants for S2F10~’Spectrochim. Acts 36A, 761-767 (1980). E. Fukushima, A. A. V. Gibson, and T. A. Scot~ “ERRATUM: Carbon- 13 NMR of Carbon Monoxide. I. L. H. Jones and S. A. Ekberg, “Photoinduced Reaction Pressure Dependence of Translational Motion in of UFC with SiHd in a Low Temperature SiHq Matrix,” J. Beta-CO, [J. Chem. Phys. 66, 4811-17 (1977)]/’ J. Chem. Phys. 71(11), 4764-65 (1979). Chem. Phys. 68,2022 (1978). L. H. Jones, S. Ekberg, and L. B. Asprey, “Laser E. Fukushima and G. Halstead, “NMR of Excitation of SF6 in Low Temperature Matricesj’ J. Polycryst+line NaUFb,” in Magnetic Resonance and Chem. Phys. 70, 1566-67 (1979). Related Phenomena (1978), Proc. XX Congress Am- pere, Tallinn, USSR, Aug. 21-26, 1978, E. Kundla, E. L, H. Jones, Craig Kennedy, and S. Ekberg, “Potential Lippmaa and T. Saluvere, Eds. (Springer-Verlag, Berlin, Constants of CF,~’ J. Chem. Phys. 69,833-838 (1978). 1979) p. 378. L. H. Jones, B. J. Krohn, and R. C. Kennedy, “The v, E. Fukushima and S. B. W. Roeder, “Spurious Ringing Fundamental of Three Isotopic Species of CFd/’ J. Mol. in Pulse NMR/’ J. Magn. Reson. 33, 199-203 (1979). Spectrosc. 70,288-93 (1978).

E. Fukushima and K. D. Swenson, “Use of CAMAC L. H. Jones and R. R. Ryan, “Potential Constants and for Computer Interface in NMR~’ J. Magn. Reson. 39, Dissociation Pathways~ J. Mol. Struct. 46, 35-42 325-328 (1980). (1978).

139 L. H. Jones, B. I. Swanson, and S. A. Ekberg, “Tem- G. J. Kubas, A. C. Larson, and R. R. Ryan, “Reactions perature Reversible IR Spectral Changes and Site Struc- of Quinuclidme N-Oxide and Other Amine Oxides with ture Dynamics for SeFc Isolated in Krypton Matrices:’ Sulfur Dioxide. Structure of Quinuclidine Sulfur Triox- Chem. Phys. Lett. 74,331 (1980). ide~’ J. Org. Chem. 44(22), 3867-71 (1979).

L. H. Jones, B. L Swanson, and S. A. Ekberg, “High G. J. Kubas, R. R. Ryan, and V. McCarty, “Bonding of Resolution Infrared Matrix Isolation Spectroscopy of q2-Sulfur Dixoide: Structures of Tricarbonyl SF~ and BC1,,” Chem. Phys. Lett. 68(2,3), 499-500 (1,10-phenanthroline)-(q’-sulfur dioxide)molybdenum(0) (1979), and Dicarbonyl(2,2’-bipyridyl)bis-(q2sulfur dioxide) molybdenum(0),” Inorg. Chem. 19(10), 3003-3007 L. H. Jones, R. C. Taylor, and R. T. Paine, “Potential (1980). Constants of Borane Carbonylj” J. Chem. Phys. 70, 749-57 (1979). A. C. Larson, “Restrained Refinement of Disodium Adenosine 5’-Triphosphate Trihydrate,” Acts, Cryst. V. H. Kollman, J. L. Hanners, R. E. London, E. G. B34, 3601-04 (1978). Adame, and T. E. Walker, “Photosynthetic Preparation and Characterization of 13C-Labeled Carbohydrates in K. M. Leary, J. L. Lyman, L. B. Asprey, and S. M. Agmenellum quadruplicatum,” Carbohydr. Res. 73, Freund, “COz Laser Induced Reactions of SF5C1,” J. 193-202 (1979). Chem. Phys. 68, 1671-76 (1978).

V. H. Kollman, R. E. London, J. L. Hanners, C. T. R. LeSar, S. A. Ekberg, L. H. Jones, R. L. Mills, L. A. Gregg, and T. W. Whaley, “Photosynthetic Preparation Schwalbe, and D. Schiferl, “Raman Spectroscopy of of Galactose-13Cb and Glycerol-13C3 Using a Marine Solid Nitrogen up to 374 kbar~’ Solid State Commun. Red Alga:’ J. Labelled Comp. Radiopharm. XVI(6), 32, 131-134 (1979). 833-42 (1979). E. K. S. Liu, “Chemistry of Trifluoromethyl Com- V. H. Kollman, R. E. London, J. L. Hanners, and T. E. pounds. 2. Synthesis and Characterization of Walker, “Photosynthetic Preparation of 13C-Labeled Bis(pyridine)bis(trifluoromethyl)-zinc~’ Inorg. Chem. Sugars Using a Blue-Green Alga7 in Stable Isotopes, 19(1), 266-68 (1980). Proc. 3rd Int. Conf., May 23-26, 1978, Oak Brook, Illinois, E. R. Klein and P. D. Klein, Eds. (Academic E. K. S. Liu and L. B. Asprey, “Chemistry of Press, New York, 1979), pp. 19-27. Trifluoromethyl Compounds. I. NMR Evidence for Bis(trifluoromethyl)zinc and Methyl(trifluoromethyl) G. J. Kubas, “Five-co-ordinate Molybdenum and zinc:’ J. Organometal. Chem. 169, 249-254 (1979). Tungsten Complexes, [M(CO)~(PCyq)z], which Re- versibly add Dinitrogen, Dihydrogen, and Other Small R. E. London, “Correlation of Carboxyl Carbon Thra- Molecules:’ J. Chem. Sot., Chem. Commun. No. 2, tion Shifts and pK Valuesj’ J. Magn. Reson. 38, 173-177 61-62 (1980). (1980).

G. J. Kubas, “Tetrakis(acetonitrile)copper(I) Hexa- R. E. London, “Intramolecular Dynamics of Proteins fluorophosphatey Inorg. Synth. XIX, 90-92 (1979). and Peptides as Monitored by Nuclear Magnetic Relaxa- tion Measurements,” in Magnetic Resonance in Biology, G. J. Kubas, “Diagnostic Features of Transition- Z.,J. S. Cohen, Ed. (John Wiley& Sons, Inc., New York, Metal-SOz Coordination Geometries’ Inorg. Chem. 18, 1980) Chap. 1, pp. 1-69. Invited review. 182-188 (1979). R. E. London, “Quantitative Evaluation of y-Turn G. J. Kubas, “A Convenient Method for Deoxygenating Conformation in Proline-Containing Peptides Using 13C Solvents for Benchtop Inert-Atmosphere Reactions’ NMR~’ Int. J. Pept. Protein Res. 14,377-87 (1979). AMchimica Acts 1l(l), 10 (1978).

