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 Chemistry 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 Standards, 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 opportunity 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- ments—any organization that has an

active stake in helping U.S. business

compete more effectively.

Researchers at NIST are developing automated production

techniques for rapidly solidified metal powders.
Cooperative Research at NIST

NIST will work with any company,

trade association, university, or other government agency to solve problems of mutual concern. Its highly skilled staff of some 3,000 conduct a wide range of projects, many at the forefront of science

and technology. About half of the Insti- tute's scientists and engineers are focusing their efforts on the emerging technologies, including advanced materials,

optoelectronics, automation, computing,

superconductivity, biotechnology, and

thin-layer technology.

One of the most popular ways NIST

research and facilities are made accessible to U.S. industry is through the Insti- tute's Research Associate Program,

Under this program, companies, trade

associations, and technical societies pay

their scientists and engineers to work in NIST laboratories with NIST researchers on a specific project.

The longest running research as- sociate program has been a remarkably

successful collaboration with the Ameri- can Dental Association. Started in 1928, the alliance has resulted in the panoramic x-ray machine, composite restorative materials, and the high-speed

turbine handpiece, for example, as

well as major contributions to dozens

of standards for dental materials and

hundreds of scientific papers.

In another type of cooperative venture, companies subscribe to a consortium that provides resources for NIST

to solve a specific problem facing the

industry. This arrangement has advantages when a complex problem—usually

development of generic technology or measurement techniques—confronts a

particular industry and the research is too costly or not possible for individual companies to undertake. Companies also donate or loan equipment or software to the Institute when

NIST researchers are working on a proj- ect that could ultimately improve their products or the way they do business. In such situations, these firms actively consult or advise NIST researchers on the needs and concerns of the industry.

To aid firms in building a competitive

advantage, NIST makes available for cooperative research its extensive re- search and testing facilities at its headquarters in Gaithersburg, Md., and its

site in Boulder, Colo. A 20-megawatt

research reactor with a cold neutron

source, a synchrotron ultraviolet radiation

facility, a supercomputer, a large-scale

structures testing facility, a metals- processing laboratory, a fire research

facility, and a computer network and

security facility are but a few of the facili- ties available. In certain cases, NIST

makes its facilities available to companies for proprietary research on a cost- recovery basis, when equal or superior

facilities are not otherwise available. Described below are a few brief ex- amples of different types of cooperative

projects and the results they have pro- duced so far. The scope, duration, and

structure of the cooperative projects are

tailored to the problem to be solved. They can last for a few weeks or a few

years and involve one, several, or even hundreds of organizations. The goal is to solve the problem at hand quickly, effi- ciently, and effectively.

Crucible Materials, Inc. and the Metal Powder

General Electric Corp. are con- Processing

tinuing to work with NIST in a consortium to develop automated proc- essing technology for rapidly solidified metal powders. Rapidly solidified metal powders provide a basis for alloys that can exhibit, after consolidation, unique

properties, such as high strength-toweight ratios, excellent fracture tough- ness and fatigue resistance, unusual

magnetic properties, and high corrosion

resistance. Current processes for producing

these powders are both labor intensive and lacking in reproducibility; rejection rates are high. The goal of the industry/

NIST project is to develop generic

research results that will facilitate the automation of different atomization facili- ties for producing rapidly solidified metal powders, while improving product quality

and productivity.

Consortium researchers are designing

process models, an expert system, and

automated control strategies that will be

linked by a computerized control system

for the intelligent processing of rapidly

solidified metal powders. A major component of the system is an optically

based, on-line sensor for monitoring

the metal powders while they are being

produced.

3
Cooperative Research at NIST

Magnetic

Microscope N

1ST has developed an instrument

for providing innages of the magnetic microstructure of materials

with a resolution about a factor of 100 better than conventional imaging

techniques. Using a technique called Scanning Electron Microscopy with

Polarization Analysis (SEMPA), re- searchers are able to provide direct im- ages of magnetic microstructure with a

resolution of about 0.05 microns.

In cooperation with industry, this "magnetic microscope" is being used to observe details of the magnetic domain

structure responsible for the performance

of high-technology materials. The ability to see magnetic domains with such clarity is important to the information storage

device industry. For example, the storage capacity and fidelity of magnetic

tapes and disks depends upon how

small magnetic "bits" can be made and

the sharpness of the boundaries be- tween the bits. Until now improvements

have been limited by the inability to measure magnetic microstructure at the submicron level. This research has involved extensive

collaboration with industry. A number of industrial scientists—from Honeywell,

Control Data Corp., Kodak, Westinghouse, Digital Equipment Corp., among

others—provided samples for highresolution analysis. Control Data Corp.

and Kodak sent researchers to NIST to

help improve the method. Other companies provided some funds for equipment

and measurement services. NIST scientists are now working with an industrial consortium—Perkin-Elmer, Control Data

Corp., and Honeywell—to develop a second generation, commercially

available magnetic microscope. They

also are helping several universities to establish SEMPA capabilities.

For the past several years, NIST has

worked with government, industry,

and standards groups in support of national and international standardization

of Open Systems Interconnection (OSi).

International standards for OSI are being

developed to overcome common problems that users of computer systems

face in integrating large and small computers, networks, workstations, and communications services, and in transferring information between different systems.

To advance this goal, NIST established OSINET, a cooperative government/industry research network that is expediting the development and use of commercial OSI products. With 25 participants and network nodes throughout the United States and in several overseas lo- cations, OSINET is a successful research

tool for remote testing of OSI protocols

and for vendor interoperability testing.

OSINET also is used by government

and industry managers to assess the

Open Systems

Interconnection

Network

(OSINET)

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

4
Cooperative Research at NIST

Optical Fiber

IMetroiogy

Radioactivity

IMeasurements

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.

A'

s optical fiber metrology moved

from the laboratory to commercial

^applications, NIST worked with the

Electronic Industries Association and its associated Telecommunications Industry

Association, as well as other organizations, 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

well as at connections. NIST, with the cooperation of the industry, conducted

comparative measurements of various

techniques used to make this measurement, identified the shortcomings of various approaches, and provided the

technical basis for a voluntary standard

for this measurement.

r\i A'

collaborative project sponsored

by NIST and the U.S. Council for LEnergy Awareness (USCEA) has

confirmed the ability of radiochemistry

laboratories in the nuclear-power industry

to assay several types of radionuclides

with sufficient accuracy. In the first year

of the program, two USCEA research

associates worked with NIST scientists

to prepare and distribute special test samples to 12 utilities that operate over 30 percent of the existing generating

units in the United States. The company

supplying radiochemistry measurement

services to the largest number of U.S. power-generating units also was tested. Additional tests involving gaseous

radionuclides, mixtures, and special

forms simulating field samples are scheduled with three more utilities planning to participate. A unique feature of the program is the participation of the

industry's three major suppliers of commercial calibration and test samples.

These companies not only take part in tests prepared for the power-plant

laboratories, they also have their measuring ability checked by sending

materials they have certified to NIST for verification.

Electronics technician Micfiael Huff (left) and project chief

Kang Lee monitor the Mare Island Flexible Workstation , the

first large-scale transfer of flexible and automation technology from the At\ARFto a production facility.

n a cooperative project with the Navy,

Westinghouse Corp., and Warner &

Swasey Company, NIST researchers

have designed and assembled a stateof-the-art manufacturing system for the Navy shipyard at Mare Island, Calif. The

flexible manufacturing workstation is capable of operating, largely unattended,

24 hours a day.

Consisting of an automated multi- purpose machining center, industrial robot, automated storage and retrieval system, and various control computers,

the Mare Island workstation incorporates

several advanced automation tech- niques, such as chuck jaw changing and

tool-condition monitoring. The workstation is designed to produce any of 84 different parts used in nuclear submarines. These parts are not stockpiled,

rather they are produced on demand.

Current manual methods require an average of 17 hours to make one such

part. The new workstation reduces that to under 30 minutes. The advanced tech- niques used in the workstation, many of which were developed in NIST's Auto- mated Manufacturing Research Facility

(AMRF), are applicable to a variety of manufacturing operations. The AMRF is an experimental facility designed to study the application of advanced

robotic and computer-control techniques

to small-batch manufacturing.

Automated

iVianufacturing

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 ion chromatography

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
Analytical Chemistry

Atomic

Spectroscopy a;

Analytical Mass

Spectrometry

tomic spectroscopy methods are probably the most widely used anaklytical techniques in industry today.

Considerable research is required, however, to keep up with the changing

needs of industry. At NIST, research in atomic spectrometry is focused on

several different areas. For instance,

researchers are working to improve the

analytical capabilities of direct current plasma (DCP) and inductively coupled

plasma (ICP), as well as experimenting

with the glow discharge as an atom re- servoir. Additional research concerns the use of spark sampling for the direct analysis of solids, the continued development

of laser-enhanced ionization (LEI) in flames, and the evaluation of various

types of coupled chromatographicspectrometric systems to improve the ac- curacy of spectroscopic measurements.

NIST scientists also are developing a

series of neutral density filters that can be issued as Standard Reference Materials for verifying the accuracy of the transmittance and absorbance scales of

ultraviolet, visible, and near infrared absorption spectrophotometers.

Contact: Robert L. Watters, B222

Chemistry BIdg., 301/975-4122.

nalytical mass spectrometry has

played a key role in industries,

ksuch as the semiconductor in- dustry, which require accurate measure- ments of trace elements in their raw

materials, products, and product containers. The inorganic mass spectrometry

program at NIST is concerned with developing analytical capabilities for making highly accurate determinations of trace inorganics using stable isotope dilu- tion and highly precise measurements of isotopic compositions, as well as the

highly accurate measurement of absolute

isotopic compositions to redetermine

atomic weights. Areas of research in- clude instrumentation in spark source, thermal source, inductively coupled

plasma source, and laser source mass

spectrometry and chemical separations

at the trace level using ion chromatography and other techniques.

Contact: John D. Fassett, A21 Physics

BIdg., 301/975-4109.

Electroanalytical research plays a

key role in the development of methods and materials for en- vironmental and clinical determinations.

A broad range of electroanalytical and

chromatographic techniques, such as

voltammetry, oculometry, ion chromatography, and chelation ion chromatography, are used by researchers at NIST for analysis and research. Scientists at the

Institute have developed novel methods

and instrumentation, such as microwave

decomposition equipment and unique

laboratory robotic equipment that uses

hierarchical computer control. Instrumentation is available for making accurate

pH, potentiometric, coulometric, conductometric, voltammetric, and ion chromatographic measurements and for research

in analytical laboratory automation.

Contact: H.M. "Skip" Kingston, A345

Chemistry BIdg., 301/975-4136.

Inorganic

Electroanalytical

Research

M

ore than 50 billion chemical

analyses are performed annually

in the United States. Researchers

at NIST help to ensure the accuracy of these analyses by developing new analytical procedures and improving the

reliability and accuracy of present

methods. One technique under study is activation analysis, a highly sensitive analytical technique not normally available in industrial laboratories. In this research,

methods of nuclear analysis are investi- gated utilizing the 20-MW NIST research

reactor. All areas of the technique are re- searched, including the capabilities of cold-neutron activation, the use of monitor activation, radiochemical separations,

the determination of new mathematical

procedures for the resolution of gamma

spectra, the development of prompt

gamma activation techniques, and the use of charged-particle activation techniques.

Contact: Robert R. Greenberg, BIOS

Reactor BIdg., 301/975-6285.

Activation

Analysis

7
Analytical Chemistry

Liquid

Chromatography

Electrochemistry Al

Ithough liquid clnromatograplny

(LC) is one of the most widely used

Lanalytical techniques in industrial laboratories, its use can be made even more widespread by improvements in detection methods. NIST researchers are working to develop novel approaches for the electrochemical detection of organic

analytes separated by liquid chromatography. For this technique to be applied

most effectively, the electrode reaction mechanisms of the compounds to be detected must be investigated using tech- niques such as cyclic and reverse-pulse

voltammetry, oculometry, and LC/

ultraviolet spectroscopy. Ongoing NIST

work focuses on the use of differential pulse and dual-electrode detection, as

well as the development of single- and

array-microelectrode detectors. Re- searchers also are developing new liquid

chromatographic separations employing

specific chemical interactions, including

chelation, ion-pairing, charge transfer complexation, and acid-base equilibria.

Contact: William A. MacCrehan, Al 13

Chemistry BIdg., 301/975-3122.

To help improve the specificity and sensitivity of biosensing

devices, research chemists Anne Plant and Steven

Choquette investigate the optical characteristics of fluores- cent molecules used in the amplification of biosensor

response.

Biosensors are the newest generation of analytical devices with the

potential for widespread use in bio- medical and industrial monitoring applications. Biosensors will incorporate the

latest advances in biotechnology to pro- vide high specificity and sensitivity. Biologically derived substances have great value as components of rapid-sensing

devices because of their binding specificity, the strength of their interactions,

and their potential for use in a wide

variety of amplification schemes. Im- munological, enzymatic, and receptorligand interactions are being explored as

the basis for analytical devices.

NIST researchers are using a variety

of optical and electrochemical tech- niques for detection. Detection can be

based on such diverse changes as size and rotational mobility of analytes or binding agents upon interaction, or can be

the result of enzymatic activity which oc- curs due to analyte binding, causing en- hanced fluorescence or electrochemical

signal. Amplification can be achieved

with release to liposome-encapsulated

molecules, multi-turnover enzyme reactions, ion-exchange polymer-modified

electrodes, and so forth. Combining high

specificity for analytes with efficient amplification provides the potential for ex- tremely sensitive devices.

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

Supercritical fluid chromatography

(SFC) in both capillary and packed

columns offers several advantages

over liquid and gas chromatography

(GC) for high-efficiency separations of nonvolatile molecules. NIST researchers

in this area are investigating the vari- ables that influence the retention, selectivity, and efficiency of SFC systems and

the development of SFC as a useful analytical technique to provide highefficiency separations of complex

mixtures. Both packed-column and capillary SFC instrumentation are used for making state-of-the-art measurements. The application of supercritical fluid extraction combined with SFC and GC

analysis is under investigation.

Contact: Stephen N. Chesler,

301/975-3102 or Stephen A. Wise,

301/975-31 12, Al 13 Chemistry BIdg.

Bioanalytical

Sensors

Supercritical

Fluid

Chromatography

8
Analytical Chemistry

Liquid

Chromatographic

Stationary Phases Li

iquid chromatography (LC) on

chemically bonded stationary

.phases (e.g., Ci8, Cs, NH2, and

NO2) offers unique capabilities for the separation of isomeric compounds or compound classes. However, significant

differences in retention and selectivity

characteristics, such as relative retention, have been observed among

commercial phases produced by differ- ent manufacturers and even within differ- ent batches prepared by the same

manufacturer.

NIST researchers are working to un- derstand which factors influence LC re- tention on these various stationary

phases to predict, improve, and control the separation selectivity. In reversed- phase LC on Cis phases, polycyclic aro- matic hydrocarbons have been used as model nonpolar solutes to study retention mechanisms and selectivity. The scientists have studied various physical

parameters of these solutes to determine

their influence on retention and selectivity

in LC. Their investigations have focused

on both the physical and chromatographic characterization of these station- ary phases. A variety of methods are

available at NIST for physical characterization of these materials, including

carbon analysis, gas adsorption surface area techniques, infrared and nuclear magnetic resonance spectroscopy, and

small-angle neutron scattering techniques. Currently, NIST scientists are attempting to develop chromatographic

test mixtures to evaluate LC stationary

phase characteristics and chromatographic performance. Such "perform- ance" standards would allow direct comparison of the various LC phases pro- duced by different manufacturers and

provide insight into the development of improved stationary phases for specific

separations.

Contact: Stephen A. Wise,

301/975-31 12 or Lane C. Saunders,

301/975-3117, A1 13 Chemistry BIdg.

Analysts are able to use multidimensional (dual column) and very highresolution (100,000 plates) gas

chromatographic methods to perform dif- ficult separations to facilitate speciesspecific quantitation. These highresolution techniques are being investi- gated at NIST to develop highly specific

analytical procedures to quantitate pg/g

organic constituents contained in complex environmental and clinical matrices. Research in this area focuses on optimizing multidimensional gas chromatographic experiments in which two

capillary columns, each possessing in- dividual and different retention mechanisms, are serially connected by a pneumatic switch. In addition, scientists

at NIST are using and developing

tailored, very high-resolution capillary

columns. An independently controllable,

dual-oven gas chromatograph is avail- able for multidimensional research. Additional facilities and equipment include

state-of-the-art sample preparation and

gas chromatography laboratories, eight

capillary gas chromatographs with multi- ple specific and nonspecific detectors,

and a large laboratory information man- agement system (LIMS).

