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Home , Crystal chemistry

U.S. DEPARTMENT OF COMMERCE Robert A. Mosbacher, Secretary

National Institute of Standards and Technology Gailhersburg, MD 20899 301/975-2000 Boulder, CO 80303 303/497-3000

October 1989

NIST Special Publication 763 Supersedes Special Publication 723

Any mention of commercial products is for information only; it does not imply recommendation or endorsement by the National Institute of Standards and Technology nor does it imply that the products mentioned are necessarily the best available for the purpose.

The National Bureau of Standards became the National Institute of Standards and Technology on

August 23, 1988, under the Omnibus Trade and Competitiveness Act. NIST retains all NBS functions. Its new programs will encourage improved use of technology by U.S. industry. Nisr Contents

Cooperative Research at NIST 2

Research Opportunities 6

Analytical 7

Applied Mathematics 12

Atomic, Molecular, and Optical Physics 14

Building Technology 18

Ceramics 20

Chemical Technology 23

Computer Systems 30

Electronics and Electrical Engineering 34

Fire Research 40

Manufacturing Engineering 41

Materials Reliability 42

Metallurgy 44

Neutron Scattering and Diffraction 46

Nondestructive Evaluation 48

Polymers 49

Radiation Research 52

Standard Reference Data 56 Cooperative Research at NIST

Cooperation has always been part of the Institute's way of doing

business. Since its inception in 1901 as the National Bureau of Stand- ards, NIST scientists and engineers have conducted collaborative studies with researchers from industry. Research consortia formed at the Institute were among the first in the nation.

In a given year, about 1 ,200 scientists and engineers from industry, universities, and other government agencies come to NIST to participate in cooperative re- search projects, both long- and short- term. Less formal interactions are nearly continuous. For example, more than 15,000 people attend workshops and conferences held at NIST each year, NIST researchers publish about 1,400 papers and reports annually, and one- on-one technical consultations between Institute scientists and those in other organizations occur daily. Through these collaborations, re- searchers from industry, universities, and other government agencies get an oppor- tunity to work with NIST specialists, many of whom are renowned experts in their fields, and to use the Institute's premier research and testing facilities. They take newly developed technology back to their organizations to be incorporated immediately into new ideas, new processes, and new products. NIST researchers, in turn, learn firsthand the views and needs of Institute clients and, as a result, NIST is better able to direct its research to meet these needs. Operated on an annual budget of about $285 million, NIST has been a valuable behind-the-scenes partner of industry and academia, providing the standards and measurement techniques that foster technological advance, domestic and international commerce, and, ultimately, economic progress. With the enactment of the Omnibus Trade and Competitiveness Act in 1988, however, the Institute not only underwent a name change, but was designated the federal government's catalyst for speeding in- novation and accelerating the adoption of new technologies and new ideas by U.S. companies. The 1988 law opens more avenues for cooperation between NIST and industry, universities, federal laboratories, state and local govern- Researchers at are developing automated production ments—any organization that has an NIST for rapidly solidified powders. active stake in helping U.S. business techniques compete more effectively. Cooperative Research at NIST

NIST will work with any company, site in Boulder, Colo. A 20-megawatt trade association, university, or other research reactor with a cold neutron government agency to solve problems of source, a synchrotron ultraviolet radiation mutual concern. Its highly skilled staff of facility, a supercomputer, a large-scale some 3,000 conduct a wide range of structures testing facility, a - projects, many at the forefront of science processing laboratory, a fire research and technology. About half of the Insti- facility, and a computer network and tute's scientists and engineers are focus- security facility are but a few of the facili- ing their efforts on the emerging tech- ties available. In certain cases, NIST nologies, including advanced materials, makes its facilities available to compa- optoelectronics, automation, computing, nies for proprietary research on a cost- superconductivity, biotechnology, and recovery basis, when equal or superior thin-layer technology. facilities are not otherwise available. One of the most popular ways NIST Described below are a few brief ex- research and facilities are made acces- amples of different types of cooperative sible to U.S. industry is through the Insti- projects and the results they have pro- tute's Research Associate Program, duced so far. The scope, duration, and Under this program, companies, trade structure of the cooperative projects are associations, and technical societies pay tailored to the problem to be solved. their scientists and engineers to work in They can last for a few weeks or a few NIST laboratories with NIST researchers years and involve one, several, or even on a specific project. hundreds of organizations. The goal is to The longest running research as- solve the problem at hand quickly, effi- sociate program has been a remarkably ciently, and effectively. successful collaboration with the Ameri- can Dental Association. Started in 1928, Crucible Materials, Inc. and the Metal Powder the alliance has resulted in the pano- General Electric Corp. are con- Processing ramic x-ray machine, composite restora- tinuing to work with NIST in a tive materials, and the high-speed consortium to develop automated proc- turbine handpiece, for example, as essing technology for rapidly solidified well as major contributions to dozens metal powders. Rapidly solidified metal of standards for dental materials and powders provide a basis for alloys that hundreds of scientific papers. can exhibit, after consolidation, unique In another type of cooperative ven- properties, such as high strength-to- ture, companies subscribe to a consor- weight ratios, excellent fracture tough- tium that provides resources for NIST ness and fatigue resistance, unusual to solve a specific problem facing the magnetic properties, and high corrosion industry. This arrangement has advan- resistance. tages when a complex problem—usually Current processes for producing development of generic technology or these powders are both labor intensive measurement techniques—confronts a and lacking in reproducibility; rejection particular industry and the research is rates are high. The goal of the industry/ too costly or not possible for individual NIST project is to develop generic companies to undertake. research results that will facilitate the Companies also donate or loan equip- automation of different atomization facili- ment or software to the Institute when ties for producing rapidly solidified metal NIST researchers are working on a proj- powders, while improving product quality ect that could ultimately improve their and productivity. products or the way they do business. In Consortium researchers are designing such situations, these firms actively con- process models, an expert system, and sult or advise NIST researchers on the automated control strategies that will be needs and concerns of the industry. linked by a computerized control system To aid firms in building a competitive for the intelligent processing of rapidly advantage, NIST makes available for solidified metal powders. A major com- cooperative research its extensive re- ponent of the system is an optically search and testing facilities at its head- based, on-line sensor for monitoring quarters in Gaithersburg, Md., and its the metal powders while they are being produced.

3 Cooperative Research at NIST

Magnetic 1ST has developed an instrument help improve the method. Other compa- Microscope for providing innages of the mag- nies provided some funds for equipment N netic microstructure of materials and measurement services. NIST scien- with a resolution about a factor of tists are now working with an industrial 100 better than conventional imaging consortium—Perkin-Elmer, Control Data techniques. Using a technique called Corp., and Honeywell—to develop a Scanning Electron Microscopy with second generation, commercially Polarization Analysis (SEMPA), re- available magnetic microscope. They searchers are able to provide direct im- also are helping several universities to ages of magnetic microstructure with a establish SEMPA capabilities. resolution of about 0.05 microns. In cooperation with industry, this the past several years, NIST has Open Systems "magnetic microscope" is being used to Forworked with government, industry, Interconnection observe details of the magnetic domain and standards groups in support of Network structure responsible for the performance national and international standardization (OSINET) of high-technology materials. The ability of Open Systems Interconnection (OSi). to see magnetic domains with such clar- International standards for OSI are being ity is important to the information storage developed to overcome common prob- device industry. For example, the lems that users of computer systems storage capacity and fidelity of magnetic face in integrating large and small com- tapes and disks depends upon how puters, networks, workstations, and com- small magnetic "bits" can be made and munications services, and in transferring the sharpness of the boundaries be- information between different systems. tween the bits. Until now improvements To advance this goal, NIST estab- have been limited by the inability to lished OSINET, a cooperative govern- measure magnetic microstructure at the ment/industry research network that is submicron level. expediting the development and use of This research has involved extensive commercial OSI products. With 25 partici- collaboration with industry. A number of pants and network nodes throughout the industrial scientists—from Honeywell, United States and in several overseas lo- Control Data Corp., Kodak, Westing- cations, OSINET is a successful research house, Digital Equipment Corp., among tool for remote testing of OSI protocols others—provided samples for high- and for vendor interoperability testing. resolution analysis. Control Data Corp. OSINET also is used by government and Kodak sent researchers to NIST to and industry managers to assess the

NIST computer scientists are working with researctiers from private industry to develop security features for "open" computer networks.

4 Cooperative Research at NIST

applicability of OSI to the needs of their organizations, to monitor the progress of OSI products, and to acquire practical experience in using OSI technology.

Optical Fiber s optical fiber metrology moved IMetroiogy from the laboratory to commercial A'^applications, NIST worked with the

Electronic Industries Association and its associated Telecommunications Industry Association, as well as other organiza- tions, to develop the measurements upon which voluntary industry standards could be based. The NIST work, which usually involved industry-wide round robins, has provided the measurement basis for 28 industry standards adopted by these voluntary standards groups. For example, the diameter of the core of a fiber affects the loss of light during transmission as Electronics technician Micfiael Huff (left) project well as at connections. NIST, with the and chief

Kang Lee monitor the Mare Island Flexible Workstation , cooperation of the industry, conducted the first large-scale transfer of flexible comparative measurements of various and automation tech- nology from the At\ARFto a production facility. techniques used to make this measure- ment, identified the shortcomings of various approaches, and provided the n a cooperative project with the Navy, Automated technical basis for a voluntary standard Westinghouse Corp., and Warner & iVianufacturing for this measurement. Swasey Company, NIST researchers have designed and assembled a state- Radioactivity collaborative project sponsored of-the-art manufacturing system for the IMeasurements A'by NIST and the U.S. Council for Navy shipyard at Mare Island, Calif. The r\iLEnergy Awareness (USCEA) has flexible manufacturing workstation is confirmed the ability of capable of operating, largely unattended, laboratories in the nuclear-power industry 24 hours a day. to assay several types of radionuclides Consisting of an automated multi- with sufficient accuracy. In the first year purpose machining center, industrial of the program, two USCEA research robot, automated storage and retrieval associates worked with NIST scientists system, and various control computers, to prepare and distribute special test the Mare Island workstation incorporates samples to 12 utilities that operate over several advanced automation tech- 30 percent of the existing generating niques, such as chuck jaw changing and units in the United States. The company tool-condition monitoring. The worksta- supplying radiochemistry measurement tion is designed to produce any of services to the largest number of U.S. 84 different parts used in nuclear sub- power-generating units also was tested. marines. These parts are not stockpiled, Additional tests involving gaseous rather they are produced on demand. radionuclides, mixtures, and special Current manual methods require an forms simulating field samples are average of 17 hours to make one such scheduled with three more utilities plan- part. The new workstation reduces that to ning to participate. A unique feature of under 30 minutes. The advanced tech- the program is the participation of the niques used in the workstation, many of industry's three major suppliers of com- which were developed in NIST's Auto- mercial calibration and test samples. mated Manufacturing Research Facility These companies not only take part in (AMRF), are applicable to a variety of tests prepared for the power-plant manufacturing operations. The AMRF is laboratories, they also have their an experimental facility designed to measuring ability checked by sending study the application of advanced materials they have certified to NIST for robotic and computer-control techniques verification. to small-batch manufacturing.

5 Research Opportunities

NIST welcomes collaboration with If you are interested in working with scientists and engineers from NIST on a project, large or small, write industry, universities, and other or call the NIST Office of Technology government agencies on most of its Commercialization, 301/975-3085, or projects. To give those interested in one of the contacts given with the cooperative research an idea of the wide project descriptions. (Unless otherwise array of NIST programs, a sampling of specified, all contacts are at the National specific Institute research projects is Institute of Standards and Technology, described on the following pages. Gaithersburg, MD 20899.)

A collaborative effort between NIST and Dionex Corporation resulted in the development of a chelation system. H.M. (Skip) Kingston of NIST (left) and Archava Siriraks of Dionex are shown with the system, which was named one of the 100 most significant products of 1968 by Research and Development magazine.

6

Atomic tomic methods are Electroanalytical research plays a Inorganic Spectroscopy probably the most widely used ana- key role in the development of Electroanalytical Research a;klytical techniques in industry today. methods and materials for en- Considerable research is required, how- vironmental and clinical determinations. ever, to keep up with the changing A broad range of electroanalytical and needs of industry. At NIST, research in chromatographic techniques, such as atomic spectrometry is focused on voltammetry, oculometry, ion chromatog- several different areas. For instance, raphy, and chelation ion chromatogra- researchers are working to improve the phy, are used by researchers at NIST for analytical capabilities of direct current analysis and research. Scientists at the plasma (DCP) and inductively coupled Institute have developed novel methods plasma (ICP), as well as experimenting and instrumentation, such as microwave with the glow discharge as an re- decomposition equipment and unique servoir. Additional research concerns the laboratory robotic equipment that uses use of spark sampling for the direct analy- hierarchical computer control. Instrumen-

sis of solids, the continued development tation is available for making accurate of laser-enhanced ionization (LEI) in pH, potentiometric, coulometric, conduc- flames, and the evaluation of various tometric, voltammetric, and ion chromato- types of coupled chromatographic- graphic measurements and for research spectrometric systems to improve the ac- in analytical laboratory automation. curacy of spectroscopic measurements. NIST scientists also are developing a Contact: H.M. "Skip" Kingston, A345 series of neutral density filters that can Chemistry BIdg., 301/975-4136. be issued as Standard Reference Mate- rials for verifying the accuracy of the transmittance and absorbance scales of ore than 50 billion chemical Activation are annually Analysis ultraviolet, visible, and near infrared ab- analyses performed sorption spectrophotometers. M in the United States. Researchers at NIST help to ensure the accuracy of these analyses developing new ana- Contact: Robert L. Watters, B222 by Chemistry BIdg., 301/975-4122. lytical procedures and improving the reliability and accuracy of present methods. One technique under study is Analytical Mass nalytical has activation analysis, a highly sensitive ana- Spectrometry played a key role in industries, lytical technique not normally available in ksuch as the in- industrial laboratories. In this research, dustry, which require accurate measure- methods of nuclear analysis are investi- ments of trace elements in their raw gated utilizing the 20-MW NIST research materials, products, and product contain- reactor. All areas of the technique are re- ers. The inorganic mass spectrometry searched, including the capabilities of program at NIST is concerned with cold-neutron activation, the use of moni- developing analytical capabilities for tor activation, radiochemical separations, making highly accurate determinations of the determination of new mathematical trace inorganics using stable isotope dilu- procedures for the resolution of gamma tion and highly precise measurements of spectra, the development of prompt isotopic compositions, as well as the gamma activation techniques, and the highly accurate measurement of absolute use of charged-particle activation isotopic compositions to redetermine techniques. atomic weights. Areas of research in- clude instrumentation in spark source, Contact: Robert R. Greenberg, BIOS thermal source, inductively coupled Reactor BIdg., 301/975-6285. plasma source, and laser source mass spectrometry and chemical separations at the trace level using ion chromatogra- phy and other techniques.

Contact: John D. Fassett, A21 Physics BIdg., 301/975-4109.

7 Analytical Chemistry

Liquid Ithough liquid clnromatograplny Biosensors are the newest genera- Bioanalytical Chromatography (LC) is one of the most widely used tion of analytical devices with the Sensors AlLanalytical techniques in industrial potential for widespread use in bio- laboratories, its use can be made even medical and industrial monitoring applica- more widespread by improvements in de- tions. Biosensors will incorporate the tection methods. NIST researchers are latest advances in biotechnology to pro- working to develop novel approaches for vide high specificity and sensitivity. Bio- the electrochemical detection of organic logically derived substances have great analytes separated by liquid chromatog- value as components of rapid-sensing raphy. For this technique to be applied devices because of their binding speci- most effectively, the electrode reaction ficity, the strength of their interactions, mechanisms of the compounds to be de- and their potential for use in a wide tected must be investigated using tech- variety of amplification schemes. Im- niques such as cyclic and reverse-pulse munological, enzymatic, and receptor- voltammetry, oculometry, and LC/ ligand interactions are being explored as ultraviolet spectroscopy. Ongoing NIST the basis for analytical devices. work focuses on the use of differential NIST researchers are using a variety pulse and dual-electrode detection, as of optical and electrochemical tech- well as the development of single- and niques for detection. Detection can be array-microelectrode detectors. Re- based on such diverse changes as size searchers also are developing new liquid and rotational mobility of analytes or bind- chromatographic separations employing ing agents upon interaction, or can be specific chemical interactions, including the result of enzymatic activity which oc- chelation, ion-pairing, charge transfer curs due to analyte binding, causing en- complexation, and acid-base equilibria. hanced fluorescence or electrochemical signal. Amplification can be achieved Contact: William A. MacCrehan, Al 13 with release to liposome-encapsulated Chemistry BIdg., 301/975-3122. , multi-turnover enzyme reac- tions, ion-exchange -modified electrodes, and so forth. Combining high specificity for analytes with efficient ampli- fication provides the potential for ex- tremely sensitive devices.

Contact: Richard A. Durst, Al 13 Chemistry BIdg., 301/975-31 18.

Supercritical fluid chromatography Supercritical (SFC) in both capillary and packed Fluid columns offers several advantages Chromatography over liquid and (GC) for high-efficiency separations of nonvolatile molecules. NIST researchers in this area are investigating the vari- ables that influence the retention, selec- tivity, and efficiency of SFC systems and the development of SFC as a useful ana- lytical technique to provide high- efficiency separations of complex mixtures. Both packed-column and capil- lary SFC instrumentation are used for making state-of-the-art measurements. The application of supercritical fluid ex- traction combined with SFC and GC To help improve the specificity and sensitivity of biosensing analysis is under investigation. devices, research chemists Anne Plant and Steven Choquette investigate the optical characteristics of fluores- Contact: Stephen N. Chesler, cent molecules used in the amplification of biosensor response. 301/975-3102 or Stephen A. Wise, 301/975-31 12, Al 13 Chemistry BIdg.