140 R. E. London, “Carbon-Carbon Coupling in Aspartic and Glutamic Acids:’ J. Am. Chem. Sot. 100, [90%-’3C-2]Histidine/’ J. Chem. Sot., Chem. Commun. 3723-29 (1978). 1070-71 (1978). R. E. London, T. E. Walker, D. M. Wilson, and N. A. R. E. London, “On the Interpretation of *3CSpin Lattice Matwiyoff, “Application of Doubly Decoupled 13C{IH, Relaxation Resulting from Ring Puckering in Proline~ J. 14N}NMR Spectroscopy to Studies of the Conformation Am. Chem. Sot. 100,2678-85 (1978). and Dynamics of the Choline Headgroup of Phos- pholipids,” Chem. Phys. Lipids 25,7-14 (1979). R. E. London and J. Avitabile, Jr., “Internal Diffusion Model. Application to Methionine Relaxation in N. A. Matwiyoff, “Architecture and Dynamics of Dihydrofolate Reductasefl J. Am. Chem. Sot. 100, Isotonically Labelled Marcomolecules by Nuclear Mag- 7159-7165 (1978). netic Resonance Spectroscopy;’ in ESR and Nh4R of Paramagnetic Specity in Biological and Related Sys- R. E. London and J. W. Avitabile, Jr., “Carbon-13 tems, I. Bertini and R. S. Drago, Eds. (D. Reidel Publ. Relaxation Times in a Hydrocarbon Chain Undergoing Co., Hingham, Massachusetts, 1979), pp. 28-53. Gauch-Trans Isomerism,” Proc. Symp. Bimolecular Structure and Function, University of Missouri, Colum- N. A. Matwiyoff, R. E. London, T. E. Walker, R. bia, Missouri, May 1977, P. F. Agris, Ed. (Academic Blakley, and L. Cocco, ‘6*3CNMR Studies of Bacterial Press, 1978) pp. 78-85. Dihydrofolate Reductase Containing [Methyl-’3C] Methionine and [Guanido-13C]Arginine~’ in Stable R. E. London, J. P. Groff, and R. L. Blakley, “13CNMR Isotopes, Proc. 3rd Int. Conf., May 23-26, 1978, Oak E~dence of the Slow Exchange of Tryptophans in Brook, Illinois, E. R. Klein and P. D. Klein, 13ds. Dihydrofolate Reductase Between Stable Conforma- (Academic Press, New York, 1979) pp. 299-305. tions;’ Biochem. Biophys. Res. Commun. 86(3), 779-786 (1979). B. B. McInteer, “Isotope Separation by Distillation: Design of a Carbon- 13 Plantj’ Sep. Sci. Technol. 15(3), R. E. London, N. A. Matwiyoff, J. M. Stewart, and J. R. 491-508 (1980). Cann, “A *3CNuclear Magnetic Resonance Study of the Cis-Trans Isomerism in X-Pro-Pro Tripeptides,” T. R. Mills, “Carbon Isotope Separation by Absorptive Biochemistry 17,2277-83 (1978). Distillation,” Sep. Sci. Technol. 15(3), 475-490 (1980).

R. E. London and A. D. Sherry, “Conformation Ex- D. C. Moody and J. D. Odom, “The Chemistry of amination of Uridine Diphosphoglucose Using Lan- Trivalent Uranium. The Synthesis” and Reaction thanide-Nitrilotriacetate Chelates as Shift Probes;’ Chemistry of the Tetrahydrofuran Adduct of Uranium Biochemistry 17, 3662-3666 (1978). Trichloride, UCIJ(THF)x~’ J. Inorg. Nucl. Chem. 41, 533-35 (1979). R. E. London, John M. Stewart, John R. Cann, and N. A. Matwiyoff, “13C and ‘H NMR Studies of Bradykinin D. C. Moody, R. A. Penneman, and K. V. Salazar, “The and Selected Peptide Fragments,” Biochemistry 17, Chemistry of Trivalent Uranium. 2. Synthesis of 2270-7 (1978). UC13(18-crown-6) and U(BHd)3(18-crown-6)~’ Inorg. Chem. 18,208-209 (1979). R. E. London, J. M. Stewart, J. R. Cann, R. Williams, and N. A. Matwiyoff, “Carbon-13 NMR Spectroscopy D. C. Moody and R. R. Ryan, “Novel “Reactivity and of [20Y0-1,2-~3Cz-Glyc]-Bradykinin. Role of Serine in Low Temperature (–60”C) Structure of RU(CO)Z Reducing Structural I-leterogeneity~’ J. Am. Chem. Sot. (q2-S0,.SO~(PPh,),;’ J. Chem. Sot., Chem. Commun. 101(9), 2455-2462 (1979). No. 24, 1230-1231 (1980).

R. E. London, T. E. Walker, V. H. Kollman, and N. A. D. C. Moody and R. R. Ryan, “Di[(benzo- Matwiyoff, “Studies of the pH Dependence of ‘3C Shifts 15-crown -5)sodium] Tetrachloro-dioxouranate, and Carbon-Carbon Coupling Constants of [U-]3C] C,gH40Cl,Na201,U,” Cryst. Struct. Comm. 8(4), 933-36 (1979). 141

— D. C. Moody and R. R. Ryan, “Structures of (Sulfur Chromium Hexacyanate,” Acts Crystallogr. B34, dioxidc)tris-(tripheny lphosphine)nickel( 0), 1398-99 (1979). Ni(SO~PPhJ)j, and Bis(sulfur dioxide)bis

142 Resonance,” Thesis, University of New Mexico, 1979: R. E. London, “Carbon-Carbon Coupling in Los Alamos National Laboratory report LA-7774-T [13-’3Cl]Tryptophan7 Org. Magn. Reson. (April, 1979). R. E. London and T. E. Walker, “Asymmetric NMR Spectra of Weakly Coupled Nuclei: A Common Charac- PAPERS ACCEPTED FOR PUBLICATION FY 1980 teristic in the 13C NMR Spectra of [U-13C] Labeled Molecules and in Natural Abundance Proton-Coupled M. Alei, Jr., L. O. Morgan, and W. E. Wageman, “lSN 13CSpectr%” Org. Magn. Reson. NMR Study of Complexation of l-Methylirnidazole by Zn(II) and Cd(II) in Aqueous Solution: Inorg. Chem. B. B. McInteer and J. G. Montoya, “An Automated Mass Spectrometer for Nitrogen Isotope Analysis: M. J. O. Anteunis, F. Borremans. J. M. Stewart, and R. Anal. Biochem. E. London, “A 360 MHz ‘HNMR Confirmational Analysis of Gly-Pro-X Peptides (X = Ala, Cha, Phe)j’ J. D. C. Moody, M. Goldblatt, B. B. McInteer, and T. R. Am. Chem. Sot. Mills, “Alumina Catalyzed Isotope Exchange in CO,” J. Catal. P. G. Eller and R. A. Penneman, “Physiochemical Properties of Curium, “ in Chemistry of the Actinides, D. C. Moody and R R. Ryan, “Trans- Seaborg and Katz, Eds. (Invited chaper). Hydridocarbonyltris-( triphenylphosphine) cobalt(I), CoP30C~~H4c,” Cryst. Struct. Commun. P. G. Eller and P. J. Vergamini, “Nuclear Magnetic Resonance and Chemical Studies of Uranium(V) Alkox- D. C. Moody and R. R. Ryan, “Novel Reactivity and ides:’ Inorg. Chem. Low Temperature (-60”C) Structure of RU(CO)2 (q2-SOZ”SOxpPh3)2,” J. Chem. Sot., Chem. Commun. C. T. Gregg, J. Rudnick, B. B. McInteer, and W. W. Shreeve, “The Effect of Ethanol on Complete Oxidation R. A. Penneman, “Americium/’in Encyclopedia of Sci- of C- 13 Galactose in Alcoholic Liver Disease,” J. Nucl. ence and Technology, 5th Ed. (McGraw-Hill Book Co.) Med. R. A. Penneman, “Neptunium~ in Encyclopedia oj G. W. Halstead and P. G. Eller, “Uranium(V) Fluorides Science and Technology, 5th Ed., (McGraw-Hill Book and Alkoxides:’ Inorg. Synth. co.)

G. J. Kubas and R. R. Ryan, “Chlorobis W. W. Schulz and R. A. Penneman, “Physicochernical (Tricyclohexylphosphine)-(Sulfti Dioxide)Rhodium(I), Properties of Americium” in Chemistty of the Actinides, A Square Planar SOz-Transition Metal Complex~’ Inorg. Seaborg and Katz, Eds. (Invited chapter). Chem. Acts. B. L Swanson and L. H. Jones, “Matrix-Molecule G. J. Kubas, R. R. Ryan, and V. McCarty, “Bonding of Interactions, Dynamics, and Exchange Phenomena in q2-Suifur Dioxide: Structures of Tricarbonyl- Low Temperature Matrices: SF6 in Argon and Kryp- (1,10-phenanthroline)-(q2-sulfur dioxide)molybdenum(0) ton,” J Chem. Phys. and Dicarbonyl(2,2’-tipyridyl)bis-(q2-sulfur dioxide) molybdenum/’ Inorg. Chem. 19(10), 3003-3007 (1980). PAPERS AND TALKS PRESENTED AT SCIEN- TIFIC MEETINGS IN FY 1980 G. J. Kubas and P. J. Vergamini, “Synthesis, Character- ization and Reactions of Iron-Sulfur Clusters containing M. Alei, Jr., L. O. Morgan, and W. E. Wageman, “~sN the S2 Ligand. [CpzFez(S~(SR)2 ]0’+1,[CpAFe#S]O’+1’+2, NMR Study of Complexation of Histidine by Zn(II) and and [CpdFe4Sc],” Inorg. Chemb Cd(II) in Aqueous Solution: 180th ACS National Meeting, Las Vegas, Nevada, August 24-29, 1980.