Contact: Stephen N. Chester,

301/975-3102 or Franklin Guenther,

301/975-3105, A1 13 Chemistry BIdg.

Amajor task in the industrial production of organic fine chemicals,

drugs and antibiotics, and bio- molecules is the characterization of the product for both compositional analysis

and quality control. Nuclear magnetic res- onance (NMR) spectroscopy has proved

to be a powerful and widely used tool for these and related purposes. One NIST program in this area in- volves the development of new and im- proved methods for the structural, quantitative, and conformational analysis

of materials of chemical and biotechnological 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

Multidimensional

and Very HighResolution Gas

Chromatography

Nuclear

Magnetic

Resonance

Spectroscopy of

Bio-organics

9
Analytical Chemistry

Protein

Characterization

by TwoDimensional

Electrophoresis

goal of this work is the development of new two-dinnensional spectrum editing

and filtering techniques and their appli- cation to structural and conformational

characterization via correlations with multinuclear chemical shifts, coupling

constants, relaxation times, and nuclear

Overhauser effects. Scientists at NIST

use a high-field (400-MHz) multinuclear

NMR spectrometer equipped with a proc- ess controller, a high-capacity data acquisition system, an array processor, and

an off-line data processing station.

Contact: Bruce Coxon, A361 Chemistry

BIdg., 301/975-3135.

N

1ST researchers are using a two- dimensional electrophoresis sys- tem to characterize proteins and

peptides. They are probing the influence

of size, shape, and charge on migration

characteristics in the electrophoretic medium. Although well-defined protein

"markers," especially of high molecular

weight, are required to allow standardization of polyacrylamide gel electro- phoretic systems, charged polymeric

materials other than proteins may be considered for markers. Because staining

and detection of such markers is of special interest, the researchers plan to examine the mechanisms of silver stains using neutron activation techniques. Additional studies will be directed toward

understanding the interactions of proteins with metal ions. The researchers will use image processing by state-of-the-art instrumentation to form meaningful

databases. As part of this program, NIST

plans to issue well-characterized mixtures of proteins as Standard Reference

Materials (SRM's) that will be used to assess the abilities of existing and new

electrophoretic techniques to separate

and detect proteins.

Contact: Dennis Reeder, A361

Chemistry BIdg., 301/975-3128.

The new technique of electrophoresis

in small bore capillaries promises to revolutionize the separation of charged molecules. However, since the highest efficiencies are obtained with small sample sizes (nL) in narrow bore

(=10 iim) columns, this presents a chal- lenge in microdetection technology. Detection schemes being investigated at NIST include conductivity, amperometry,

UV absorbance, fluorescence, and mass

spectrometry. Much work is needed to design the chemistry of the mobile phase

and capillary column to suit the analytical

need. Ion-pair, complexing, and micellar agents, as well as pH manipulation, can

be used to enhance the selectivity of the separations of ionic and neutral molecules. Derivatization of the capillary sur- face can control the bulk electro-osmotic

flow and prevent the adsorption of the analyte molecules. NIST researchers will use the technique to investigate the fun- damental property of the electrophoretic

mobility and to determine important analytes such as proteins, peptides, DNA

fragments, and trace metals.

Contact: William A. MacCrehan, A1 13 Chemistry BIdg., 301/975-3122.

Interpreting the relationship between

the physical and chemical microstructure of materials is important in understanding their macroscopic behavior and

in extending their in-service perform- ance. Conventional microbeam tech- niques for elemental/molecular compositional analysis on the micrometer

scale, such as the electron microprobe

and ion microscope, have been re- stricted to quantitative analysis at in- dividual locations. Mapping of the

distribution of constituents has been

possible only at the qualitative or semiquantitative level. However, recent NIST

research developments have led to the production of the first true quantitative

elemental compositional maps. Quantitative compositional mapping with the electron 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.

Capillary Zone

Electrophoresis

Microbeam

Compositional

Mapping

10
Analytical Chemistry

Trace Gas

Measurement

Techniques

Current research activities at NIST in- clude extending compositional mapping

to analytical electron microscopy, laser Raman microanalysis, and laser microprobe mass analysis. Potential projects

could involve applying the compositional

mapping instruments to materials characterization problems, developing new tech- niques for compositional mapping on

other microanalysis instruments, and in- vestigating basic topics in elemental and

molecular quantitative analysis with mi- crobeam instrumentation. Among the equipment available at NIST is an electron microprobe, an analytical scanning electron microscope,

200- and 300-kV analytical electron mi- croscopes, an ion microscope (secondary ion mass spectrometry, SIMS), a

time-of-flight SIMS, a laser microprobe mass analyzer, two laser Raman microprobes of NIST design, and extensive

computer facilities, including a VAX

11/780 computer, micro-Vaxes, and a DeAnza image processor.

Contact: Dale E. Newbury, B364

Chemistry BIdg., 301/975-3921.

/\r

ccurate measurement of gaseous

species is of great importance to Lmany industries for a number of applications ranging from the quantification

of pollutant and toxic gas emissions to the quality control of products. The validity of data derived from such measure- ments is tied directly to the availability of useful gas measurement techniques and

to the degree of understanding of their capabilities and limitations. Although a

variety of techniques have been applied

to trace gas analysis, more research is needed to improve the present state of the art. This research is particularly important 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 partsper-billion levels. Current NIST research

focuses on new detection systems using

chemiluminescence, electrochemistry, in- frared diode laser systems, capillary gasliquid and gas-solid chromatography

coupled to mass spectrometry, and

isotope-dilution mass spectrometry.

Institute scientists also are examining the use of class-specific detectors for gas

chromatography and evaluating electronic circuitry to optimize signals and re- duce instrumentation noise and drift.

Contact: William D. Dorko, 8364

Chemistry BIdg., 301/975-3916.

Inorganic and organic compressed

gas mixtures are employed extensively

throughout industry to calibrate equipment used to assess the quality of products and the effectiveness of emission

controls. Although the stability of these

mixtures is critical to their successful

use, a number of instances have been

noted in which instability has been observed, particularly in mixtures containing low levels of reactive gaseous

species, such as nitrogen oxides, sulfur dioxide, and hydrocarbons. The reasons

for instability may differ somewhat for different gaseous species, but they are

related to at least two possible phenomena: gas-phase reactions and gas-metal

interactions with the internal surface of the cylinder. NIST researchers are working to improve the understanding and

predictability of these phenomena. Their techniques involve those employed in surface science studies and other approaches, such as Fourier-transform

infrared, diode laser, and other spectroscopies; mass spectrometry; metal analysis; trace water and oxygen analysis;

chemiluminescence analysis; and the use of specifically doped mixtures and

homogeneous gas phase kinetics.

Contact: Walter L. Zielinski, Jr., B364

Chemistry BIdg., 301/975-3918.

Instability off Compressed Gas

Mixtures

11
Applied Mathematics

Performance I n a project designed to measure the of Parallel I performance of parallel computers,

Computers | nist researchers are focusing on two

major questions: How can codes be im- proved? and What types of codes should

be run on a given machine? They are

evaluating the performance of algorithms on parallel computers by using data motion as the principal determining factor. Their approach to performance measure- ment is to develop a taxonomy of algorithmic paradigms based on how the data move during a calculation, rather than on what the specific computation

steps are. The scientists will implement benchmark codes typical of applications in each class of the taxonomy on two differ- ent parallel computers in order to obtain

detailed measures of performance. The

target machines for measurements are

representative of the two main classes of MIMD parallel architectures: loosely

coupled, message-passing machines

and tightly coupled, shared-memory

machines.

Contact: Francis Sullivan, A438

Administration BIdg., 301/975-2732.

Design for Quality

t;

"hrough its Design for Quality pro- gram, NIST supports collaborative research within NIST and with in- dustry, technical societies, and universities to develop and refine effective and

efficient statistical, mathematical, and

computer-based techniques for quality

improvement. These techniques are designed for ease of use by industrial scientists and engineers and are disseminated

through research collaborations with in- dustry, tutorials, and workshops.

Statistically planned experiments

(SPE's), effective and efficient techniques

for improving quality, are being used to accelerate the development of new and

improved industrial process designs. At NIST, researchers are employing these

techniques to improve fabrication of advanced ceramics for cutting tools and of superconducting ceramics. SPE's are

also being used to develop a reliable and cost-effective method to measure

the size distribution of silicon nitride powders. Collaborative research opportunities for developing other SPE's exist

in the following areas: polymers and

other composites processing, dental and

medical materials fabrication, automated

flexible manufacturing, integrated circuit fabrication, optoelectronics, and bio- process engineering.

Contact: Raghu N. Kacker, A337

Administration BIdg., 301/975-2109.

Quality assurance for physical and

chemical measurements supporting technology transfer and

on-line quality control demands statistical methods applicable to complex models.

NIST researchers critique methods for

their resistance to outliers and their capacity to detect autocorrelation in highly precise measurement systems.

In multivariate settings, such as electronic test systems, estimation of uncertainty and statistical tolerance limits can

be complicated by variance components

from multiple sources. Researchers also are investigating the applicability of artifi- cial intelligence to complex analyses. Calibrations, where instrument response

depends on stimuli over a regime, support critical measurement areas such as

radiation dose measurements. NIST re- search in this area is focused on optimal

procedures to accommodate real-life models such as random changes in in- strument response over time and gradual

instrumental drift.

Contact: Carroll Croarkin, A337

Administration BIdg., 301/975-2849.

AtNIST, researchers are designing

comprehensive software for modeling and database applications in materials science and engineering. NIST

research on computer-aided modeling of the behavior of structural materials and

components ranges from microscopic

feature analysis of fatigue, fracture, phase change, creep, and polymer crystallization to the stress-life prediction of structural reliability of critical components

based on mechanical and flaw-detection

testing. In these studies, NIST researchers emphasize the interplay among the choices of data representation, appropriate physical principles, incisive mathematical and computational tools, and

integrated software for graphics and

Measurement

Assurance

Computational

Mechanics

12
Applied Mathematics

Nonlinear

Mechanics

Vector

Algorithms and

Mathematical

Software

databases. In addition, they are inter- ested in mathematical theories of elasticity, plasticity, viscoelasticity, as well as

mathematical methods using matrix

theory, finite-element algorithms, bifurcation analysis, statistical distribution con- cepts and sampling theory, and

stochastic differential equations.

Contact: Jeffrey T. Fong, A302

Administration BIdg., 301/975-2720.

M

athematical analysis, used with symbolic computation, leads to

efficient analytical approximations

by computers. Perturbation algorithms

applied to nonlinear differential equations, especially in celestial mechanics,

result in analytical developments where

the complexity grows exponentially with the order of the approximation. Several

different avenues are being explored by

scientists at NIST to simplify literal developments generated by perturbation

algorithms applied to nonlinear systems.

These include identification of algebraic

structures on the domain of the normalization, smoothing transformations to elimi- nate perturbation terms outside the

kernel of the Lie derivative, preparatory

transformations of a geometric nature, and the creation of natural intermediaries. Problems being examined at NIST

are resonances at an equilibrium, per- turbed pendulums, and the major theories of celestial mechanics. NIST re- searchers, using a LISP computer, are focusing their studies on algorithms

amenable to computer automation

through symbolic processors.

Contact: Andre Deprit, A302

Administration BIdg., 301/975-2709.

Jl

'0 make effective use of vector computers, new algorithms appropriate

to the special architecture of these

machines need to be designed and incor- porated in high-quality mathematical soft- ware for general use. Very successful

vector algorithms have been developed

for computations in numerical linear algebra (e.g., computation of the discrete

Fourier transform), but few are available

for combinatorial problems. One area of

NIST research is concerned with developing vector algorithms appropriate to the combinatorial problems encountered in molecular dynamics simulations, particularly three-dimensional simulations with very large ensembles of particles. Other

areas of interest include methods for solv- ing highly nonlinear elliptic and parabolic

partial differential equations as well as

nonlinear constrained and unconstrained

optimization problems and the solution of nonlinear systems of equations. NIST re- searchers also are working on the solution of integral equations and numerical

evaluation of integrals. Software development goals include portable, interactive packages, which integrate modern

graphics with numerical algorithms.

Contact: Paul Boggs, A151 Technology

BIdg., 301/975-3800.

Researchers at NIST are developing

and applying advanced methods

for the use of state-of-the-art, computer-based scientific graphics for visual rendering of complex experimental, computational, and analytic results in physics

and chemistry. Researchers take advantage of a collection of vector and raster workstations, photographic and video

hardware, high-speed networking for transmitting large graphics data sets be- tween computers and graphics devices,

and computational geometry algorithms

and software for the analysis of two- and

three-dimensional data sets. Recent activities include the development of easy

user interfaces to manipulate static objects and of techniques to manipulate dynamic objects in automated design and

manufacturing systems, the display of quasicrystal structures with icosahedral

symmetries, the display of scanning electron tunneling microscopy data with

polarization analysis, and the study of models of turbulent combustion showing

the dependence of solutions on time and

fuel-oxidizer mixture parameters.

Contact: Sally E. Howe, B146

Technology BIdg., 301/975-3807.

Scientific

Visualization

13
Atomic, Molecular, and Optical Physics

studies of

Semiconductor

Materials T!

"he growth of gallium arsenide

(GaAs) semiconductors on silicon substrates has generated considerable interest due to the excellent mechanical strength and thermal properties

of the substrates—qualities not provided

by the GaAs material alone. A major diffi- culty in growing GaAs on silicon has

been the mismatch of lattice constants and the concomitant incorporation defects. However, new studies show that a

better match of the lattices can be

achieved if the silicon substrate is cut at a small angle to the crystal plane. NIST

scientists are investigating the interaction

of relevant semiconductor materials with

silicon substrates, using sensitive,

tunable laser sources to detect the in- dividual states of the atoms and

molecules as they interact with the growth substrate and growing material. Complete surface diagnostics and ultra- high vacuum conditions are used in this work. The researchers are determining

the sticking coefficients and adsorption

energies of individual spin-orbit states of gallium atoms and other dopant atoms

plus the effects of vibrational excitation of arsenic dimers on the growth of GaAs

semiconductor materials. Another study involves the deposition

of thin films of amorphous silicon, which

are used in photosensitive devices and

in photovoltaic cells. Scientists are ex- amining mechanisms involved in silane discharge and thermal chemical vapor

deposition (CVD) production of such

films. Mass spectrometry is used to study

gas discharge processes, gas chemistry,

and surface chemistry and their effect on

film growth, character, and quality. Re- searchers are operating a thresholdionization mass spectrometer that can

detect H and Six Hn radicals at densities

of 1 part per million of parent silane gases. The spectrometer also has a

threshold sensitivity in the neighborhood

of 10^^ cm""^ in the reactor vessel. All electronics, vacuum, and gas-handling

apparatus necessary for examining rf and dc discharges and thermal CVD

under controlled conditions are available as is a pulsed laser for use in studying

surface species by laser blowoff.

Contact: Stephen R. Leone,

303/497-3505 or Alan C. Gallagher,

303/497-3936, Div. 577, NIST, Boulder,

CO 80303.

M

any sensitive and sophisticated

applications of lasers depend on

the laser's spectral coherence,

frequency stability, and low-intensity noise. NIST scientists have been working on laser intensity stabilization, laser frequency linewidth reduction with active

control techniques, and several methods

for producing quantitative laser fre- quency scans. Two new systems have

been developed. One, based on optical

sideband production by broadband mi- crowave phase modulation of the laser, allows scans over a ±5 GHz range, with inaccuracy below 10 kHz. The other scan

technique utilizes a novel interferometer/

phase-locked rf system, which maps opti- cal frequency change into corresponding

phase change of an rf signal suitable for control, stabilization, and scanning. This system is intrinsically free of errors that accumulate over large scans. By combining a Lambdameter for coarse wavelength identification and a single

absorption line used as absolute cali- bration, NIST scientists can scan a

few dozen angstroms with sub-MHz

accuracy. Another NIST system under development works entirely externally to a

continuous-wave laser to shift the output

laser frequency and reduce the intensity

in a controlled manner. The first application of this is a box which will sit in the output beamline of any laser and "eat" both frequency noise and amplitude

noise in the intrinsic output of the laser.

Institute scientists have demonstrated

this function by combining an external

electro-optic phase shifter and an

acousto-optic frequency shifter that also

functions as a fast controlled optical at- tenuator. Residual noise levels near the values fixed by the fundamental quantum

fluctuations have been achieved in laboratory experiments.