8 Analytical Chemistry

Liquid iquid chromatography (LC) on Analysts are able to use multidimen- Multidimensional Chromatographic chemically bonded stationary sional (dual column) and very high- and Very High- Stationary Resolution Phases Li.phases (e.g., Ci8, Cs, NH2, and resolution (100,000 plates) gas Gas Chromatography NO2) offers unique capabilities for the chromatographic methods to perform dif- separation of isomeric compounds or ficult separations to facilitate species- compound classes. However, significant specific quantitation. These high- differences in retention and selectivity resolution techniques are being investi- characteristics, such as relative reten- gated at NIST to develop highly specific tion, have been observed among analytical procedures to quantitate pg/g commercial phases produced by differ- organic constituents contained in com- ent manufacturers and even within differ- plex environmental and clinical matrices. ent batches prepared by the same Research in this area focuses on optimiz- manufacturer. ing multidimensional gas chromato- NIST researchers are working to un- graphic experiments in which two derstand which factors influence LC re- capillary columns, each possessing in- tention on these various stationary dividual and different retention mecha- phases to predict, improve, and control nisms, are serially connected by a the separation selectivity. In reversed- pneumatic switch. In addition, scientists phase LC on Cis phases, polycyclic aro- at NIST are using and developing matic hydrocarbons have been used as tailored, very high-resolution capillary model nonpolar solutes to study retention columns. An independently controllable, mechanisms and selectivity. The scien- dual-oven gas chromatograph is avail- tists have studied various physical able for multidimensional research. Addi- parameters of these solutes to determine tional facilities and equipment include their influence on retention and selectivity state-of-the-art sample preparation and in LC. Their investigations have focused gas chromatography laboratories, eight on both the physical and chromato- capillary gas chromatographs with multi- graphic characterization of these station- ple specific and nonspecific detectors, ary phases. A variety of methods are and a large laboratory information man- available at NIST for physical charac- agement system (LIMS). terization of these materials, including carbon analysis, gas adsorption surface Contact: Stephen N. Chester, area techniques, infrared and nuclear 301/975-3102 or Franklin Guenther, magnetic resonance spectroscopy, and 301/975-3105, A1 13 Chemistry BIdg. small-angle neutron scattering tech- niques. Currently, NIST scientists are major task in the industrial produc- Nuclear attempting to develop chromatographic tion of organic fine chemicals, Magnetic test mixtures to evaluate LC stationary A drugs and antibiotics, and bio- Resonance phase characteristics and chromato- Spectroscopy of molecules is the characterization of the graphic performance. Such "perform- Bio-organics product for both compositional analysis ance" standards would allow direct and quality control. Nuclear magnetic res- comparison of the various LC phases pro- onance (NMR) spectroscopy has proved duced by different manufacturers and to be a powerful and widely used tool for provide insight into the development of these and related purposes. improved stationary phases for specific One NIST program in this area in- separations. volves the development of new and im- proved methods for the structural, Contact: Stephen A. Wise, quantitative, and conformational analysis 301/975-31 12 or Lane C. Saunders, materials of chemical and biotechno- 301/975-3117, A1 13 Chemistry BIdg. of logical importance. The principal tech- niques being investigated include multinuclear, two-dimensional NMR and

its combination with multiple quantum methods and polarization transfer tech- niques (DEPT and POMMIE). A specific

9 Analytical Chemistry

goal of this work is the development of new technique of electrophoresis Capillary Zone new two-dinnensional spectrum editing Thein small bore capillaries promises to Electrophoresis and filtering techniques and their appli- revolutionize the separation of cation to structural and conformational charged molecules. However, since the characterization via correlations with highest efficiencies are obtained with multinuclear chemical shifts, coupling small sample sizes (nL) in narrow bore constants, relaxation times, and nuclear (=10 iim) columns, this presents a chal- Overhauser effects. Scientists at NIST lenge in microdetection technology. De- use a high-field (400-MHz) multinuclear tection schemes being investigated at NMR spectrometer equipped with a proc- NIST include conductivity, amperometry, ess controller, a high-capacity data ac- UV absorbance, fluorescence, and mass quisition system, an array processor, and spectrometry. Much work is needed to an off-line data processing station. design the chemistry of the mobile phase and capillary column to suit the analytical Contact: Bruce Coxon, A361 Chemistry need. Ion-pair, complexing, and micellar BIdg., 301/975-3135. agents, as well as pH manipulation, can be used to enhance the selectivity of the separations of ionic and neutral mole- Protein 1ST researchers are using a two- cules. Derivatization of the capillary sur- Characterization dimensional electrophoresis sys- face can control the bulk electro-osmotic by Two- tem to characterize proteins N and flow and prevent the adsorption of the an- Dimensional peptides. They are probing the influence Electrophoresis alyte molecules. NIST researchers will of size, shape, and charge on migration use the technique to investigate the fun- characteristics in the electrophoretic me- damental property of the electrophoretic dium. Although well-defined protein mobility and to determine important ana- "markers," especially of high molecular lytes such as proteins, peptides, DNA weight, are required to allow stand- fragments, and trace metals. ardization of polyacrylamide gel electro- phoretic systems, charged polymeric Contact: William A. MacCrehan, A1 13 materials other than proteins may be con- Chemistry BIdg., 301/975-3122. sidered for markers. Because staining and detection of such markers is of special interest, the researchers plan to Interpreting the relationship between Microbeam examine the mechanisms of silver stains the physical and chemical microstruc- Compositional using neutron activation techniques. Ad- ture of materials is important in under- Mapping ditional studies will be directed toward standing their macroscopic behavior and understanding the interactions of pro- in extending their in-service perform- teins with metal . The researchers will ance. Conventional microbeam tech- use image processing by state-of-the-art niques for elemental/molecular com- instrumentation to form meaningful positional analysis on the micrometer databases. As part of this program, NIST scale, such as the electron microprobe plans to issue well-characterized mix- and ion microscope, have been re- tures of proteins as Standard Reference stricted to quantitative analysis at in- Materials (SRM's) that will be used to dividual locations. Mapping of the assess the abilities of existing and new distribution of constituents has been electrophoretic techniques to separate possible only at the qualitative or semi- and detect proteins. quantitative level. However, recent NIST research developments have led to the Contact: Dennis Reeder, A361 production of the first true quantitative Chemistry BIdg., 301/975-3128. elemental compositional maps. Quantita- tive compositional mapping with the elec- tron microprobe has been demonstrated down to levels of 0.1 weight percent, while quantitative isotope ratio measure- ment in images has been demonstrated with the ion microscope.

10 Analytical Chemistry

Current research activities at NIST in- Institute scientists also are examining the clude extending compositional mapping use of class-specific detectors for gas to analytical electron microscopy, laser chromatography and evaluating elec- Raman microanalysis, and laser micro- tronic circuitry to optimize signals and re- probe mass analysis. Potential projects duce instrumentation noise and drift. could involve applying the compositional mapping instruments to materials charac- Contact: William D. Dorko, 8364 terization problems, developing new tech- Chemistry BIdg., 301/975-3916. niques for compositional mapping on other microanalysis instruments, and in- vestigating basic topics in elemental and Inorganic and organic compressed Instability off molecular quantitative analysis with mi- gas mixtures are employed extensively Compressed Gas crobeam instrumentation. throughout industry to calibrate equip- Mixtures Among the equipment available at ment used to assess the quality of prod- NIST is an electron microprobe, an ana- ucts and the effectiveness of emission lytical scanning electron microscope, controls. Although the stability of these 200- and 300-kV analytical electron mi- mixtures is critical to their successful croscopes, an ion microscope (second- use, a number of instances have been ary ion mass spectrometry, SIMS), a noted in which instability has been ob- time-of-flight SIMS, a laser microprobe served, particularly in mixtures contain- mass analyzer, two laser Raman micro- ing low levels of reactive gaseous probes of NIST design, and extensive species, such as nitrogen oxides, sulfur computer facilities, including a VAX dioxide, and hydrocarbons. The reasons 11/780 computer, micro-Vaxes, and a for instability may differ somewhat for DeAnza image processor. different gaseous species, but they are related to at least two possible phenom-

Contact: Dale E. Newbury, B364 ena: gas-phase reactions and gas-metal Chemistry BIdg., 301/975-3921. interactions with the internal surface of the cylinder. NIST researchers are work- ing to improve the understanding and Trace Gas ccurate measurement of gaseous predictability of these phenomena. Their Measurement species is of great importance to techniques involve those employed in Techniques /\rLmany industries for a number of ap- studies and other ap- plications ranging from the quantification proaches, such as Fourier-transform of pollutant and toxic gas emissions to infrared, diode laser, and other spectros- the quality control of products. The valid- copies; mass spectrometry; metal analy- ity of data derived from such measure- sis; trace water and oxygen analysis; ments is tied directly to the availability of chemiluminescence analysis; and the useful gas measurement techniques and use of specifically doped mixtures and to the degree of understanding of their homogeneous gas phase kinetics. capabilities and limitations. Although a variety of techniques have been applied Contact: Walter L. Zielinski, Jr., B364 to trace gas analysis, more research is Chemistry BIdg., 301/975-3918. needed to improve the present state of the art. This research is particularly impor- tant due to the growing need for the analysis of specific gas species in multi-

component gaseous mixtures; it also is necessary to extend accurate analyses to below the parts-per-million and parts- per-billion levels. Current NIST research focuses on new detection systems using chemiluminescence, electrochemistry, in- frared diode laser systems, capillary gas- liquid and gas-solid chromatography coupled to mass spectrometry, and isotope-dilution mass spectrometry.

11 Applied Mathematics

Performance I n a project designed to measure the flexible manufacturing, integrated circuit of Parallel I performance of parallel computers, fabrication, optoelectronics, and bio- Computers | nist researchers are focusing on two process engineering. major questions: How can codes be im- proved? and What types of codes should Contact: Raghu N. Kacker, A337 be run on a given machine? They are Administration BIdg., 301/975-2109. evaluating the performance of algorithms on parallel computers by using data mo- tion as the principal determining factor. Quality assurance for physical and Measurement Their approach to performance measure- chemical measurements sup- Assurance ment is to develop a taxonomy of algo- porting technology transfer and rithmic paradigms based on how the on-line quality control demands statistical data move during a calculation, rather methods applicable to complex models. than on what the specific computation NIST researchers critique methods for steps are. their resistance to outliers and their The scientists will implement bench- capacity to detect autocorrelation in mark codes typical of applications in highly precise measurement systems. each class of the taxonomy on two differ- In multivariate settings, such as elec- ent parallel computers in order to obtain tronic test systems, estimation of uncer- detailed measures of performance. The tainty and statistical tolerance limits can target machines for measurements are be complicated by variance components representative of the two main classes of from multiple sources. Researchers also MIMD parallel architectures: loosely are investigating the applicability of artifi- coupled, message-passing machines cial intelligence to complex analyses. Cal- and tightly coupled, shared-memory ibrations, where instrument response machines. depends on stimuli over a regime, sup- port critical measurement areas such as Contact: Francis Sullivan, A438 radiation dose measurements. NIST re- Administration BIdg., 301/975-2732. search in this area is focused on optimal procedures to accommodate real-life models such as random changes in in- Design for Quality "hrough its Design for Quality pro- strument response over time and gradual

gram, NIST supports collaborative instrumental drift. t;research within NIST and with in- dustry, technical societies, and universi- Contact: Carroll Croarkin, A337 ties to develop and refine effective and Administration BIdg., 301/975-2849. efficient statistical, mathematical, and computer-based techniques for quality improvement. These techniques are de- NIST, researchers are designing Computational Mechanics signed for ease of use by industrial scien- Atcomprehensive software for model- tists and engineers and are disseminated ing and database applications in through research collaborations with in- and engineering. NIST dustry, tutorials, and workshops. research on computer-aided modeling of Statistically planned experiments the behavior of structural materials and (SPE's), effective and efficient techniques components ranges from microscopic for improving quality, are being used to feature analysis of fatigue, fracture, accelerate the development of new and phase change, creep, and polymer crys- improved industrial process designs. At tallization to the stress-life prediction of NIST, researchers are employing these structural reliability of critical components techniques to improve fabrication of ad- based on mechanical and flaw-detection vanced for cutting tools and of testing. In these studies, NIST research- superconducting ceramics. SPE's are ers emphasize the interplay among the also being used to develop a reliable choices of data representation, appro- and cost-effective method to measure priate physical principles, incisive mathe- the size distribution of nitride matical and computational tools, and powders. Collaborative research oppor- integrated software for graphics and tunities for developing other SPE's exist in the following areas: and other composites processing, dental and medical materials fabrication, automated

12 Applied Mathematics

databases. In addition, they are inter- NIST research is concerned with develop- ested in mathematical theories of elastic- ing vector algorithms appropriate to the ity, plasticity, viscoelasticity, as well as combinatorial problems encountered in mathematical methods using matrix molecular dynamics simulations, particu- theory, finite-element algorithms, bifurca- larly three-dimensional simulations with tion analysis, statistical distribution con- very large ensembles of particles. Other cepts and sampling theory, and areas of interest include methods for solv- stochastic differential equations. ing highly nonlinear elliptic and parabolic partial differential equations as well as Contact: Jeffrey T. Fong, A302 nonlinear constrained and unconstrained Administration BIdg., 301/975-2720. optimization problems and the solution of nonlinear systems of equations. NIST re- searchers also are working on the solu- Nonlinear athematical analysis, used with tion of integral equations and numerical Mechanics symbolic computation, leads to evaluation of integrals. Software develop- efficient analytical approximations M ment goals include portable, interactive by computers. Perturbation algorithms packages, which integrate modern applied nonlinear to differential equa- graphics with numerical algorithms. tions, especially in celestial mechanics, result in analytical developments where Contact: Paul Boggs, A151 Technology the complexity grows exponentially with BIdg., 301/975-3800. the order of the approximation. Several different avenues are being explored by scientists at NIST to simplify literal Researchers at NIST are developing Scientific developments generated by perturbation and applying advanced methods Visualization algorithms applied to nonlinear systems. for the use of state-of-the-art, com- These include identification of algebraic puter-based scientific graphics for visual structures on the domain of the normaliza- rendering of complex experimental, com- tion, smoothing transformations to elimi- putational, and analytic results in physics nate perturbation terms outside the and chemistry. Researchers take advan- kernel of the Lie derivative, preparatory tage of a collection of vector and raster transformations of a geometric nature, workstations, photographic and video and the creation of natural intermediar- hardware, high-speed networking for ies. Problems being examined at NIST transmitting large graphics data sets be- are resonances at an equilibrium, per- tween computers and graphics devices, turbed pendulums, and the major theo- and computational geometry algorithms ries of celestial mechanics. NIST re- and software for the analysis of two- and searchers, using a LISP computer, are three-dimensional data sets. Recent ac- focusing their studies on algorithms tivities include the development of easy amenable to computer automation user interfaces to manipulate static ob- through symbolic processors. jects and of techniques to manipulate dy- namic objects in automated design and Contact: Andre Deprit, A302 manufacturing systems, the display of Administration BIdg., 301/975-2709. quasicrystal structures with icosahedral symmetries, the display of scanning elec- tron tunneling microscopy data with Vector '0 make effective use of vector com- polarization analysis, and the study of Algorithms and puters, new algorithms appropriate models of turbulent combustion showing Mathematical Jlto the special architecture of these the dependence of solutions on time and Software machines need to be designed and incor- fuel-oxidizer mixture parameters. porated in high-quality mathematical soft- ware for general use. Very successful Contact: Sally E. Howe, B146 vector algorithms have been developed Technology BIdg., 301/975-3807. for computations in numerical linear alge- bra (e.g., computation of the discrete Fourier transform), but few are available for combinatorial problems. One area of

13 Atomic, Molecular, and Optical Physics

studies of "he growth of gallium arsenide any sensitive and sophisticated Laser Semiconductor (GaAs) on silicon applications of lasers depend on Stabilization Materials T!substrates has generated consider- M the laser's spectral coherence, able interest due to the excellent me- frequency stability, and low-intensity chanical strength and thermal properties noise. NIST scientists have been working of the substrates—qualities not provided on laser intensity stabilization, laser by the GaAs material alone. A major diffi- frequency linewidth reduction with active culty in growing GaAs on silicon has control techniques, and several methods been the mismatch of lattice constants for producing quantitative laser fre- and the concomitant incorporation de- quency scans. Two new systems have fects. However, new studies show that a been developed. One, based on optical better match of the lattices can be sideband production by broadband mi-

achieved if the silicon substrate is cut at crowave phase modulation of the laser, a small angle to the crystal plane. NIST allows scans over a ±5 GHz range, with scientists are investigating the interaction inaccuracy below 10 kHz. The other scan of relevant semiconductor materials with technique utilizes a novel interferometer/

silicon substrates, using sensitive, phase-locked rf system, which maps opti- tunable laser sources to detect the in- cal frequency change into corresponding

dividual states of the and phase change of an rf signal suitable for molecules as they interact with the control, stabilization, and scanning. This growth substrate and growing material. system is intrinsically free of errors that Complete surface diagnostics and ultra- accumulate over large scans. By com- high vacuum conditions are used in this bining a Lambdameter for coarse work. The researchers are determining wavelength identification and a single the sticking coefficients and adsorption absorption line used as absolute cali- energies of individual spin-orbit states of bration, NIST scientists can scan a gallium atoms and other dopant atoms few dozen angstroms with sub-MHz plus the effects of vibrational excitation of accuracy. arsenic dimers on the growth of GaAs Another NIST system under develop- semiconductor materials. ment works entirely externally to a Another study involves the deposition continuous-wave laser to shift the output of thin films of amorphous silicon, which laser frequency and reduce the intensity are used in photosensitive devices and in a controlled manner. The first applica- in photovoltaic cells. Scientists are ex- tion of this is a box which will sit in the amining mechanisms involved in silane output beamline of any laser and "eat" discharge and thermal chemical vapor both frequency noise and amplitude deposition (CVD) production of such noise in the intrinsic output of the laser. films. Mass spectrometry is used to study Institute scientists have demonstrated gas discharge processes, gas chemistry, this function by combining an external and surface chemistry and their effect on electro-optic phase shifter and an film growth, character, and quality. Re- acousto-optic frequency shifter that also searchers are operating a threshold- functions as a fast controlled optical at- ionization mass spectrometer that can tenuator. Residual noise levels near the detect H and Six Hn radicals at densities values fixed by the fundamental quantum

of 1 part per million of parent silane fluctuations have been achieved in gases. The spectrometer also has a laboratory experiments. threshold sensitivity in the neighborhood of 10^^ cm""^ in the reactor vessel. All Contact: John L. Hall, Div. 577, NIST, electronics, vacuum, and gas-handling Boulder, CO 80303, 303/497-3126.

apparatus necessary for examining rf and dc discharges and thermal CVD under controlled conditions are available spectroscopy provides informa- Study of Atomic X-raytion on electronic structure and on Structure of as is a pulsed laser for use in studying the local atomic structure of atoms Matter with surface species by laser blowoff. X Rays in matter. A synchrotron radiation beam- Contact: Stephen R. Leone, line has been constructed by NIST scien- 303/497-3505 or Alan C. Gallagher, tists at the National Synchrotron Light 303/497-3936, Div. 577, NIST, Boulder, CO 80303.

14 Atomic, Molecular, and Optical Physics

Source, providing the highest flux, inten- sity, and energy-resolving power of any existing beamline in the x-ray energy range from 500 to 5000 eV. NIST equip- ment complements the synchrotron radia- tion instrumentation. X-ray absorption spectroscopy techniques, such as x-ray absorption near-edge structure (XANES) and extended x-ray absorption fine struc- ture (EXAFS), have been used to deter- mine the atomic structure of metals, semiconductors, polymers, catalysts, bio- logical molecules, and other materials of interest to industry. Researchers also use x-ray emission spectroscopy, x-ray photoelectron spectroscopy, and Auger electron spectroscopy to probe the elec- tronic structure of solids, liquids, or gases by using additional experimental capabilities. The x-ray standing wave technique Physicist Wayne Itano studies mercury ions, which are liliely uses interference between incident and to be the basis for new standards of timel(eeping. diffracted x rays to determine the precise location of impurities or imperfections atomic standards. NIST scientists cur- within a crystal or at its interfaces. The rently are working on an optically technique can be used to investigate the pumped cesium-beam standard that location of dopants and imperfections in should significantly surpass the perform- semiconductors or optical crystals, ance of standards based on magnetic growth of overlayers on crystals, and the state selection and detection. Their stud- structure of catalysts supported on crys- ies on ion storage and radiative cooling tal substrates. In addition, evanescent are exploring the potential for standards

x rays, which penetrate only a few operating at accuracy levels of 1 part in nanometers from an interface, can be lO''^ and perhaps beyond. controlled to study chemical composition Aerospace systems often require ex- in the vicinity of an interface. treme phase stability, which has led to a NIST scientists recently pioneered a need for high-quality phase noise charac- new technique, diffraction of evanescent terization amplifiers, frequency multi- X rays (DEX), which combines and ex- pliers, oscillators, and other electronic tends the capabilities of the x-ray stand- components. NIST has initiated a pro- ing wave method and experiments gram to develop methods for measuring based on evanescent x rays. The syn- phase noise in such components over a chrotron radiation beamline provides broad frequency range (into the millime- an ideal facility for applying these ter range). The work will involve primarily techniques. the two-oscillator technique, but other techniques will be studied. Contact: Paul L. Cowan, 301/975-4846 Requirements for synchronization or Richard D. Deslattes, 301/975-4841, (time) and syntonization (frequency) of A141 Physics BIdg. broadly dispersed sets of nodes for com- munication, navigation, and other elec- tronic systems are increasing signifi- Frequency, Time, dvancements in communication cantly. Because of the inherent reliability, and Phase Noise and navigation systems require simplicity, and low cost of using satellite Measurement /Ackatomic oscillators with increased transfer, NIST is studying several pos- performance and reliability. NIST has sible approaches for using this tech- several programs aimed at providing ad- nique. The NIST Time Scale and reliable vanced frequency standards with the ties to many other international timing potential for benefiting commercial centers provide the basis for perform- ance analysis of these time-transfer

15 Atomic, Molecular, and Optical Physics

techniques. In addition, Xhe Institute is ultraviolet and x-ray optical systems; and equipped with Global Positioning Systenn the calibration, characterization, and receivers, Earth communication termi- development of spectrometers and nals, and automated systems for statisti- detectors. cal analysis of system performance. NIST scientists are particularly interested in conducting collaborative Contact: Donald B. Sullivan, Div. 576, research in the use of soft x-ray synchro- NIST, Boulder, CO 80303, 303/497-3772. tron radiation for high-resolution lithog- raphy; measurement of the reflection characteristics of novel, high-efficiency,