143 L. B. Asprey and P. G. Eller, “Fluorination Reactions of B. B. McInteer, “Isotope Separation by Distillation: UFc~ ,7th European Symp. Fluorine Chemistry, Venice, Design of a Carbon-13 Plant:’ Symposium on Separa- September 15-19, 1980. tion Science and Technology for Energy Applications, Gatlinburg, Tennessee, October 30- November 2, 1979. L. B. Asprey and L. H. Jones, “Laser-Induced Separa- Sep. Sci. Technol. 15(3), 491-508 (1980). tion of Sulfur Isotopes in Thiophosphoryl Fluoride,” 35th Northwest - 5th Biennial Rocky Mountain ACS B. B. McInteer, “Automation of a Mass Spectrometer Joint Regional Meeting, Salt Lake City, Utah, June for Nitrogen Isotope Ratio Analysis,” 7th Int. Symp. 12-14, 1980. Mass Spectrometry in Biochemistry Medicine, and En- vironmental Research, Milan, Italy, June 16-18, 1980. P. G. Eller, “SOz Insertion Reactions of d- and f-Element Complexes,” Southwest Regional ACS Meeting, Austin, T. R. Mills, “Carbon Isotope Separation by Absorptive Texas, December 5-7, 1979. Distillation/’ Symposium on Separation Science and Technology for Energy Applications, Gatlinburg, Ten- P. G. Eller, “Crystal Structure of Hg(DHDECMP- nessee, October 30 - November 2, 1979. Sep. Sci. H)(NOj)7 (Presented by R. T. Paine), Actinide Work-’ Technol. 15(3), 475-490 (1980). shop IV, Los Alamos, New Mexico, May 13-14, 1980. *D. C. Moody, “The Chemistry of Trivalent Uranium,” *P. G. Eller, “SOz Interactions with f- and d-Element University of South Carolina, Columbia, South Caroli- Organometailics/’ Ohio State University, Columbus, na, November 30, 1979. Ohio, May 30, 1980. D. C. Moody, R. R. Ryan, and G. J. Kubas, “Activation P. G. Eller, “SOz Interactions with f- and Early of S-O Bonds in Transition Metal-Sulfur Dioxide Com- d-E1ement Organo-metallics,” 180th ACS National plexes:’ 179th ACS Meeting, Houston, Texas, March meeting, Las Vegas, Nevada, August 24-29, 1980. 24-28, 1980. ACS Abstracts of Papers 179, INOR-34 (1980). E. Fukushima and K. D. Swenson, “Use of CAMAC for Computer Interface in NMR~’ 21st Experimental Nucle- R. A. Penneman, “A Zirconium Molybdate as a ar Magnetic Resonance Spectroscopy Conference, Flori- Plutonium Host; IAEA Symposium on the Manage- da State University, Tallahassee, Florida, March 16-20, ment of Alpha-Contaminated Wastes, Vienna, Austria, 1980. June 2-6, 1980.

G. D. Jarvinen, G. J. Kubas, and R. R. Ryan, “Sulfur H. D. Ramsey, D. G. Clifton, S. W. Hayter, R. A. Dioxide Complexes of Mo(O) and W(0): Intercon- Penneman, and Eldon L. Christensen, “Status of 241Am version of ql and 112Geometries and a Novel S02 Recovery and Puritlcation at LCISAlamos Scientific Bridging Structure:’ ACS Combined Regional Meeting Laboratory;’ ACS Int. Symp. Industrial-Scale Prod- Southeast-Southwes~ New Orleans, Louisiana, Decem- uction-Separation-Recovery of Transplutonium Ele- ber 10-13, 1980. ments,” Las Vegas, Nevada, August 24-29, 1980. [To be published in ACS Symposium Series.] G. J. Kubas and R. R. Ryan, “Coordina- tively-Unsaturated Mo(O) and W(0) Complexes M. J Reisfeld, H. Flicker, and M. Goldblatt, “Analysis of M(CO)J(PCyJ)2, which Reversibly Add N2, H2, and the Fourier Transform Spectrum of 13C180Zin the 4.3 Other Small Molecules: 179th ACS National Meeting, ~m and 16 ym Regions,” 35th Annual Symp. Molecular Houston, Texas, March 24-28, 1980. ACS Abstracts of Spectroscopy, Columbus, Ohio, June 16-20, 1980. Papers 179, INOR-28 (1980). M. J. Reisfeld, H. Flicker, and M. Goldblatt, “Analysis G. J. Kubas, “New Aspects of the Coordination of the Spectra of l*C1702, *2C’70*a0, and 13C*70Zin the Chemistry and Bonding of SOZ, an Exceptionally Ver- Vz (15 ~m) Region,” 35th Annual Symp. Molecular satile Small Molecule,” Gordon Research Conference on Spectroscopy, Columbus, Ohio, June 16-20, 1980. ● Inorganic Chemistry, New Hampton, New Hampshire, ———————— August 4-8, 1980. ‘Invited talk.

144 R. R. Ryan, G. J. Kubas, D. C. Moody, and P. G. Eller, J. E. Bonelli, J. P. Greenberg, A. L. Lazrus, J. E. “Activation of Sulfur Dioxide by Transition Metal Spencer, and W. A. Sedlacek, “Laboratory Simulation of Complexes,” 2nd Int. Symp. Homogeneous Catalysis, Impregnated Filter Collection of Stratospheric Hydrogen Diisseldorf, Germany, September 1-3, 1980. Chloride and Chlorine Nitrate,” Atmospheric Environ- ment 12, 1591-94 (1978). B. 1. Swanson and L. H. Jones, “High Resolution Infrared Studies of Dynamics and Exchange R. W. Charles, C. E. Honey, Jr., J. W. Tester, L. A. Phenomenon in Low Temperature Matrices,” poster Blatz, and C. O. Gngsby, “Experimentally Determined session, Gordon Conference, Wolfeboro, New Hamp- Rock-Fluid Interactions Applicable to a Natural Hot shire, August 18-22, 1980. Dry Rock Geothermal System,” TMS Pap. Sel. A80-8 (1980). B. I. Swanson and L. H. Jones, “Application of High Resolution FTIR to the Study of Dynamics in Low C. C. Cummings, A. E. Ogard, and R. H. Shaw, “Target Temperature Matrices,” Symp. Fourier Transform Insertion and Handling System for the Isotope Prod- Methods, 180th ACS National Meeting, Las Vegas, uction Facility,” Proc. 26th Conf. Remote Systems Nevada, August 24-29, 1980. Technology, 1978, pp. 201-206.

P. J. Vergamini and G. J. Kubas, “Synthesis, Structure, D. B. Curtis and A. J. Gancarz, “Lead Isotopes as and Properties of Complexes Containing Organometallic Indicators of Environmental Contamination from the Cluster Llgands~ 179th ACS National Meeting, Hous- Uranium Mining and Milling Industry in the Grants ton, Texas, March 24-28, 1980. ACS Aiostracts of Mineral Belt, New Mexico,” Proc. NEA Seminar for the Papers 179, INOR-94 ( 1980). Management, Stabilization and Environmental Impact of Uranium Mill Tailings OECD, Paris, France, 143 T. E. Walker, D. L. Anton, H. P. C. Hogenkamp, and N. (1978). A. Matwiyoff, “Carbon-13 Nuclear Magnetic Resonan- ce Studies of the Structure of Vitamin B-12 Derivatives,” D. B. Curtis, E. S. Gladney, and E. T. Jurney, “Potential American Society of Biological Chemists, Biophysical Interferences in the Determination of Sulfur by Thermal Society, New Orleans, Louisiana, June 1-5, 1980. Ab- Neutron Induced Prompt y-Ray Spectrometry,” Anal. stract in Federation Proc. 39, No. 6, May 1980. Chem. 51, 158 (1979).

D. B. Curtis and R. A. Schmitt, “The Petrogenesis of L-6 CNC-7 Chondrites: Insights from the Chemistry of Minerals; PUBLICATIONS 1978-80 Geochem. Cosmochin. Acts 43, 1091-1103 (1978).