Contact: John L. Hall, Div. 577, NIST,

Boulder, CO 80303, 303/497-3126.

X-ray spectroscopy provides information on electronic structure and on

the local atomic structure of atoms

in matter. A synchrotron radiation beamline has been constructed by NIST scientists at the National Synchrotron Light

Laser

Stabilization

Study of Atomic

Structure of

Matter with

X Rays

14
Atomic, Molecular, and Optical Physics

Frequency, Time,

and Phase Noise

Measurement

Source, providing the highest flux, intensity, and energy-resolving power of any

existing beamline in the x-ray energy

range from 500 to 5000 eV. NIST equipment complements the synchrotron radiation 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, biological 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 electronic structure of solids, liquids, or gases by using additional experimental

capabilities.

The x-ray standing wave technique uses interference between incident and

diffracted x rays to determine the precise

location of impurities or imperfections

within a crystal or at its interfaces. The

technique can be used to investigate the

location of dopants and imperfections in semiconductors or optical crystals,

growth of overlayers on crystals, and the

structure of catalysts supported on crystal substrates. In addition, evanescent

x rays, which penetrate only a few nanometers from an interface, can be

controlled to study chemical composition

in the vicinity of an interface. NIST scientists recently pioneered a new technique, diffraction of evanescent

X rays (DEX), which combines and ex- tends the capabilities of the x-ray standing wave method and experiments

based on evanescent x rays. The syn- chrotron radiation beamline provides an ideal facility for applying these

techniques.

Contact: Paul L. Cowan, 301/975-4846

or Richard D. Deslattes, 301/975-4841,

A141 Physics BIdg.

/Ac

dvancements in communication

and navigation systems require

katomic oscillators with increased

performance and reliability. NIST has

several programs aimed at providing advanced frequency standards with the

potential for benefiting commercial

Physicist Wayne Itano studies mercury ions, which are liliely to be the basis for new standards of timel(eeping.

atomic standards. NIST scientists currently are working on an optically

pumped cesium-beam standard that should significantly surpass the perform- ance of standards based on magnetic

state selection and detection. Their studies on ion storage and radiative cooling

are exploring the potential for standards

operating at accuracy levels of 1 part in lO''^ and perhaps beyond.

Aerospace systems often require ex- treme phase stability, which has led to a need for high-quality phase noise characterization amplifiers, frequency multipliers, oscillators, and other electronic components. NIST has initiated a pro- gram to develop methods for measuring

phase noise in such components over a broad frequency range (into the millimeter range). The work will involve primarily the two-oscillator technique, but other techniques will be studied. Requirements for synchronization

(time) and syntonization (frequency) of broadly dispersed sets of nodes for communication, navigation, and other electronic systems are increasing signifi- cantly. Because of the inherent reliability, simplicity, and low cost of using satellite transfer, NIST is studying several possible approaches for using this technique. The NIST Time Scale and reliable

ties to many other international timing centers provide the basis for perform- ance analysis of these time-transfer

15
Atomic, Molecular, and Optical Physics

Surface

Characterization

Ultraviolet and

Soft X-ray

Radiation Effects

techniques. In addition, Xhe Institute is equipped with Global Positioning Systenn

receivers, Earth communication terminals, and automated systems for statisti- cal analysis of system performance.

Contact: Donald B. Sullivan, Div. 576,

NIST, Boulder, CO 80303, 303/497-3772.

Oi

, urface characterizations are used in .a great variety of scientific and tech-

' nological applications. Two beamlines at the NIST synchrotron ultraviolet radiation facility (SURF-II) have been in- strumented for surface characterization. Although the principal characterization techniques utilized are photoelectron

spectroscopy and photon-stimulated desorption of positive ions, surfaces also can be characterized by Auger-electron

spectroscopy and low-energy electron

diffraction. An ancillary chamber is being

constructed in which films of different materials can be deposited and transferred

to the main chamber for characterization without exposure to the atmosphere. A

facility for cooling specimens to cryo- genic temperatures is available. Plans

call for the installation of an ellipsoidal mirror analyzer, which will be used to measure the energy and angular distribu- tions of photoemitted electrons and the energy, angular, and mass distributions

of desorbed ions.

Contact: Richard L. Kurtz, B248

Chemistry BIdg., 301/975-2544.

"0 produce radiation for experimental purposes, NIST has built a synchrotron ultraviolet radiation facility (SURF-II). SURF-II is a 300-MeV electron storage ring that radiates high-intensity

synchrotron radiation in the energy range

from about 3 nm (400 eV) in the soft x-ray region to wavelengths in the visible re- gion of the spectrum. The radiation is highly collimated, nearly linearly

polarized, and of calculable intensity. Six beam lines are available, and a user's program is in operation. SURF-II is well suited for many different types of re- search, including atomic, molecular, bio- molecular, and solid-state physics;

surface and materials science; radiation chemistry and radiation effects on matter;

ultraviolet and x-ray optical systems; and

the calibration, characterization, and

development of spectrometers and

detectors. NIST scientists are particularly interested in conducting collaborative research in the use of soft x-ray synchrotron radiation for high-resolution lithography; measurement of the reflection characteristics of novel, high-efficiency,

multilayer far-ultraviolet optical devices;

and calibration, characterization, and

development of spectrometers and detectors. Other available equipment in- cludes a state-of-the-art multipurpose

detector calibration facility, a large ul- trahigh vacuum spectrometer calibration chamber, and a beamline dedicated to high-resolution radiation research with a 6.65-m vacuum spectrometer with a re- solving power of about 300,000.

Contact: Robert D. Madden, A249

Physics BIdg., 301/975-3726 or William R. Ott, B206 Metrology BIdg.,

301/975-3709.

Aspart of its research to understandand measure various forms of radiation, NIST is conducting vacuum ultraviolet studies involving radiation damage, polymerization of organic

molecules, and solar simulation. NIST

scientists have worked with researchers

from industry to develop and test vacuum ultraviolet instrumentation, new

spectrometer designs, and detector sys- tems, especially for flight in space. They

also have collaborated on special sources, narrow band filters, and lasers. NIST scientists are interested in doing

cooperative research in several other areas, including studying hollow cathode

lamps, laser plasmas, and spark dis- charge light sources as secondary standards. State-of-the-art radiometric facilities and advanced optical equipment are

available at NIST for these studies.

Contact: J. Mervin Bridges,

301/975-3228 or Jules Z. Klose,

301/975-3230, B66 Physics BIdg.

Vacuum

Ultraviolet

Radiometry

16
Atomic, Molecular, and Optical Physics

Submicron

Physics Wi

Characterization

of LowTemperature

Plasmas

^ell-characterized, focused electron beams are used to investi- gate the properties of surfaces and magnetic materials on a microscopic

scale. As part of a broad-based research

program at NiST, scientists are exploring

the physics of submicron systems using

electron microprobes. The program in- cludes studies of electron-surface inter- actions, surface magnetism, electron

interaction theory, and electron spin

polarization phenomena. Among the ex- tensive experimental facilities available

for this research are sources and detectors of spin polarized electrons, a scanning electron microscope equipped for secondary electron spin polarization

analysis, and a scanning tunneling

microscope.

Scanning electron microscopy with

polarization analysis is a unique measure- ment capability developed by NIST scientists to allow the high-resolution (-10 nm)

imaging of magnetic microstructure inde- pendently of surface topography. With

this technique, researchers are studying

fundamental magnetic phenomena, the properties of high-density magnetic re- cording media, and small-particle magnetism. NIST researchers are using the scanning tunneling microscope to study

surface topography at the atomic level, mechanisms of film growth at the submonolayer level, reconstructions of semiconductor surfaces, and, ultimately, correlation of surface microstructure

with macroscopic properties.

Contact: Robert J. Celotta, B210

Metrology BIdg., 301/975-3710.

Ti

"he properties of low-temperature

plasmas play a key role in the proc- essing of materials such as semiconductors. Proper characterization of these

plasmas is essential to develop accurate plasma diagnostics and useful plasma

models for specific applications. At NIST,

plasma discharges are characterized util- izing optical emission spectroscopy,

laser-induced fluorescence, laser scattering, and optogalvanic methods. Modeling of the plasma is also an integral part

of this characterization. Discharge

sources include low-pressure RF plas- mas, stabilized arcs, glow discharges,

heat pipes with laser resonance ionization, and inductively coupled plasmas.

An extensive array of laboratory

equipment is available to accomplish

this characterization, including several Nd:YAG pumped, high-resolution

(<0.1 cm"^) dye lasers; Ar ion-pumped

dye and ring dye lasers; a Fizeau wavemeter; a high-throughput (f/4), highresolution (<0.01 A) spectrometer with an automated intensified diode array detector; a 80-MHz quadrature He-Ne laser in- terferometer; UV spectrometers; grazing

incidence spectrometers; laboratory computers; and miscellaneous optics. The

principal quantities measured are particle density distributions, both spatially

and temporally, for electrons, atoms,

ions, and molecules. Also included are

electric-field distributions, electron and

ion temperatures, and nonequilibrium

phenomena.

Contact: James R. Roberts, A167

Physics BIdg., 301/975-3225.

Anew capability for fabricating relatively high reflectivity, normal inci- dence optics for the extreme vacuum ultraviolet (XUV) spectral region

has emerged since the beginning of this decade. When a large number of carefully deposited layers of selected materials are placed on a very smooth

surface, the reflectivity of the surface can be improved by several orders of magnitude. This new capability has allowed the construction of XUV telescopes revealing

images of the sun at selected wavelengths (e.g., 175 A relevant to Fe^'*' emission) in unprecedented detail and XUV

microscopes with submicrometer resolution for biological studies. A characterization facility, which is available to all researchers on a cooperative basis, is now in operation at NIST to measure reflectivity of these optics between 80 and

600 A as a function of angle and

wavelength. This facility is capable of pre- cise measurements of single thin films and bulk material samples for derivation

of optical constants in this region of the spectrum. Plans for the future include a new monochromator-reflectometer sys- tem to operate from 30 to 600 A and an

optical test bench to measure the focusing properties of curved optics.

Contact: James R. Roberts, A167

Physics BIdg., 301/975-3225.

XUV Multilayer

Characterization

17
Building Technology

Cement and

Concrete N

Structural

Engineering

1ST researchers are undertaking a computer-oriented research pro- gram to develop a fundamental un- derstanding of the relationship between

chemistry, microstructure, and service

life of concrete and other inorganic build- ing materials. The goal of the program is to be able to predict the behavior of these materials and their service life- times. The service life of concrete largely

depends on the rate of moisture ingress

and of transport of dissolved salts and

gases in the pore system of concrete. Models are being developed to consider

service conditions, including composition

of the environment; the transport rate of reactants by diffusion, convection, and

capillary forces; and reaction mechanisms. Researchers are developing mathematical and simulation models to predict the relationships between pore

structure and diffusion and permeability

of concrete. Research projects include development and validation of mathematical models of microstructure development in cement pastes as the cement hydrates,

the effects of microstructure on permeability and fracture of concrete, and mechanisms of degradation of concrete.

Artificial intelligence systems are being

developed for optimizing the selection of materials and for diagnosing the causes

of material degradation. The research is performed using a variety of techniques,

including scanning electron microscopy,

computerized image analysis, x-ray dif- fraction, and thermal analysis.

Contact: James R. Clifton, B348 Building

Research BIdg., 301/975-6707.

E;

'xperimental and analytical research

is under way at NIST to develop de-

.sign criteria for precast concrete frames and masonry structural components subjected to dynamic loads

such as winds and earthquakes. The

work involves identifying limit states and

establishing criteria to ensure structural

safety. The researchers use a unique

computer-controlled test facility that can impose forces and/or displacements in three directions simultaneously and a

12-million-pound capacity universal test- ing machine with a lateral load capacity

of 1 .5 million pounds that can accommodate large-scale structural components

60 feet tall. A high-performance

computer graphics laboratory including a VAX computer system and specialized

graphics-based finite-element software is utilized for the analytical work.

Contact: H.S. Lew, B168 Building

Research BIdg., 301/975-6061.

The NIST lighting program focuses on fundamental measurements of

interior luminance and illuminance

distributions, light fixture output, and

the interaction between lighting and

HVAC (heating, ventilating, and air- conditioning) systems. A continuing chal- lenge is to develop metrics for lighting

quality that evaluate the combined ef- fects of illuminance, luminance, contrast, color rendering, lighting geometry, and

configuration.

In the past, researchers have focused on mathematical formulas for predicting

the chromatic contribution to brightness,

computer programs for predicting energy

effects of daylight use, detailed calculation of lighting geometry, and assess- ments of color appearance under

different illuminants. Current research in- cludes a major project on the measure- ment and modeling of the interaction of lighting and HVAC in a simulated interior office module. This research is expected

to result in the development of a detailed computer model for predicting the effects

of different types of lighting and HVAC

systems. Modifications will be made to the facility in the near future to study the

effects of dimming, thermal mass, and external solar conditions.

Contact: Belinda L. Collins, A313

Building Research BIdg., 301/975-6455.

M

easurement and testing procedures, technical data, and comprehensive indoor air-quality

models are being developed by NIST re- searchers as part of a multiyear program

to improve indoor air quality in buildings.

Experiments are being conducted in several large buildings to develop test methods to evaluate how air moves into and within large commercial buildings.

The researchers are developing comprehensive computer models to predict

pollutant levels from sources introduced

Lighting

Indoor Air Quality
Building Technology

Materials research engineer Leslie Struble uses a cylinder

and piston device to study the causes of concrete failure.

into buildings from outdoor air and those

generated inside from sources as combustion equipment and floor and wall coverings.

The first phase of the research is complete, and models exist that can predict indoor contaminant levels as functions of emission, dilution, and intra- building air movement. The models currently are being extended to model reactive contaminants. Test procedures also are being developed to evaluate the ef- fectiveness of various filter media for re- moving gaseous pollutants. A test facility for this purpose has been designed and

assembled. Test methods will be devel- oped for commercial gaseous air filters and for those used in residences.

Contact: Richard A. Grot, A313 Building

Research BIdg., 301/975-6431.

NIST is conducting basic and applied research to determine the

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 analysis, 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 chromatography, gas chromatography, and spectroscopy 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.

NIST researchers are exploring the use of refrigerant mixtures to im- prove the efficiency of refrigeration

cycles and to replace harmful chloro- fluorocarbon (CFC) refrigerants that are damaging the ozone layer of the upper at- mosphere. The scientists evaluate a wide

variant of refrigeration cycles by using a breadboard heat pump to "plug" and "un- plug" circuits and components. The

breadboard heat pump will be altered to test new refrigeration cycles based on

the results of a theoretical study being

conducted to find the optimal combination of mixtures and appropriate refrigeration cycles for the best and most versatile performance.

The "best" of the advanced cycles will be selected, equipment built, and eval- uated. A minibreadboard that will use a

very small charge will also be built so

that rare refrigerants of limited production can be studied.

Contact: David A. Didion, B1 14 Building

Research BIdg., 301/975-5881.

Organic Building

Materials

Refrigeration

Machinery

19
Building Technology Ceramics

Thermal

Insulation

Building Controls

R:

I esearchers at NIST are developing

basic data and simulation models

, for heat, air, and moisture transfer through building envelope components.

They are developing and validating a

theoretical model for moisture transfer, completing research required to develop

a low-conductivity Standard Reference

Material (SRM), developing a thermal

conductivity database for chlorofluorocar- bon (CFC) blown thermal insulation products, and refining a dynamic test procedure for building components.

A 1 -meter guarded hot plate is used

to develop SRM's; to determine thermal

conductivity values for various materials,

such as CFC blown insulation; and to pro- vide measurement services to manufacturers and researchers. A calibrated hot box is used to measure the steady-state

and dynamic performance of full-scale wall systems.

Contact: A. Hunter Fanney, B320

Building Research BIdg., 301/975-5864.

N

1ST research is fostering the devel- opment of more intelligent, inte- grated, and optimized building

mechanical systems. A dynamic building/

HVAC control system simulation program

is used to study HVAC/control system dynamics and interactions. An expanded

building management and controls laboratory 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 combined to evaluate control system perform- ance, make control strategy decisions

that optimize building performance, and

perform diagnostics to advise the build- ing operator or manager on building

operations, equipment problems, or main- tenance requirements. Work has begun

for the Department of Energy to develop

an HVAC/building emulator/EMCS tester, which will provide a method for evaluating application algorithms.