Surface , urface characterizations are used in multilayer far-ultraviolet optical devices; Characterization .a great variety of scientific and tech- and calibration, characterization, and ' Oinological applications. Two beam- development of spectrometers and de- lines at the synchrotron ultraviolet NIST tectors. Other available equipment in- radiation facility (SURF-II) have been in- cludes a state-of-the-art multipurpose for strumented surface characterization. detector calibration facility, a large ul- Although the principal characterization trahigh vacuum spectrometer calibration techniques utilized are photoelectron chamber, and a beamline dedicated to spectroscopy and photon-stimulated de- high-resolution radiation research with a sorption of positive ions, surfaces also 6.65-m vacuum spectrometer with a re- can be characterized by Auger-electron solving power of about 300,000. spectroscopy and low-energy electron diffraction. An ancillary chamber is being Contact: Robert D. Madden, A249 constructed in which films of different ma- Physics BIdg., 301/975-3726 or terials can be deposited and transferred William R. Ott, B206 Metrology BIdg., to the main chamber for characterization 301/975-3709. without exposure to the atmosphere. A facility for cooling specimens to cryo- genic temperatures is available. Plans part of its research to understand Vacuum call for the installation of an ellipsoidal Asand measure various forms of Ultraviolet Radiometry mirror analyzer, which will be used to radiation, NIST is conducting measure the energy and angular distribu- vacuum ultraviolet studies involving radia- tions of photoemitted electrons and the tion damage, polymerization of organic energy, angular, and mass distributions molecules, and solar simulation. NIST of desorbed ions. scientists have worked with researchers from industry to develop and test Contact: Richard L. Kurtz, B248 vacuum ultraviolet instrumentation, new Chemistry BIdg., 301/975-2544. spectrometer designs, and detector sys- tems, especially for flight in space. They also have collaborated on special "0 Ultraviolet and produce radiation for experimental sources, narrow band filters, and lasers. Soft X-ray purposes, NIST has built a syn- NIST scientists are interested in doing Radiation Effects facility chrotron ultraviolet radiation cooperative research in several other (SURF-II). SURF-II is a 300-MeV electron areas, including studying hollow cathode storage ring that radiates high-intensity lamps, laser plasmas, and spark dis- synchrotron radiation in the energy range charge light sources as secondary stand- from about 3 nm (400 eV) in the soft x-ray ards. State-of-the-art radiometric facilities region to wavelengths in the visible re- and advanced optical equipment are gion of the spectrum. The radiation is available at NIST for these studies. highly collimated, nearly linearly polarized, intensity. Six and of calculable Contact: J. Mervin Bridges, beam lines are available, and a user's 301/975-3228 or Jules Z. Klose, program is in operation. SURF-II is well 301/975-3230, B66 Physics BIdg. suited for many different types of re- search, including atomic, molecular, bio- molecular, and solid-state physics; surface and materials science; and radiation effects on matter;

16 Atomic, Molecular, and Optical Physics

Submicron ^ell-characterized, focused elec- equipment is available to accomplish Physics tron beams are used to investi- this characterization, including several Wigate the properties of surfaces Nd:YAG pumped, high-resolution and magnetic materials on a microscopic (<0.1 cm"^) dye lasers; Ar ion-pumped scale. As part of a broad-based research dye and ring dye lasers; a Fizeau program at NiST, scientists are exploring wavemeter; a high-throughput (f/4), high- the physics of submicron systems using resolution (<0.01 A) spectrometer with an electron microprobes. The program in- automated intensified diode array detec- cludes studies of electron-surface inter- tor; a 80-MHz quadrature He-Ne laser in- actions, surface magnetism, electron terferometer; UV spectrometers; grazing interaction theory, and electron spin incidence spectrometers; laboratory com- polarization phenomena. Among the ex- puters; and miscellaneous optics. The tensive experimental facilities available principal quantities measured are par- for this research are sources and detec- ticle density distributions, both spatially tors of spin polarized electrons, a scan- and temporally, for electrons, atoms, ning electron microscope equipped for ions, and molecules. Also included are secondary electron spin polarization electric-field distributions, electron and analysis, and a scanning tunneling ion temperatures, and nonequilibrium microscope. phenomena. Scanning electron microscopy with polarization analysis is a unique measure- Contact: James R. Roberts, A167 ment capability developed by NIST scien- Physics BIdg., 301/975-3225. tists to allow the high-resolution (-10 nm) imaging of magnetic microstructure inde- pendently of surface topography. With Anew capability for fabricating rela- XUV Multilayer this technique, researchers are studying tively high reflectivity, normal inci- Characterization fundamental magnetic phenomena, the dence optics for the extreme properties of high-density magnetic re- vacuum ultraviolet (XUV) spectral region cording media, and small-particle mag- has emerged since the beginning of this netism. NIST researchers are using the decade. When a large number of care- scanning tunneling microscope to study fully deposited layers of selected mate- surface topography at the atomic level, rials are placed on a very smooth mechanisms of film growth at the sub- surface, the reflectivity of the surface can monolayer level, reconstructions of semi- be improved by several orders of magni- conductor surfaces, and, ultimately, tude. This new capability has allowed the correlation of surface microstructure construction of XUV telescopes revealing with macroscopic properties. images of the sun at selected wave- lengths (e.g., 175 A relevant to Fe^'*' emis-

Contact: Robert J. Celotta, B210 sion) in unprecedented detail and XUV Metrology BIdg., 301/975-3710. microscopes with submicrometer resolu- tion for biological studies. A charac-

terization facility, which is available to all Characterization "he properties of low-temperature researchers on a cooperative basis, is of Low- plasmas play a key role in the proc- now in operation at NIST to measure re- Temperature Tiessing of materials such as semicon- flectivity of these optics between 80 and Plasmas ductors. Proper characterization of these 600 A as a function of angle and plasmas is essential to develop accurate wavelength. This facility is capable of pre- plasma diagnostics and useful plasma cise measurements of single thin films models for specific applications. At NIST, and bulk material samples for derivation plasma discharges are characterized util- of optical constants in this region of the izing optical emission spectroscopy, spectrum. Plans for the future include a laser-induced fluorescence, laser scatter- new monochromator-reflectometer sys- ing, and optogalvanic methods. Model- tem to operate from 30 to 600 A and an ing of the plasma is also an integral part optical test bench to measure the focus- of this characterization. Discharge ing properties of curved optics. sources include low-pressure RF plas- mas, stabilized arcs, glow discharges, Contact: James R. Roberts, A167 heat pipes with laser resonance ioniza- Physics BIdg., 301/975-3225. tion, and inductively coupled plasmas. An extensive array of laboratory

17 Building Technology

Cement and 1ST researchers are undertaking a computer graphics laboratory including a Concrete computer-oriented research pro- VAX computer system and specialized N gram to develop a fundamental un- graphics-based finite-element software is derstanding of the relationship between utilized for the analytical work. chemistry, microstructure, and service life of concrete and other inorganic build- Contact: H.S. Lew, B168 Building ing materials. The goal of the program is Research BIdg., 301/975-6061. to be able to predict the behavior of these materials and their service life- NIST lighting program focuses Lighting times. The service life of concrete largely The depends on the rate of moisture ingress on fundamental measurements of and of transport of dissolved salts and interior luminance and illuminance gases in the pore system of concrete. distributions, light fixture output, and Models are being developed to consider the interaction between lighting and service conditions, including composition HVAC (heating, ventilating, and air- of the environment; the transport rate of conditioning) systems. A continuing chal- reactants by diffusion, convection, and lenge is to develop metrics for lighting capillary forces; and reaction mecha- quality that evaluate the combined ef- nisms. Researchers are developing math- fects of illuminance, luminance, contrast, ematical and simulation models to color rendering, lighting geometry, and predict the relationships between pore configuration. structure and diffusion and permeability In the past, researchers have focused of concrete. on mathematical formulas for predicting Research projects include develop- the chromatic contribution to brightness, ment and validation of mathematical mod- computer programs for predicting energy els of microstructure development in effects of daylight use, detailed calcula- cement pastes as the cement hydrates, tion of lighting geometry, and assess- the effects of microstructure on permea- ments of color appearance under bility and fracture of concrete, and mech- different illuminants. Current research in- anisms of degradation of concrete. cludes a major project on the measure- Artificial intelligence systems are being ment and modeling of the interaction of developed for optimizing the selection of lighting and HVAC in a simulated interior materials and for diagnosing the causes office module. This research is expected of material degradation. The research is to result in the development of a detailed performed using a variety of techniques, computer model for predicting the effects including scanning electron microscopy, of different types of lighting and HVAC computerized image analysis, x-ray dif- systems. Modifications will be made to fraction, and thermal analysis. the facility in the near future to study the effects of dimming, thermal mass, and ex- Contact: James R. Clifton, B348 Building ternal solar conditions. Research BIdg., 301/975-6707. Contact: Belinda L. Collins, A313 Building Research BIdg., 301/975-6455. Structural 'xperimental and analytical research Engineering is under way at NIST to develop de- testing Indoor Air Quality E;.sign criteria for precast concrete easurement and proce- frames and masonry structural com- dures, technical data, and com- prehensive indoor air-quality ponents subjected to dynamic loads M such as winds and earthquakes. The models are being developed by NIST re- work involves identifying limit states and searchers as part of a multiyear program establishing criteria to ensure structural to improve indoor air quality in buildings. safety. The researchers use a unique Experiments are being conducted in computer-controlled test facility that can several large buildings to develop test air into impose forces and/or displacements in methods to evaluate how moves three directions simultaneously and a and within large commercial buildings. 12-million-pound capacity universal test- The researchers are developing compre- ing machine with a lateral load capacity hensive computer models to predict pollutant levels from sources introduced of 1 .5 million pounds that can accommo- date large-scale structural components 60 feet tall. A high-performance Building Technology

NIST is conducting basic and ap- Organic Building plied research to determine the Materials

quality and predict the service life of organic building materials, such as protective coatings for steel, adhesives, roofing materials, and plastics. The re- searchers are investigating degradation mechanisms, improving characterization methods, and designing mathematical models of the degradation processes. They then use research results to derive stochastic models, which have a basis in reliability theory and life-testing analy-

sis, to predict the service life of these materials. Institute scientists are using computer analysis of infrared thermographic im- ages to study the rates of corrosion and the formation and growth of blisters beneath opaque protective coatings. They employ gel-permeation chromatog- raphy, gas chromatography, and spec- troscopy to study the mechanisms of photolytic and thermal degradation of poly (methyl methacrylate). Reliability theory and life-testing analysis tech- niques are used to predict service lives of the materials.

Contact: Larry W. Masters, B348 Building Research BIdg., 301/975-6707.

Materials research engineer Leslie Struble uses a cylinder and piston device to study the causes of concrete failure. NIST researchers are exploring the Refrigeration use of refrigerant mixtures to im- Machinery into buildings from outdoor air and those prove the efficiency of refrigeration generated inside from sources as com- cycles and to replace harmful chloro- bustion equipment and floor and wall fluorocarbon (CFC) refrigerants that are coverings. damaging the ozone layer of the upper at- The first phase of the research is mosphere. The scientists evaluate a wide complete, and models exist that can pre- variant of refrigeration cycles by using a dict indoor contaminant levels as func- breadboard heat pump to "plug" and "un- tions of emission, dilution, and intra- plug" circuits and components. The building air movement. The models cur- breadboard heat pump will be altered to rently are being extended to model reac- test new refrigeration cycles based on tive contaminants. Test procedures also the results of a theoretical study being are being developed to evaluate the ef- conducted to find the optimal combina- fectiveness of various filter media for re- tion of mixtures and appropriate refrigera- moving gaseous pollutants. A test facility tion cycles for the best and most versa- for this purpose has been designed and tile performance. assembled. Test methods will be devel- The "best" of the advanced cycles will oped for commercial gaseous air filters be selected, equipment built, and eval- and for those used in residences. uated. A minibreadboard that will use a very small charge will also be built so Contact: Richard A. Grot, A313 Building that rare refrigerants of limited production Research BIdg., 301/975-6431. can be studied.

Contact: David A. Didion, B1 14 Building Research BIdg., 301/975-5881.

19 Building Technology Ceramics

Thermal esearchers at NIST are developing of ceramics is a complex I Sintering Insulation basic data and simulation models process that involves the interaction Processing

R:, for heat, air, and moisture transfer of many different processing vari- through building envelope components. ables. The influence of these processing They are developing and validating a variables on sintering cannot be deter- theoretical model for moisture transfer, mined simply by measuring final density completing research required to develop or some other end-point property. Chemi- a low-conductivity Standard Reference cal composition of the ceramic powders Material (SRM), developing a thermal is known to be of major importance and, conductivity database for chlorofluorocar- under certain conditions, can mask ef- bon (CFC) blown thermal insulation prod- fects of most other processing variables. ucts, and refining a dynamic test As part of a ceramics program, NIST procedure for building components. scientists are investigating the effect of A 1 -meter guarded hot plate is used trace levels of impurities using clean- to develop SRM's; to determine thermal room processing to produce, compact, conductivity values for various materials, and sinter ultrahigh purity ceramics. such as CFC blown insulation; and to pro- Results from this research will en- vide measurement services to manufac- hance investigations of other processing turers and researchers. A calibrated hot variables, including particle size, shape, box is used to measure the steady-state agglomeration, compaction method, and and dynamic performance of full-scale atmosphere under controlled composi- wall systems. tion conditions. The data can be used to design better models for microstructure Contact: A. Hunter Fanney, B320 evolution during sintering. Use of predic- Building Research BIdg., 301/975-5864. tive models, in conjunction with other ongoing efforts to produce unique com- positions and phases, can lead to new Building Controls 1ST research is fostering the devel- advanced ceramic materials with unique opment of more intelligent, inte- microstructure and properties. N grated, and optimized building building/ mechanical systems. A dynamic Contact: Edwin R. Fuller, Jr., A256 HVAC control system simulation program Materials BIdg., 301/975-5795. is used to study HVAC/control system dy- namics and interactions. An expanded building management and controls labo- ratory is used to assist the building controls industry in the development, evaluation, and testing of communication protocol standards for the open ex- change of information. The application of knowledge-based systems to buildings is a new area of re- search. Plans call for exploring how real- time models, "tuning" techniques, forecasting, optimal control theory, and a rule-based expert system can be com- bined to evaluate control system perform- ultra-clean ceramic processing laboratory is ance, make control strategy decisions The NIST specially designed for the production and processing of ad- that optimize building performance, and vanced ceramic powders and samples with controlled levels perform diagnostics to advise the build- of impurities dopants. ing operator or manager on building and operations, equipment problems, or main- tenance requirements. Work has begun Researchers in the NIST ceramics Tribology of for the Department of Energy to develop tribology program are investigating Ceramics an HVAC/building emulator/EMCS tester, the fundamental mechanisms of which will provide a method for evaluat- friction and wear of advanced materials ing application algorithms. and lubricants and are developing test methods for evaluating the performance Contact: George E. Kelly, B1 14 Building of these materials. The program's Research BIdg., 301/975-5870.

20 Ceramics

primary focus is on the characterization the fracture properties of monolithic of the interfacial phenomena that occur ceramics. These forces have been when two solid surfaces interact. Re- measured for mica, sapphire, and fused search activities include analysis of silica surfaces, using a crossed cylinders chemical reactions and formation of tribo- apparatus. chemical films, physical and mechanical A second program uses an indenta- behavior of surface films, and deforma- tion strength procedure to determine the tion and fracture processes leading to R-curve behavior of monolithic alumina wear and failure. Tribology laboratories ceramics and to relate the R-curve to the consist of state-of-the-art tribometers, specific microstructure of the material. such as high temperature (1000 °C) wear In-situ microscopic observations of the testers, and analytical instruments, such crack growth demonstrate the presence as time-resolved micro-Raman laser sys- of grain bridging and frictional sliding in tems, which can be used for cooperative the crack wake as a significant source of research with industry and other federal material toughening. agencies. NIST researchers are compil- The program in composites is ing wear data in the form of "wear maps" aimed at determining the effects of the and are studying the mechanisms of fiber/matrix interface on fracture behavior wear of structural ceramics at elevated of these materials. An instrumented mi- temperatures, self-lubricating metal- croindenter is available to measure the matrix and ceramic-matrix composites, fiber/matrix interface strengths. Re- and wear resistant coatings. searchers also are investigating the stresses developed in composites during Contact: Said Jahanmir, A215 Metrology conventional sintering processes to deter- BIdg., 301/975-3671. mine methods of reducing these stresses through the use of fiber coatings—thus minimizing or eliminating cracking of the Electro-optic mperfections in highly perfect crystals matrix as densification proceeds. Crystals typically limit their performance in high- High-temperature deformation and technology applications such as opti- fracture behavior of ceramics are other cal communications and optical signal areas of research. Creep and creep rup- processing. In particular, limitations in ture of several varieties of siliconized SIC the perfection of electro-optic and photo- have been investigated and their be- refractive materials, such as lithium nio- havior related to differences in micro- bate and bismuth silicon oxide, have structure, particularly grain size. inhibited severely the development of op- Research continues on whisker- tical switches and modulators. NIST re- reinforced SIsNa and AI2O3, SIC, and searchers are investigating crystal other high-temperature materials. Facili- perfection at a unique, monochromatic ties exist for performing creep measure- x-ray topography facility at the NIST/ ments in tension, compression, and Naval Research Laboratory beamlines on flexure at temperatures up to 1800 °C. the high-energy ring at Brookhaven The tensile creep apparatus is almost National Laboratory's National Syn- completely automated, and measure- chrotron Light Source. The data collected ments are made using a laser imaging from current studies, conducted jointly technique. Displacement measurements with growers of high-quality crystal, are are accurate to ±1 nm at 1500 °C. expected to improve substantially the quality, and hence the performance, of Contact: David C. Cranmer, A361 these crystals. Materials Bldg., 301/975-5753.

Contact: Bruce W. Steiner, A329 of particle Ceramic Powder Materials Bldg., 301/975-5977. Improved characterization size, shape, and crystal chemistry of Characterization ceramic powders is important to the everal long-term programs are and production of high- Mechanical I development Properties off being conducted at NIST on the quality ceramics for advanced techno- Ceramics O1'fracture, creep, and creep rupture logical applications. To obtain precise of monolithic and composite ceramics. Researchers, for example, are examining the effect of very near surface forces on

21 , .

Ceramics

and reproducible measurements of these Ceramic phase equilibria studies at Ceramic Phase characteristics, NIST scientists are utiliz- NIST involve complementary re- Equilibria ing a variety of instrumental methods, in- search activities in experim.ental cluding scanning electron microscopy theoretical, data-evaluation, and compila- with image analysis. Theoretical inves- tion aspects of ceramic phase equilibria. tigations and statistical analyses of data The data-evaluation and compilation are then used to compare the results of work is carried out under the joint Ameri- the measurement methods. can Ceramic Society (ACerS)/NIST pro- Improved understanding of the gram to provide industry and others with changes which occur in materials at high a comprehensive database of up-to- temperatures is necessary to process date, critically evaluated phase diagram and use advanced materials. High- information. Ceramic phase diagrams are temperature x-ray diffraction provides a being determined for systems of techni- means for NIST scientists to record these cal importance, such as high-transition- changes as they occur. Current studies temperature ceramic superconductors. focus on formation of high Tc ceramic su- perconductors, reactions in ceramic Contact: Stephen Freiman, A329 composite materials, sintering of ceram- Materials BIdg., 301/975-5761 ics, and high-temperature phases in superalloys. A scanning electron microscope scientists are investigating low- Ceramic NIST Chemistry (SEM), equipped with an image analysis temperature synthetic approaches system and backscatter electron imag- to both oxide and nonoxide ce- ramic powders coatings. are ing, is used to obtain a precise under- and They standing of the relationship between using novel chemistry and techniques to microstructure and bulk physical and solve the problems of generating homo- chemical properties of powders and ce- geneous, multicomponent materials with ramics. A special sample holder can be predictable and optimal properties. The researchers are studying the following installed in the large SEM sample cham- ber so a sample may be obser\/ed while materials: high Tc ceramic superconduc- tors; ultrafine ceramic powders with high- a crack is being driven through it. To improve measurement procedures, electrical conductivity; ceramic coatings NIST researchers are studying the sam- with selected optical, electronic, or struc- ple preparation factors that influence par- tural properties; ultrafine magnetic com- posites; whiskers-ceramic matrix ticle size measurements. Measurements ceramic of particle size distribution by sedigraph composites; and ultrafine, pure oxide and centrifugal photosedimentation and powders. Depending upon requirements of the study and the powder, synthesis is of specific surface are used in conjunc- tion with quantitative SEM/image analysis carried out either in small bulk reactors or in reactor. to document fully the geometric charac- a flow researchers are examining the re- teristics of a powder. The properties of The lationship of sur- powder suspensions and the effect of the process conditions to suspending liquid on the surface chemis- face chemistry of the powder, particle try of the powder are studied also. Ele- size and shape, the phases formed of mental characterization of the treated during thermal treatment the powder, and properties of the powder or sintered powder is characterized by various spec- troscopic methods. Suspension proper- ceramic, such as electrical conductivity. ties are characterized by measurements Coupled with the powder synthesis is the development of characterization of pH, surface charge, ionic activity, including Fourier acoustophoresis, zeta potential, and vis- methods, micro-Raman, coelastic properties. NIST scientists also transform , and nu- clear spectroscopy. are studying the application of colloidal magnetic resonance processing methods to the formation of monolithic and composite ceramics. Contact: Joseph R. Ritter, 301/975-6106 or Pu Sen Wang, 301/975-6104, A256 Materials BIdg. Contact: James P. Cline, 301/975-5793, James F. Kelly, 301/975-5794, or Subhaschandra Malghan, 301/975-6101 A256 Materials BIdg.