M. Alei, Jr., “Rapid Synthesis of Isotonically Labelled H. O. Denschlag, H. Braun, W. Faubel, G. Fischbach, Methanes,” J. Labelled Compd. Radiopharm. 17, 115-19 H. Meixler, G. Paffrath, W. Porsch, M. Weis, H. (1980). Schrader, G. SiegerL J. Blachot, Z. B. Alfassi, H. N. Erten, T. Izak-Biran, T. Tamai, A. C. Wahl, and K. M. Alei, Jr., L. O. Morgan, W. E. Wageman, and T. W. Wolfsberg, “Distribution of Nuclear Charge and Whaley, “pH Dependence of 15N NMR Shifts and Angular Momentum in Chains 132-137, 99, and 102 of Coupling Constants in Aqueous Imadazole and 23SU (nt~,~ at Various Kinetic Energies and Charge 1-Methyl Imidazole: Comments on Estimation of States of the Fragments,” Physics and Chemistry oj Tautomeric Equilibrium Constants for Aqueous His- Fission, Vol. II, IAEA, Vienn% 153-177 (1979). tidine~’ J. Am. Chem. Sot. 102(9), 2881-2887 (1980). B. R. Erdal, B. P. Bayhurst, W. R. Daniels, S. J. B. P. Bayhurst, J. S. Gilmore, R. J. Prestwood, R. E. DeVilliers, G. H. Heiken, F. O. Lawrence, M. L. Sykes, Whipple, and P. M. Wanek, “Spallation Yields of ‘zFe, J. R. Smyth, J. L. Thompson, E. N. Vine, and K. 67CU, c7Ga, and 201Tl from Reactions of 800-MeV Wolfsberg, “Parameters Affecting Radionuclide Migra- Protons with Ni, As, Pb, and Bi Targets/’ J. Labelled tion in Geologic Medi&” Scient@ Basis for Nuclear Cmpds. Radiopharm. 16, 212-213 (1979).

145 Waste Management, Vol. 2, C. J. M. Northrup, Ed. H. A. O’Brien, Jr., A. E. Ogard, and P. M. Gran~ “The (Plenum Press, New York) pp. 609-616. LASL Medical Radioisotope Research Program: An Overview of LAMPF and the Isotope Production Facil- B. R. Erdal, B. P. BayhursL W. R. Daniels, S. J. ity,” Prog. Nucl. Med. 4, 16-22 (1978). DeVilliers, F. O. Lawrence, J. L. Thompson, and K. Wolfsberg, “Parameters Affecting Radionuclide Migra- C. J. Orth, J. D. Knight, K. Wolfsberg, and M, W. tion of Argillaceous Media;’ Proc. of the Workshop on Johnson, “Nuclear Disintegration of Some Complex the Use of Argillaceous Materials for the Isolation of Nuclei by 60-MeV Muons:’ Phys. Rev. C 21, 1967 Radioactive Waste, Paris, September 10-12, 1979 (Nu- (1980). clear Energy Agency, Organization for Economic Co-Operation and Development Paris, France) pp. R J. Otto, G. T. Seaborg, and M. M. Fowler, “Recoil 55-66. Range Distributions of Heavy Mass Products in Deep Inelastic Reaction with Gold and Uranium Targets:’ B. R. Erdal, W. R. Daniels, D. C. Hoffman, F. O. Phys. Rev. C 17, 1071 (1978). Lawrence, and K. Wolfsberg, “Sorption and Migration of Radionuclides in Geologic Media:’ Scientific Basis M. A. Shapiro, E. R. Reiter, R. D. Cadle, and W. A. for Nuclear Waste Management, Vol. 1, G. J. Mc- Sedlacek, “Vertical Mass and Trace Constituent Trans- Carthy, Ed., (Plenum Press, New York, 1979) pp. ports in the Vicinity of Jet Streams;’ Arch. Met. Geoph. 423-426. Biokl., Ser. B 28, 193-206 (1980).

A. J. Gancarz, “Chronology of the Cluff Lake Uranium J. R. Smyth, J. Thompson, and K. Wolfsberg, “Micro- Deposi~ Saskatchewan, Canad%” Proc. Int, Uranium autoradiographic Studies of the Sorption of U and Am Symp. Pine Creek Geosyncline, Northwest Territory, on Natural Rock Samples:’ Radioactive Waste Manage- Australia, 91-94, (1979). ment, Vol. 1 (1), 13-24 (Harwood Academic Publishers, New York, 1980). A. J. Gancarz, “U-Pb Age (2.05 X 109 years) of the Oklo Uranium Deposit: Natural Fission Reactors, E. N. Vine, D. Young, W. Vine, and W. Wolf, “An 513-520 (IAEA, Vienna, 1978). Improved Synthesis of 18F-5-fluorouracil~ Int. J, Ap- plied Rad. Isot. 30401 (1979). E. S. Gladney and D. B. Curtis, “Comment on De- termination of Fluoride by Neutron Activation K. Wolfsberg, W. R. Daniels, D. C. Hoffman, and B. R. Analysis:’ Anal. Chem. 50,376 (1978). Erdal, “Migration of Radionuclides in Geologic Media — Laboratory and Field Studies:’ Effluent and Environ- E. S. Gladney, D. B. Curtis, and E. T. Jumey, “Muki- mental Radiation Surveillance, ASIM STP 698, J. J. Element Analysis of Major and Minor Elements by Kelly, Ed. (American Society for Testing and Materials, Thermal Neutron Induced Capture Gamma-Ray Spec- 1980) pp. 252-254. trometryfl J. Radio. Chem. 46, 299-308 (1978).

E. S. Gladney, L. F. Wangen, D. B. Curtis, and E. T. PAPERS ACCEPTED FOR PUBLICATION IN FY Jurney, “Observations on Boron Release from Coal 1980 Fired Power Plants:’ Env. Sci. Tech. 12, 1084 (1978). M. Alei, Jr., P. J. Vergamini, and W. E. Wageman, “15N P. M. Grant, B. R. Erdal, R. E. Whipple, R. J. Daniels, NMR of cis-Diarnine-Platinum(II) Complexes in and H. A. O’Brien, Jr., “Half-lives of ‘2Sr and 82Rb~ Aqueous Solution,” J. Inorg. Chem. Phys. Rev. C18, 2799 (1978). W. W. Berg, P. J. Crutzen, H. E. Grahek, S. N. Gitlin, H. A. O’Brien, Jr., P. M. Grant, and A. E. Ogard, “The and W. A. Sedlacek, “First Measurements of Total LASL Medical Radioisotope Research Program: Radio- Chlorine Bromine in the Lower Stratosphere:’ Geophys. chemistry Problems and New Developments,” Prog. Res. Lett. Nucl.-. Med 4,93-99 (1978). 146 D. B. Curtis, E. S. Gladney, and E. T. Jurney, “The 1980,” Los Alamos National Laboratory report Cosmochemistry of Boron,” Geochem. Cosmochim. LA-8586-PR (January 1981). Acts. B. R. Erdal, compiler, “Laboratory Studies of Radio- B. R. Erdal, B. P. Bayhurst, B. M. Crowe, W. R. nuclide Distribution Between Selected Groundwaters Daniels, D. C. Hoffman, F. O. Lawrence, J. R. Smyth, J. and Geologic Media, October l—December 31, 1979/’ L. Thompson, and K. Wolfsberg, “Laboratory Studies of Los Alamos National Laboratory report LA-821O-PR Radionuclide Transport in Geologic Medi&” Proc, Int. (March 1980). Symp. Underground Disposal of Radioactive Wastes, Otaniemi, Finland. B. R. Erdal, compiler, “Laboratory Studies of Radio- nuclide Distributions Between Selected Groundwaters A. J. Gancarz, G, A. Cowan, D. B. Curtis, and W. J. and Geologic Media, January l—March 31, 1980~’ Los Maeck, “99Tc, Pb and Ru Migration Around the Oklo Alamos National Laboratory report LA-8339-PR (May Natural Fission Reactors:’ Proc. Int. Symp. Scient.Mc 1980). Basis for Nuclear Waste Mangement. B. R. Erdal, compiler, “Laboratory Studies of Radio- M. Megan, A. Shaw, W. A. Sedlacek, P. R. Guthals, M. nuclide Distributions Between Selected Groundwaters M. Fowler, and R. Megill, “Measurements of Nitric and Geologic Medi% April l—June 30, 1980~ Los Oxide After a Nuclear Burst: J. Geophys. Res. (green). Alamos National Laboratory report LA-8472-PR (Sep- tember 1980). W. A. Sedlacek, “Use of Ozone and Aitken Nuclei as Natural Tracers to Examine the Exchange of Air E. S. Gladney, D. B. Curtis, D. R. Perrin, J. W. Owens, Between the Troposphere and Stratosphere in the Vicini- and W. E. Goode, “Nucleu Techniques for the ty of The Tropopause Fold:’ S. Barr and T. Gedayloo, Chemical Analysis of Environmental Materials,” Los Eds., Proc. Atmospheric Tracers and Tracer Application Alamos National Laboratory report LA-8192-MS (Jan- Workshop, Los Alamos, New Mexico, May 22-24, USry 1980). 1979, Los Alamos National Laboratory report LA-8 144-C (December 1979). A. E. Norris, “Fission Product Release, July l—Septem- ber 30, 1979/’ Los Alamos National Laboratory report E. N. Vine, B. P. Bayhurst, W. R. Daniels, S. J. LA-8149-PR (November 1979). DeVilliers, B. R. Erdal, F. O. Lawrence, and K. Wolfsberg, “Radionuclide Transport and Retardation in A. E. Norris, “Oklo - Natural Fission Reactor Program Tufffl Scientific Basis fo~‘Nuclear Waste Management July l—September 30, 1979,” Los Alamos National Vol. 3, J. G. Moore, Ed. (Plenum, New York). Laboratory report LA-8189-PR (January 1980).