Contact: George E. Kelly, B1 14 Building

Research BIdg., 301/975-5870.

Sintering of ceramics is a complex

process that involves the interaction

of many different processing vari- ables. The influence of these processing

variables on sintering cannot be deter- mined simply by measuring final density

or some other end-point property. Chemical composition of the ceramic powders

is known to be of major importance and,

under certain conditions, can mask ef- fects of most other processing variables. As part of a ceramics program, NIST

scientists are investigating the effect of trace levels of impurities using clean- room processing to produce, compact,

and sinter ultrahigh purity ceramics.

Results from this research will en- hance investigations of other processing

variables, including particle size, shape,

agglomeration, compaction method, and

atmosphere under controlled composition conditions. The data can be used to design better models for microstructure

evolution during sintering. Use of predictive models, in conjunction with other ongoing efforts to produce unique compositions and phases, can lead to new

advanced ceramic materials with unique

microstructure and properties.

Contact: Edwin R. Fuller, Jr., A256

Materials BIdg., 301/975-5795.

Ceramic

Processing

The NIST ultra-clean ceramic processing laboratory is specially designed for the production and processing of advanced ceramic powders and samples with controlled levels of impurities and dopants.

Researchers in the NIST ceramics

tribology program are investigating the fundamental mechanisms of

friction and wear of advanced materials and lubricants and are developing test methods for evaluating the performance

of these materials. The program's

Tribology of

Ceramics

20
Ceramics

Electro-optic

Crystals

primary focus is on the characterization

of the interfacial phenomena that occur when two solid surfaces interact. Re- search activities include analysis of chemical reactions and formation of tribo- chemical films, physical and mechanical

behavior of surface films, and deformation and fracture processes leading to wear and failure. Tribology laboratories consist of state-of-the-art tribometers,

such as high temperature (1000 °C) wear

testers, and analytical instruments, such

as time-resolved micro-Raman laser sys- tems, which can be used for cooperative

research with industry and other federal agencies. NIST researchers are compiling wear data in the form of "wear maps"

and are studying the mechanisms of wear of structural ceramics at elevated temperatures, self-lubricating metalmatrix and ceramic-matrix composites,

and wear resistant coatings.

Contact: Said Jahanmir, A215 Metrology

BIdg., 301/975-3671.

mperfections in highly perfect crystals

typically limit their performance in hightechnology applications such as opti- cal communications and optical signal

processing. In particular, limitations in the perfection of electro-optic and photorefractive materials, such as lithium nio- bate and bismuth silicon oxide, have

inhibited severely the development of optical switches and modulators. NIST re- searchers are investigating crystal

perfection at a unique, monochromatic

x-ray topography facility at the NIST/

Naval Research Laboratory beamlines on

the high-energy ring at Brookhaven

National Laboratory's National Synchrotron Light Source. The data collected from current studies, conducted jointly with growers of high-quality crystal, are expected to improve substantially the

quality, and hence the performance, of these crystals.

the fracture properties of monolithic ceramics. These forces have been

measured for mica, sapphire, and fused

silica surfaces, using a crossed cylinders

apparatus.

A second program uses an indentation strength procedure to determine the R-curve behavior of monolithic alumina

ceramics and to relate the R-curve to the

specific microstructure of the material.

In-situ microscopic observations of the crack growth demonstrate the presence

of grain bridging and frictional sliding in the crack wake as a significant source of material toughening.

The program in composites is aimed at determining the effects of the

fiber/matrix interface on fracture behavior

of these materials. An instrumented mi- croindenter is available to measure the

fiber/matrix interface strengths. Re- searchers also are investigating the stresses developed in composites during

conventional sintering processes to deter- mine methods of reducing these stresses through the use of fiber coatings—thus minimizing or eliminating cracking of the

matrix as densification proceeds.

High-temperature deformation and

fracture behavior of ceramics are other areas of research. Creep and creep rupture of several varieties of siliconized SIC have been investigated and their behavior related to differences in microstructure, particularly grain size. Research continues on whiskerreinforced SIsNa and AI2O3, SIC, and

other high-temperature materials. Facili- ties exist for performing creep measure- ments in tension, compression, and

flexure at temperatures up to 1800 °C. The tensile creep apparatus is almost

completely automated, and measure- ments are made using a laser imaging

technique. Displacement measurements

are accurate to ±1 nm at 1500 °C.

Contact: David C. Cranmer, A361

Materials Bldg., 301/975-5753.

Mechanical

Properties off Ceramics

Contact: Bruce W. Steiner, A329

Materials Bldg., 301/975-5977.

O1

I everal long-term programs are being conducted at NIST on the

'fracture, creep, and creep rupture

of monolithic and composite ceramics.

Researchers, for example, are examining

the effect of very near surface forces on

Improved characterization of particle

size, shape, and crystal chemistry of ceramic powders is important to the development and production of highquality ceramics for advanced technological applications. To obtain precise

Ceramic Powder

Characterization

21
Ceramics

and reproducible measurements of these

characteristics, NIST scientists are utiliz- ing a variety of instrumental methods, in- cluding scanning electron microscopy

with image analysis. Theoretical investigations and statistical analyses of data

are then used to compare the results of the measurement methods.

Improved understanding of the changes which occur in materials at high

temperatures is necessary to process

and use advanced materials. Hightemperature x-ray diffraction provides a means for NIST scientists to record these

changes as they occur. Current studies

focus on formation of high Tc ceramic su- perconductors, reactions in ceramic

composite materials, sintering of ceramics, and high-temperature phases in superalloys.

A scanning electron microscope

(SEM), equipped with an image analysis

system and backscatter electron imaging, is used to obtain a precise understanding of the relationship between

microstructure and bulk physical and

chemical properties of powders and ceramics. A special sample holder can be

installed in the large SEM sample chamber so a sample may be obser\/ed while a crack is being driven through it. To improve measurement procedures,

NIST researchers are studying the sample preparation factors that influence particle size measurements. Measurements

of particle size distribution by sedigraph

and centrifugal photosedimentation and

of specific surface are used in conjunction with quantitative SEM/image analysis

to document fully the geometric characteristics of a powder. The properties of powder suspensions and the effect of the suspending liquid on the surface chemistry of the powder are studied also. Ele- mental characterization of the treated powder is characterized by various spectroscopic methods. Suspension properties are characterized by measurements

of pH, surface charge, ionic activity, acoustophoresis, zeta potential, and vis- coelastic properties. NIST scientists also are studying the application of colloidal processing methods to the formation of monolithic and composite ceramics.

Contact: James P. Cline, 301/975-5793,

James F. Kelly, 301/975-5794, or Subhaschandra Malghan, 301/975-6101

A256 Materials BIdg.

Ceramic phase equilibria studies at Ceramic Phase

NIST involve complementary re- Equilibria

search activities in experim.ental

theoretical, data-evaluation, and compilation aspects of ceramic phase equilibria.

The data-evaluation and compilation

work is carried out under the joint Ameri- can Ceramic Society (ACerS)/NIST pro- gram to provide industry and others with a comprehensive database of up-todate, critically evaluated phase diagram

information. Ceramic phase diagrams are being determined for systems of technical importance, such as high-transitiontemperature ceramic superconductors.

Contact: Stephen Freiman, A329

Materials BIdg., 301/975-5761

NIST scientists are investigating low- Ceramic

temperature synthetic approaches Chemistry

to both oxide and nonoxide ce- ramic powders and coatings. They are using novel chemistry and techniques to solve the problems of generating homogeneous, multicomponent materials with predictable and optimal properties. The

researchers are studying the following

materials: high Tc ceramic superconductors; ultrafine ceramic powders with highelectrical conductivity; ceramic coatings

with selected optical, electronic, or structural properties; ultrafine magnetic composites; ceramic whiskers-ceramic matrix composites; and ultrafine, pure oxide

powders. Depending upon requirements

of the study and the powder, synthesis is carried out either in small bulk reactors or

in a flow reactor. The researchers are examining the re- lationship of process conditions to sur- face chemistry of the powder, particle size and shape, the phases formed

during thermal treatment of the powder,

and properties of the powder or sintered ceramic, such as electrical conductivity.

Coupled with the powder synthesis is the development of characterization methods, including micro-Raman, Fourier transform infrared spectroscopy, and nuclear magnetic resonance spectroscopy.

Contact: Joseph R. Ritter, 301/975-6106

or Pu Sen Wang, 301/975-6104, A256

Materials BIdg.

22
Chemical Technology

Center for

Advanced

Research in Biotechnology

Chemical and

Biochemical

Thermodynamics

The Center for Advanced Research

in Biotechnology (CARB), a joint re- search venture between NIST and

the University of Maryland, studies protein structure/function relationships. Scientists at CARB are focusing on the measurement of protein structure by

x-ray crystallography and nuclear magnetic resonance spectroscopy, and the manipulation of structure by molecular

biological techniques including site- directed mutagenesis. Protein modeling,

molecular dynamics, and computational

chemistry are used to understand protein structure and to predict the effects of specific structural modifications on the properties of proteins and enzymes. A

variety of physical chemistry methods

are used to measure and analyze structural changes, activities, and thermodynamic behavior of proteins under

investigation. CARB maintains state-of- the-art facilities for crystallography, NMR

spectroscopy, molecular biology, and

physical biochemistry. Its computer facili- ties include a mini-supercomputer,

several high-resolution graphics workstations, and access to the NiST Cyber 205

supercomputer.

Contact: Walter J. Stevens, 9600

Gudelsky Dr., Rockville, MD 20850,

301/251-2272.

NIST researchers have developed

precision oxygen combustion cal- orimeters to measure the enthalpy

of combustion, from which enthalpy of formation can be derived, for samples

varying in mass from 10 milligrams to 2.5 kilograms. These instruments are used to characterize thermodynamic

properties for species of interest to bio- chemistry, organic chemistry (including strained species), phosphorous chemistry, and heterogeneous fuel technologies. The measurements also serve as

the basis for Standard Reference Materials and Standard Reference Data for a

variety of technologies, including energy.

In the area of biothermodynamics,

NIST researchers have developed accurate and precise microcalorimeters to measure the heat released in enzymecatalyzed biochemical reactions of inter- est to technology. When coupled with equilibrium measurements, these measurements enable the reliable modeling of

the thermodynamics of these processes. These data are used to predict reliably the efficiency of biochemical processes

outside the normal measurement ranges

for temperature, pH, and ionic strength.

Contact: Stanley Abram.owitz, B348

Chemistry BIdg., 301/975-2587.

NIST maintains several data centers

that evaluate thermodynamic data

in inorganic, organic, and aqueous

chemistry. Researchers in the data centers examine existing data, extrapolate

these data to temperatures outside the range of measurement, create algorithms

for data evaluation and manipulation,

and produce reliable estimation schemes

for predicting the properties of species

for which measurements are not avail- able. Current interests include the technological problems of combustion, nuclear waste disposal, and atmospheric ozone

depletion; the prediction of the formation

properties of organic species in the gaseous, liquid, solid, and aqueous

phases; and the production of databases

of the ubiquitous biochemical species of interest to biotechnology. The data center researchers are active in national standards-setting organizations such as ASTM, have bilateral collaborative re- search projects with research organizations in several countries, and are active

in international research organizations

such as CODATA and lUPAC.

Contact: Stanley Abramowitz, B348

Chemistry BIdg., 301/975-2587.

The chemical kinetics program at NIST provides reliable chemical

kinetics data, measurement

methods, and theoretical models. Applications of this research include combustion, new chemical technologies, the chemistry of the upper atmosphere and

other planetary atmospheres, effects of ionizing radiation on materials, solar energy conversion, biotechnology, flue- gas cleanup chemistry, acid rain, toxic waste incineration, coal conversion, and

analytical applications of kinetics. Among

the experimental projects under way at NIST are pulse radiolysis of aqueous

solutions, and kinetic mass spectrometric

studies (Fourier transform ion cyclotron resonance, high-pressure mass

Thermodynamic

Data Evaluation

Chemical

Kinetics

23
Chemical Technology

Separations

spectrometry, tandem mass spectrometry) of the kinetics and thermochemistry of ion/molecule reactions and

ion/molecule clustering processes. Researchers also are studying free- radical l<inetics using heated singlepulse shock tubes, flash photolysis

kinetic absorption spectroscopy and a

flash photolysis resonance fluorescence

technique, vacuum ultraviolet laser photolysis with kinetic absorption detection,

and high-temperature reactors. Reso- nance enhanced multiphoton ionization (REMPI) spectroscopy is used to provide

nev^, previously unobtainable data about

the electronic structures of a w\6e variety

of free radicals. REMPI procedures also lead to very sensitive and selective schemes for the optical detection of the

radicals. An important focus of the kinetics program is the production of data- bases of evaluated chemical kinetic data, as well as the design of databases

and relevant software.

Contact: Sharon G. Lias, A260

Chemistry BIdg., 301/975-2562.

0(

eparation and purification are criti- cal steps in the manufacture of '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 purity. 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 investigating novel facilitated transport membranes

for use in acid gas removal and air separations. 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 adsorption of biological macromolecules to ultrafiltration membranes, with the objective of developing better predictive models for fouling, flux decline, and chromatographic applications. Other study areas

include pervaporation membranes for close boiling mixtures and composite

and polysaccharide membranes for small biomolecule separations.

To assist the biotechnology industry,

NIST scientists are developing the fun- damental transport data, experimental

methods, and models for a number of aqueous two-phase partitioning systems.

These liquid-liquid extraction processes

are useful for inexpensively and selectively separating proteins and other bio- molecules from complex mixtures. Fundamental studies of electrophoresis, novel crystallization technologies, and

chromatography are also being conducted. State-of-the-art analytical tech- niques are used to characterize the processes under study. The insights

gained from the separations program at NIST have been the basis of applied

research in novel bioreactor designs

for the production of stereospecific

chemicals.

Contact: Subhas K. Sikdar,

303/497-5232, Paul Todd, 303/497-5563,

or John Pellegrino, 303/497-3416,

Div. 583, NIST, Boulder, CO 80303.

Research chemists Ewa Gajewski (left) and Miral Dizdaroglu

determine the chemical structure of a major type of DNA

damage caused by oxygen-derived free radicals.

24
Chemical Technology

Properties of

Fluids

Thermophysicai

and Supercritical

Properties of

Mixtures

"hermophysical properties data are

essential for the design and operation of many chemical processes

such as supercritical extraction. To

obtain these data, NiST scientists are using three new phase equilibria apparatus for studies at elevated temperatures.

One apparatus is used to perform VLE

measurements on carbon dioxide- hydrocarbon systems and refrigeranthydrocarbon systems, the second is a dew/bubble point apparatus extending to 800 K, and the third employs a palladiumsilver membrane to measure the fugacity

of hydrogen-containing mixtures. Five ex- ceptional instruments are available for making PVT, PVTx, and heat capacity

measurements on pure fluids and fluid mixtures: an isochoric PVT apparatus, a

Burnett apparatus, a combined Burnett/ isochoric PVT apparatus, a magnetic

suspension densimeter for PVT and PVTx measurements, and an instrument to measure constant volume heat capacity.

Facilities also exist to determine properties along the tvi'o-phase coexistence line of pure fluids and mixtures and to make

sound speed measurements. A well- equipped analytical laboratory and

specialized apparatus enable NIST re- searchers to devise techniques for characterizing fluids and fluid mixtures when

the temperatures, pressures, and times

involved can result in reactions during

the measurement process.

Contact: William M. Haynes, Div. 584,

Boulder, CO 80303, 303/497-3247 or Michael R. Moldover, A103 Physics

BIdg., 301/975-2459.

r

, hemical process technology re- quires an accurate knowledge of 'various thermophysicai properties

of pure, polyfunctional chemicals and

their mixtures. Research is being con- ducted at NIST on the most important of these properties—equilibrium phase

composition, density, and enthalpy. NIST

researchers are developing predictive

methods for the properties of chemically

dissimilar compounds, especially complex mixtures and aqueous solutions. Another project, a combined experimental and theoretical study, is aimed at developing accurate predictive models

for the thermodynamic and transport

properties of near critical and supercriti- cal mixtures. This work includes PVTx and VLE measurements on mixtures containing carbon dioxide, halogenated hydrocarbons, and similar supercritical solvents. Other experimental work in- volves using supercritical chromatography to measure diffusion coefficients in supercritical mixtures and theoretical studies to focus on the application of ex- tended corresponding states to supercriti- cal systems.

Contact: James F. Ely, 303/497-5467

or Thomas J. Bruno, 303/497-5158,

Div. 584, NIST, Boulder, CO 80303;

J.M.H.L. Sengers, A121 Physics BIdg.,

301/975-2463.