22 Chemical Technology

Center for The Center for Advanced Research the thermodynamics of these processes. Advanced in Biotechnology (CARB), a joint re- These data are used to predict reliably Research in search venture between NIST and the efficiency of biochemical processes Biotechnology the University of Maryland, studies pro- outside the normal measurement ranges tein structure/function relationships. for temperature, pH, and ionic strength. Scientists at CARB are focusing on the measurement of protein structure by Contact: Stanley Abram.owitz, B348 x-ray and nuclear mag- Chemistry BIdg., 301/975-2587. netic resonance spectroscopy, and the manipulation of structure by molecular several Thermodynamic biological techniques including site- NIST maintains data centers directed mutagenesis. Protein modeling, that evaluate thermodynamic data Data Evaluation molecular dynamics, and computational in inorganic, organic, and aqueous chemistry are used to understand protein chemistry. Researchers in the data cen- structure and to predict the effects of ters examine existing data, extrapolate specific structural modifications on the these data to temperatures outside the properties of proteins and enzymes. A range of measurement, create algorithms variety of methods for data evaluation and manipulation, are used to measure and analyze struc- and produce reliable estimation schemes tural changes, activities, and thermo- for predicting the properties of species dynamic behavior of proteins under for which measurements are not avail- investigation. CARB maintains state-of- able. Current interests include the techno- nuclear the-art facilities for crystallography, NMR logical problems of combustion, spectroscopy, , and waste disposal, and atmospheric ozone of formation physical . Its computer facili- depletion; the prediction the in the ties include a mini-supercomputer, properties of organic species several high-resolution graphics worksta- gaseous, liquid, solid, and aqueous tions, and access to the NiST Cyber 205 phases; and the production of databases supercomputer. of the ubiquitous biochemical species of interest to biotechnology. The data cen- ter researchers are active in national Contact: Walter J. Stevens, 9600 standards-setting organizations such as Gudelsky Dr., Rockville, MD 20850, 301/251-2272. ASTM, have bilateral collaborative re- search projects with research organiza- tions in several countries, and are active Chemical and NIST researchers have developed in international research organizations Biochemical precision oxygen combustion cal- such as CODATA and lUPAC. Thermodynamics orimeters to measure the enthalpy of combustion, from which enthalpy of Contact: Stanley Abramowitz, B348 formation can be derived, for samples Chemistry BIdg., 301/975-2587. varying in mass from 10 milligrams to 2.5 kilograms. These instruments are program at Chemical used to characterize thermodynamic TheNIST provides reliable chemical Kinetics properties for species of interest to bio- measurement chemistry, organic chemistry (including kinetics data, methods, and theoretical models. Appli- strained species), phosphorous chemis- cations of this research include combus- try, and heterogeneous fuel technolo- tion, new chemical technologies, the gies. The measurements also serve as chemistry of the upper atmosphere and the basis for Standard Reference Mate- other planetary atmospheres, effects of rials and Standard Reference Data for a ionizing radiation on materials, solar variety of technologies, including energy. energy conversion, biotechnology, flue- In the area of biothermodynamics, cleanup chemistry, acid rain, toxic NIST researchers have developed accu- gas waste incineration, coal conversion, and rate and precise microcalorimeters to analytical applications of kinetics. Among measure the heat released in enzyme- the experimental projects under way at catalyzed biochemical reactions of inter- NIST are pulse radiolysis of aqueous est to technology. When coupled with solutions, and kinetic mass spectrometric equilibrium measurements, these meas- studies (Fourier transform ion cyclotron urements enable the reliable modeling of resonance, high-pressure mass

23 —

Chemical Technology

spectrometry, tandem mass spec- and polysaccharide membranes for trometry) of the kinetics and thermochem- small biomolecule separations. istry of ion/ reactions and To assist the biotechnology industry, ion/molecule clustering processes. NIST scientists are developing the fun- Researchers also are studying free- damental transport data, experimental radical l

Separations eparation and purification are criti- cal steps in the manufacture of 0('chemical products using existing and emerging process technologies, such as biotechnology. Separation proc- esses affect both the economies of pro- duction and the fundamental ability to produce a product of desired form or pu- rity. NIST is creating an engineering science base in two broad areas membrane-based separations and bioseparations. In the membrane area, NIST scientists are studying gas separations, bio- molecule transport and adsorption, and reactive membranes; in the area of gas separations, researchers are investigat- ing novel facilitated transport membranes for use in acid gas removal and air sepa- rations. Reactive membrane systems are being studied for trace component re- moval and for gas cleanup/recycle appli- cations. In an interdisciplinary project, researchers are examining the adsorp- tion of biological macromolecules to ultra- filtration membranes, with the objective of developing better predictive models for fouling, flux decline, and chromato- Research chemists Ewa Gajewski (left) and Miral Dizdaroglu graphic applications. Other study areas determine the chemical structure of a major type of DNA include pervaporation membranes for damage caused by oxygen-derived free radicals. close boiling mixtures and composite

24 Chemical Technology

Properties of "hermophysical properties data are for the thermodynamic and transport Fluids essential for the design and opera- properties of near critical and supercriti- tion of many chemical processes cal mixtures. This work includes PVTx such as supercritical extraction. To and VLE measurements on mixtures con- obtain these data, NiST scientists are taining carbon dioxide, halogenated hy- using three new phase equilibria appara- drocarbons, and similar supercritical tus for studies at elevated temperatures. solvents. Other experimental work in- One apparatus is used to perform VLE volves using supercritical chromatogra- measurements on carbon dioxide- phy to measure diffusion coefficients in hydrocarbon systems and refrigerant- supercritical mixtures and theoretical hydrocarbon systems, the second is a studies to focus on the application of ex- dew/bubble point apparatus extending to tended corresponding states to supercriti- 800 K, and the third employs a palladium- cal systems. silver membrane to measure the fugacity of hydrogen-containing mixtures. Five ex- Contact: James F. Ely, 303/497-5467 ceptional instruments are available for or Thomas J. Bruno, 303/497-5158, making PVT, PVTx, and heat capacity Div. 584, NIST, Boulder, CO 80303; measurements on pure fluids and fluid J.M.H.L. Sengers, A121 Physics BIdg., mixtures: an isochoric PVT apparatus, a 301/975-2463. Burnett apparatus, a combined Burnett/ isochoric PVT apparatus, a magnetic suspension densimeter for PVT and PVTx wide array of experimental and Properties of interfaces measurements, and an instrument to A theoretical tools are being applied measure constant volume heat capacity. to obtain practical and fundamen- Facilities also exist to determine proper- tal understanding of the structure, proper- ties along the tvi'o-phase coexistence line ties, and effects of interfaces between of pure fluids and mixtures and to make fluid phases. NIST scientists are investi- sound speed measurements. A well- gating a number of problems in this area equipped analytical laboratory and ranging from the conceptually simple specialized apparatus enable NIST re- (e.g., measuring and/or calculating the in- searchers to devise techniques for char- terfacial tension between a liquid and its acterizing fluids and fluid mixtures when vapor) to the more complicated (e.g., de- the temperatures, pressures, and times termining the phase behavior of surfac- involved can result in reactions during tant mixtures at water-air interfaces, the the measurement process. thicknesses of adsorbed liquid layers at solid-gas interfaces, the stability of Contact: William M. Haynes, Div. 584, foams, and the evolution of mists). NIST Boulder, CO 80303, 303/497-3247 or facilities include an automated ellipsome- Michael R. Moldover, A103 Physics ter and an automated film balance, BIdg., 301/975-2459. quasieiastic light scattering for studying the evolution of mists, an apparatus for measuring foam stability, and simple re- interfacial Thermophysicai , hemical process technology setups for measuring tension. and Supercritical quires an accurate knowledge of Computing facilities include a CDC 855, Properties of r'various thermophysicai properties a Cyber 205 supercomputer, software, Mixtures of pure, polyfunctional chemicals and and experience in simulation of fluids. their mixtures. Research is being con- Research projects are planned in sev- ducted at NIST on the most important of eral areas. One project will involve apply- these properties—equilibrium phase ing quasieiastic light scattering to the composition, density, and enthalpy. NIST measurement of interfacial tension of researchers are developing predictive liquid-vapor mixtures at high pressure methods for the properties of chemically and the measurement of the dynamics of dissimilar compounds, especially com- wetting layers. Another project will focus plex mixtures and aqueous solutions. on measuring the permeability, surface Another project, a combined experimen- viscosity, and surface-diffusion coeffi- tal and theoretical study, is aimed at cients of surfactant layers. The research- developing accurate predictive models ers will test NIST theories developed for the large increase of the surface tension

of a liquid-vapor interface when it forms in a confined geometry (such as in a pore

25 .

Chemical Technology

within a pellet) and for the large effects of frequency and wavelength, the speed of ions on the thicknesses of adsorbed lay- the radio wave, and hence the ers. They will also study the evolution of constant, can be deduced. By then ap- the drop-size distribution of simple, but plying a mixing rule and the dielectric nontrivial, mists comprised of two hy- properties of the individual components, drocarbons suspended in their own researchers can determine the solids vapor. fraction in a slurry. NIST is extending the project to incorporate systems with ax- Contact: Michael R. Moldover, A103 ially varying dielectric constants, adsorp- Physics BIdg., 301/975-2459. tion columns and settling suspensions, for example. Other measurements, such as polarization rotation in a swirling slurry of hlorofluorocarbons Properties (CFC's) have flow and Doppler shifts due to fluid flow, Atmospherically been used widely for the past 50 are being planned. Safe Refrigerants r years as refrigerants; as foam in building insulation, furniture, car seats; Contact: Adolfas K. Gaigalas, 109 Fluid and in many other applications. Recent Mechanics BIdg., 301/975-5941 evidence has shown, however, that chlorofluorocarbons (CFC's) are break- ing down the ozone layer which protects The accelerating costs of scarce Flow the Earth from harmful levels of ultraviolet fluid resources— particularly petro- Measurement radiation. Alternative chemicals must be chemical fluids—are producing in- Research and Standards found to replace the existing fluids within creased concerns about the perform- the next decade. For this to be achieved, ance levels of flow meters. Improved flow an accurate knowledge of their ther- measurement traceability needs to be es- mophysical properties is required. NIST tablished and maintained so that realis- has a research program designed to pro- tic, quantified data are generated on a vide these data to industry, ultimately in continuing basis to assure practical fluid the form of interactive computer codes. measurements at satisfactory, specified The research includes extensive experi- levels of performance. To achieve the mental measurements on pure fluids and desired flow measurement traceability, mixtures, including PVT, PVTx, vapor NIST is designing transfer standards to pressure, saturation density, heat capac- link the performance of calibration facili-

ity, thermal conductivity, viscosity, sound ties to appropriate national reference speed, and surface tension. The pro- standards. gram also includes substantial effort in Because of the importance of these modeling fluid properties and in develop- measurements, transfer standards need ing equations of state. to be designed so that high levels of con- fidence can be placed in them and their Contact: Neil A. Olien, Div. 580, NIST, performance. The new transfer standards Boulder, CO 80303, 303/497-5108. will be rigorously evaluated against NIST fluid flow calibration standards. As part of evaluation, the appropriate range of cali- "he successful of Radio Frequency processing paper brations will be done on the developed Wave Diagnostic pulp, flour, coal slurries, and sludge standards so that performance levels of Disperse I depends[ on accurate measure- Systems can be assured at specified levels. Cur- ments of the percent of solids sus- rent fluid metering research programs pended in water in a pipeline. To help use laser Doppler velocimetry (LDV) tech- improve these measurements, NIST is niques to focus on the pipeflows pro- studying the propagation of radio waves duced by conventional pipeline elements inside a conducting pipe filled with com- and by standard flow conditioning ele- plex materials. One result of this research ments. New experimental programs are has been the successful measurement of feasible using LDV or other anemometry the solid slurry, which was accomplished or flow visualization techniques to study by measuring the wavelength and at- other flows. NIST also has computational tenuation of radio waves in a pipeline capabilities to model numerically a num- with a 32-element antenna array placed ber of closed conduit flow fields. along the axial direction. From the known

Contact: George E. Mattingly, 103 Fluid Mechanics BIdg., 301/975-5939.

26 Chemical Technology

Fluidized-Bed 'he understanding of transport and include on-line gas monitors, gas chro- Reactors kinetic processes in fluidized beds matography with mass-spectrometric de- I at elevated temperatures is of great tection, and FTIR spectroscopy. importance in many areas of cliemical en- gineering, including pyrolysis and com- Contact: Andrej Macek, B312 Physics bustion of solid and liquid fuels, catalytic BIdg., 301/975-2610. reactions, and destruction of tnazardous wastes. NIST maintains a fluidized-bed facility designed and instrumented to understand performance of thin- Chemical Sensor Research address research problems in these tech- Tofilm and chemical sensors, NIST nical areas. Past projects include time- scientists are conducting research resolved optical temperature measure- aimed at improving their accuracy, stabil- ments of single particles inside the bed, ity, selectivity, and response, as well as as well as optical studies of mixing of developing ideas for new measurement solid particles at elevated temperatures. techniques. Activities incorporate adhe- Currently, the facility is used for stud- sion, oxidation, interlaminar diffusion, sur- ies of pyrolysis and combustion of chlori- face adsorption and desorption, and nated hydrocarbons representative of phase morphology to investigate mecha- hazardous-waste constituents. Re- nisms of chemical sensing. The scientists searchers are investigating the effects of use analytical methods to relate the struc- temperature, residence time, and chemi- ture and composition of sensing devices cal composition of bed particles on de- to fabricating parameters and perform- struction efficiency of the model ance. Research areas include thin-film compounds and the formation of interme- thermocouples, thin-film resistance de- diate products of incomplete combus- vices, moisture sensors, pH sensors, tion. The analytical instruments used and gas detectors. Fabrication facilities

Mechanical engineers George Mattingly (rigtit) and T.T. Yeh (center), with technician Boyd Shomalier, study flow-measuring devices using laser Doppler velocimetry at the NIST fluid metering research facility.

27 Chemical Technology

available are rf and dc sputtering for both also expected to provide a powerful tool alloy and reactive film deposition and for cell activity and intracellular kinetics gas reactors. The feasibility of thin-film measurements. systems as chemical sensors is being de- termined as the scientists investigate the Contact: Hratch G. Semerjian, B312 electronic properties of films and single Physics BIdg., 301/975-2609. crystals for dielectric strength, surface conductance, and capacitance. For surface-sensitive techniques, they are Biological cells are known to be elec- Electrical in employing x-ray and uv photoemission, trically active as demonstrated by Measurements Bioreactors thermal desorption spectroscopy, SIMS, the membrane potential present in and in-situ electrical measurements to all living cells. A NIST program is con- characterize appropriate chemisorptive cerned with developing measurement and molecular film systems. techniques for observing electrical activ- ity of cell suspensions to provide fun- Contact: Kenneth G. Kreider, damental data for sensor development in B312 Physics BIdg., 301/975-2619 bioreactors. Both linear and nonlinear or Stephen Semancik, B346 Physics electrical responses are under investiga- BIdg., 301/975-2606. tion. The nonlinear properties are espe- cially interesting since they are expected to originate from the cell membrane. Optical Sensing ndustries now recognize the potential Theoretical investigations are in progress in Bioreactors benefit of applying recent advances in to relate the observed electrical behavior molecular biology in a diversity of sec- to the activity of membrane transport pro- tors, such as the production of new teins. The researchers are working to drugs, food additives, and chemicals achieve a better understanding of the and conversion of biomass. However, im- coupling of applied electric fields to mem- plementation of bioprocesses requires a brane proteins, which can lead to practi- closely controlled environment, normally cal schemes to influence the activity of realizable only in batch processes. This cells. Research areas include electrical is primarily due to the complex kinetics of impedance measurements, study of mi- most bioreactions, separate periods of crowave propagation in cell suspen- growth and product formation, bio- sions, electrostimulation of membrane catalyst degeneration, contaminant risks, processes, and observation of electro- and mechanical difficulties of handling phoretic mobility with dynamic light scat- rheologically complex materials. For tering. Additional work is planned to bioprocesses to be implemented in the measure the modulation of fluorescence future, new on-line measurement tech- from membrane proteins by applied elec- niques must be developed as well as tric fields. nonintrusive measurement methods to avoid the difficulties associated with sam- Contact: Adolfas K. Gaigalas, 109 Fluid pling contamination and long response Mechanics BIdg., 301/975-5941 or

time. R. Dean Astumian, 1 1 1 Fluid Mechanics To help solve some of these prob- BIdg., 301/975-5951. lems, NIST scientists are developing opti- cal techniques for making nonintrusive, rapid, and selective measurements. minimize the cost of high-priced Particulate fuel, industry obtain and Droplet Using fiber optics, they are able to To U.S. needs to maximum energy output from fuel Diagnostic in develop probes which are sterilizable, Spray Flames can provide measurements with good combustion. NIST researchers are tack- im- spatial resolution, and can be multi- ling this problem by attempting to plexed to provide multipoint monitoring prove combustion efficiency. The capability. Researchers are employing researchers are studying the dynamics droplet va- fluorescence techniques to determine of spray flames to investigate characteristics of amino acids, dipep- porization, pyrolysis, combustion, and tides, polypeptides, and esters while particulate formation processes and to Raman and resonance Raman scattering delineate the effect of chemical and physical properties of fuels on the above will be used to provide more species selectivity. Fluorescence techniques are processes. The research results will provide an experimental database, with