E. Vine, A. C. Wahl, “Fractional Independent Yields of A. E. Norris, “Fission Product Release, October l—De- lo~c md ~FSTcfrom Therm~-NeutrOn Induced Fission cember 31, 1979; Los Alamos National Laboratory of 23SUand of 239Pu: J. I.norg. Nucl. Chem. report LA-8272-PR (March 1980).

A. E. Norris, “Oklo - Natural Fission Reactor Program, LA REPORTS October l—December 31, 1979: Los Alamos National Laboratory report LA-828 1-PR (March 1980). D. B. Curtis and A. J. Gancarz, “An Interim Report on Studies of Uranium, Thorium and Lead Migration at A. E. Norris, “Fission Product kelease, January Key Lake, Saskatchewan, Canada,” Los Alamos Na- l—March 31, 1980/’ Los Alamos National Laboratory tional Laboratory report LA-8440-MS (July 1980). report LA-8389-PR (June 1980),

W. R. Daniels, compiler, “Laboratory Studies of Radio- A. E. Norris, “Oklo - Natural Fission Reactor Program, nuclide Distributions Between Selected Groundwaters January l—March 31, 1980~’ Los Alamos National and Geologic Media, October 1, 1979—September 30, Laboratory report LA-8479-PR (August 1980).

14f A. E. Norris, “Fission Product Release, April l—June Dry Rock Geothermal System,” AIME Annual Meeting, 30, 19807 Los Alamos National Laboratory report 1980, Las Vegas, Nevada. LA-8539-PR (September 1980). W. E. Clements, S. Barr, and M. Fowler, “Effective W. A. Sedlacek, “Use of Ozone and Aitken Nuclei as Transport Velocity and Plume Elongation in Nocturnal Natural Tracers to Examine the Exchange of Air Valley Wind Fields? Second Joint Conf. Applications of Between the Troposphere and Stratosphere in the Vicini- Air Pollution Meteorology, New Orleans, Louisiana, ty of the Tropopause Fold;’ in “Proceedings of the March, 1980. Atmospheric Tracers and Tracer Application Work- shop,” Los Alamos National Laboratory report D. B. Curtis, “Boron Abundances in Meteorites: A New LA-8 144-C (December 1980). Perspective,” 43rd Annual Meteoritical Society Meeting, La Jolla, California, September 2—8, 1980. E. N. Vine, R. D. Aguilar, B. P. Bayhurst, W. R. Daniels, S. J. Devilliers, B. R. Erdal, F. O. Lawrence, S. S. J. DeVilliers, B. P. Bayhurst, W. R. Daniels, F. O. Maestas, P. Q. Oliver, J. L. Thompson, and K. Lawrence, E. N. Vine, and K. Wol.fsberg, “Sorptive Wolfsberg, “Sorption-Desorpt.ion Studies on Tuff II. A Properties of Tuff/’ ACS Meeting, Las Vegas, Nevada, Continuation of Studies with Samples from Jackass August 24—29, 1980. Flats, Nevada and Initial Studies with Samples from Yucca Mountain, Nevada;’ Los Alamos National Labo- S. J. DeVilliers, B. R. Erdal, and K. Wolfsberg, ratory report LA-8 11O-MS (January 1980). “Groundwater Composition and Element Concentration as Factors Affecting the Sorption Behavior of Geologic K. Wolfsberg, B. R. Erdal, and B. M. Crowe, compilers, Media,” ACS 35th Northwest-5th Biennial Rocky “Research and Development Related to the Nevada Mountain Joint Regional Meeting, Salt Lake City, Utah, Nuclear Waste Storage Investigations, April l—June June 12— 14, 1980. 30, 1980~’ Los Alamos National Laboratory report LA-8471-PR (October 1980). D. J. Frank, “The Use of Intermediate Range Mass Spectrometry in the Measurement of Heavy Methanes as K. Wolfsberg, B. R. Erdal, and B. M. Crowe, compilers, Atmospheric Tracers:’ 28th Annual Conference on “Research and Development Related to the Nevada Mass Spectrometry and Allied Topics, New York, May Nuclear Waste Storage Investigations, July l—Septem- 25—30, 1980. ber 30, 1980/’ Los Alamos National Laboratory report LA-86 12-PR (February 1981). P. R. Guthals, “Project Akstream” presentation to Command StatT, 24th Composite Wing, USAF, Pan- ama, November 1979. PAPERS AND TALKS PRESENTED AT SCIEN- TIFIC MEETINGS IN FY 1980 C. Honey, C. Grigsby, J. Tester, L. Blatz, and R. Charles, “Interaction of Water with Crystalline Base- J. C. Banar, “Advances in Lead Isotopic Analysis:’ 28th ment Rock in Fractured Hot Dry Geothermal Reser- Annual Conference on Mass Spectrometry and Allied voirs, Tests, and Laboratory Experiments,” Int. Assoc. Topics, New York, May 25-30, 1980. Geochemistry and Cosmochemistry Meeting, Edmon- ton, Alberta, 1980. R. W. Charles, “Rock Alteration in an Experimentally Imposed Temperature Gradienh” Int. Assoc. A. E. Norris, “Fission Product Release:’ National Geochemistry and Cosmochemistry Meeting, Edmon- Nuclear Waste Storage Isolation Information Meeting, ton, Alberta, July 14-24, 1980. Columbus, Ohio, October 30—November 1, 1979.

R. W. Charles, C. E. Honey, J. W. Tester, L. A. Blatz, D. J. Rokop, “The Utilization of Electrodeposition and and C. O. Grigsby, “Experimentally Determined Pulse Counting for Medium Precision Analyses of Rock-Fluid Interactions Applicable to a Natural Hot

148 Nanogram Size Samples of Uranium and Plutonium< R. S. Bhalerao, L. C. Liu, and C. M. Shakin, “Theo- 28th Annual Conference on Mass Spectrometry and retical Models for the Calculation of the Reaction n+d Allied Topics, New York, May 25—30, 1980. ~ P+p in the Resonance Region,” Nuovo Chnento 56A, 502-506 (1980). W. A. Sedlacek, “Aerial Sampling of Soufriere of St. Vincent:’ American Geophysical Union Meeting, San T. J. Bornhorst and J. P. Balagna, “Instrumental Neu- Francisco, California, December 3, 1979. tron Activation Analysis of French Geochemical Refer- ence Samples,” Geostandards Newsletter 3, 177-180 W. A. Sedlacek, “Aircratl Measurements of Volcanic (1979). Debris in the Stratosphere;’ Tenth International Laser Radar Conference Symposium on Mt. St. Helens, Silver H. C, Brit~ E. Cheifetz, D. C. Hoffman, J. B. Wilhelmy, Springs, Maryland, October 6—9, 1980. R. J. Dupzyk, and R. W. Lougheed, “Fission Barriers for 2S5ES,2SCES,and 2ssFm~’ Phys. Rev. C 21, 761-763 J. L. Thompson, W. R. Daniels, B. R. Erdal, S. Maestas, (1980). E. N. Vine, and K. Wolfsberg, “Microautoradiographic Studies of Radionuclide Sorption in Geologic Medi&” H. C. Britt, A. Gavron, P. D. Goldstone, R. Schoen- ACS 35th Northwest-5th Biennial Rocky Mountain mackers, J. Weber, and J. Wilhelrny, “Yet More Com- Joint Regional Meeting, Salt Lake City, Utah, June plexity in Fission: Barriers for Nuclei with N = 13— 14, 1980. 150-154: Phys. Rev. Letters 40, 1010-1013 (1978).