Awide array of experimental and

theoretical tools are being applied

to obtain practical and fundamental understanding of the structure, properties, and effects of interfaces between

fluid phases. NIST scientists are investi- gating a number of problems in this area

ranging from the conceptually simple

(e.g., measuring and/or calculating the in- terfacial tension between a liquid and its vapor) to the more complicated (e.g., determining the phase behavior of surfactant mixtures at water-air interfaces, the thicknesses of adsorbed liquid layers at solid-gas interfaces, the stability of foams, and the evolution of mists). NIST

facilities include an automated ellipsometer and an automated film balance,

quasieiastic light scattering for studying

the evolution of mists, an apparatus for measuring foam stability, and simple

setups for measuring interfacial tension. Computing facilities include a CDC 855, a Cyber 205 supercomputer, software,

and experience in simulation of fluids. Research projects are planned in several areas. One project will involve applying quasieiastic light scattering to the measurement of interfacial tension of liquid-vapor mixtures at high pressure and the measurement of the dynamics of wetting layers. Another project will focus on measuring the permeability, surface

viscosity, and surface-diffusion coeffi- cients of surfactant layers. The researchers 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

Properties of

interfaces

25
Chemical Technology

Properties of

Atmospherically

Safe Refrigerants

Radio Frequency

Wave Diagnostic

of Disperse

Systems

within a pellet) and for the large effects of ions on the thicknesses of adsorbed lay- ers. They will also study the evolution of the drop-size distribution of simple, but

nontrivial, mists comprised of two hydrocarbons suspended in their own

vapor.

Contact: Michael R. Moldover, A103

Physics BIdg., 301/975-2459.

r

hlorofluorocarbons (CFC's) have

been used widely for the past 50

years as refrigerants; as foam in building insulation, furniture, car seats; and in many other applications. Recent

evidence has shown, however, that chlorofluorocarbons (CFC's) are breaking down the ozone layer which protects the Earth from harmful levels of ultraviolet radiation. Alternative chemicals must be

found to replace the existing fluids within the next decade. For this to be achieved, an accurate knowledge of their ther- mophysical properties is required. NIST

has a research program designed to pro- vide these data to industry, ultimately in the form of interactive computer codes.

The research includes extensive experimental measurements on pure fluids and

mixtures, including PVT, PVTx, vapor

pressure, saturation density, heat capacity, thermal conductivity, viscosity, sound

speed, and surface tension. The pro- gram also includes substantial effort in modeling fluid properties and in developing equations of state.

Contact: Neil A. Olien, Div. 580, NIST,

Boulder, CO 80303, 303/497-5108.

I [

"he successful processing of paper

pulp, flour, coal slurries, and sludge

depends on accurate measure- ments of the percent of solids sus- pended in water in a pipeline. To help

improve these measurements, NIST is studying the propagation of radio waves

inside a conducting pipe filled with complex materials. One result of this research

has been the successful measurement of the solid slurry, which was accomplished

by measuring the wavelength and at- tenuation of radio waves in a pipeline

with a 32-element antenna array placed

along the axial direction. From the known

frequency and wavelength, the speed of the radio wave, and hence the dielectric constant, can be deduced. By then applying a mixing rule and the dielectric properties of the individual components,

researchers can determine the solids

fraction in a slurry. NIST is extending the

project to incorporate systems with axially varying dielectric constants, adsorption columns and settling suspensions,

for example. Other measurements, such

as polarization rotation in a swirling slurry flow and Doppler shifts due to fluid flow, are being planned.

Contact: Adolfas K. Gaigalas, 109 Fluid Mechanics BIdg., 301/975-5941

The accelerating costs of scarce

fluid resources—particularly petrochemical fluids—are producing in- creased concerns about the perform- ance levels of flow meters. Improved flow measurement traceability needs to be es- tablished and maintained so that realistic, quantified data are generated on a

continuing basis to assure practical fluid measurements at satisfactory, specified

levels of performance. To achieve the desired flow measurement traceability,

NIST is designing transfer standards to

link the performance of calibration facili- ties to appropriate national reference

standards. Because of the importance of these

measurements, transfer standards need

to be designed so that high levels of confidence can be placed in them and their performance. The new transfer standards

will be rigorously evaluated against NIST

fluid flow calibration standards. As part of evaluation, the appropriate range of cali- brations will be done on the developed

standards so that performance levels can be assured at specified levels. Current fluid metering research programs

use laser Doppler velocimetry (LDV) tech- niques to focus on the pipeflows pro- duced by conventional pipeline elements

and by standard flow conditioning ele- ments. New experimental programs are

feasible using LDV or other anemometry

or flow visualization techniques to study

other flows. NIST also has computational

capabilities to model numerically a number of closed conduit flow fields.

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

Flow

Measurement

Research and

Standards

26
Chemical Technology

Fluidized-Bed

Reactors

I

'he understanding of transport and

kinetic processes in fluidized beds

at elevated temperatures is of great

importance in many areas of cliemical engineering, including pyrolysis and combustion of solid and liquid fuels, catalytic

reactions, and destruction of tnazardous wastes. NIST maintains a fluidized-bed

facility designed and instrumented to address research problems in these technical areas. Past projects include time- resolved optical temperature measure- ments of single particles inside the bed, as well as optical studies of mixing of solid particles at elevated temperatures.

Currently, the facility is used for studies of pyrolysis and combustion of chlori- nated hydrocarbons representative of hazardous-waste constituents. Re- searchers are investigating the effects of temperature, residence time, and chemical composition of bed particles on destruction efficiency of the model

compounds and the formation of intermediate products of incomplete combustion. The analytical instruments used

include on-line gas monitors, gas chro- matography with mass-spectrometric detection, and FTIR spectroscopy.

Contact: Andrej Macek, B312 Physics

BIdg., 301/975-2610.

To understand performance of thinfilm and chemical sensors, NIST

scientists are conducting research

aimed at improving their accuracy, stability, selectivity, and response, as well as developing ideas for new measurement

techniques. Activities incorporate adhesion, oxidation, interlaminar diffusion, sur- face adsorption and desorption, and

phase morphology to investigate mechanisms of chemical sensing. The scientists use analytical methods to relate the struc- ture and composition of sensing devices

to fabricating parameters and perform- ance. Research areas include thin-film thermocouples, thin-film resistance devices, moisture sensors, pH sensors, and gas detectors. Fabrication facilities

Chemical Sensor

Research

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

Optical Sensing

in Bioreactors

available are rf and dc sputtering for both

alloy and reactive film deposition and

gas reactors. The feasibility of thin-film systems as chemical sensors is being determined as the scientists investigate the

electronic properties of films and single

crystals for dielectric strength, surface

conductance, and capacitance. For

surface-sensitive techniques, they are employing x-ray and uv photoemission,

thermal desorption spectroscopy, SIMS,

and in-situ electrical measurements to characterize appropriate chemisorptive

and molecular film systems.

Contact: Kenneth G. Kreider,

B312 Physics BIdg., 301/975-2619

or Stephen Semancik, B346 Physics

BIdg., 301/975-2606.

ndustries now recognize the potential benefit of applying recent advances in molecular biology in a diversity of sectors, such as the production of new

drugs, food additives, and chemicals

and conversion of biomass. However, im- plementation of bioprocesses requires a

closely controlled environment, normally

realizable only in batch processes. This

is primarily due to the complex kinetics of most bioreactions, separate periods of growth and product formation, bio- catalyst degeneration, contaminant risks, and mechanical difficulties of handling

rheologically complex materials. For bioprocesses to be implemented in the

future, new on-line measurement tech- niques must be developed as well as

nonintrusive measurement methods to avoid the difficulties associated with sampling contamination and long response

time.To help solve some of these problems, NIST scientists are developing opti- cal techniques for making nonintrusive,

rapid, and selective measurements.

Using fiber optics, they are able to develop probes which are sterilizable, can provide measurements with good

spatial resolution, and can be multi- plexed to provide multipoint monitoring

capability. Researchers are employing

fluorescence techniques to determine

characteristics of amino acids, dipeptides, polypeptides, and esters while Raman and resonance Raman scattering

will be used to provide more species

selectivity. Fluorescence techniques are

also expected to provide a powerful tool

for cell activity and intracellular kinetics measurements.

Contact: Hratch G. Semerjian, B312

Physics BIdg., 301/975-2609.

Biological cells are known to be electrically active as demonstrated by

the membrane potential present in

all living cells. A NIST program is con- cerned with developing measurement

techniques for observing electrical activity of cell suspensions to provide fun- damental data for sensor development in bioreactors. Both linear and nonlinear

electrical responses are under investigation. The nonlinear properties are especially interesting since they are expected

to originate from the cell membrane.

Theoretical investigations are in progress

to relate the observed electrical behavior

to the activity of membrane transport proteins. The researchers are working to achieve a better understanding of the coupling of applied electric fields to membrane proteins, which can lead to practi- cal schemes to influence the activity of

cells. Research areas include electrical impedance measurements, study of mi- crowave propagation in cell suspensions, electrostimulation of membrane

processes, and observation of electro- phoretic mobility with dynamic light scattering. Additional work is planned to measure the modulation of fluorescence

from membrane proteins by applied electric fields.

Contact: Adolfas K. Gaigalas, 109 Fluid Mechanics BIdg., 301/975-5941 or

R. Dean Astumian, 1 1 1 Fluid Mechanics

BIdg., 301/975-5951.

To minimize the cost of high-priced

fuel, U.S. industry needs to obtain maximum energy output from fuel combustion. NIST researchers are tackling this problem by attempting to im- prove combustion efficiency. The

researchers are studying the dynamics

of spray flames to investigate droplet vaporization, pyrolysis, combustion, and

particulate formation processes and to delineate the effect of chemical and

physical properties of fuels on the above

processes. The research results will provide an experimental database, with

Electrical

Measurements in Bioreactors

Particulate

and Droplet

Diagnostic in Spray Flames

28
Chemical Technology

Pressure

Standards

well-defined boundary conditions, for developing and validating spray combustion models.

The experiments are being carried out

in a spray combustion facility, with a moveable-vane swirl burner, which simulates operating conditions found in practi- cal combustion systems. A combination

of nonintrusive probing techniques is used to obtain comprehensive data on

spray combustion characteristics, includ- ing soot particle and droplet size, number density and volume fraction, gas

composition, and velocity and temperature fields. Currently NIST scientists are focusing

their efforts on laser scattering and

laser Doppler velocimetry measurements

in order to determine the correlation between droplet size and velocity dis- tributions, respectively, in both low- temperature and burning sprays.

Contact: Hratch G. Semerjian, B312

Physics BIdg., 301/975-2609.

/Ar A'

chieving better understanding and

control of the pressure measureiment process will lead to better

quality control in the manufacture of new

materials and better design and perform- ance of transducers for thousands of applications in modern technology. The

measurement of pressure from subatmospheric to 100,000 psi and above

with uncertainties of tens to hundreds of parts per million is essential in modern

technology. The most fundamental instru- ment at these high pressures is the deadweight piston gauge. In the piston gauge

a force generated in a working fluid acts against the surfaces of a piston and

against the walls of a cylinder that confines the piston. At high pressures, the

materials undergo significant distortion, which leads to limitations and uncertainties in the area on which fluid is acting.

The fluid interacts with the side of the pis- ton creating upward forces that are diffi- cult to interpret. NIST scientists are using

various tools—finite element analysis to characterize distortion, better hydrodynamic measurement and modeling of the annular region through which the fluid flows, and improved piston gage de- signs—to understand these effects.

Contact: Charles D. Ehrlich, A45

Metrology BIdg., 301/975-4834.

Improved industrial processes and

sophisticated scientific research re- quire temperature sensors that cover

wider temperature ranges with better ac- curacy and precision than previously re- quired. For example, the degradation of thermocouples exposed to high temperatures for extended periods of time repre- sents a serious impediment to temperature measurements in jet engines, fur- naces, and so forth. NIST has several

projects under way to test and improve

the performance of currently available sensors, including thermocouples, re- sistance thermometers of various types,

and optical fiber thermometers. The

temperature range covered by these

projects extends from about 0.2 K to 2100 °C. NIST has excellent temperature

calibration facilities, an automated laboratory equipped to evaluate thermocouples

at high temperatures, several laboratories equipped for work on resistance ther- mometers, and a laboratory to evaluate

optical fiber thermometers. NIST scientists are planning a series of new materials, new principles, and new techniques

to provide highly precise and accurate temperature measurements.

Contact: A. 0. McCoubrey, B128 Physics

BIdg., 301/975-4802.

.S. industry increasingly relies on

real-time monitoring of process

parameters, particularly temperature and pressure, to produce efficiently a desired end-product, to warrant safe

operation, and to assure equity in commerce. This trend is pervasive in the chemical and materials processing in- dustries, as well as in energy and raw

materials production and transfer. NIST

currently has a research program and is developing a test facility to provide a reli- able basis for the evaluation and calibration of transducer dynamical response

functions. The research seeks to develop a primary standard for dynamic temperature and pressure based on the fun- damental properties of the molecular

constituents of a dynamical system. Infor- mation about the molecules is accessed

via laser-optical diagnostic techniques,

and measurement times of the order of 10 nanoseconds at accuracy levels of 5 percent appear feasible. Through the

Temperature

Sensor Research

Dynamic

Pressure and

Temperature

Research
Chemical Technology Computer Systems

Vacuum and

Leak Standards

use of these measurement techniques, an accurately characterized dynamical

source will be developed. This reference source and its associated measurement

system will provide industry with a means

for assuring the accuracy of transducers

used to measure time varying temperature and pressure.

Contact: Gregory J. Rosasco, B118

Physics BIdg., 301/975-4813.

M

any industries depend on accurate vacuum (pressure) and leak measurements for research and

development and for process and quality

control. NIST develops and maintains pressure and vacuum standards from

above atmospheric pressure to ultrahigh vacuum; leak or flow standards are also operated from 10""^ to below 10"^ std

cc/s. Facilities for this research include

five ultrahigh vacuum systems; two low- range flowmeters; high-accuracy mercury manometers; pressure and vacuum

control systems; and a variety of vacuum, electronic, data acquisition, and

data analysis equipment.

These facilities and measurement

capabilities are used by NIST re- searchers to develop improved measure- ment techniques and equipment and to investigate the performance of vacuum

and pressure equipment, specifically mechanical pressure gauges, momentum

transfer gauges, ionization gauges,

standard leaks, and residual gas analyzers. In addition, NIST plans to use this measurement capability to investigate

properties of materials and physical phe- nomena of fundamental interest. Among

the planned projects is the development

of reference standards for the transition regime between low pressures measured

by mechanical or electromechanical

gauges and pressures measured by vacuum technology devices. The

development of accurate methods to measure and characterize ultrahigh vacuum systems is also under

investigation.

Contact: Charles R. Tilford, A51

Metrology BIdg., 301/975-4828.

Computer systems are critical ele- ments of today's business and

scientific environments. However,

as sensitive and critical information is processed and stored on computer sys- tems that are often interconnected by

local area networks, there is an increasing need for methods to protect that infor- mation from unauthorized access or modification. But selection of information

security measures should be based on a

cost analysis of such measures and the

resulting reduction in losses. NIST re- searchers are investigating various

technologies that can be employed to achieve additional control and security of information on computer systems. Their research involves the identification, analysis, development, and application of these technologies.

Although it is desirable to have security mechanisms as an integral part of computer systems and networks, this is not always possible or economical be- cause such mechanisms are often not

part of the original system design. NIST

researchers also are examining the tech- nology available to enhance the security

of existing systems. This research in- volves identifying, analyzing, and comparing security mechanisms used in isolation or combination.

Contact: Stuart Katzke, A216

Technology BIdg., 301/975-2929.

NIST has initiated a program to bring together government organizations and contractors interested

in interoperability and security in the Open Systems Interconnection (OSI)

computer network architecture and the Integrated Services Digital Network

(ISDN) communications architecture. Researchers in the laboratory-based

program develop prototype systems to demonstrate the interoperability of pro- posed standards for OSI and ISDN using a selected set of security services. These

standards are expected to be implemented in commercial applications with a broad market. The technical objectives of the pro- gram are: ( 1

) to develop demonstration

prototypes of applications and equipment, including hardware and software,

that provide one or more levels of security in an OSI and/or ISDN environment;

Computer

Systems Security

Integrated OSI,

ISDN, and

Security Program

30
Computer Systems

NIST researchers are working with the Defense Advanced Research Projects Agency and a private company to develop a

prototype system using a "smart" token that will make it tougher for hackers to gain access to a computer network.