28 Chemical Technology

well-defined boundary conditions, for Improved industrial processes and Temperature developing and validating spray combus- sophisticated scientific research re- Sensor Research tion models. quire temperature sensors that cover The experiments are being carried out wider temperature ranges with better ac- in a spray combustion facility, with a curacy and precision than previously re- moveable-vane swirl burner, which simu- quired. For example, the degradation of lates operating conditions found in practi- thermocouples exposed to high tempera- cal combustion systems. A combination tures for extended periods of time repre- of nonintrusive probing techniques is sents a serious impediment to tempera- used to obtain comprehensive data on ture measurements in jet engines, fur- spray combustion characteristics, includ- naces, and so forth. NIST has several ing soot particle and droplet size, num- projects under way to test and improve ber density and volume fraction, gas the performance of currently available composition, and velocity and tempera- sensors, including thermocouples, re- ture fields. sistance thermometers of various types, Currently NIST scientists are focusing and optical fiber thermometers. The their efforts on laser scattering and temperature range covered by these laser Doppler velocimetry measurements projects extends from about 0.2 K to in order to determine the correlation 2100 °C. NIST has excellent temperature between droplet size and velocity dis- calibration facilities, an automated labora- tributions, respectively, in both low- tory equipped to evaluate thermocouples temperature and burning sprays. at high temperatures, several laborato- ries equipped for work on resistance ther- Contact: Hratch G. Semerjian, B312 mometers, and a laboratory to evaluate Physics BIdg., 301/975-2609. optical fiber thermometers. NIST scien- tists are planning a series of new mate- rials, new principles, and new techniques Pressure chieving better understanding and to provide highly precise and accurate Standards control of the pressure measure- temperature measurements. /ArA'iment process will lead to better quality control in the manufacture of new Contact: A. 0. McCoubrey, B128 Physics materials and better design and perform- BIdg., 301/975-4802. ance of transducers for thousands of ap- plications in modern technology. The measurement of pressure from sub- .S. industry increasingly relies on Dynamic atmospheric to 100,000 psi and above real-time monitoring of process Pressure and Temperature hundreds of parameters, particularly tempera- with uncertainties of tens to Research parts per million is essential in modern ture and pressure, to produce efficiently technology. The most fundamental instru- a desired end-product, to warrant safe ment at these high pressures is the dead- operation, and to assure equity in com- weight piston gauge. In the piston gauge merce. This trend is pervasive in the a force generated in a working fluid acts chemical and materials processing in- against the surfaces of a piston and dustries, as well as in energy and raw against the walls of a cylinder that con- materials production and transfer. NIST fines the piston. At high pressures, the currently has a research program and is materials undergo significant distortion, developing a test facility to provide a reli- which leads to limitations and uncertain- able basis for the evaluation and calibra- ties in the area on which fluid is acting. tion of transducer dynamical response The fluid interacts with the side of the pis- functions. The research seeks to develop ton creating upward forces that are diffi- a primary standard for dynamic tempera- cult to interpret. NIST scientists are using ture and pressure based on the fun- properties of the molecular various tools—finite element analysis to damental characterize distortion, better hydrody- constituents of a dynamical system. Infor- namic measurement and modeling of the mation about the molecules is accessed annular region through which the fluid via laser-optical diagnostic techniques, the order of flows, and improved piston gage de- and measurement times of nanoseconds at accuracy levels of signs—to understand these effects. 10 5 percent appear feasible. Through the Contact: Charles D. Ehrlich, A45 Metrology BIdg., 301/975-4834. Chemical Technology Computer Systems

use of these measurement techniques, Computer systems are critical ele- Computer an accurately characterized dynamical ments of today's business and Systems Security source will be developed. This reference scientific environments. However, source and its associated measurement as sensitive and critical information is system will provide industry with a means processed and stored on computer sys- for assuring the accuracy of transducers tems that are often interconnected by used to measure time varying tempera- local area networks, there is an increas- ture and pressure. ing need for methods to protect that infor- mation from unauthorized access or Contact: Gregory J. Rosasco, B118 modification. But selection of information Physics BIdg., 301/975-4813. security measures should be based on a cost analysis of such measures and the resulting reduction in losses. NIST re- Vacuum and any industries depend on accu- searchers are investigating various Leak Standards rate vacuum (pressure) and leak technologies that can be employed to measurements for M research and achieve additional control and security of development and for process and quality information on computer systems. Their control. NIST develops and maintains research involves the identification, analy- pressure and vacuum standards from sis, development, and application of above atmospheric pressure to ultrahigh these technologies. vacuum; leak or flow standards are also Although it is desirable to have secu- 10""^ 10"^ operated from to below std rity mechanisms as an integral part of cc/s. Facilities for this research include computer systems and networks, this is five ultrahigh vacuum systems; two low- not always possible or economical be- range flowmeters; high-accuracy mer- cause such mechanisms are often not cury manometers; pressure and vacuum part of the original system design. NIST control systems; and a variety of researchers also are examining the tech- vacuum, electronic, data acquisition, and nology available to enhance the security data analysis equipment. of existing systems. This research in- These facilities and measurement volves identifying, analyzing, and com- capabilities are used by NIST re- paring security mechanisms used in searchers to develop improved measure- isolation or combination. ment techniques and equipment and to investigate the performance of vacuum Contact: Stuart Katzke, A216 and pressure equipment, specifically me- Technology BIdg., 301/975-2929. chanical pressure gauges, momentum transfer gauges, ionization gauges, standard leaks, and residual gas analy- NIST has initiated a program to Integrated OSI, zers. In addition, NIST plans to use this bring together government organi- ISDN, and measurement capability to investigate zations and contractors interested Security Program properties of materials and physical phe- in interoperability and security in the nomena of fundamental interest. Among Open Systems Interconnection (OSI) the planned projects is the development computer network architecture and the of reference standards for the transition Integrated Services Digital Network regime between low pressures measured (ISDN) communications architecture. by mechanical or electromechanical Researchers in the laboratory-based gauges and pressures measured by program develop prototype systems to vacuum technology devices. The demonstrate the interoperability of pro- development of accurate methods to posed standards for OSI and ISDN using measure and characterize ultrahigh a selected set of security services. These vacuum systems is also under standards are expected to be imple- investigation. mented in commercial applications with a broad market. Contact: Charles R. Tilford, A51 The technical objectives of the pro-

Metrology BIdg., 301/975-4828. gram are: ( 1 ) to develop demonstration prototypes of applications and equip- ment, including hardware and software, that provide one or more levels of secu- rity in an OSI and/or ISDN environment;

30 Computer Systems

general methodology for designing con- formance tests, to use this methodology to generate test suites, and to evaluate the test suites for effectiveness. A proto- type implementation of the IRDS specifi- cations, which may be suitable for such tasks as modeling the structure of a standard and for recording the parts of a standard specifically tested, will be used in this project.

Contact: Alan Goldfine, A266 Technology BIdg., 301/975-3252.

NIST researchers are helping to pro- Public Key tect data communicated through Cryptographic computer networks by developing Protocols protocols for secure key distribution and secure data transmission using public key algorithms. The protocols are in- tended to protect keys from initial genera- tion to final distribution to all authorized parties. In designing the protocols, re- NIST researchers are working with the Defense Advanced Re- searchers are giving special attention to search Projects Agency and a private company to develop a preventing substitution of the keys by un- prototype system using a "smart" token that will make it authorized parties. The protocols will tougher for hackers to gain access to a computer network. transmit keys and data within a large computer network with automated (2) to develop specifications for data for- communications capabilities and will be mats, protocols, interfaces, and support consistent with those used in the Open systems for security in an OSI/ISDN en- Systems Interconnection Reference vironment thiat can be used as a basis for Model. Project results will be published in Federal information Processing Stand- a NIST publication on public key crypto- ards; and (3) to provide a laboratory in graphic protocols. which users, developers, and vendors jointly can define, develop, and test sys- Contact: Stuart Katzke, A216 tems that will provide a range of telecom- Technology BIdg., 301/975-2929. munications, network management, and security services in a distributed informa- tion processing environment. Geographic information systems Geographic (GIS) technology allows users to information Contact: Stuart Katzke, A216 collect, manage, and analyze Systems Technology BIdg., 301/975-2929. large volumes of spatially referenced and associated data. New research directions are emerging from the inter- Database Testing "0 implement the management of disciplinary uses of GIS. NIST re- information resources, NIST re- searchers are exploring future GIS t;searchers are developing test technology through studies into inte- methods and techniques to evaluate im- grating computer graphics standards, plementations of network database lan- database management standards, ex- guage (NDL), structured query language pert systems technology, and optical (SQL), information resource dictionary disk technology to support GIS applica- system (IRDS), Abstract Syntax Notation tions. Their research is focused on 1 (ASN.1), and data descriptive file providing GIS compatibility through (DDF) for conformance to federal, standards and conformance testing national, and international standards. The for future GIS standards such as the researchers are attempting to derive a

31

II Computer Systems

Digital Cartographic Data Standard. Be- using the same grammar, devising a cause tine activities of many governmen- portable compiler for Estelle and the tal and private organizations are land supporting runtime libraries. and/or locationally related, GIS tech- nology will be important in integrating ex- Contact: Kevin Mills, B21 7 Technology isting spatial data for these organizations. BIdg., 301/975-3618.

Contact: Henry Tom, A266 Technology BIdg., 301/975-3271. protect computer systems and Networic Security Tonetworks, NIST is developing a com- Architecture prehensive security architecture Computer "he development of several graphics consistent with the Open Systems Inter- Graphics Testing standards and work on related con- connection (OSI) Reference Model. Tiformance testing and measurement Cryptographic functions are being imple- techniques for graphics software are mented in certain OSI layers to provide under way at NIST. Specifically, NIST re- data secrecy, data integrity, and peer en- searchers are testing implementations of tity authentication. The research will com- the graphical kernel system (GKS), the bine the security standards for individual computer graphics metafile (CGM), GKS OSI layers into a unified security frame- for three dimensions, and the program- work. As part of this project, NIST re- mers hierarchical interactive graphics searchers will define a common interface standard (PHIGS) for conformance to for cryptographic algorithms and develop existing and emerging federal, national, a key management methodology and international standards. Researchers capable of providing keys to the crypto- are attempting to derive a general graphic functions of any layer. methodology for designing conformance tests, to use this methodology to gen- Contact: Stuart Katzke, A216 erate test suites, and to evaluate the test Technology BIdg., 301/975-2929. suites for effectiveness. The computer graphics laboratory, which contains various computer graphics hardware and researchers are working with Network NIST IManagement software systems designed to support industry to establish a set of stand- ards to exchange network standard specifications, is used in these manage- ment information between heterogenous efforts. An existing test suite for GKS is available with FORTRAN interface. Prior- management systems. Their goal is to es- tablish integrated, in- ity is being given to testing methodolo- a standard enabling of gies and test suites for PHIGS, CGM, and teroperable, automated management multivendor systems, routers, the conversion of FORTRAN tests for all computer computer graphics standards to other bridges, switches, multiplexors, mo- languages (C, Pascal, and Ada). dems, and provider services. The re- searchers are defining protocols to

Contact: Mark W. Skall, A266 exchange management information; Technology BIdg., 301/975-3265. identifying, collecting, and specifying the format of managed objects; defining pro- tocols to support management functions Automated 1ST researchers are designing in the areas of fault, configuration, per- Protocol Methods tools for editing, compiling, and in- formance, security, and accounting: and N terpreting computer communica- implementing prototype management tions protocol specifications. The goal of systems reflecting the protocols and

the research is to advance the state of specifications. Other research areas of the art in using such tools to realize auto- interest include network management matically executable implementation of user displays, network management the protocols. As part of this project, applications software development, and NIST researchers are developing a application of expert systems to network syntax-directed editor for Estelle and, management.

Contact: Kevin L. Mills, B217 Technology BIdg., 301/975-3618.

32 Computer Systems

Directory n cooperation with industry, NIST is and demonstrate data/media inter- Services and pursuing development of commercial change tests and to verify conformance Dynamic Routing off-the-slnelf products implementing to established or planned national and in- standard distributed directory services ternational standards for rewritable and and dynamic routing. The distributed write once, read many (WORM) type directory services require research work optical disks. The program will be coordi- in several areas, including access con- nated with voluntary standards com- trol, replication of information, extension mittees and interested federal agencies. of directory schemas, and distributed update. Proposed solutions to these Contact: Dana S. Grubb, A61 directory problems are implemented and Technology BIdg., 301/975-2915. tested in a NIST prototype directory im- plementation conforming to the inter- national directory standard (X.500). NiST researchers are developing Distributed The NIST dynamic routing research is standards and guidelines for im- Systems focused on exchange of routing informa- plementation and use of dis- tion between routing systems in autono- tributed computer systems. Their current mous domains. NIST researchers pro- activities include: participation in the pose and analyze a variety of mecha- development of a voluntary industry nisms to accommodate such exchanges, standard for distributed transaction proc- and they investigate proposed algo- essing, development of a software back- rithms through simulation models. The plane (a standard platform for the aim of this research is development of an development of distributed applications), international standard for exchange of research in distributed information re- routing information between autonomous trieval systems, and formal description domains. of distributed systems. The distributed systems laboratory is maintained to sup-

Contact: Kevin L. Mills, B217 port prototype development of research Technology BIdg., 301/975-3618. activities.

Contact: Wayne H. McCoy, A216 Performance of 1ST researchers in the area of Technology BIdg., 301/975-2984. Modern- computer-systems performance Architecture N are promoting the effective evalua- Computers tion and efficient use of advanced com- Recent advances in automatic Automatic puters by the federal government. Their speech recognition technology Speech Recognition areas of interest include: characterization have resulted in improved abilities of new computer architectures to identify to recognize correctly continuous speech improved ADP technology for applica- with lexicon sizes of at least 1 ,000 words. tions; exploration of economical program- Speech databases are typically large in ming methods that standardize across size (gigabytes) and too costly for any classes of architecture; and design of co- one organization to develop. To improve herent evaluations that economically and the technology, the research community reliably characterize the machines. Two relies heavily on shared use of the dedicated, instrumented multiprocessors databases and standard test methodolo- serve as special project resources. One gies. With support from DARPA and has 16 nodes loosely coupled as a hyper- other agencies, NIST has collected material and, using cube, and the other has 16 processors in speech database CD- a shared-memory configuration. ROM technology, distributed this material to more than 100 research organizations. Contact: Robert Carpenter, B364 Researchers at NIST also have Materials BIdg., 301/975-5677. developed CD-ROM format speech databases that are used for speech rec- ognition research in large vocabulary Optical Disic s industrial standards for optical speech (5,000-word office correspon- disk media evolve, test methods dence), word spotting, speaker identifica- a:Iwill be needed for conformance tion/verification, and goal-directed testing of the media, NIST researchers are setting up a laboratory to develop

33 Electronics and Computer Systems Electrical Engineering

spontaneous speech. Among the re- Researchers in the NIST antenna Antenna search facilities are a VAX 1 1/780, a Sun metrology program are developing Measurements workstation, and speech processing reliable techniques and standards peripherals and software tools. Areas of for measuring key performance parame- interest include characterization of the ters of antennas and components used speech database materials (e.g., with satellites, earth terminals, radars, acoustic-phonetic locators and classifi- and communications systems. Scientists ers), artificial neural nets, performance now are using near-field scanning to measurement, and natural languages. characterize microwave and millimeter- wave antennas. Their current goals are to Contact: David S. Pallett, A216 improve software and error analysis for Technology BIdg., 301/975-2935. the spherical near-field technique and to apply all the near-field techniques to higher frequencies. Other research areas Image mage-recognition research at NIST io- include spacecraft and phased-array Recognition cuses on developing methods for eval- antenna measurements and antenna sys- uation of image quality, compression tems measurements using celestial radio efficiency, and image systems used in sources. optical-character recognition. These methods of evaluation are designed to in- Contact: Alien C. Newell, Div. 723.05, clude highly parallel computers and NIST, Boulder, CO 80303, 303/497-3743. special-purpose chips as well as conven- tional computer architectures. The methods being developed are used for Inadequate knowledge of the electro- Dielectric automated fingerprint recognition, auto- magnetic properties of materials inhib- Properties of mation of data entry from images of its development of new technologies, Materials forms, and measurement of recognition drives up the cost of systems and com- systems on realistic applications. A ponents, and may prevent achievement general model of the recognition process of optimal performance levels. A rela- in parallel computers is being imple- tively new NIST program in materials is mented to provide better methods to ana- aimed at developing primary standards lyze the performance of SIMD (single and accurate techniques for measuring instruction multiple data) computers for the dielectric properties of materials used image compression, image quality eval- in electromagnetic applications. Scien- uation, and recognition accuracy. tists at NIST have developed new preci- sion measurement techniques for com- Contact: Charles L. Wilson, A216 plex permittivity based on improved Technology BIdg., 301/975-2080. theory and new cavity and transmission line sample holders. The researchers cur- rently are performing the necessary error Integrated cooperation with industrial and other analyses and, in the future, plan to cover Services Digital Inusers, NIST advances the develop- a variety of important materials and Networi(s ment of standards for Integrated Serv- temperature ranges over the frequency ices Digital Networks (ISDN) which range of approximately 10 MHz to 100 combine voice, data, text, and image GHz. Reliable nondestructive methods communications over a single network are needed to measure complex permit- connection. Research in this area fo- tivity and the reflectivity of large sheets of cuses on the measurement capabilities material or structures. and testbed facilities required to develop conformance tests and performance Contact: William A. Kissick, Div. 723.02, metrics for emerging ISDN standards. NIST, Boulder, CO 80303, 303/497-3339. Activities include support for standards writing, development of the technical foundation for implementation agree- NIST researchers are engaged in a Electromagnetic ments on protocol options, and testing wide range of projects aimed at Interference and Compatibility ISDN implementations for interoperabiiity. quantifying electromagnetic inter- ference (EMI) and electromagnetic com- Contact: George Kraft, 8364 Materials patibility (EMC). One thrust of the NIST BIdg., 301/975-3389. work is to develop measurement tech- niques and methodologies for measuring

34 :

Electronics and Electrical Engineering

emission of unintentional radiation from interference devices (SQUID's), and electronic devices. Another aspect under laser-based magneto-optical systems. active investigation is the susceptibility of The primary emphasis of the program is electronic equipment to such radiation. on computer-related magnetics, but work The researchers are identifying and defin- is also under way on the basic physics of ing quantities that characterize the sus- magnetic materials, such as spin ceptibility of a device and then develop- glasses, and on the measurement of very ing methods to measure those quantities. low-level magnetic effects. In a related Successful completion of this research program in eddy current nondestructive should result in the development of stand- evaluation (NDE), researchers are ards and measurement techniques for developing methods for mapping the EMI and EMC, which are meaningful, very small ac magnetic fields associated technically practical, and reliable. These with eddy current test probes. techniques could then be incorporated into voluntary standards by both U.S. Contact: Fred R. Fickett, Div. 724.05, and international standard organizations. NIST, Boulder, CO 80303, 303/497-3785.

Contact: Motohisa Kanda, Div. 723.03, NIST, Boulder, CO 80303, 303/497-5320.

Advanced "he rapidly developing and expand- Microwave/ ing microwave technology requires

Millimeter Wave I research in advanced microwave Metrology measurements and standards. The micro- wave industry and the Department of Defense depend on NIST for calibrations of transfer standards to provide the meas- urement traceability required for quality assurance and performance evaluations. NIST researchers have developed new, highly accurate six-port techniques for automated measurements of microwave power, attenuation, impedance, scatter- ing parameters, and noise. They cur- Douglas T. Tamura, an electronics technician, aligns anten- rently are developing greatly improved nas being calibrated on the extrapolation range, which is part power and impedance standards and ex- of the near-field antenna measurement facility. tending measurement services to cover millimeter waves and miniature coaxial advances in superconductiv- Superconductor connectors. Collaborative work is particu- Recent ity have resulted in a critical need Measurements larly desirable in microwave and millime- for measurement technology to ter wave circuit theory as applied to both characterize the different types of super- traditional and advanced circuits and which now range from very systems such as MIMIC devices. Applica- conductors, fine filament alloy conductors used in the tions include development of advanced Super Collider cables automated network analyzers using Superconducting to a variety of high-temperature ceramic six-ports. superconductors. Active research pro- grams at NIST involve measurement tech- Contact: David Russell, Div. 723.01, niques for critical current, critical NIST, Boulder, CO 80303, 303/497-3148. magnetic field, ac losses, magnetic hys- teresis, and electron tunneling. In addi- Magnetics "0 provide a sound basis for meas- tion, specialized experimental work is urement techniques, NIST research- being done to determine the effect of t;ers are developing a basic under- strain on the superconducting properties standing of the magnetic properties of of low-temperature commercial conduc- materials and structures. Specifically, tors and the high-temperature materials. they are studying precision cryogenic vi- brating sample magnetometers, systems based on superconducting quantum

35 I

Electronics and Electrical Engineering

In a recent collaboration with industry, presently available device material. A the resistance of contacts between nor- number of measurement techniques are mal metals and high-temperature super- used in this work, including ellipsometry, conductors was decreased by eight optical absorption, photoluminescence, orders of magnitude, allowing accurate infrared and . Hall measurements of the magnetic-field de- effect and resistivity measurements, pendence of the critical current. A stand- capacitance-voltage profiling, deep-level ard for measuring critical current in transient spectroscopy, photoconductiv-

low-temperature superconductors has ity and photocapacitance, infrared imag- been published through ASTM, and a ing, and x-ray topography absorption Standard Reference Material (SRM) has and rocking curve analysis using syn- been produced for use in calibrating criti- chrotron radiation. cal current measurement apparatus. A

new Reference Material for large currents Contact: Michael I, Bell, 301/975-2044 is under development. or David G. Seller, 301/975-2074, A305 Technology Bldg. Contact: Fred Fickett, Div. 724.05, NIST, Boulder, CO 80303, 303/497-3785. Studies of structural properties of Synchrotron matter have always relied on the Radiation Raman Scattering ome of the world's most advanced use of x-ray techniques. Accord- measurement facilities for the rapid ingly, NIST has constructed several x-ray 'advancement of electrical and elec- beam lines at the National Synchrotron tronic technology are available at NIST. Light Source, Brookhaven National One example is the Raman spectroscopy Laboratory. One of these beams pro- facility, which is used for light-scattering vides collimated, intense energy-tunable studies of liquids, solids, and gases. X rays between 5 and 30 keV, which are Specific research conducted at the facil- 4 to 6 orders of magnitude brighter than ity includes chemical and structural X rays from conventional laboratory analysis of thin films and ion-implanted sources. The facility supports x-ray ab- layers, investigations of impurities and sorption and x-ray fluorescence measure- other defects in semiconductors, studies ments; x-ray scattering, diffraction, and of the structural and electrical properties standing wave capabilities are being of seiniconductor superlattices and quan- added. Researchers are investigating tum wells, and development of new quan- semiconductor structures, including titative spectroscopic methods. ohmic and Schottky metallizations, Equipment is available for studies of AIGaAs/GaAs interfaces, buried im- the pressure and temperature depend- planted layers, and heavily doped layers. ence of Raman spectra in the range 4 to A number of collaborative projects are 600 K and up to approximately 100 kbar under way with industrial and university using a diamond-anvil pressure cell. The research groups and with other govern- laboratory is equipped with variable ment laboratories. wavelength lasers, multiple-grating mono- chromators, and automated digital data Contact: Charles E. Bouldin,

acquisition and processing. 301/975-2046 or Michael I. Bell 301/975-2044, A305 Technology Bldg.