J. L. Thompson, B. R. Erdal, W. R. Daniels, E. N. Vine, H. C. Britt and J. B. Wilhelmy, “Simulated (n,f) Cross and K. Wolfsberg, “Microautoradiography: A Useful Sections for Exotic Actinide Nuclei:’ Nucl. Sci. Eng. 72, Technique for Investigating Radionuclide Transport in 222-229 (1979). Geologic Media? Fourth International Conference on Nuclear Methods in Environmental and Energy Re- E. Cheifetz, H. A. Selic, A. Wolf, R. Chechik, and J. B. search, Columbi~ Missouri, April 14-17, 1980. Wilhelmy, “Even-Even Neutron-Rich Isotopes:’ in Nu- clear Spectroscopy of Fission Products, Till von Egidy, Ed., Conference Series 51 (The Institute of Physics, CNC-11 London, 1980), pp. 193-207. PUBLICATIONS 1978-1980 B. J. Dropesky, G. W. Butler, C. J. Orth, R. A. Williams, H. Backe, F. Weik, P. A. Butler, V. Metag, J. B. M. ,A. Yates-Williams, G. Fnedlander, and S. B. Kauf- Wilhelmy, D. Habs, G. Himmele, and H. J. Spech~ man, “Absolute Cross Sections for the 12C(rr*,ZN)l*C “Direct Observation of Coulomb Fission of 238Uwith Reactions Between 40 and 600 MeV,” Phys. Rev. C 20, 184W Projectiles: Phys. Rev. Letters 43, 1077-1080 1844-1856 (1979). (1979). G. P. Ford, “Calculation of Nuclear Level Densities of S. J. Balestrini, R. Decker, H. Wollnik, K. D. Wunsch, “Fe, ‘gCo, “%li, CICU,62Ni, C3CU,and csCu~’ Nucl. Sci. G. Jung, E. Koglin, and G. Siegert, “Independent Yields Eng. 66, 334-348 (1978). of Rb and Cs Isotopes from Therrnal-Neutron Induced Fission of 23’U~ Phys. Rev. C 20, 2244-2248(1979). P. Glassel, D. V. Harrach, Y. Civelekoglu, R. Miinner, H. J. Specht, J. B. Wilhelmy, H. Freiesleben, and K. D. R. S. Bhalerao, L. C. Liu, and C. M. Shakin, “System- Hildenbrand, “TIMeeParticle Exclusive Measurements of atic Features of Pion-Nucleus Interaction,” Phys. Rev. C the Reactions 238U+ 23*Uand 23*U+ 248Cm,” Phys. 21, 1903-1912 (1980). Rev. Letters 43, 1483-1486 (1979).

R. S. Bhalerao, L. C. Liu, and C. M. Shakin, D. C. Hoffman, “Element 107,” in McGraw-Hill Year- “Self-Energy of the A Resonance in Finite Nuclei and book of Science and Technology— 1977 Review/l 978 Fermi Broadening,” Phys. Rev. C 21,2103-2106 (1980). Preview, (McGraw-Hill, Book Company, New York, 1978) pp. 156-158.

149 D. C. Hoffman, “Neutron Multiplicity Measurements for “Coulomb Capture Ratios of Negative Muons in Nz + Spontaneous Fission of Cf and Fm Isotopes and Re- 0,, NO, and CO~’ Phys. Lett. 79A, 377-379 (1980). levance to Neutron Emission for Superheavy Elements:’ in Superheavy Elements, Int. Symp. Superheavy Ele- D. Liesen, P. Armbruster, F. Bosch, S. Hagmann, P. H. ments, Texas Technical University, Lubbock, Texas, Mokler, H. J. Wollersheim, H. Schmidt-Bocking, R. March 9-11, 1978, M. A. K. Lodhi, Ed. (Pergarnon Schuch, and J. B. Wilhelmy, “Experimental Confirma- Press, New York, 1978) pp. 89-102. tion of a Scaling Law for the lsc Excitation Probabtity for ZI + Zz > 120, and Its Breakdown in Pb + Cm D. C. Hoffman, G. P. Ford, J. P. Balagna, and L. R. Collisions at Very Small Internuclear Distances:’ Phys. Veeser, “Neutron Multiplicity Measurements of Cf and Rev. Letters 44,983 (1980). Fm Isotopes:’ Phys. Rev. C 21,637-646 (1980). L. C. Liu and C. M. Shakin, “Pion-Nucleus Elastic D. C. Hoffman, J. B. Wilhelmy, J. Weber, W. R. Scattering: Theory and Applications: in Progress in Daniels, E. K. Hulet, R. W, Lougheed, J. H. Landrum, J. Particle and Nuclear Physics, Sir Denys Wilkinson, Ed. F. Wild, and R. J. Dupzyk, ” 12.3-min ~bCf and 43-mi.n (Pergamon Press Ltd., Oxford, 1980), Vol. 5, Chap. 5, ~sMd and Systematic of the Spontaneous Fission pp. 206-243. Properties of Heavy Nuclides:’ Phys. Rev. C 21, 972-981 (1980). L. F. Mausner, M. A. Moinester, J. D. Knight, S. Cochavi, and S. S. Friedland, “In-vivo Beam Local- C. M. Hohenberg, K. Marti, F. A. Podosek, R. C. ization by Positron Activation in Pion Therapy: Radia. Reedy, and J. R. Shirck, “Comparisons Between Ob- Res. 80, 10-23, (1979). served and Predicted Cosrnogenic Noble Gases in Lunar Samples;’ in Proc. Ninth Lunar and Planeta~ Science R. A. Naumann, G. Schmidt, J. D. Knight, L. F. Coqf, Houston, Texas, March 13— 17, 1978 (Pergamon Mausner, C. J. Orth, and M. E. Schillaci, Press, New York, 1978) pp. 2311-2344. “Negative-Muon Capture Ratios for Alloys and Alkali Halide Solid Solutions;’ Phys. Rev. A 21, 639-644 E. K. Hulet, R. W. Lougheed, J. H. Landrum, J. F. Wild, (1980). D. C. Hoffman, J. Weber, and J. B. Wilhelmy, “Sponta- neous Fission of 2s9Fm:’ Phys. Rev. C 21, 966-971 C. J. Orth, W. R. Daniels, B. J. Dropesky, R. A. (1980). Williams, G. C. Giesler, and J. N. Ginocchio, “Products of Stopped-Pion Interactions with Cu and Ta,” Phys. R. L. Hutson, J. D. Knight, M. Leon, M. E. Schillaci, H. Rev. C 21,2524-2534 (1980). B. Knowles, and J. J. Reidy, “Negative Muon Capture in Noble Gas Mixtures,” Phys. Lett. 76A, 226-228 (1980). C. J. Orth, B. J. Dropesky, R. A. Williams, G. C. Giesler, and J. Hudis, “Pion-Induced Spallation of S. V. Jackson, J. W. Starrier, W. R. Daniels, M. E. Copper Across the (3,3) Resonance/’ Phys. Rev. C 18, Bunker, and R. A. Meyer, “N = 85 Nuclei, II. Decay of 1426-1435 (1978). 4.15-h l’~s to Levels of ‘49GW Phys. Rev. C 18, 1840-1856 (1978). C. J. Orth, J. D. KnighL K. Wolfsberg, and M. W. Johnson, “Nuclear” Disintegration of Some Complex S. B. Kaufman, E. P. Steinberg, and G. W. Butler, Nuclei by 60-MeV Muons: Phys. Rev. C 21, 1967-1973 “Spallation of Gold by 100-300 MeV Pioni~’ Phys. Rev. (1980). C 20,2293-2307 (1979). D. G. Perry and G. C. Giesler, “Philosophy of a S. B. Kaufman, E. P. Steinberg, and G. W. Butler, Computer-Automated Counting System~’ IEEE Trans. “(n,zN) Reactions on ~Mg and 197Au~’Phys. Rev. C Nucl. Sci. NS-26, 4591-4595 (1979). 20,262-266 (1979). N. T. Porile, B. J. Dropesky, and R. A. Williams, J. D. Knigh4 C. J. Orth, M. E. Schillaci, R. A. Nauman, “Emission of 24Na Fragments in the Interaction of 197Au F. J. Hartman, J. J. Reidy, and H. Schneuwly,

150 with Intermediate-Energy Pions and Protons,” Phys. High-Energy Protons,” Phys. Rev. C 17, 1368-1381, Rev. C 18,2231-2240(1978). (1978).