(2) to develop specifications for data for- mats, protocols, interfaces, and support

systems for security in an OSI/ISDN en- vironment thiat can be used as a basis for Federal information Processing Standards; and (3) to provide a laboratory in which users, developers, and vendors

jointly can define, develop, and test sys- tems that will provide a range of telecommunications, network management, and

security services in a distributed information processing environment.

Contact: Stuart Katzke, A216

Technology BIdg., 301/975-2929.

Database Testing

t;

"0 implement the management of information resources, NIST re- searchers are developing test methods and techniques to evaluate im- plementations of network database lan- guage (NDL), structured query language

(SQL), information resource dictionary

system (IRDS), Abstract Syntax Notation

1 (ASN.1), and data descriptive file (DDF) for conformance to federal,

national, and international standards. The

researchers are attempting to derive a

general methodology for designing con- formance tests, to use this methodology

to generate test suites, and to evaluate

the test suites for effectiveness. A prototype implementation of the IRDS specifications, 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 protect data communicated through

computer networks by developing

protocols for secure key distribution and

secure data transmission using public

key algorithms. The protocols are in- tended to protect keys from initial generation to final distribution to all authorized

parties. In designing the protocols, re- searchers are giving special attention to preventing substitution of the keys by un- authorized parties. The protocols will transmit keys and data within a large

computer network with automated

communications capabilities and will be

consistent with those used in the Open

Systems Interconnection Reference

Model. Project results will be published in a NIST publication on public key cryptographic protocols.

Contact: Stuart Katzke, A216

Technology BIdg., 301/975-2929.

Geographic information systems

(GIS) technology allows users to

collect, manage, and analyze

large volumes of spatially referenced

and associated data. New research

directions are emerging from the inter- disciplinary uses of GIS. NIST re- searchers are exploring future GIS

technology through studies into inte- grating computer graphics standards,

database management standards, expert systems technology, and optical disk technology to support GIS applications. Their research is focused on

providing GIS compatibility through

standards and conformance testing

for future GIS standards such as the

Public Key

Cryptographic

Protocols

Geographic

information

Systems

II

31
Computer Systems

Computer

Graphics Testing

Automated

Protocol Methods

Digital Cartographic Data Standard. Be- cause tine activities of many governmental and private organizations are land and/or locationally related, GIS tech- nology will be important in integrating existing spatial data for these organizations.

Contact: Henry Tom, A266 Technology

BIdg., 301/975-3271.

Ti

"he development of several graphics

standards and work on related con- formance testing and measurement

techniques for graphics software are under way at NIST. Specifically, NIST re- searchers are testing implementations of the graphical kernel system (GKS), the computer graphics metafile (CGM), GKS

for three dimensions, and the program- mers hierarchical interactive graphics

standard (PHIGS) for conformance to existing and emerging federal, national,

and international standards. Researchers

are attempting to derive a general

methodology for designing conformance

tests, to use this methodology to generate test suites, and to evaluate the test suites for effectiveness. The computer

graphics laboratory, which contains

various computer graphics hardware and

software systems designed to support

standard specifications, is used in these

efforts. An existing test suite for GKS is available with FORTRAN interface. Priority is being given to testing methodologies and test suites for PHIGS, CGM, and

the conversion of FORTRAN tests for all computer graphics standards to other languages (C, Pascal, and Ada).

Contact: Mark W. Skall, A266

Technology BIdg., 301/975-3265.

N

1ST researchers are designing

tools for editing, compiling, and in- terpreting computer communications protocol specifications. The goal of the research is to advance the state of the art in using such tools to realize automatically executable implementation of the protocols. As part of this project,

NIST researchers are developing a

syntax-directed editor for Estelle and,

using the same grammar, devising a

portable compiler for Estelle and the supporting runtime libraries.

Contact: Kevin Mills, B21 7 Technology

BIdg., 301/975-3618.

To protect computer systems andnetworks, NIST is developing a comprehensive security architecture consistent with the Open Systems Inter- connection (OSI) Reference Model.

Cryptographic functions are being implemented in certain OSI layers to provide

data secrecy, data integrity, and peer entity authentication. The research will combine the security standards for individual OSI layers into a unified security framework. As part of this project, NIST re- searchers will define a common interface

for cryptographic algorithms and develop

a key management methodology

capable of providing keys to the cryptographic functions of any layer.

Contact: Stuart Katzke, A216

Technology BIdg., 301/975-2929.

NIST researchers are working with industry to establish a set of stand- ards to exchange network management information between heterogenous

management systems. Their goal is to establish a standard enabling integrated, in- teroperable, automated management of multivendor computer systems, routers, bridges, switches, multiplexors, modems, and provider services. The re- searchers are defining protocols to exchange management information;

identifying, collecting, and specifying the format of managed objects; defining pro- tocols to support management functions

in the areas of fault, configuration, per- formance, security, and accounting: and

implementing prototype management

systems reflecting the protocols and

specifications. Other research areas of interest include network management

user displays, network management

applications software development, and

application of expert systems to network

management.

Contact: Kevin L. Mills, B217

Technology BIdg., 301/975-3618.

Networic Security

Architecture

Network

IManagement

32
Computer Systems

Directory

Services and

Dynamic Routing

Performance of

ModernArchitecture

Computers

Optical Disic

n cooperation with industry, NIST is pursuing development of commercial

off-the-slnelf products implementing

standard distributed directory services

and dynamic routing. The distributed directory services require research work

in several areas, including access control, replication of information, extension

of directory schemas, and distributed update. Proposed solutions to these

directory problems are implemented and

tested in a NIST prototype directory im- plementation conforming to the inter- national directory standard (X.500).

The NIST dynamic routing research is focused on exchange of routing information between routing systems in autono- mous domains. NIST researchers pro- pose and analyze a variety of mechanisms to accommodate such exchanges,

and they investigate proposed algo- rithms through simulation models. The

aim of this research is development of an

international standard for exchange of routing information between autonomous

domains.

Contact: Kevin L. Mills, B217

Technology BIdg., 301/975-3618.

N

1ST researchers in the area of computer-systems performance

are promoting the effective evaluation and efficient use of advanced computers by the federal government. Their areas of interest include: characterization

of new computer architectures to identify

improved ADP technology for applications; exploration of economical programming methods that standardize across

classes of architecture; and design of co- herent evaluations that economically and

reliably characterize the machines. Two

dedicated, instrumented multiprocessors serve as special project resources. One

has 16 nodes loosely coupled as a hypercube, and the other has 16 processors in a shared-memory configuration.

Contact: Robert Carpenter, B364

Materials BIdg., 301/975-5677.

a:

s industrial standards for optical disk media evolve, test methods

Iwill be needed for conformance

testing of the media, NIST researchers

are setting up a laboratory to develop

and demonstrate data/media inter- change tests and to verify conformance

to established or planned national and in- ternational standards for rewritable and

write once, read many (WORM) type

optical disks. The program will be coordi- nated with voluntary standards committees and interested federal agencies.

Contact: Dana S. Grubb, A61

Technology BIdg., 301/975-2915.

NiST researchers are developing

standards and guidelines for im- plementation and use of dis- tributed computer systems. Their current

activities include: participation in the development of a voluntary industry

standard for distributed transaction processing, development of a software backplane (a standard platform for the development of distributed applications),

research in distributed information retrieval systems, and formal description

of distributed systems. The distributed systems laboratory is maintained to support prototype development of research

activities.

Contact: Wayne H. McCoy, A216

Technology BIdg., 301/975-2984.

Recent advances in automatic

speech recognition technology

have resulted in improved abilities to recognize correctly continuous speech

with lexicon sizes of at least 1 ,000 words.

Speech databases are typically large in size (gigabytes) and too costly for any one organization to develop. To improve

the technology, the research community

relies heavily on shared use of the databases and standard test methodologies. With support from DARPA and

other agencies, NIST has collected speech database material and, using CDROM technology, distributed this material

to more than 100 research organizations.

Researchers at NIST also have

developed CD-ROM format speech

databases that are used for speech rec- ognition research in large vocabulary

speech (5,000-word office correspondence), word spotting, speaker identification/verification, and goal-directed

Distributed

Systems

Automatic

Speech

Recognition

33
Computer Systems

Electronics and

Electrical Engineering

Image

Recognition

Integrated

Services Digital

Networi(s

spontaneous speech. Among the re- search facilities are a VAX 1 1/780, a Sun

workstation, and speech processing

peripherals and software tools. Areas of interest include characterization of the speech database materials (e.g., acoustic-phonetic locators and classifi- ers), artificial neural nets, performance

measurement, and natural languages.

Contact: David S. Pallett, A216

Technology BIdg., 301/975-2935.

mage-recognition research at NIST io- cuses on developing methods for eval- uation of image quality, compression

efficiency, and image systems used in optical-character recognition. These

methods of evaluation are designed to in- clude highly parallel computers and

special-purpose chips as well as conventional computer architectures. The

methods being developed are used for automated fingerprint recognition, auto- mation of data entry from images of forms, and measurement of recognition

systems on realistic applications. A

general model of the recognition process

in parallel computers is being implemented to provide better methods to analyze the performance of SIMD (single

instruction multiple data) computers for image compression, image quality evaluation, and recognition accuracy.

Contact: Charles L. Wilson, A216

Technology BIdg., 301/975-2080.

In

cooperation with industrial and other

users, NIST advances the development of standards for Integrated Services Digital Networks (ISDN) which

combine voice, data, text, and image

communications over a single network

connection. Research in this area fo- cuses on the measurement capabilities

and testbed facilities required to develop

conformance tests and performance

metrics for emerging ISDN standards.

Activities include support for standards

writing, development of the technical foundation for implementation agree- ments on protocol options, and testing

ISDN implementations for interoperabiiity.

Contact: George Kraft, 8364 Materials

BIdg., 301/975-3389.

Researchers in the NIST antenna

metrology program are developing

reliable techniques and standards

for measuring key performance parameters of antennas and components used

with satellites, earth terminals, radars,

and communications systems. Scientists now are using near-field scanning to characterize microwave and millimeter- wave antennas. Their current goals are to improve software and error analysis for the spherical near-field technique and to apply all the near-field techniques to higher frequencies. Other research areas

include spacecraft and phased-array antenna measurements and antenna sys- tems measurements using celestial radio sources.

Contact: Alien C. Newell, Div. 723.05,

NIST, Boulder, CO 80303, 303/497-3743.

Inadequate knowledge of the electro- magnetic properties of materials inhibits development of new technologies,

drives up the cost of systems and components, and may prevent achievement

of optimal performance levels. A relatively new NIST program in materials is aimed at developing primary standards

and accurate techniques for measuring

the dielectric properties of materials used

in electromagnetic applications. Scientists at NIST have developed new preci- sion measurement techniques for complex permittivity based on improved

theory and new cavity and transmission

line sample holders. The researchers currently are performing the necessary error analyses and, in the future, plan to cover

a variety of important materials and

temperature ranges over the frequency

range of approximately 10 MHz to 100

GHz. Reliable nondestructive methods

are needed to measure complex permittivity and the reflectivity of large sheets of material or structures.

Contact: William A. Kissick, Div. 723.02,

NIST, Boulder, CO 80303, 303/497-3339.

NIST researchers are engaged in a wide range of projects aimed at quantifying electromagnetic inter- ference (EMI) and electromagnetic compatibility (EMC). One thrust of the NIST

work is to develop measurement tech- niques and methodologies for measuring

Antenna

Measurements

Dielectric

Properties of

Materials

Electromagnetic

Interference and

Compatibility

34
Electronics and Electrical Engineering

Advanced

Microwave/

Millimeter Wave

Metrology

Magnetics

emission of unintentional radiation from

electronic devices. Another aspect under

active investigation is the susceptibility of electronic equipment to such radiation. The researchers are identifying and defin- ing quantities that characterize the susceptibility of a device and then developing methods to measure those quantities.

Successful completion of this research

should result in the development of stand- ards and measurement techniques for EMI and EMC, which are meaningful,

technically practical, and reliable. These

techniques could then be incorporated

into voluntary standards by both U.S. and international standard organizations.

Contact: Motohisa Kanda, Div. 723.03,

NIST, Boulder, CO 80303, 303/497-5320.

I

:

"he rapidly developing and expanding microwave technology requires

research in advanced microwave

measurements and standards. The micro- wave industry and the Department of Defense depend on NIST for calibrations

of transfer standards to provide the measurement 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 currently are developing greatly improved

power and impedance standards and ex- tending measurement services to cover

millimeter waves and miniature coaxial connectors. Collaborative work is particularly desirable in microwave and millimeter wave circuit theory as applied to both

traditional and advanced circuits and

systems such as MIMIC devices. Applications include development of advanced

automated network analyzers using

six-ports.

Contact: David Russell, Div. 723.01,

NIST, Boulder, CO 80303, 303/497-3148.

t;

"0 provide a sound basis for measurement techniques, NIST researchers are developing a basic understanding of the magnetic properties of materials and structures. Specifically,

they are studying precision cryogenic vi- brating sample magnetometers, systems

based on superconducting quantum

interference devices (SQUID's), and

laser-based magneto-optical systems.

The primary emphasis of the program is on computer-related magnetics, but work

is also under way on the basic physics of magnetic materials, such as spin

glasses, and on the measurement of very

low-level magnetic effects. In a related program in eddy current nondestructive

evaluation (NDE), researchers are developing methods for mapping the very small ac magnetic fields associated

with eddy current test probes.

Contact: Fred R. Fickett, Div. 724.05,

NIST, Boulder, CO 80303, 303/497-3785.

Douglas T. Tamura, an electronics technician, aligns anten- nas being calibrated on the extrapolation range, which is part

of the near-field antenna measurement facility.

Recent advances in superconductivity have resulted in a critical need

for measurement technology to characterize the different types of super- conductors, which now range from very

fine filament alloy conductors used in the Superconducting Super Collider cables

to a variety of high-temperature ceramic

superconductors. Active research pro- grams at NIST involve measurement tech- niques for critical current, critical magnetic field, ac losses, magnetic hysteresis, and electron tunneling. In addition, specialized experimental work is being done to determine the effect of

strain on the superconducting properties

of low-temperature commercial conductors and the high-temperature materials.

Superconductor

Measurements

35
I

Electronics and Electrical Engineering

Raman Scattering

Compound

Semiconductor

Studies

In a recent collaboration with industry, the resistance of contacts between nor- mal metals and high-temperature super- conductors was decreased by eight

orders of magnitude, allowing accurate measurements of the magnetic-field de- pendence of the critical current. A stand- ard for measuring critical current in low-temperature superconductors has

been published through ASTM, and a Standard Reference Material (SRM) has

been produced for use in calibrating criti- cal current measurement apparatus. A

new Reference Material for large currents

is under development.

Contact: Fred Fickett, Div. 724.05, NIST,

Boulder, CO 80303, 303/497-3785.

ome of the world's most advanced

measurement facilities for the rapid

'advancement of electrical and electronic technology are available at NIST. One example is the Raman spectroscopy

facility, which is used for light-scattering

studies of liquids, solids, and gases.

Specific research conducted at the facility includes chemical and structural analysis of thin films and ion-implanted

layers, investigations of impurities and

other defects in semiconductors, studies

of the structural and electrical properties

of seiniconductor superlattices and quantum wells, and development of new quantitative spectroscopic methods.

Equipment is available for studies of the pressure and temperature depend- ence of Raman spectra in the range 4 to 600 K and up to approximately 100 kbar

using a diamond-anvil pressure cell. The

laboratory is equipped with variable wavelength lasers, multiple-grating monochromators, and automated digital data

acquisition and processing.

Contact: Michael I. Bell, A305

Technology Bldg., 301/975-2044.

I esearch to improve the metrology

used to characterize compound

semiconductors, including alloys

and artificially structured materials, is under way at NIST. Scientists are studying the electrical, optical, and physical

properties of materials, such as gallium

arsenide and mercury cadmium telluride, to better understand and characterize

presently available device material. A

number of measurement techniques are used in this work, including ellipsometry,

optical absorption, photoluminescence,

infrared and Raman spectroscopy. Hall effect and resistivity measurements,

capacitance-voltage profiling, deep-level

transient spectroscopy, photoconductivity and photocapacitance, infrared imaging, and x-ray topography absorption

and rocking curve analysis using syn- chrotron radiation.

Contact: Michael I, Bell, 301/975-2044

or David G. Seller, 301/975-2074, A305

Technology Bldg.