Contact: Michael I. Bell, A305 Technology Bldg., 301/975-2044. NIST conducts research in semicon- Silicon ductor materials, processes, de- Characterization Compound esearch to improve the metrology vices, and integrated circuits to I Semiconductor used to characterize compound provide the necessary basis for under- Studies semiconductors, including alloys standing measurement-related require- and artificially structured materials, is ments in semiconductor technology. As under way at NIST. Scientists are study- part of this program, NIST scientists are ing the electrical, optical, and physical employing electrical, optical, and x-ray properties of materials, such as gallium methods to study the resistivity, dopant arsenide and mercury cadmium telluride, to better understand and characterize

36 7

Electronics and Electrical Engineering

distribution, and concentration of electri- ness of semiconductor processing equip- cally inactive impurities, such as carbon ment, to obtain crucial parameters for and oxygen, in silicon. They are develop- process or circuit simulators, and for ing new or improved techniques by two- product acceptance. NIST work involves and three-dimensional mapping of these test structure design, modeling, data ac- properties, refining the quantitative quisition, and data analysis. Institute en- aspects of existing methods, and devel- gineers are investigating artificial intelli- oping nondestructive methods. Measure- gence techniques for the rapid diagnosis ment techniques include four-probe, of IC manufacturing processes and for spreading resistance, and capacitance- establishing methods to determine the voltage; Fourier transform infrared spec- reliability of thin films used in state-of-the- troscopy; deep-level transient spectros- art microcircuits. copy; x-ray topography; and synchrotron radiation studies. Contact: Loren W. Linholm, B360 Technology BIdg., 301/975-2052.

Contact: Michael I. Bell, A305 Technology BIdg., 301/975-2044 or Jeremiah R. Lovi^ney, B310 Tech- develop physically sound tech- Semiconductor nology BIdg., 301/975-2048. Toniques for characterizing, analyzing, Devices and predicting the operation and performance of semiconductor devices, Semiconductor Theoretical and experimental re- NIST researchers are designing and Processing search on semiconductor materials improving measurement methods to de- and process physics at NIST is fo- termine critical device parameters for cused on improving understanding of in- both VLSI-scale and power devices. Re- tegrated circuit fabrication technology search in device modeling includes two- and increasing capability to characterize dimensional silicon MOSFET and GaAs materials and processes. Utilizing proc- MESFET model development and inves- essing equipment and techniques appro- tigations into the validity of the physical priate to VLSI chip fabrication, NIST assumptions typically employed in silicon scientists are conducting experimental bipolar and GaAs device models. Theo- studies on issues related to state-of-the- retical research is carried out on the art semiconductor processing in a well- transport of ions and electrons in semi- equipped clean-room semiconductor conductors for improved process model- processing laboratory. Researchers are ing, and experimental research on studying ion-implantation damage, oxida- the nature and characterization of elec- tion grow/th and interface trap formation, tronic states in oxides and at oxide/ materials effects caused by ion etching, semiconductor interfaces is under way. thin-film properties, and plasma and ion- NIST scientists are developing methods beam chemistry. Other areas of interest for physical and electrical measurements include submicron (submicrometer) of device and material parameters which photolithography, reactive ion etching, are critical for verifying the accuracy and development of Standard Reference validity of device models. In addition, Materials for use in the semiconductor they are researching the electrical and industry, and chemical and vapor thermal properties of power semiconduc- deposition. tor devices.

Contact: Donald Novotny, 301/975-2699 Contact: Herbert S. Bennett, B310 or James Comas, 301/975-2061, A35 Technology BIdg., 301/975-2053. Technology BIdg.

controlled grow/th capabilities of Molecular Beam The Epitaxy Advanced Integrated circuit test structures and molecular beam epitaxy (MBE) have integrated test methods developed by NIST are resulted in the fabrication of struc- Circuit Test widely used by the semiconductor in- tures that represent a new class of semi- Structure dustry and other government agencies. conductors with properties which do not Metrology These devices can be used to charac- exist in bulk materials. The MBE program terize integrated circuit (IC) manufactur- at NIST includes the growth and charac- ing processes, to evaluate the effective- terization of GaAs and AIGaAs layers, as well as the growth of heterostructures for

37 , —

Electronics and Electrical Engineering

superlattice and quantum confinement stability, and performance under tem- studies. Scientists examine fundamental perature shock and power interruption.

properties of the MBE layers using photo- The aim of these investigations is to luminescence, deep-level-transient spec- identify devices suitable for a rugged troscopy, Hall effect, secondary-ion- 10-V transportable standard capable of mass spectroscopy, and in-situ reflection providing sub-part-per-million (ppm) ac- electron diffraction (RED). Studies are curacy when used as a transport stand- under way to correlate RED oscillation in- ard between laboratories. The effects of tensity measurements with material qual- temperature extremes, physical shock, ity and growth parameters.The MBE and shipping delays on diode output are program is an interactive effort, and of special interest. cooperative research opportunities exist NIST also is producing a stable

in a variety of materials characterization 1 .018-V output derived from a solid-state and device-related areas. reference. Researchers are focusing on the design and manufacture of low-noise, Contact: James Comas, 301/975-2061 stable resistors that are immune to

Wen Tseng, 301/975-5291 , or Joseph temperature shock and power interrup- Pellegrino, 301/975-2123, A357 tion. Facilities are available to test Zener Technology BIdg. diodes with 0.1-ppm resolution and to manufacture both bulk metal foil and wire- wound resistors. Scientists are able to study in detail the dependence of device performance on fabrication parameters as a result of high-accuracy measure- ments referenced to national standards and through collaborative efforts on the fabrication of Zener devices.

Contact: Bruce F. Field, B258 Metrology BIdg., 301/975-4230 or Alan F. Clark, B258 Metrology BIdg., 301/975-2139.

Thermal voltage and current con- Advanced AC verters offer the most accurate and Voltage and broadband method for measuring Current Measurements ac voltage and current for applications in communications, power generation, aero- space, and defense. Thermal transfer standards are calibrated by NIST in terms of reference converters which have themselves been characterized by refer- Wen Tseng, materials research engineer, observes an in-situ ence to the NIST primary standards reflection electron diffraction pattern during the growth of special multijunction thermal converters gallium arsenide. whose performance is known. These pri- mary and working standards in common use throughout the metrology community Solid-state DC irecision voltage standards based employ thermal converters fabricated Voltage on solid-state references are find- Standards from wire elements. Researchers at NIST Ring increasing use in do voltage are studying new methods for the manu- metrology, particularly in the design and facture of film thermal converter struc- support of high-accuracy digital volt- tures made by the use of photolithog- meters and automated test equipment. raphy on silicon substrates. The applica- To improve the quality of these stand- tion of this new technology may result in ards, NIST scientists are carrying out a improved performance and reduction in research program on Zener diodes and the cost of thermal converters. similar devices. They are investigating device properties such as temperature Contact: Joseph R. Kinard, coefficient, short-term noise, long-term 301/975-4250 or Norman B. Belecki, 301/975-4223, B146 Metrology BIdg.

38 Electronics and Electrical Engineering

Waveform s part of a program aimed at high-speed, high-accuracy digital-to- Recorder meeting the metroiogical needs analog conversion; precision, high- Standards A;^involved in improving signal acqui- speed switching; assembly and sition and processing systems, NIST interpretive level programming for hard- researchers are developing theory, ware control; and wideband, fast-settling methods, and standards for waveform amplifiers. metrology of conducted signals. The scientists are conducting the theoretical Contact: Barry A. Bell B162 Metrology and experimental research necessary to BIdg., 301/975-2402. develop standards for determining the performance of waveform recorders oper- strategies are needed to eval- Testing ating nominally below 10 MHz and will New develop techniques for synthesis of preci- uate the performance of complex Electronic Systems sion waveforms and for characterization electronic circuits using the fewest of those waveforms. Theoretical studies possible tests. A new program is under will be conducted on Fourier analysis, de- way at NIST which includes theoretical convolution techniques, and time-domain studies of modeling for nonlinear sys- analysis. Program plans include experi- tems, optimization techniques using mental work in precision pulse genera- matrices, statistical and random proc- tion, static and dynamic testing, and esses, and artificial intelligence. In addi- assembly and interpretive level program- tion, experimental work will address test ming for hardware control. strategies for component and instrument testing; fault diagnosis, function testing,

Contact: Barry A. Bell, B162 Metrology and calibration; and computer analysis BIdg., 301/975-2402. using both desktop computers and supercomputers.

Electro-optical esearchers at NIST are developing Contact: Barry A. Bell, B162 Metrology

I Metrology electro-optical methods to measure BIdg., 301/975-2402. r:.electrical quantities and phenom- ena as part of a program to develop theory, methods, and physical standards Scientists at NIST are developing Gaseous for measuring electrical quantities in measurement methods to charac- advanced high-voltage/high-power sys- terize gaseous dielectrics for high- tems. Theoretical studies are focused on voltage power systems. Theoretical work the use of finite-element code for electric- is expected to address Boltzmann equi- field computation and computer-aided librium statistics, chemical kinetics code, data acquisition and analysis. Experimen- and computer-aided data acquisition will tal research includes high-voltage ac, and analysis. Experimental work do, and impulse measurements; high- focus on high-voltage ac and dc tests, speed camera techniques; optical multi- gas chromatograph and mass spectrom- channel analyzers; and lasers and eter techniques for chemical charac- detectors. terization, and partial discharge mea- surements. Much of MIST'S work in ad-

Contact: William E. Anderson, B344 vanced power metrology is performed in Metrology BIdg., 301/975-2403. newly completed high-voltage and high- current laboratories. These facilities can generate voltage pulses with peak ampli- AC Voltage 1ST is conducting both theoretical tudes up to 600,000 volts and current Standards and experimental research on the pulses with peak amplitudes up to N synthesis of precision ac wave- 100,000 amperes. forms for use in ac voltage standards operating nominally below 10 MHz. The Contact: William E. Anderson, B344 theoretical work includes Walsh functions Metrology BIdg., 301/975-2403. and Fourier analysis, time-domain analy- sis, and precision RMS-to-dc conversion techniques. Experimental work involves

39 Fire Research

Flammability and nstitute researchers are creating ways hand-calculation methods for estimating Toxicity to measure and characterize the com- hazards and production of design Measurement bustibility of furnishings and building curves/tables to be used by architects materials and the extent to which com- and engineers. To ensure widespread bustion products affect living organisms. use, the necessary data must be readily NIST research typically focuses on as- available, and data input and presenta- sessing the appropriate applications of tion must be in terms readily under- the NIST toxicity screening test, evaluat- standable by the average professional. ing the extent to which a limited number Thus, the projects include a strong em- of gases determine the lethality of com- phasis on state-of-the-art computer bustion products, and developing a graphics and computer-aided design methodology for predicting soot and gas techniques. production in full-scale fires from bench- scale methods. In addition. Institute re- Contact: Richard W. Bukowski, B356 searchers are generating a detailed Polymer BIdg., 301/975-6850. model for the burning of upholstered furniture and aiding the use of the cone fire fun- calorimeter in engineering and code Predicting growth requires a Fire Growth and Extinction applications. damental understanding of elemen- tal fire processes. The Institute is Contact: Vytenis Babrauskas, A363 helping to improve this understanding by Polymer BIdg., 301/975-6679. developing predictive methods to de- scribe the processes of fire growth and the elemental processes of fire growth Fire Simulation "his project in fire research is de- and extinction as related to gaseous, liq- signed to provide the expedient uid, and solid fuel combustion and the transfer of scientifically based tech- performance of fire safety systems. Re- nology from NIST to the professional user searchers are exploring fire growth within community and to create a link between a single compartment, the spread of fire NIST computer-based activity and others to adjoining spaces in multicompartment doing similar or complementary work. structures, and the action of fire suppres- Over the past decade, NIST researchers sants. In addition, they are examining the have developed many computer models overall dynamics of the fire scenario and of various aspects of fire. Researchers related elemental processes, such as ig- develop engineering systems for design nition, flame spread, pyrolysis, extinction, application as well as expert systems, and fire-related transport processes. For collect supporting data and programs, these studies, they utilize mathematical and operate a working and training techniques, experimental studies, correla- laboratory dedicated to computer model- tions, and similitude methods to develop ing and other fire-safety computations. predictions.

Contact: Harold E. Nelson, A247 Contact: James G. Quintiere, B250 Polymer BIdg., 301/975-6869. Polymer BIdg., 301/975-6863.

Hazard Analysis "he United States has one of the NIST is conducting research to Polymer worst fire records in the industrial- develop a scientific base for the Combustion ized world. NIST researchers are gasification and combustion of nat- Research helping to reduce the losses and the cost ural and synthetic polymers, particularly of fire protection by providing scientific for the more applied fire research activi- and engineering bases needed by manu- ties. For example, NIST scientists are facturers and the fire protection commu- working on the kinetics and heats of com- nity. One project involves the develop- bustion for wood, theoretical modeling ment of predictive, analytical methods of thermal degradation of polymers, which permit the quantitative assess- smoldering research, and detailed de- ment of hazard and risk from fires. Re- gradation mechanisms of polymers. searchers base these methods on numerical modeling but also include Contact: Takashi Kashiwagi, B258 Polymer BIdg., 301/975-6693.

40 Manufacturing Engineering

Automated Automated manufacturing systems Manufacturing include flexible, small-batch manu- Systems facturing systems, and machine Hardware tools into which intelligent sensors and controls of the production processes, as well as the machining itself, have been embedded. To support such develop- ments by industry, NIST scientists are in- vestigating generic control systems, full-task programming, data organization, sensor organization, system initialization, and the object-data analogy. In the area of process monitoring, researchers are developing techniques for dimensional and surface condition monitoring during the machining process. NIST efforts in real-time error correc- tion of machine tools are centered on ex- tending microprocessor-based tech- niques for real-time correction of the kine- matic (as well as static) machine errors and tool wear for conventional machining as well as diamond turning. The re- searchers are studying transient waves in solids by investigating the origin, prop- agation, measurement, and direct- and inverse-prediction of micromechanical waves in acoustic emission and ultra- sonics. Transducer field studies are fo- cused on the fields produced in solids by electromechanical transducers by model- ing and measuring the fields point-by- point within the solids.

Contact: Donald S. Blomquist, B108 Sound BIdg., 301/975-6600.

Precision Precision engineering forms the foun- Engineering and dation for established devices such Nanotechnoiogy as modern coordinate measuring machines (CMM's) as well as for the emerging "nanotechnoiogy" of nano- structures—the fabrication of devices with physical features of the order of Metrologist Ralph Veale monitors the performance of a robot 1 nanometer (one-billionth of a meter or at the inspection workstation in the NIST Automated Manufac- 40-billionths of an inch) in size. Nano- turing Research Facility. technoiogy holds the promise of many new industrial products including, for ex- researchers are developing the capabili- ample, mechanical pumps small enough ties to precisely observe, locate, fabri- to be implanted into arteries, surgically al- cate, and measure the nanometer-sized tered DNA molecules, and electronic de- features of such devices. vices hundreds of times smaller than those available today. Using an array of Contact: Dennis A. Swyt, A109 state-of-the-art coordinate measuring ma- Metrology BIdg., 301/975-3463. chines and advanced electron-probe in- struments, NIST precision engineering

41 Manufacturing Engineering « Materials Reliability

Automated 'or industries creating and using NIST researchers are exploring Composite IManufacturing ' computer-controlled manufacturing ways to achieve the great potential iVIechanics Systems Software Rsystems, software systems are the of composite materials for struc- critical element. NIST provides research tural applications. Using acoustical and for software in automated manufacturing optical techniques, the researchers are systems in several areas. In automated investigating the mechanisms of fracture process planning, researchers are inves- in laminated plates. In support of the non- tigating data structures for automated destructive evaluation program, re- process planning, distributed system searchers are using finite-element architectures, machinable-feature identifi- and finite-difference methods to simulate cation, and expert systems/machine- and model acoustic-wave propagation. learning for manufacturing systems. Another project involves refining theoreti- Researchers also are studying architec- cal models and computer programs to tures, algorithms, and techniques for real- predict near- and far-field singularities of time adaptive control, scheduling, and the various damage types in laminated optimization of cell- and workstation-level structures. NIST scientists also are moni- operations for FMS cell and work- toring damage initiation in situ by embed- station control systems. In addition, for ding optical fiber sensors in composite manufacturing systems architectures, structures. Ail projects emphasize evalua- they are devising functional models of tion of the potential structural perform- manufacturing organizations to standard ance of new advanced composite system architectures. materials.

Contact: Howard M. Bloom, A127 Contact: Ronald D. Kriz, Div. 430, NIST, Metrology BIdg., 301/975-3508. Boulder, CO 80303, 303/497-3547.

Robot Systems 1ST conducts research in NIST scientists are developing Nondestructive intelligent-machine systems for acoustic and electromagnetic sen- Evaluation (NDE) N manufacturing, construction, sors for material characterization, space satellite servicing, and intelligent including electromagnetic-acoustic trans- vehicle applications. NIST researchers ducers (EMAT's), arrays of piezoelectric are investigating standard architectures polymers, and eddy current and capaci- for real-time intelligent control, which in- tive probes. volves hierarchical task decomposition, EMAT's are used for noncontacting

world modeling, and sensory processing. applications, where it is not possible to The research includes real-time plan- have an intervening material couple ning; the representation of space, time, sound from transducer to specimen. objects, and events; and the analysis of For example, an EMAT embedded in a data from a variety of sensors, such as rail is used to inspect railroad wheels for TV cameras, sonar, and tactile arrays. cracks in a roll-by mode. Researchers Researchers are also studying program- are investigating the possible use of ming methods and operator interfaces EMAT's at the input to an automated for intelligent vehicles and telerobots. press shop, where automobile body Methods are being developed for parts are formed. Formability measure- measuring the performance of intelligent ments could be made on moving sheet, machine systems, including software per- and materials with improper formability formance. Research in advanced struc- would be rejected from the production tures for robot systems includes robot line. cranes and inflatable structures. Acoustic arrays are useful in medical imaging, where their unique advantages Contact: James S. Albus, B124 allow suppression of artifacts to give bet- Metrology BIdg., 301/975-3418. ter image quality. Research is being con- ducted by NIST to use these techniques to characterize composites. Various types of arrays are being constructed and interfaced with signal processing devices. Materials Reliability

NIST scientists Inave developed eddy aimed at two complementary quantities: current probes and techniques for detect- fracture-driving force and fracture re- ing and sizing small defects that could sistance. Fracture-driving force is prove to be critical in aircraft and other analogous to stress but is much more structures. Capacitive probes are being complicated. By measuring stresses and investigated as a noncontacting means strains in the material surrounding a to monitor sintering of ceramics, with crack, fracture-driving force at the crack possible use as a process control in the tip can be calculated mathematically. A production of superconductors. Another previous NIST technique used 36 strain application under study is noninvasive gauges but now a new grid method has cure monitoring of composites. been developed in which a fine grid is bonded to the specimen. A photographic Contact: Alfred V. Clark, Div. 430, NIST, image of the deformed grid is read using Boulder, CO 80303, 303/497-3159. an automated laser diffractometry sys- tem. All in-plane strain components are measured with a precision of 50 micro- Thermo- etals producers and manufac- strain and a spatial resolution of 1 mm. mechanical turers rely heavily pilot-scale on Fracture resistance is studied by ex- Processing M or production facilities for the amining fracture surfaces with a scan- of alloys or development new new manu- ning electron microscope to find the facturing schedules. This is not only ex- microscopic origins of brittle fracture or pensive but can also yield unreliable the nuclei of the voids that join to form results. These processing problems can ductile fracture surfaces. A quantitative be alleviated by using a more economi- metallography facility makes it possible cal, versatile, and reproducible labora- to measure accurately the density and tory facility. Controlled thermomechanical characteristics of inclusions fundamental processing (TMP) offers the opportunity to the fracture process. to produce superior steels at lower cost

due to the elimination of post-heat treat- Contact: David T. Read, Div. 430, NIST, ment—an energy-intensive process. Boulder, CO 80303, 303/497-3853. NIST scientists and engineers have designed and built a computerized, laboratory-scale, hot-deformation appara- tus that can simulate manufacturing processes, such as forging and plate roll- ing, and measure important properties in- curred during processing. The apparatus can be used to study static and dynamic recrystallization, high-temperature defor- mation resistance in terms of true stress- strain curve at high strain rates, and phase transformation characteristics. The apparatus is used to characterize directly cooled forging steel during simu- lated forging operations in an attempt to develop optimized steels and forging procedures. This computer-generated diagram shows a stress wave moving along the fiber orientation in a unidirectional graphite- Contact: Yi-Wen Cheng, Div. 430, NIST, epoxy composite. Each of the humps represents a period of Boulder, CO 80303, 303/497-5545. the wave and the ripples coming off these periods.