R. C. Reedy, “Planetary Gamma-Ray Spectroscopy,” in J. B. Wilhelmy, H. C. Brim D. C. Hoffman, W. R. Proc. Ninth Lunar and Planetary Science Co~, Hous- Daniels, E. Cheifetz, A. Gavron, J. Weber, E. K. Hulet, ton, Texas, March 13— 17, 1978 (Pergamon Press, New J. H. Landrum, R. W. Lougheed, and J. F. Wild, York, 1978) pp. 296112984. “Fission Properties of the Heavy Actinides,” S-Afr. Tydskr. Fis. 1, 116-117 (1978). R. C. Reedy, “Elemental Analysis of Planetary Surfaces Via Orbital Gamma-Ray Spectroscopy,” in Computers K. E, Williams and G. T. Seaborg, “New Isotope 242Bk~’ in Activation Analysis and Gamma-Ray Spectroscopy, Phys. Rev. C 19, 1794-1800 (1979). Proc. Am. Nucl. Sot. Topical Co~erence at Mayaguez, P. R., 1978, B. S. Carpenter, M. D. D’Agostino, and H. P. Yule, Eds., (Technical Information Center, U. S. PAPERS ACCEPTED FOR PUBLICATION IN FY DOE, 1979), pp. 684-697. 1980

R. C. Reedy, G. F. Herzog, and E. K. Jessberger, “The E. Cheifetz, H. C. Britt, and J. B. Wilhelmy, “Determinat- Reaction Mg(n,a)Ne at 14.1 and 14.7 MeV: Cross ion of Fission Probabilities for Actinide Nuclei Excited Sections and Implications for Meteorites,” Earth Planet, by the (lzC, 8Be~.,.)Reaction;’ Phys. Rev. C. Sci. Lett. 44,341-348 (1979). D. V. Harrach, P. G~assel, Y. Civelekoglu, R. Miner, S. Regnier, C. M. Hohenberg, K. Marti, and R. C. H. J. Specht, J. B. Wilhelmy, H. Feiesleben, and K. D. Reedy, “Predicted Versus Observed cosmic- Hildenbrand, “Fission Properties of Very Heavy Nuclei Ray-Produced Noble Gases in Lunar Samples: Im- Produced in Deep Inelastic Collisions,” Znt. Symp. on proved Kr Production Ratios,” in Proceedings of the Physics and Chemistry of Fission, Jiilich, Federal Re- Tenth Lunar and Planetary Science Conference, R. B. public of Germany, May 1979, Paper IAEA- Merrill, Ed. (Pergamon Press, New York, 1979) pp. SM-24 l/D4. 1565-1586. E. S. Gladney, D. R. Perrin, J. P. Balagna, and C. H. A. Selic, E. Chiefetz, A. Wolf, and J. B. Wilhelmy, Warner, “Evaluation of a Boron-Filtered Epithermal “Neutron-Rich Fragments from Spontaneous Fission of Neutron Irradiation Facility:’ Analyt. Chem. 254Cf/’in Nuclear Spectroscopy of Fission Products, Till von Egidy, Ed., Conference Series 51 (The Institute of L. C. Liu, “Two-Nucleon Processes in a Physics, London, 1980) pp. 316-320. Coupled-Channel Approach to Pion-Nucleus Single Charge Exchange Reactions; Phys. Rev. C. J. I. Trombka, R. L. Schmadeback, M. J. Bielefeld, L. G. Evans, A. .E. Metzger, E. L. Haines, C, S. Dyer, S. M, J. M. Nhschke, M. Fowler, A. Ghiorso, R. Leber, D. M. Seltzer, R. C. Reedy, and J. R. Arnold, “Analytical Lee, M. J. Nurmia, L. P. Somerville, K. E. Williams, E. Methods in Determining Elemental Composition from K. Hulet, J. Landrum, R. Lougheed, J. Wild, C. Bemis, Apollo X-Ray and Gamma-Ray Spectrometer Data,” in R. !Mva, P. Eskola, “Search for an 80 ms Spontaneous Computers in Activation Analysis and Gamma-Ray Fission Activity in Bombardments of 249Bkwith lSN,” Spectroscopy, Proc. Amer. Nucl. Sot. Topical Con- Nuc]. Phys. A. ference at Mayaguez, P.R., 1978, B. S. Carpenter, M. D. D’Agostino, and H. P. Yule, Eds., (Technical Informa- R. C. Reedy, “Lunar Radionuclide Records of Average tion Center, U. S. DOE, 1979) pp. 26-38. Solar-Cosmic-Ray Fluxes Over the Last Ten Million Years,” Proc. ConJ Ancient Sun. G. D. Westfall, R. G. Sextro, A. M. Poskanzer, A. M. Zebelman, G. W. Butler, and E. K. Hyde, “Energy R. C. Reedy, “Silver Isotopic Anomalies in Iron Spectra of Nuclear Fragments Produced by Meteorites - Cosmic-Ray Production and Other Possible

151 Sources: Proc. Eleventh Lunar and Planeta~ Sci. T. J. Bomhorst, W. E. Elston, R. S. Della Vane, and J. P. cod Balagna, “Distribution of Uranium in M~d-Tertiary Vol-- canic Rocks, Mogollan-Datil Volcanic Field:’ Southwest G. J. Russell, J. S. Gilmore, R. E. Prael, H. Robinson, Section of Am. Assoc. of Petroleum Geologists, El Paso, and S. D. Howe, “Spallation Target- Texas, Feb. 28—29, 1980. Moderator-Reflector Studies at the Weapons Neutron Research Facility:’ Proc. Symp. Neutron Cross Sections S. J. DeVilliers, B. P. Bayhurst, W. R. Daniels, F. O. from 10-50 MeV. Lawrence, E. N. Vine, and K. Wolfsberg, “Sorptive Properties of TuffV Am. Chem. Sot. Meeting, Las E. P. Steinberg, S. B. Kaufman, and G. W. Butler, “Pion Vegas, Nevada, August 25—29, 1980. Interactions with Complex Nuclei in the Resonance Region; Proc. Second Con$ Nuclear Reaction A4echa- J. D. Knigh4 C. J. Orth, M. E. Schillaci, R. A. nisms, Varema, Italy, June 18—21, 1979. Naumann, F. J. Hartrnann, J. J. Reidy, and H. Schneuw- Iy, “Capture of Negative Muons in Some Simple Co- D. J. Vieir% G. W. Butler, D. G. Perry, A. M. valent Molecules—Can it Provide Chemical Structure Poskanzer, L. P. Remsberg and J. B. Natowitz, “Search ‘ Information?” ACS 35th Northwest-5th Biennial Rocky for Light Neutron-Deficient Nuclei Produced in 800 Mountain Joint Regional Meeting Salt Lake City, Utah, MeV Proton Spallation Reactions;’ Proc. Sixth Int. June 12— 14, 1980. Cow Atomic Masses, East Lansing, Michigan, Septem- ber 18—21, 1979. J. R. Lapides, M. S. Spergel, O. W. Lazareth, P. W. Levy, R. C. Reedy, and J. I. Trombka, “The Effects of Hydrogen on Gamma-Ray Emission from Planetary LA REPORTS Surfaces;’ Eleventh Lunar and Planetary Sci. Conf., Houston, Texas, March 17—21, 1980. J. P. Balagna, “Nuclear Radiation Measurement Facil- ities at the Radiochemistry Laboratory at the Los L. C. Liu, “Pion-Nucleus Optical Potential: Theory and Alamos Scientific Laboratory,” LA-8337-MS (August Applications: seminar MP Division, April 1980. 1980). L. C. Liu, “Dynamics of Single Charge Exchange D. M. Helm and T. J. Bomhorst, “Probes: October 1, Reactions: Am. Phys. Sot. Spring Meeting, Washing- 1977—September 30, 1978V LA-7796-PR (May 1979). ton, D.C., April 28—May 1, 1980.