Studies of structural properties of matter have always relied on the use of x-ray techniques. Accordingly, NIST has constructed several x-ray beam lines at the National Synchrotron

Light Source, Brookhaven National Laboratory. One of these beams pro- vides collimated, intense energy-tunable

X rays between 5 and 30 keV, which are

4 to 6 orders of magnitude brighter than

X rays from conventional laboratory sources. The facility supports x-ray absorption and x-ray fluorescence measurements; x-ray scattering, diffraction, and

standing wave capabilities are being

added. Researchers are investigating

semiconductor structures, including

ohmic and Schottky metallizations,

AIGaAs/GaAs interfaces, buried im- planted layers, and heavily doped layers.

A number of collaborative projects are under way with industrial and university

research groups and with other govern- ment laboratories.

Contact: Charles E. Bouldin,

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

NIST conducts research in semiconductor materials, processes, devices, and integrated circuits to provide the necessary basis for understanding measurement-related require- ments in semiconductor technology. As

part of this program, NIST scientists are employing electrical, optical, and x-ray methods to study the resistivity, dopant

Synchrotron

Radiation

Silicon

Characterization

36
Electronics and Electrical Engineering

Semiconductor

Processing

Advanced

integrated

Circuit Test

Structure

Metrology

distribution, and concentration of electri- cally inactive impurities, such as carbon

and oxygen, in silicon. They are developing new or improved techniques by two- and three-dimensional mapping of these

properties, refining the quantitative

aspects of existing methods, and devel- oping nondestructive methods. Measure- ment techniques include four-probe,

spreading resistance, and capacitancevoltage; Fourier transform infrared spectroscopy; deep-level transient spectroscopy; x-ray topography; and synchrotron

radiation studies.

Contact: Michael I. Bell, A305

Technology BIdg., 301/975-2044

or Jeremiah R. Lovi^ney, B310 Technology BIdg., 301/975-2048.

Theoretical and experimental re- search on semiconductor materials and process physics at NIST is fo- cused on improving understanding of in- tegrated circuit fabrication technology

and increasing capability to characterize

materials and processes. Utilizing proc- essing equipment and techniques appropriate to VLSI chip fabrication, NIST

scientists are conducting experimental

studies on issues related to state-of-theart semiconductor processing in a well- equipped clean-room semiconductor

processing laboratory. Researchers are studying ion-implantation damage, oxidation grow/th and interface trap formation, materials effects caused by ion etching,

thin-film properties, and plasma and ion- beam chemistry. Other areas of interest include submicron (submicrometer)

photolithography, reactive ion etching,

development of Standard Reference

Materials for use in the semiconductor

industry, and chemical and vapor

deposition.

Contact: Donald Novotny, 301/975-2699

or James Comas, 301/975-2061, A35

7

Technology BIdg.

Integrated circuit test structures and

test methods developed by NIST are widely used by the semiconductor in- dustry and other government agencies.

These devices can be used to characterize integrated circuit (IC) manufacturing processes, to evaluate the effectiveness of semiconductor processing equipment, to obtain crucial parameters for process or circuit simulators, and for product acceptance. NIST work involves

test structure design, modeling, data acquisition, and data analysis. Institute en- gineers are investigating artificial intelli- gence techniques for the rapid diagnosis

of IC manufacturing processes and for establishing methods to determine the

reliability of thin films used in state-of-theart microcircuits.

Contact: Loren W. Linholm, B360

Technology BIdg., 301/975-2052.

To develop physically sound tech- niques for characterizing, analyzing,

and predicting the operation and

performance of semiconductor devices,

NIST researchers are designing and

improving measurement methods to de- termine critical device parameters for both VLSI-scale and power devices. Re- search in device modeling includes two- dimensional silicon MOSFET and GaAs

MESFET model development and investigations into the validity of the physical

assumptions typically employed in silicon bipolar and GaAs device models. Theoretical research is carried out on the

transport of ions and electrons in semiconductors for improved process modeling, and experimental research on

the nature and characterization of electronic states in oxides and at oxide/

semiconductor interfaces is under way. NIST scientists are developing methods

for physical and electrical measurements

of device and material parameters which

are critical for verifying the accuracy and

validity of device models. In addition,

they are researching the electrical and

thermal properties of power semiconductor devices.

Contact: Herbert S. Bennett, B310

Technology BIdg., 301/975-2053.

The controlled grow/th capabilities of molecular beam epitaxy (MBE) have

resulted in the fabrication of struc- tures that represent a new class of semiconductors with properties which do not

exist in bulk materials. The MBE program

at NIST includes the growth and characterization of GaAs and AIGaAs layers, as

well as the growth of heterostructures for

Semiconductor

Devices

Molecular Beam

Epitaxy

37
Electronics and Electrical Engineering

superlattice and quantum confinement

studies. Scientists examine fundamental

properties of the MBE layers using photoluminescence, deep-level-transient spectroscopy, Hall effect, secondary-ion- mass spectroscopy, and in-situ reflection electron diffraction (RED). Studies are under way to correlate RED oscillation in- tensity measurements with material quality and growth parameters.The MBE

program is an interactive effort, and

cooperative research opportunities exist

in a variety of materials characterization and device-related areas.

Contact: James Comas, 301/975-2061

Wen Tseng, 301/975-5291 , or Joseph

Pellegrino, 301/975-2123, A357

Technology BIdg.

stability, and performance under temperature shock and power interruption.

The aim of these investigations is to

identify devices suitable for a rugged

10-V transportable standard capable of providing sub-part-per-million (ppm) ac- curacy when used as a transport stand- ard between laboratories. The effects of temperature extremes, physical shock,

and shipping delays on diode output are

of special interest. NIST also is producing a stable

1 .018-V output derived from a solid-state reference. Researchers are focusing on

the design and manufacture of low-noise, stable resistors that are immune to temperature shock and power interruption. Facilities are available to test Zener

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.

Wen Tseng, materials research engineer, observes an in-situ reflection electron diffraction pattern during the growth of

gallium arsenide.

Solid-state DC

Voltage

Standards R

irecision voltage standards based

on solid-state references are find- ing increasing use in do voltage

metrology, particularly in the design and

support of high-accuracy digital volt- meters and automated test equipment.

To improve the quality of these standards, NIST scientists are carrying out a

research program on Zener diodes and

similar devices. They are investigating

device properties such as temperature

coefficient, short-term noise, long-term

Thermal voltage and current converters offer the most accurate and

broadband method for measuring

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- ence to the NIST primary standards

special multijunction thermal converters whose performance is known. These pri- mary and working standards in common

use throughout the metrology community

employ thermal converters fabricated

from wire elements. Researchers at NIST

are studying new methods for the manufacture of film thermal converter struc- tures made by the use of photolithography on silicon substrates. The application of this new technology may result in improved performance and reduction in the cost of thermal converters.

Contact: Joseph R. Kinard,

301/975-4250 or Norman B. Belecki,

301/975-4223, B146 Metrology BIdg.

Advanced AC

Voltage and

Current

Measurements

38
Electronics and Electrical Engineering

Waveform

Recorder

Standards

Electro-optical

Metrology

AC Voltage

Standards

A;

s part of a program aimed at meeting the metroiogical needs

^involved in improving signal acquisition and processing systems, NIST

researchers are developing theory,

methods, and standards for waveform

metrology of conducted signals. The

scientists are conducting the theoretical and experimental research necessary to develop standards for determining the performance of waveform recorders operating nominally below 10 MHz and will develop techniques for synthesis of preci- sion waveforms and for characterization

of those waveforms. Theoretical studies

will be conducted on Fourier analysis, deconvolution techniques, and time-domain

analysis. Program plans include experimental work in precision pulse generation, static and dynamic testing, and

assembly and interpretive level programming for hardware control.

Contact: Barry A. Bell, B162 Metrology

BIdg., 301/975-2402.

r:

I esearchers at NIST are developing

electro-optical methods to measure

.electrical quantities and phenomena as part of a program to develop

theory, methods, and physical standards

for measuring electrical quantities in advanced high-voltage/high-power sys- tems. Theoretical studies are focused on

the use of finite-element code for electricfield computation and computer-aided

data acquisition and analysis. Experimental research includes high-voltage ac, do, and impulse measurements; highspeed camera techniques; optical multi- channel analyzers; and lasers and

detectors.

Contact: William E. Anderson, B344

Metrology BIdg., 301/975-2403.

N

1ST is conducting both theoretical and experimental research on the synthesis of precision ac waveforms for use in ac voltage standards

operating nominally below 10 MHz. The

theoretical work includes Walsh functions and Fourier analysis, time-domain analysis, and precision RMS-to-dc conversion

techniques. Experimental work involves

high-speed, high-accuracy digital-toanalog conversion; precision, highspeed switching; assembly and

interpretive level programming for hard- ware control; and wideband, fast-settling

amplifiers.

Contact: Barry A. Bell BIdg., 301/975-2402.

B162 Metrology

New strategies are needed to eval- uate the performance of complex

electronic circuits using the fewest

possible tests. A new program is under

way at NIST which includes theoretical studies of modeling for nonlinear sys- tems, optimization techniques using

matrices, statistical and random processes, and artificial intelligence. In addition, experimental work will address test strategies for component and instrument

testing; fault diagnosis, function testing,

and calibration; and computer analysis

using both desktop computers and

supercomputers.

Contact: Barry A. Bell, B162 Metrology

BIdg., 301/975-2402.

Scientists at NIST are developing

measurement methods to characterize gaseous dielectrics for highvoltage power systems. Theoretical work

is expected to address Boltzmann equilibrium statistics, chemical kinetics code,

and computer-aided data acquisition

and analysis. Experimental work will focus on high-voltage ac and dc tests, gas chromatograph and mass spectrometer techniques for chemical characterization, and partial discharge measurements. Much of MIST'S work in advanced power metrology is performed in newly completed high-voltage and high- current laboratories. These facilities can

generate voltage pulses with peak amplitudes up to 600,000 volts and current pulses with peak amplitudes up to 100,000 amperes.

Contact: William E. Anderson, B344

Metrology BIdg., 301/975-2403.

Testing

Electronic

Systems

Gaseous

Dielectrics

39
Fire Research

Flammability and

Toxicity

Measurement

Fire Simulation

nstitute researchers are creating ways

to measure and characterize the combustibility of furnishings and building materials and the extent to which combustion products affect living organisms.

NIST research typically focuses on as- sessing the appropriate applications of the NIST toxicity screening test, evaluating the extent to which a limited number

of gases determine the lethality of combustion products, and developing a methodology for predicting soot and gas

production in full-scale fires from benchscale methods. In addition. Institute re- searchers are generating a detailed model for the burning of upholstered

furniture and aiding the use of the cone

calorimeter in engineering and code

applications.

Contact: Vytenis Babrauskas, A363

Polymer BIdg., 301/975-6679.

"his project in fire research is designed to provide the expedient

transfer of scientifically based tech- nology from NIST to the professional user community and to create a link between

NIST computer-based activity and others doing similar or complementary work. Over the past decade, NIST researchers

have developed many computer models

of various aspects of fire. Researchers

develop engineering systems for design

application as well as expert systems,

collect supporting data and programs, and operate a working and training

laboratory dedicated to computer modeling and other fire-safety computations.

Contact: Harold E. Nelson, A247

Polymer BIdg., 301/975-6869.

hand-calculation methods for estimating

hazards and production of design

curves/tables to be used by architects and engineers. To ensure widespread

use, the necessary data must be readily

available, and data input and presentation must be in terms readily understandable by the average professional.

Thus, the projects include a strong emphasis on state-of-the-art computer

graphics and computer-aided design

techniques.

Contact: Richard W. Bukowski,

Polymer BIdg., 301/975-6850.

B356

Predicting fire growth requires a fun- damental understanding of elemental fire processes. The Institute is helping to improve this understanding by

developing predictive methods to describe the processes of fire growth and

the elemental processes of fire growth

and extinction as related to gaseous, liq- uid, and solid fuel combustion and the performance of fire safety systems. Researchers are exploring fire growth within a single compartment, the spread of fire to adjoining spaces in multicompartment

structures, and the action of fire suppressants. In addition, they are examining the

overall dynamics of the fire scenario and

related elemental processes, such as ig- nition, flame spread, pyrolysis, extinction,

and fire-related transport processes. For these studies, they utilize mathematical

techniques, experimental studies, correlations, and similitude methods to develop

predictions.

Contact: James G. Quintiere, B250

Polymer BIdg., 301/975-6863.

Fire Growth and

Extinction

Hazard Analysis "he United States has one of the worst fire records in the industrial- ized world. NIST researchers are helping to reduce the losses and the cost

of fire protection by providing scientific and engineering bases needed by manufacturers and the fire protection community. One project involves the development of predictive, analytical methods

which permit the quantitative assess- ment of hazard and risk from fires. Re- searchers base these methods on

numerical modeling but also include

NIST is conducting research to develop a scientific base for the

gasification and combustion of natural and synthetic polymers, particularly

for the more applied fire research activities. For example, NIST scientists are working on the kinetics and heats of combustion for wood, theoretical modeling

of thermal degradation of polymers,

smoldering research, and detailed degradation mechanisms of polymers.

Contact: Takashi Kashiwagi, B258

Polymer BIdg., 301/975-6693.

Polymer

Combustion

Research

40
Manufacturing Engineering

Automated

Manufacturing

Systems

Hardware

Precision

Engineering and

Nanotechnoiogy

Automated manufacturing systems

include flexible, small-batch manufacturing systems, and machine

tools into which intelligent sensors and

controls of the production processes, as

well as the machining itself, have been

embedded. To support such developments 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 correction 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, propagation, 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 modeling and measuring the fields point-bypoint within the solids.

Contact: Donald S. Blomquist, B108

Sound BIdg., 301/975-6600.

Precision engineering forms the foun- dation for established devices such

as modern coordinate measuring

machines (CMM's) as well as for the emerging "nanotechnoiogy" of nanostructures—the fabrication of devices

with physical features of the order of

1 nanometer (one-billionth of a meter or

40-billionths of an inch) in size. Nanotechnoiogy holds the promise of many

new industrial products including, for ex- ample, mechanical pumps small enough

to be implanted into arteries, surgically al- tered DNA molecules, and electronic devices hundreds of times smaller than those available today. Using an array of state-of-the-art coordinate measuring machines and advanced electron-probe in- struments, NIST precision engineering

Metrologist Ralph Veale monitors the performance of a robot

at the inspection workstation in the NISTAutomated Manufacturing Research Facility.

researchers are developing the capabilities to precisely observe, locate, fabri- cate, and measure the nanometer-sized

features of such devices.

Contact: Dennis A. Swyt, A109

Metrology BIdg., 301/975-3463.

41
Manufacturing Engineering « Materials Reliability

Automated

IManufacturing

Systems Software R

'or industries creating and using

' computer-controlled manufacturing

systems, software systems are the

critical element. NIST provides research

for software in automated manufacturing

systems in several areas. In automated

process planning, researchers are investigating data structures for automated

process planning, distributed system

architectures, machinable-feature identifi- cation, and expert systems/machinelearning for manufacturing systems.

Researchers also are studying architectures, algorithms, and techniques for real- time adaptive control, scheduling, and

optimization of cell- and workstation-level operations for FMS cell and workstation control systems. In addition, for manufacturing systems architectures,

they are devising functional models of manufacturing organizations to standard

system architectures.

NIST researchers are exploring

ways to achieve the great potential

of composite materials for structural applications. Using acoustical and

optical techniques, the researchers are

investigating the mechanisms of fracture

in laminated plates. In support of the nondestructive evaluation program, re- searchers are using finite-element and finite-difference methods to simulate

and model acoustic-wave propagation.

Another project involves refining theoreti- cal models and computer programs to predict near- and far-field singularities of the various damage types in laminated

structures. NIST scientists also are monitoring damage initiation in situ by embedding optical fiber sensors in composite

structures. Ail projects emphasize evaluation of the potential structural perform- ance of new advanced composite

materials.

Composite

iVIechanics

Contact: Howard M. Bloom, A127

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

Robot Systems N1ST conducts research in intelligent-machine systems for manufacturing, construction,

space satellite servicing, and intelligent vehicle applications. NIST researchers

are investigating standard architectures

for real-time intelligent control, which in- volves hierarchical task decomposition,

world modeling, and sensory processing.

The research includes real-time planning; the representation of space, time,

objects, and events; and the analysis of data from a variety of sensors, such as TV cameras, sonar, and tactile arrays. Researchers are also studying programming methods and operator interfaces

for intelligent vehicles and telerobots. Methods are being developed for measuring the performance of intelligent

machine systems, including software per- formance. Research in advanced struc- tures for robot systems includes robot cranes and inflatable structures.