Fracture esearch in fracture mechanics Mechanics 1—^ helps to determine the perform-

I I ance and safety requirements of structural materials. NIST's most ad- vanced measurement techniques are

43 Materials Reliability

Cryogenic omprehensive low-temperature is limiting , Corrosion a major factor in Corrosion Data Materials facilities are available to conduct the service life and cost of many Program ^ r' both characterization testing and products, plants, equipment. and fundamental studies on the mechanical The costs of metallic corrosion to the U.S. and physical properties of high-strength economy are estimated to be $200 billion structural alloys, high-conductivity metals in 1988 dollars, $30 billion of which could and superconductors, metal and be saved by using existing technology. polymer-based composites, and polymer The National Association of Corrosion En- foams. Properties studied include tensile gineers (NACE) and NIST have joined to- strength, compression, fatigue, creep, gether in a collaborative NACE/NIST fracture toughness, stress relaxation, Corrosion Data Program to reduce the elasticity (ultrasonic), and thermal expan- enormous costs of corrosion. The focus 10"'' sion. Strain sensitivities of at liquid of this program is to establish an eval- helium temperature (4 K) are now pos- uated corrosion database that can be sible, permitting precise low-temperature accessed easily by computer using intel- microstrain measurements. Researchers ligent interfaces to obtain data in a num- are assembling equipment to permit load ber of graphical, tabular, or textual capacities of 5 MN for testing at 4.2 K. formats. The researchers are developing evaluation methodologies and a proto- Contact: Richard P. Reed, Div. 430, type database for areas covering ther- NIST, Boulder, CO 80303, 303/497-3870. modynamic and kinetic corrosion data. NIST scientists are emphasizing interac- tions with industry both to help set priori- Joining "he integrity of Research welded joints is a pri- ties for data projects and as a source of mary concern in the design and fab- corrosion data for the database. rication of engineering structures.

Researchers at NIST are investigating Contact: David B. Anderson, A109 ways to improve the fracture resistance Materials BIdg., 301/975-6026. of weldments and are assessing weld quality by nondestructive evaluation (NDE) techniques. Specific goals of the Corrosion has been recognized as a Corrosion research are to improve fracture tough- major cause of degradation of all Measurements

ness in the heat-affected zone of steel kinds of metallic structures, with fi- weldments and in the weld metal of mate- nancial costs well in the billions-of-dollar rials for low-temperature service and to range. Since corrosive reactions are of improve the soundness of welds through electrochemical nature, electrochemical increased understanding of the metal measurements can give important infor- transfer process in arc welding. In addi- mation about the chemical processes tion, the researchers are applying fine- causing the corrosion and the rate of cor- resolution NDE techniques to evaluate rosion as well as its forms, whether uni- solder joints in printed circuit boards for form or localized. Researchers at NIST the electronics industry. NIST scientists are determining current and potential have developed techniques to reduce and their variations with time, measuring porosity in aluminum weldments, to re- the frequency spectrum of the ac im- duce spatter in gas metal arc welding of pedance of corroding electrodes, and steels, and to predict accurately the Fer- detecting and analyzing random fluctua- rite Number in stainless steel welds. tions of electrical parameters. The NIST welding and NDE laborato- Electrochemical methods for measur- ries house equipment for shielded metal ing corrosion rates offer the possibility of arc, gas metal arc, and gas tungsten arc tracking the process in a nondestructive welding; radiographic and penetrant way and assessing the effect of various techniques for nondestructive evaluation environmental variables. Other electro- of weldments; and a precision power chemical techniques can shed light on supply, high-speed photography, and the kinetics of the corrosion reactions laser shadow techniques for metal- and on the critical factors which may con- transfer studies. tribute either to catastrophic failures or corrosion prevention. Contact: Thomas A. Siewert, Div. 430, NIST, Boulder, CO 80303, 303/497-3523. Contact: Ugo Bertocci, B242 Materials BIdg., 301/975-6017.

44 Metallurgy

alloys produced by each of the three major rapid solidification techniques: at- omization techniques in which fine liquid droplets are formed and rapidly frozen to produce alloy powder; ribbon techniques in which a very thin liquid stream or rib- bon is rapidly solidified; and rapid surface-melting and refreezing tech- niques in which a directed energy source, such as an electron beam, is scanned across a surface. The emphasis in the NIST work is on measurement and predictive modeling of the rapid solidifica- tion processes. Researchers are study- ing crystalline and metallic glass, as well as the new quasicrystal alloys dis- covered at NIST. Efforts are under way to apply advanced sensors to an inert gas atomization system to allow feedback and control of this process. Because Arnold Kahn (left), a NIST physicist, and Michael Mester, a processing conditions influence alloy research associate from the Aluminum Association, have homogeneity, microstructure, extended developed a process control sensor, designed to be used in solid solubility, and the production of the production of extruded aluminum products. new alloy phases, control of these fea- tures is critical for producing special Process Control pecial facilities at NIST enable re- properties in these new materials. Sensors searchers to develop advanced S;' measurement methods and stand- Contact: John R. Manning, A149 ards in support of emerging sensors and Materials Bldg., 301/975-6157. their application to process modeling and control for intelligent processing of corrosion of metals in natural and Field Corrosion materials. Measurement methods avail- The is very of Metals able include ultrasound, eddy currents, manmade environments costly to industry and government. and acoustic emission. In particular, non- For several years, NIST researchers have contact ultrasonic facilities have been de- involved in developing methods for signed featuring high-intensity pulsed been measuring the corrosion of metals in field lasers and electromagnetic acoustic conditions, such as steel piling in soil transducers. Coupled with state-of-the- and seawater, electric utility lines in soil, art materials-processing equipment and and most recently, steel in concrete. To expertise, these facilities offer a unique measure the corrosion of reinforcing steel opportunity to ascertain feasibility and in concrete bridge decks, NIST scientists develop prototype specifications for a have developed a small, portable com- wide spectrum of sensor needs, includ- puter system. With this system, scientists ing the measurement of internal tempera- are able to use electrochemical tech- ture, phase transformations, surface- niques normally limited to the laboratory modified layers, porosity, grain size, and to measure the corrosion. This new ap- inclusion/segregate distributions. proach, which allows faster, more accu- rate corrosion measurements, can be Contact: H. Thomas Yolken, A165 used to evaluate the effectiveness of pro- Materials BIdg., 301/975-6140. tection systems in place. The system has been applied to several bridges in Mary- Rapid •he rapid solidification of alloys can land and Washington state. Solidification produce new types of materials, un- t;obtainable by conventional means. Contact: Edward Escalante, B250 Because of their special properties, Materials Bldg., 301/975-6014. rapidly solidified alloys are being investi- gated widely and are beginning to be in- troduced into commercial devices. Equipment is available at NIST to study

45 Neutron Scattering

Metallurgy and Diffraction

steel Slag "hermochemical databases and models are needed by the U.S. T.steel industry for the design of new or innproved steel-making processes. To design such processes, NIST researchers are involved in three pro- grams: measuring refractory and slag thermochemical equilibria, evaluating the scattered literature data, and developing computer models that relate experimen- tal data to industrial conditions. Unique experimental facilities are available at NIST for measuring key phase equilibria and kinetics.

Contact: John W. Hastie, B108 Materials BIdg., 301/975-5754.

The NIST Cold Neutron Research Facility, designed as a ,orrosive reactions the en- Environmentally between national user facility, will house a number of special instru- Induced Fracture materials vironment and advanced ments with application to a wide range of materials problems. of Advanced P' can dramatically alter the fracture Materials resistance of the material. To assist in ore than 50 billion chemical ana- Activation the development of advanced materials, lyses are performed annually in Analysis NIST scientists are studying the mecha- the United States. NIST helps to nisms by which environments can induce M ensure the accuracy of these analyses crack propagation at stresses well below by developing new analytical procedures those which cause normal fracture. Re- and improving the reliability and ac- searchers are developing experimental curacy of present methods. One tech- techniques to evaluate and quantify the nique under study is activation analysis, susceptibility of different types of ad- which is a highly sensitive, nondestruc- vanced materials. Experiments are being tive analytical technique not available in conducted to investigate the mecha- most industrial laboratories. Researchers nisms of hydrogen absorption, dissolu- are investigating methods of nuclear tion, and environmentally induced analysis utilizing the NIST 20-MW re- cleavage on different types of materials, search reactor. Research is performed in specifically low-density, high-strength all areas of the technique, including the Al-Li alloys; intermetallic compounds; capabilities of cold-neutron activation, and composites as well as simple the use of sample self-consistent (moni- model systems. tor) activation, determination of new math- ematical procedures for the resolution of Contact: Richard E. Picker, B252 gamma spectra, the development of Materials BIdg., 301/975-6023. prompt-gamma activation techniques, and the use of charged-particle activa- tion techniques. The NIST Cold Neutron Magnetic s part of the NIST program in mag- Facility will include a new Materials netic materials, researchers are Research depth-profiling instrument and a A'^studying the magnetic properties neutron prompt-gamma activation station. To- of alloys and their relationship to metallur- gether, these are expected to form the gical structure. Composition-modulated best capability in the world for chemical alloys, granular metals, metallic glasses, analysis with neutron beams. and icosahedral crystals are among the materials being investigated. The mag- Contact: Robert R. Greenberg, 8108 netic properties are characterized by Reactor Building, 301/975-6285. ac magnetic susceptibility measure- ments, magneto-optic Kerr effect, and Mdssbauer effect observations. Neutron radiography has been a Neutron well-established tool for nonde- Nondestructive Contact: Lawrence H. Bennett, B154 (NDE) structive evaluation for some time. Evaluation Materials BIdg., 301/975-5966. More recent neutron applications in NDE

46 i Neutron Scattering and Diffraction

include neutron diffraction for texture and catalysts and on the local trapping and residual stress determination. All three clustering of hydrogen in metals and specialties are available for co- semiconductors, which cause embrittle- operative R&D utilization and develop- ment, corrosion, or changes in electronic ment at the NIST research reactor. In properties. NIST scientists are working general these techniques parallel their with researchers from several industrial x-ray counterparts; however, in certain laboratories to study zeolites and other cases (e.g., where hydrogenous com- catalytic materials. Equipment available ponents are critical or where subsurface includes three-axis neutron crystal spec- texture or residual stress distributions are trometers and time-of-flight spectrome- sought) x rays do not provide the needed ters for inelastic scattering, which, along sensitivity or penetration. with neutron diffractometers, measure NIST scientists are continuing their col- structural and dynamic processes in the 10"^"^ 10"^"* laboration with scientists from the Smith- time regime from to s. Two sonian Institution to examine art works very-high-resolution inelastic scattering using neutron radiography. They also spectrometers will be available at the are working to apply the technique to NIST Cold Neutron Research Facility. industry-related problems and to extend Controlled temperature (0.3 -1300 K) and the existing capabilities to, for example, pressure devices are available for chang- backscatter radiography. Scientists from ing sample environments. NIST and the Department of Defense (DOD) are continuing to develop and Contact: J. Michael Rowe, apply neutron diffraction techniques to 301/975-6210 or John J. Rush, texture and residual stress characteri- 301/975-6231, A 106 Reactor Building. zation. Texture studies have centered on copper, tantalum, and uranium-alloy com- microstructure information ponents for a variety of DOD items; re- Detailed Small-Angle cent work has included ceramic super- is often a key to the prediction or Neutron Scattering conductors. Neutron residual stress stud- understanding of the performance ies have involved components made of or failure of structural materials and the above metals as well as ceramics, materials-processing conditions. Re- fiber-reinforced ceramic composites, and searchers at NIST use small-angle steel. neutron scattering (SANS) to charac- terize submicron structural and magnetic properties of materials in the size regime Contact: Henry J. Prask, 301/975-6226 1 the or Chang S. Choi, 301/975-6225, A106 from to 100 nm. Among structural Reactor Building. features in this size regime that produce SANS diffraction patterns are: small pre- cipitates or cavities in metal alloys, micro- Neutron esearchers at NIST are studying pores or cracks in ceramics, colloidal

I Spectroscopy the vibrational dynamics and diffu- suspensions and microemulsions, and

Ri, sion of hydrogen in metals and polymers and biological macro- molecular species in heterogeneous cata- molecules. These patterns can be ana- lysts, clays, and other layered materials. lyzed to give information on the size and Inelastic and quasielastic neutron scatter- shape of the scattering centers as well ing and neutron diffraction are among the as their size distribution, surface area, techniques used by the scientists to re- and number density. veal the bonding states and atomic scale A number of scientists from the chemi- interactions and diffusion paths in such cal, communications, advanced mate- materials. rials, and aerospace industries are Studies also are being conducted on already engaged in SANS research at the atomic and crystal dynamics in bulk NIST. Their measurements are carried materials and alloys. Recent progress out with long-wavelength neutrons on the has allowed in-situ spectroscopic studies 8-m-long NIST SANS spectrometer which of hydrogen and molecular species utilizes a 65-by-65-cm position-sensitive down to 0.1 of an atomic percent. These detector to record data over the entire measurements can provide direct infor- small-angle region simultaneously. The mation, for example, on the molecular processes affecting reaction and selec- tive release of chemicals in industrial

47 —

Nondestructive

Neutron Scattering and Diffraction Evaluation

addition of two 30-m SANS spectrome- Nondestructive evaluation methods Nondestructive ters in the NIST Cold Neutron Research are used throughout the manufac- Evaluation for Facility will enhance significantly resolu- turing process to monitor impor- Ceramics and Composites tion and sample throughput. Computer- tant properties and characteristics of automated apparatus is available for materials. To assist in this process, NIST maintaining samples at temperatures scientists have developed a new probe from 4 to 700 K and in magnetic fields for examining ceramics, composites, and up to 20 kilogauss. To extract structural other nonconductive materials. The information from the data, the re- probe is basically an array of capacitive searchers analyze SANS patterns with elements, each of which is essentially a an interactive color graphics system and parallel plate capacitor unfolded so the related programs. two electrodes lie in the same plane. A voltage is impressed across the elec- Contact: Charles J. Glinka, trodes, and the resultant current flow be- 301/975-6242 or James A. Gotaas, tween them is measured. The array is 301/975-6243, A106 Reactor Building. placed against the surface of the object

to be examined, or displaced from it by a

small "lift off" or, in the case of composite Neutron irecise information on the crystal materials, the array may be embedded in Diffraction structure (arrangement of atoms the composite lay up. Piand molecules) in solids is often a Early work with the capacitive array key to understanding or improving the probe shows that it has good sensitivity properties of modern materials and to both surface and subsurface discon- creating new materials with specific tinuities, such as cracks and voids of properties. Many important materials submillimeter and even micrometer di- ceramics, solidified catalysts, and rapidly mensions. Its capabilities in any given alloys—often can be obtained only in application depend upon the dielectric powdered form. constant of the material, as well as geo- NIST researchers are developing im- metric parameters, and theoretical efforts proved methods for accurate structure re- are under way to guide further develop- finement. A major effort is under way to ment work. Recent studies indicate that relate atomic arrangement and super- the probe has important potential as a conducting properties in high Tc ceramic sensor for monitoring the sintering of ce- superconductors. In addition, a number ramics and the curing of polymers and of industrial scientists are collaborating polymer-based composites because with NIST staff in neutron diffraction stud- these processes are accompanied by ies of inorganic catalysts, new kinds of changes in the dielectric constants. ionic conductors for small batteries and fuel cells, improved ceramics for micro- Contact: H. Thomas Yolken, 8344 circuit substrates and engine com- Materials BIdg., 301/975-5727. ponents, and high-performance lightweight alloys for advanced aircraft. State-of-the-art capabilities are avail- able at NIST for measuring and analyzing the crystal and magnetic structure of polycrystalline materials by neutron dif- fraction. The facilities available for diffrac- tion experiments for both powders and single crystals include a four-circle dif- fractometer and a multidetector and a high-resolution powder diffractometer, as well as instruments that allow measure- ments in an energy-dispersive mode.

Contact: Edward Prince, 301/975-6230 or Antonio Santoro, 301/975-6232, A106 Reactor Building.

48 Polymers

Composites 'iber-reinforced composites offer, elastomers, molecular composites, and Processing along with otiner advantages, ver- fibers to develop improved models of me- Fisatility in processing connbined with chanical behavior, characterize structure high strength and stiffness at low weight. from the atomic- to fine-texture level, For the current growth in the production and elucidate relationships between me- of these materials to continue, however, chanical performance and structure. more rapid and reliable processing is NIST scientists use a variety of tech- needed. To help meet this need, NIST re- niques to characterize the structure of searchers are developing new measure- polymers in the solid state. Nuclear mag- ment tools to study the reactions asso- netic resonance spectroscopy is used to ciated with processing to understand the determine molecular orientation, molecu- relationships among processing parame- lar dynamics, and microstructure on the ters, the microstructure of the fabricated 1-to 10-nm scale. Microstructural infor- materials, and their performance proper- mation is deduced from C-13 lineshapes ties. Such scientific understanding will obtained with magic angle spinning or by facilitate both advances in processing proton "spin diffusion" experiments in methods and implementation of on-line which domain-size information is inferred control and automation. The develop- from the rates at which proton magnetiza- ment of this understanding requires re- tion diffuses in the presence of magneti- searchers to monitor the materials during zation gradients. Fourier transform the curing process to observe simul- infrared spectroscopy helps to determine taneously chemistry, morphology molecular architecture, orientation, and development, flow, molecular network molecular processes, such as measure- formation, build-up of residual stresses, ment of the amount of chain scission as- interfacial effects, and wetting and sociated with mechanical deformation of spreading. polymers. Microstructural features, includ- The NiST program currently has 10 ing spherulytic morphologies, lamellar different spectroscopic, dielectric, ther- texture, fiber structures, and crystal- mal, and mechanical techniques avail- lization habits, are elucidated through op- able for cure monitoring, and others are tical and electron microscopic studies of under development. This diversity of polymers. NIST scientists are examining tools provides a unique capability for the relationships between mechanical evaluating and calibrating new measure- performance of polymers and fine struc- ment methods, for developing process tures by investigating the morphological modeling, and for analyzing model ther- changes that polymers undergo when moset systems. For example, through they are deformed. Wide- and small- cooperative projects with NIST, several angle x-ray diffraction techniques, which industries have selected and developed include the use of position-sensitive monitoring methods for their particular detectors, are also employed in these problems. investigations.

Contact: Donald L. Hunston, A209 Contact: Bruno M. Fanconi, A305 Polymer BIdg., 301/975-6837. Polymer BIdg., 301/975-6769.