G. F. Grisham, E. A. Bryant, and K. E. Williams, L. C. Liu, “Importance of Short Range Correlation in “Uraninite Leaching: Literature Survey:’ LA-7799-MS Pion-Nucleus Backward Scattering:’ Int. Conf. Nuclear (April 1979). Physics, Berkeley, California, August 24—30, 1980.

R. J. Prestwood, “Radioactivity in Perspective;’ 2nd PAPERS AND TALKS PRESENTED AT SCIEN- Annual Blue River Trauma Society, Blue River, British TIFIC MEETINGS IN FY 1980 Columbia, Canada, March 8— 15, 1980.

P. Armbruster, J. B. Wilhelmy, H. Backe, W. Benin, F. *R. C. Reedy, “Lunar Radionuclide Records of Average Bosch, P. A. Butler, et al., “Heavy Ions and Heavy Solar-Cosmic-Ray Fluxes Over the Last Ten Million Elements: Experimental Measurements in Germany: Years:’ Conf. Ancient Sun: Fossil Record in the Earth, Am. Chem. Sot. Meeting, Las Vegas, Nevada, August Moon, and Meteorites, Boulder, Colorado, October 25—29, 1980. 16—19, 1979. ——————— I. Binder, “Neutron-Induced Reactions of Tin Isotopes:’ ‘Invited talk. Am. Chem. Sot. Meeting, Las Vegas, Nevada, August 25—29, 1980.

152 R. C. Reedy, “Systematic of Nuclear Reactions in M. E. Schillacit J. D. Knight, L. F. Mausner, C. J. Orth, Meteoritesfl 43rd Annual Meteoritical Society Meeting, R. A. Naumann, and G. Schmidt, “Muonic Lyman La Jolla, California, September 2—6, 1980. X-Ray Intensities in Pure Elements;’ ACS 35th North- west-5th Biennial Rocky Mountain Joint Regional Meet- L. Rosen, D. C. Hoffman, B. J. Dropesky, and H. A. ing, Salt Lake City, Utah, June 12— 14, 1980. O’Brien, “Nuclear and Radiochemistry Facilities at LAMPF~’ ACS Meeting, Las Vegas, Nevada, August M. S. Spergel, R. C. Reedy, O. W. Lazareth, and P. W. 25—29, 1980. Levy, “Depth Dependence of Cosmogonic Nuclides in Spherical Meteoroids,” 43rd Annual Meteoritical Society ~. S. Rundberg, B. J. Dropesky, G. C. Giesler, G. W. Meeting, La Jolla, California September 2—6, 1980. Butler, S. B. Kaufman, and E. P. Steinberg, “Excitation Functions Across the (3,3) Resonance for the Pion A. Yaniv, K. Marti, and R. C. Reedy, “The Solar Single Charge Exchange Reactions 27Al(n–,n0)27Mg, Cosmic-Ray Flux During the Last Two Million Years,” csCu(rt-,nO)csNi, and 45SC(rc’,rt0)4sTi~ 179th National Eleventh Lunar and Planetary Science Conf., Houston, ACS Meeting, Houston, Texas, March 23—28, 1980. Texas, March 17—21, 1980.

G. J. Russell, J. S. Gihnore, R. E. Prael, H. Robinson, M. A. Yates-Williams, A. H. Williams, J. T. Ganley, and and S. D. Howe, “Spallation Target-Modera- J. P. Balagn~ “Development of a Radiochernical tor-Reflector Studies at the Weapons Neutron Research Diagnostic for the Helios System,” Amer. Phys. SOC. Facility;’ Symp. Neutron Cross Sections from 10-50 Meeting, Boston, Massachusetts, November 12— 16, MeV, Brookhaven National Laboratory, May 12— 14, 1979. 1980.

APPE*NDIX B

DIVISION FACILITIES

CHEMICAL SYNTHESIS EQUIPMENT Bruker CXP-200 for solid state high-resolution PAR electrochemical equipment NMR studies Three gas chromatography Infrared Vacuum lines, hoods, inert atmosphere boxes for Perkin-Elmer 180, 283, and 683 spectrometers handling air-sensitive materials and power- Nicolet FT-ir spectrometer ful oxidants (FJ Digilab l?f-ir far-ir spectrometer High-pressure autoclaves (Cryo-Matrix equipment) High-pressure liquid chromatography Laser Raman Spectrometers SPECTROSCOPIC EQUIPMENT Cary-81 laser-Rarnan spectrometer Nuclear Magnetic Resonance SPEX plus Nicolet data system, Spectra Physics Varian XL-100-Fourier Transform 171 with Art, Kr+ lasers NMR spectrometer for ‘3C and other nuclei Ultraviolet, Visible, Near-IR Spectrometers EM-390 fluorine, proton, phosphorous, NMR; Hewlett-Packard 8450A uv/visible spectrometer EM-360 proton NMR Two Cary- 14 spectrometers Spectrometers: superconducting and iron core Molectron N2-pump and dye laser magnets for NMR studies of solids X-RAY DIFFRACTION Bruker WM-300 wide-bore spectrometer for Weissenberg precession and powder diffraction high-resolution, multinuclear NMR of liquids cameras

153 Picker FACS- 1 single-crystal x-ray ~iffractometer Single beam machines (replacement being ordered) Stopped-flow kinetics apparatus for plutonium Phillips and Picker x-ray diffractometers studies Mettler hot-stage for optical microscopy Excitation lasers uv to ir, pulsed and cw INSTRUMENTS FOR ELEMENTAL ANALYSIS INSTRUMENTS FOR THEORY Atomic absorption spectrometer (in fume hood) VAX-1 1/780 computer Plasma emission spectrometer MASS SPECTROMETERS X-ray fluorescence spectrometer (automatic Two surface thermal ionization, pulse-counting in- read-out and data analysis) struments Dionex ion chromatography Four surface thermal ionization spectrometers with’ Chemical autoanalyzer ion detection by Faraday cage HYDROTHERMAL LABORATORY One “precision-ratio” gas source Circulation loops One gas-source two-stage spectrometer for “heavy Rocking vessels methanes” Permeability systems Two magnetic deflection isotope separators INSTRUMENTS FOR THERMOCHEMISTRY Two cycloidal spectrometers, masses to 80 High-temperature solution calorimeter Quadruple with gas chromatography, masses to Combustion calorimeter 1000 Room-temperature solution calorimeter Time-of-flight and automated nitrogen isotope ratio Perkin-E1mer TGS-2 thermogravimetric balance spectrometer Differential thermal analyses equipment Molecular-beam photoionization spectrometer ROCK SAMPLE PREPARATION LABORATORY MEASUREMENT AND HANDLING OF RADIO- FLUID TRANSPORT SYSTEMS ACTIVITY MICROSCOPY Automatic beta and gamma counting systems Scanning electron microscope (with nondispersive Alph% beta, and gamma-ray spectrometers x-ray analyzer) Computer control for data collection and data Optical: microautoradiography equipment reduction e MICROORGANISMS PREPARATION FACILITY Hot cells for high-level gamma- and beta-active INSTRUMENTS FOR ZN V..VO ANIMAL IMAG- materials ING Facilities for alpha-emitting materials Picker 411 gamma camera RADIOISOTOPE PRODUCTION FACILITY AT INSTRUMENTS FOR CHEMICAL KINETICS, LAMPF CHEMICAL DYNAMICS, SPECTROSCOPY CRYOGENIC SEPARATION FACILITY FOR AND ULTRASENSITIVE ANALYSIS STABLE ISOTOPES OF CARBON, OXYGEN, AND Fast-Flow tube NITROGEN Crossed molecular beam machine

154 *U.S. GOVERNMENT PRINTING OFFICE: 1981-0-777-027./71 Rh:d in the United States of Ameri~ Available from N-!bnal Technbd Infomwbn SWtice US Depwment of Commerce 528S Pcxt Royal Road Sprintwd, VA 22161

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