Polymer Structure nowledge of the relationships be- odern dental and medical mate- Dental and tween mechanical properties of rials utilize numerous substances Medical Materials Ki^polymers and polymer structure is M in an array of combinations. NIST important to the design and processing has a comprehensive program aimed at of materials for optimal performance. Re- increasing basic understanding of the searchers at NIST are studying semicrys- causes for failure or poor performance of talline polymers, polymer glasses. these materials, proposing and testing new material systems, and transferring the resultant science and technology to industry. The program has the active par- ticipation of researchers from the Ameri- can Dental Association, the National Institutes of Dental Research, dental industries, and universities.

49 Polymers

Researchers are working in a number and composite-adhesive-tooth materials. of areas. For example, in a tribology Weibull statistical analysis is employed to study, scientists are examining wear and identify the weakest links, and finite- degradation of materials in various en- element analysis is applied to define vironments, and in a bioadhesion project, stress states within systems. Scientists they are making new monomers for adhe- working in the area of precision metal sion to tissues. In addition, improved casting processes have designed a resins are being synthesized to produce unique casting monitor that can be used polymers that have improved properties, for rapidly solidified alloys. such as wear resistance, higher strength, resistance to oral fluids, or x-ray opacity. Contact: John A. Tesk, A143 Polymer Researchers have developed an in- BIdg., 301/975-6801, mouth shield for cancer patients under- going radiation therapy to protect their healthy tissues from secondary radiation NIST is conducting a number of Electrical emitted from metallic restorations. With studies on the electrical properties Properties regard to infection control, a unique of polymers. The research focuses method that uses gas plasmas to sterilize on dielectric measurements, fundamen- dental instruments has been shown to be tals and applications of piezoelectric and highly effective. pyroelectric polymers, measurement of In an effort to improve the strength of space charge distribution within polymer dental systems, different combinations of films, and electro-optic properties of materials are being designed and tested, polymers. including ceramic-metal, resin matrix Scientists at the Institute have composites, metal-cement, cement-tooth. developed instrumentation and data analysis techniques to measure the dielectric constant and loss of polymer films over a frequency range of 10'"^ to 10^ Hz in less than 30 minutes. These

developments make it possible to follow changes in the dielectric spectrum as a function of time, processing conditions, or other parameters. The toughness, flexibility, low dielec- tric constant, and an acoustic im- pedance close to water make piezo- electric polymers ideal for many trans- ducer applications. NIST researchers have considerable experience with the fundamental properties of polymers such as polyvinylidene fluoride and its copoly- mers and can work with industry to develop transducers for novel applica- tions or to assist in measuring the proper- ties of new piezoelectric polymers or composites. The scientists also have designed in- strumentation and data analysis tech- niques to measure the charge or polari- thickness of John A. Tesk sterilizes clinical instruments with a new zation distribution across the microwave-generated gas plasma method. The new tech- polymer film by analyzing the transient charge response following a pulse of nique may reduce the damage to expensive instruments caused by repeated exposure to time-consuming, traditional energy on one surface of the film. This the sterilization methods. technique has been used to detect presence of nonuniform electric fields in the poling of piezoelectric polymers and are being used currently to investigate the role of space charge in the dielectric breakdown of polymer insulation.

50 Polymers

Organic molecules with highly Blending polymers has become an Polymer Blends delocalized n-conjugated electrons offer effective method for producing great potential in the field of nonlinear op- high-performance engineering poly- tics (NLO) due to their relatively large mers. The fundamental data required to second-order susceptibilities and their design a manufacturing process include picosecond response times. Polymers the equilibrium phase diagram, the with highly delocalized electrons (such energetic interaction parameter (compati- as polydiacetylenes) are being de- bility) between the blend components, dif- signed, synthesized, and characterized fusion coefficients, and the interfaciai for their NLO properties. Other polymers tension. At NIST small-angle neutron scat- are being investigated as a medium in tering has been used to measure the in- which NLO-active molecules can be dis- teraction parameter and phase diagram solved, processed, oriented, and main- of polymer blends. NIST scientists have tained in an oriented configuration for developed forced Rayleigh scattering use in NLO devices. and temperature-jump light-scattering techniques to measure polymer-polymer Contact: George T. Davis, B320 Polymer diffusion and other parameters which BIdg., 301/975-6725. control phase separation kinetics and morphology. Currently, Institute researchers are Molecular "hermoset resins are used exten- testing various kinetic theories of phase Networks sively in practical applications, espe- separation and late-stage coarsening Ticially polymer-based composites. and are studying the control of mor- However, knowledge of the basic struc- phology and mechanical properties of tural entity of these resins, i.e., their microphase-separated polymer blends. molecular network structure, is very As part of this program, they are working limited. NIST researchers have with industry to study the homogenization developed a neutron-scattering tech- and phase coarsening of rubber blends. nique that can be used to determine quantitatively characteristics of the net- Contact: Charles C. Han, B210 Polymer work, including the average distance be- BIdg., 301/975-6771. tween crosslinks, the rigidity of the network, the molecular weight distribution between crosslinks, and the topological Small-angle x-ray scattering (SAXS) Small-Angle heterogeneity of the network structure. is used to characterize structural X-Ray Scattering Current NIST research focuses on elements of polymers, ceramics, developing correlations among chemical and metals in the 1-nm to 100-nm size compositions, processing conditions, range. This technique has been used and resulting network structure for epoxy- successfully at NIST to study phase sepa- type polymers. To establish processing- ration, crystallite morphology, molecular structure-property relationships, these dimensions, void formation, pore charac- materials are then evaluated to determine teristics, and other elements. A state-of- performance properties, such as fracture the-art 10-meter SAXS facility has been behavior. The neutron-scattering tech- constructed at NIST for such studies and nique is also being used to study how is available for cooperative research. the molecular network deforms when the This SAXS facility uses a 12-kW rotating material is placed under load. These anode source, pinhole collimation, and a studies help industry by providing guide- two-dimensional position-sensitive detec- lines for designing and processing poly- tor to provide high resolution and simul- mers for optimal performance. taneous recording of all scattering data over the entire small-angle region. In ad- Contact: Wen-li Wu, A209 Polymer BIdg., dition, a computer-assisted interactive 301/975-6839. data reduction and analysis program is available with color graphics display for the two-dimensional image. Structural and dimensional information can be ex- tracted using available model analysis and curve-fitting procedures.

51 Polymers Radiation Research

Luminescence techniques have Luminescence broad application in virtually every Spectral scientific field, including radiation Radiometry measurement, remote sensing, quantita- tion of biomolecules by intrinsic lumines- cence and immunoassay techniques, and characterization of laser, semi- conductor, and superconductor mate- rials. The accurate spectral radiometric quantitation of excitation and emission radiations is an exacting task requiring painstaking radiometric measurements and knowledge of the fundamental chemical and physical processes repre- sented by these radiative transitions. Standard lamps, both radiance and irradiance, and silicon detector radi- The small-angle x-ray scattering facility is used by NIST poly- ometry provide the accuracy base for mer physicist John Barnes to obtain information on the micro- the spectral and quantum efficiency structures of polymer blends to develop polymer alloy phase measurements. Luminescent phenomena diagrams. under investigation at NIST are photo-, chemi-, thermo-, electro-, and bio- Additional equipment is available for characterizing the crystallite orientation luminescences. These designations distribution of semicrystalline polymers usually indicate the source of the excita- using pole figure techniques. Workers tion energy. The NIST researchers are conducting radiometric from Mobil Chemical Company's re- luminescence search and development laboratory have research in the near-ultraviolet, visible, and near-infrared spectral regions and used the SAXS and pole figure facilities are developing accurate standards to characterize their processes for pro- for these ducing tear-resistant polyethylene films. and measurement procedures regions. Facilities available for this research are various laser Contact: Charles C. Han, B210 Polymer and lamp BIdg., 301/975-6771. sources, the NIST reference spectro- fluorimeter, and a low-light-level spec- troradiometer now under construction. Fluorescence 1ST researchers are evaluating Monitoring iuorescence spectroscopy, which Contact: Ambler Thompson, B306 N is used to characterize the struc- Metrology BIdg., 301/975-2333. tural and dynamic properties of polymer molecules. Fluorescence quenching is researchers are investigating Thermal employed, for example, to monitor the NIST the use of thermal imaging cam- Radiometry uniformity of mixing in polymer blends eras as a temperature-measuring and in particle-filled polymer melts. In ad- tool. These devices may prove to be very dition, excimer fluorescence is utilized to useful in determining the quality of prod- monitor the cure of thermoset resins, ucts and in investigating changes in while fluorescence anisotropy is used to different processes. Research projects monitor the non-Newtonian flow of poly- involve the development of mer solutions and melts. At NIST, the under way blackbodies, of Pt-Si measurements are carried out with a large-area use as spectrofluorimeter and a nanosecond detector standards, and the charac- terization of thermal imaging cameras. spectrofluorimeter. In combination with available at NIST includes optical fibers, which are used to get the Equipment several heat-pipe blackbodies, a Pt-Si exciting light into the interior of a com- infrared radiometer. posite part, the fluorescence techniques camera, and an are attractive for process monitoring of composites. Contact: Robert Saunders, A221 Physics BIdg., 301/975-2355. Contact: Francis W. Wang, B320 Polymer BIdg., 301/975-6726.

52 Radiation Research

UV Radiometry "he measurement of terrestrial solar Recent advances in electron acceler- Coherent X-Ray irradiance in the UV-B spectral re- ators have provided high-quality, Sources Based on High-Quality T:gion is being investigated by NIST continuously pulsed electron Electron Beams researchers in order to provide improved beams without using storage rings, open- techniques and standards in this region. ing up a host of possibilities for new Their work is of importance not only to types of intense, coherent x-ray sources. scientists studying biological effects but Insertion devices are presently used in to researchers investigating the aging of highly expensive, multi-GeV storage materials by uv light. Specific projects in- rings for coherent production of x rays. clude the development of a reference Despite small electron-beam dimensions, spectral radiometer, broadband detec- the need to maintain the lifetime of the tors, and source standards in the region. stored beam necessitates large clear A high-accuracy spectrometer, standard apertures and precludes interception of detectors, and standard sources are the beam. However, these restrictions do

available for this research. not apply if the beam is not reused. In this case, much smaller structures, even Contact: Robert Saunders, A221 Physics interceptive ones, can be used to pro- BIdg., 301/975-2355. duce coherent x rays at beam energies

well below 1 GeV. The racetrack microtron (RTM) under Accelerator "he NIST accelerator research pro- construction at NIST provides a unique Research gram is aimed at developing ad- opportunity to develop such innovative vanced particle accelerators for sources. The expected beam size and applications in free-electron lasers divergence at 185 MeV are ±160 |im and (FEL's), production of monoenergetic ±160 )irad. X-ray production mechanisms rays, X and dosimetry .The program accessible with a beam of this quality in- focuses on designing, constructing, and clude radiation from miniature undula- commissioning the NIST racetrack micro- tors, transition radiation, channeling tron (RTM), which will accelerate elec- radiation, and parametric x-ray genera- in train of trons a continuous pulses to tion. Although the full range of beam ener- energies of up to 185 MeV by recircula- gies will not be available until 1990, tion through a 12-MeV, continuous-wave researchers are using the IZ-MeV beam linac. Results of preliminary evaluations now available for an experiment with an surpass the design goals of beam quality undulator with a submillimeter magnetic by almost a factor of two. period. The unique characteristics of the RTM beam—±20-keV full-energy spread, Contact: Philip Debenham, B119 ±10-keV energy stability, normal- Radiation Physics BIdg., 301/975-5602. ized emittance, 100-percent macro- scopic duty factor, and 100-kW average power—open up a range of innovative free-electron laser (FEL) facility Free-Electron Laser applications. The major planned applica- A under construction at NIST will be tion is to drive the NIST free-electron operated as a user facility for re- laser (FEL), an intense source of radia- search in physics, chemistry, biophysics, tion with wavelengths tunable between material sciences, and medical sciences. 200 nm and 10 ^m. Researchers are The electron source for the FEL is the developing a new, continuously pulsed, NIST racetrack microtron (RTM). Be- 5-MeV injector with several amps of peak cause the RTM will provide a continuous current to facilitate lasing. They also are train of pulses and will have a wide studying, both theoretically and experi- energy range, the FEL will have unique

mentally, beam breakup in the RTM. Im- characteristics. It will be tunable over the proved techniques for measuring the range of 200 nm to 10 |im with average properties of high-quality, relativistic elec- power of 1 0 W to 200 W, and the tem- tron beams will be developed. Comple- poral structure will be a continuous train tion of construction and performance of 3-ps pulses at 66 MHz.

tests at full energy are scheduled for 1990.

Contact: Mark A. Wilson, B119 Radiation Physics BIdg., 301/975-5605.

53 Radiation Research

Collaborative opportunities exist in enhance quality-control methods Radiation both the development and the use of the Toused in industrial radiation process- Processing FEL. The FEL will have sufficient small- ing of foods and in the production signal power gain to lase in the ultravio- and use of medical devices, electronic let, but the lower wavelength limit of components, and polymers, NIST re- 200 nm to 300 nm will depend strongly searchers are developing standardi- on mirror performance. NIST researchers zation and measurement assurance will be investigating the development of methods related to industrial high-dose low-loss, high-power mirrors; laser applications of ionizing radiation. As part diagnostics and stabilization; optimiza- of this program. Institute scientists are in- tion of harmonic radiation (for wave- vestigating radiation chemical mecha- lengths as low as 30 nm); Q-switched nisms and kinetic studies applied to mode of operation; and optical pulse chemical dosimetry systems in the con- compression. They are especially inter- densed phase, including liquids, gels, ested in dynamical studies which exploit thin films, and solid-state detectors. the temporal structure of the FEL. They also plan to examine sensor materials such as doped plastics, solid- Contact: Ronald G. Johnson, B110 state matrices, fiber optics, organic dye Radiation Physics BIdg., 301/975-5568. solutions, semiconductors, scintillators, biopolymers, amino acids, metalloporphy- rins, and organic or inorganic aqueous Spectral esearch and development pro- solutions gels. of analyti- I and A number Radiometry at grams NIST span a broad spec- cal methods will be used, including trans-

Rii trum of activities associated with mission and fluorescence spectro- the measurement of optical radiation, in- photometry, electron spin resonance cluding spectral radiance measurements spectrometry, and chemiluminescence and new techniques for spectrophoto- spectrophotometry as well as fiber optics metric measurement of dense optical analysis, microcalorimetry, pulse radioly- activities the media. These cover ultravio- sis, laser-induced , and let spectral region from 200 nm to the far conductivity measurements. Various infrared region and include the develop- ment of appropriate detector method- ology to perform the measurements and relate them to the U.S. radiometric meas- urement base. Specific research and development projects involve low back- ground infrared calibrations in a cryo- genic environment, solid-state photo- diode metrology, applications of detector

metrology to all areas of radiometry, development of an absolute cryogenic radiometer, and application of laser heterodyne technology to optical density measurement. Several well-equipped laboratories for optical measurements in the uv and vis- ible spectral region are available for use, and new facilities are being developed which will enable scientists to research both detector development and optical properties of materials in the infrared spectral region.

Contact: Al Parr, A221 Physics BIdg., 301/975-3739. On the automated spectral comparator facility, physicists Jeanne Houston and Chris Cromer align the silicon photo- diode light traps that are used in photodetector research and calibration.

54 1

Radiation Research

x-ray and gamma-ray sources and elec- The use of penetrating radiation for Industrial tron accelerators with energies in the imaging is one of the most powerful Radiologic 0.1- to 10-MeV range are used in this investigative techniques available to Imaging work. Conventional ultraviolet, visible, industry for maintaining or improving the and infrared spectrophotometers and quality of products. Designers, aware of spectrofluorimeters, high-intensity this, are creating components that facili- gamma-ray sources, pulsed and con- tate such nondestructive testing. Re- tinuous beam electron accelerators, and search is under way at NIST to allow organic-chemical analytical equipment better quantification of radiographic im- are also available. ages. Particularly relevant to image eval- uation are computer-based systems that Contact: William L. McLaughlin, C209 permit pseudo three-dimensional images Radiation Physics BIdg., 301/975-5559. and the implementation of image proc- essing on these or traditional images in real time or near real time. Autoxidation/ 'he kinetic and mechanistic aspects The NIST research focuses on image Antioxidants of autoxidation in foods, organic ma- T processing for improved imaging of low I terials,t and biochemical systems; contrast for noisy images; adaption of the design of appropriate antioxidants to tomographic equipment to industrial prevent the deleterious effects of oxygen; needs and measurement of the perform- and the extension of the lifetime of chemi- ance characteristics of such systems; cal and biochemical systems are impor- and development of reliable techniques tant to many food, drug, and medical for image storage and retrieval. Available industries. NIST researchers are investi- equipment includes x-ray sources, low- gating the free-radical chemistry of or- energy electron accelerators, gamma-ray ganic molecules and biochemicals sources, and state-of-the-art radiologic susceptible to autoxidation and free- imaging devices. radical mechanisms and reaction rates of oxidants, particularly key components Contact: Charles E. Dick, C215 of foodstuffs and other life-supporting Radiation Physics BIdg., 301/975-5580. substances. In addition, the effects of oxygen pressure, temperature, additives, and concentrations on the optimization of NIST researchers are studying in- Neutron Fluence these parameters and the development dustrial applications of neutron Measurement of products less sensitive to oxidation are fluence and dose determination in and Neutron Physics being studied. the neutron energy region from thermal to NIST researchers are seeking in- 20 MeV. They are developing effective dustrial collaboration in the analysis of methods to transfer personnel protection short- and long-term intermediate spe- technology to the private sector. This re- cies in pulse-irradiated oxygenated or- search provides a basis for stand- ganic and aqueous solutions; derivation ardizing personnel protection control of kinetic data and unraveling of auto- procedures in nuclear reactor and in and radiation-stimulated oxidation proc- high-energy accelerator operations. esses; and design of new antioxidants to Specific research involves the measure- protect against food spoilage, carcino- ment of reference standard neutron reac- genesis, atherosclerosis, and nitrosa- tion cross sections; characterization of mine formation in foods. Kinetic and reference fission deposits; development analytical chemical technologies, such of neutron detectors with fast timing; and as GC/MS, HPLC, spectroscopy, chroma- calibrations using standard neutron and tography, electrophoresis, and ESR spec- gamma-ray fields. Equipment available troscopy; high-intensity gamma-ray includes a 100-kV ion generator-based sources, and pulsed- and continuous- 2.5-MeV neutron source, a 3-MV pulsed beam electron accelerators; and various positive-ion accelerator, and a 20-MW organic-chemical analytical equipment nuclear reactor. are also available. Contact: Oren A. Wasson, B1 1 Contact: Michael G. Simic, C214 Radiation Physics BIdg., 301/975-5567. Radiation Physics BIdg., 301/975-5558.

55 Standard Reference Data

Computerization sing computers to provide timely of Standard and inexpensive access to reliable Reference Data U chemical, physical, and materials data contributes greatly to increased pro- ductivity and lower manufacturing costs of industrial operations. The NIST Stand- ard Reference Data program works closely with industry to develop the tools and standards necessary for computeriz- ing industrial technical data—the num- bers, graphics, tables, and text that convey research results. The National Standard Reference Data System, coordinated by NIST, is a focal point in the United States for the evaluation of chemical, physical, and ma- terials properties data. The NIST Stand- ard Reference Data program has made a commitment to provide national leader- ship in the computerization of evaluated data, including database design, data- base and data exchange standards, and data dissemination. NIST research com- bines expertise in the physical sciences with specialized knowledge in computer Jeffrey Fuhr (left), a physicist in the NIST Atomic Transition science. Areas of activity include prep- Probabilities Data Center, demonstrates the wall-stabilized aration of databases of evaluated data arc to W.L. Wiese, head of the data center. The arc is used to and predictive software for use on per- measure atomic transition probabilities for use in plasma sonal computers, conversion and combi- modeling and analysis, including fusion research as well as nation of published data compilations laser physics and astrophysics. into searchable databases, standardi- zation of formats for scientific and en- gineering information, development of expert systems, and establishment of distributed systems linking scientific databases. The computer and telecom- munications capabilities at NIST offer challenging alternatives for the handling of these projects, with state-of-the-art mainframes, minis and micros, database management systems, graphics, and applications software available.

Contact: Malcolm W. Chase, A323 Physics BIdg., 301/975-2200.

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