Contact: James S. Albus, B124

Metrology BIdg., 301/975-3418.

NIST scientists are developing

acoustic and electromagnetic sensors for material characterization,

including electromagnetic-acoustic trans- ducers (EMAT's), arrays of piezoelectric

polymers, and eddy current and capacitive probes.

EMAT's are used for noncontacting

applications, where it is not possible to have an intervening material couple

sound from transducer to specimen.

For example, an EMAT embedded in a

rail is used to inspect railroad wheels for cracks in a roll-by mode. Researchers

are investigating the possible use of EMAT's at the input to an automated

press shop, where automobile body

parts are formed. Formability measure- ments could be made on moving sheet,

and materials with improper formability

would be rejected from the production

line.Acoustic arrays are useful in medical

imaging, where their unique advantages

allow suppression of artifacts to give better 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.

Nondestructive

Evaluation (NDE)
Materials Reliability

Thermomechanical

Processing

NIST scientists Inave developed eddy

current probes and techniques for detecting and sizing small defects that could prove to be critical in aircraft and other

structures. Capacitive probes are being

investigated as a noncontacting means

to monitor sintering of ceramics, with possible use as a process control in the production of superconductors. Another

application under study is noninvasive cure monitoring of composites.

Contact: Alfred V. Clark, Div. 430, NIST,

Boulder, CO 80303, 303/497-3159.

M

etals producers and manufacturers rely heavily on pilot-scale or production facilities for the development of new alloys or new manufacturing schedules. This is not only ex- pensive but can also yield unreliable

results. These processing problems can

be alleviated by using a more economical, versatile, and reproducible laboratory facility. Controlled thermomechanical

processing (TMP) offers the opportunity

to produce superior steels at lower cost due to the elimination of post-heat treat- ment—an energy-intensive process. NIST scientists and engineers have

designed and built a computerized,

laboratory-scale, hot-deformation apparatus 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 stressstrain curve at high strain rates, and

phase transformation characteristics. The apparatus is used to characterize

directly cooled forging steel during simulated forging operations in an attempt to develop optimized steels and forging

procedures.

Contact: Yi-Wen Cheng, Div. 430, NIST,

Boulder, CO 80303, 303/497-5545.

aimed at two complementary quantities:

fracture-driving force and fracture re- sistance. Fracture-driving force is analogous to stress but is much more

complicated. By measuring stresses and

strains in the material surrounding a

crack, fracture-driving force at the crack

tip can be calculated mathematically. A

previous NIST technique used 36 strain gauges but now a new grid method has

been developed in which a fine grid is bonded to the specimen. A photographic

image of the deformed grid is read using an automated laser diffractometry sys- tem. All in-plane strain components are measured with a precision of 50 microstrain and a spatial resolution of 1 mm.

Fracture resistance is studied by ex- amining fracture surfaces with a scanning electron microscope to find the microscopic origins of brittle fracture or the nuclei of the voids that join to form

ductile fracture surfaces. A quantitative

metallography facility makes it possible

to measure accurately the density and

characteristics of inclusions fundamental

to the fracture process.

Contact: David T. Read, Div. 430, NIST,

Boulder, CO 80303, 303/497-3853.

This computer-generated diagram shows a stress wave

moving along the fiber orientation in a unidirectional graphiteepoxy composite. Each of the humps represents a period of

the wave and the ripples coming off these periods.

Fracture esearch in fracture mechanics

Mechanics 1—^ helps to determine the performI I ance and safety requirements of structural materials. NIST's most advanced measurement techniques are

43
Materials Reliability Metallurgy

Cryogenic

Materials r

Joining Research

, omprehensive low-temperature

^ facilities are available to conduct

' both characterization testing and

fundamental studies on the mechanical

and physical properties of high-strength

structural alloys, high-conductivity metals

and superconductors, metal and

polymer-based composites, and polymer

foams. Properties studied include tensile strength, compression, fatigue, creep,

fracture toughness, stress relaxation,

elasticity (ultrasonic), and thermal expansion. Strain sensitivities of 10"'' at liquid

helium temperature (4 K) are now possible, permitting precise low-temperature

microstrain measurements. Researchers

are assembling equipment to permit load capacities of 5 MN for testing at 4.2 K.

Contact: Richard P. Reed, Div. 430,

NIST, Boulder, CO 80303, 303/497-3870.

"he integrity of welded joints is a pri- mary concern in the design and fabrication of engineering structures. Researchers at NIST are investigating

ways to improve the fracture resistance

of weldments and are assessing weld

quality by nondestructive evaluation

(NDE) techniques. Specific goals of the research are to improve fracture tough- ness in the heat-affected zone of steel weldments and in the weld metal of materials for low-temperature service and to improve the soundness of welds through

increased understanding of the metal

transfer process in arc welding. In addition, the researchers are applying fine- resolution NDE techniques to evaluate

solder joints in printed circuit boards for the electronics industry. NIST scientists have developed techniques to reduce

porosity in aluminum weldments, to re- duce spatter in gas metal arc welding of

steels, and to predict accurately the Ferrite Number in stainless steel welds. The NIST welding and NDE laboratories house equipment for shielded metal

arc, gas metal arc, and gas tungsten arc welding; radiographic and penetrant

techniques for nondestructive evaluation

of weldments; and a precision power

supply, high-speed photography, and

laser shadow techniques for metaltransfer studies.

Contact: Thomas A. Siewert, Div. 430,

NIST, Boulder, CO 80303, 303/497-3523.

Corrosion is a major limiting factor in the service life and cost of many

products, plants, and equipment.

The costs of metallic corrosion to the U.S. economy are estimated to be $200 billion

in 1988 dollars, $30 billion of which could

be saved by using existing technology.

The National Association of Corrosion En- gineers (NACE) and NIST have joined to- gether in a collaborative NACE/NIST

Corrosion Data Program to reduce the enormous costs of corrosion. The focus

of this program is to establish an eval- uated corrosion database that can be

accessed easily by computer using intel- ligent interfaces to obtain data in a number of graphical, tabular, or textual formats. The researchers are developing

evaluation methodologies and a prototype database for areas covering ther- modynamic and kinetic corrosion data. NIST scientists are emphasizing interactions with industry both to help set priori- ties for data projects and as a source of corrosion data for the database.

Contact: David B. Anderson, A109

Materials BIdg., 301/975-6026.

Corrosion has been recognized as a major cause of degradation of all kinds of metallic structures, with fi- nancial costs well in the billions-of-dollar range. Since corrosive reactions are of electrochemical nature, electrochemical

measurements can give important infor- mation about the chemical processes

causing the corrosion and the rate of cor- rosion as well as its forms, whether uni- form or localized. Researchers at NIST

are determining current and potential

and their variations with time, measuring

the frequency spectrum of the ac im- pedance of corroding electrodes, and

detecting and analyzing random fluctua- tions of electrical parameters.

Electrochemical methods for measuring corrosion rates offer the possibility of tracking the process in a nondestructive

way and assessing the effect of various

environmental variables. Other electro- chemical techniques can shed light on

the kinetics of the corrosion reactions

and on the critical factors which may contribute either to catastrophic failures or corrosion prevention.

Contact: Ugo Bertocci, B242 Materials

BIdg., 301/975-6017.

Corrosion Data

Program

Corrosion

Measurements

44
Metallurgy

Arnold Kahn (left), a NISTphysicist, and Michael Mester, a

research associate from the Aluminum Association, have

developed a process control sensor, designed to be used in the production of extruded aluminum products.

Process Control

Sensors

S;

pecial facilities at NIST enable re- searchers to develop advanced

' measurement methods and stand- ards in support of emerging sensors and

their application to process modeling

and control for intelligent processing of materials. Measurement methods avail- able include ultrasound, eddy currents, and acoustic emission. In particular, noncontact ultrasonic facilities have been designed featuring high-intensity pulsed

lasers and electromagnetic acoustic transducers. Coupled with state-of-theart materials-processing equipment and

expertise, these facilities offer a unique

opportunity to ascertain feasibility and

develop prototype specifications for a wide spectrum of sensor needs, includ- ing the measurement of internal temperature, phase transformations, surface- modified layers, porosity, grain size, and

inclusion/segregate distributions.

Contact: H. Thomas Yolken, A165

Materials BIdg., 301/975-6140.

Rapid

Solidification t;

•he rapid solidification of alloys can produce new types of materials, un- obtainable by conventional means. Because of their special properties,

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

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 studying 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

processing conditions influence alloy

homogeneity, microstructure, extended

solid solubility, and the production of new alloy phases, control of these fea- tures is critical for producing special

properties in these new materials.

Contact: John R. Manning, A149

Materials Bldg., 301/975-6157.

The corrosion of metals in natural and

manmade environments is very

costly to industry and government.

For several years, NIST researchers have

been involved in developing methods for measuring the corrosion of metals in field conditions, such as steel piling in soil and seawater, electric utility lines in soil, and most recently, steel in concrete. To measure the corrosion of reinforcing steel

in concrete bridge decks, NIST scientists have developed a small, portable computer system. With this system, scientists are able to use electrochemical tech- niques normally limited to the laboratory

to measure the corrosion. This new approach, which allows faster, more accurate corrosion measurements, can be

used to evaluate the effectiveness of protection systems in place. The system has

been applied to several bridges in Maryland and Washington state.

Contact: Edward Escalante, B250

Materials Bldg., 301/975-6014.

Field Corrosion

of Metals

45
Metallurgy

Neutron Scattering

and Diffraction

steel Slag

Thermochemistry

Environmentally

Induced Fracture

of Advanced

Materials

Magnetic

Materials

T.

"hermochemical databases and

models are needed by the U.S.

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 experimental 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.

P

,orrosive reactions between the en- vironment and advanced materials

' can dramatically alter the fracture resistance of the material. To assist in the development of advanced materials,

NIST scientists are studying the mechanisms by which environments can induce

crack propagation at stresses well below

those which cause normal fracture. Researchers are developing experimental

techniques to evaluate and quantify the

susceptibility of different types of advanced materials. Experiments are being

conducted to investigate the mechanisms of hydrogen absorption, dissolution, and environmentally induced

cleavage on different types of materials,

specifically low-density, high-strength

Al-Li alloys; intermetallic compounds;

and composites as well as simple

model systems.

Contact: Richard E. Picker, B252

Materials BIdg., 301/975-6023.

A'

s part of the NIST program in magnetic materials, researchers are

^studying the magnetic properties

of alloys and their relationship to metallurgical structure. Composition-modulated

alloys, granular metals, metallic glasses,

and icosahedral crystals are among the

materials being investigated. The magnetic properties are characterized by

ac magnetic susceptibility measurements, magneto-optic Kerr effect, and

Mdssbauer effect observations.

Contact: Lawrence H. Bennett, B154

Materials BIdg., 301/975-5966.

The NIST Cold Neutron Research Facility, designed as a

national user facility, will house a number of special instru- ments with application to a wide range of materials problems.

M

ore than 50 billion chemical analyses are performed annually in the United States. NIST helps to ensure the accuracy of these analyses

by developing new analytical procedures

and improving the reliability and ac- curacy of present methods. One tech- nique under study is activation analysis,

which is a highly sensitive, nondestructive analytical technique not available in most industrial laboratories. Researchers

are investigating methods of nuclear

analysis utilizing the NIST 20-MW re- search reactor. Research is performed in

all areas of the technique, including the

capabilities of cold-neutron activation, the use of sample self-consistent (monitor) activation, determination of new mathematical procedures for the resolution of gamma spectra, the development of prompt-gamma activation techniques,

and the use of charged-particle activation techniques. The NIST Cold Neutron Research Facility will include a new

neutron depth-profiling instrument and a prompt-gamma activation station. Together, these are expected to form the best capability in the world for chemical

analysis with neutron beams.

Contact: Robert R. Greenberg, 8108

Reactor Building, 301/975-6285.

Neutron radiography has been a

well-established tool for nondestructive evaluation for some time. More recent neutron applications in NDE

Activation

Analysis

Neutron

Nondestructive

Evaluation (NDE)

46
i Neutron Scattering and Diffraction

Neutron

Spectroscopy

include neutron diffraction for texture and

residual stress determination. All three

specialties are available for cooperative R&D utilization and development at the NIST research reactor. In general these techniques parallel their x-ray counterparts; however, in certain cases (e.g., where hydrogenous components are critical or where subsurface

texture or residual stress distributions are sought) x rays do not provide the needed

sensitivity or penetration.

NIST scientists are continuing their col- laboration with scientists from the Smithsonian Institution to examine art works

using neutron radiography. They also are working to apply the technique to industry-related problems and to extend

the existing capabilities to, for example,

backscatter radiography. Scientists from

NIST and the Department of Defense

(DOD) are continuing to develop and

apply neutron diffraction techniques to texture and residual stress characterization. Texture studies have centered on

copper, tantalum, and uranium-alloy components for a variety of DOD items; re- cent work has included ceramic super- conductors. Neutron residual stress studies have involved components made of the above metals as well as ceramics,

fiber-reinforced ceramic composites, and

steel.

Contact: Henry J. Prask, 301/975-6226

or Chang S. Choi, 301/975-6225, A106

Reactor Building.

Ri

I esearchers at NIST are studying

the vibrational dynamics and diffu-

, sion of hydrogen in metals and

molecular species in heterogeneous catalysts, clays, and other layered materials.

Inelastic and quasielastic neutron scatter- ing and neutron diffraction are among the techniques used by the scientists to re- veal the bonding states and atomic scale

interactions and diffusion paths in such

materials. Studies also are being conducted on

the atomic and crystal dynamics in bulk materials and alloys. Recent progress has allowed in-situ spectroscopic studies

of hydrogen and molecular species

down to 0.1 of an atomic percent. These

measurements can provide direct infor- mation, for example, on the molecular

processes affecting reaction and selective release of chemicals in industrial

catalysts and on the local trapping and

clustering of hydrogen in metals and

semiconductors, which cause embrittle- ment, corrosion, or changes in electronic

properties. NIST scientists are working

with researchers from several industrial laboratories to study zeolites and other

catalytic materials. Equipment available includes three-axis neutron crystal spectrometers and time-of-flight spectrometers for inelastic scattering, which, along

with neutron diffractometers, measure

structural and dynamic processes in the time regime from 10"^"^ to 10"^"*

s. Two

very-high-resolution inelastic scattering

spectrometers will be available at the NIST Cold Neutron Research Facility. Controlled temperature (0.3 -1300 K) and

pressure devices are available for changing sample environments.

Contact: J. Michael Rowe,

301/975-6210 or John J. Rush,

301/975-6231, A 106 Reactor Building.

Detailed microstructure information

is often a key to the prediction or understanding of the performance

or failure of structural materials and

materials-processing conditions. Re- searchers at NIST use small-angle neutron scattering (SANS) to characterize submicron structural and magnetic

properties of materials in the size regime

from 1 to 100 nm. Among the structural features in this size regime that produce

SANS diffraction patterns are: small precipitates or cavities in metal alloys, micro- pores or cracks in ceramics, colloidal suspensions and microemulsions, and

polymers and biological macromolecules. These patterns can be analyzed to give information on the size and

shape of the scattering centers as well as their size distribution, surface area, and number density.

A number of scientists from the chemical, communications, advanced materials, and aerospace industries are already engaged in SANS research at NIST. Their measurements are carried out with long-wavelength neutrons on the 8-m-long NIST SANS spectrometer which

utilizes a 65-by-65-cm position-sensitive detector to record data over the entire small-angle region simultaneously. The

Small-Angle

Neutron

Scattering

47
Neutron Scattering and Diffraction

Nondestructive

Evaluation

Neutron

Diffraction

addition of two 30-m SANS spectrometers in the NIST Cold Neutron Research

Facility will enhance significantly resolution and sample throughput. Computerautomated apparatus is available for maintaining samples at temperatures

from 4 to 700 K and in magnetic fields up to 20 kilogauss. To extract structural information from the data, the re- searchers analyze SANS patterns with an interactive color graphics system and

related programs.

Contact: Charles J. Glinka,

301/975-6242 or James A. Gotaas,

301/975-6243, A106 Reactor Building.

Pi

irecise information on the crystal structure (arrangement of atoms

and molecules) in solids is often a

key to understanding or improving the properties of modern materials and

creating new materials with specific

properties. Many important materials

ceramics, catalysts, and rapidly solidified alloys—often can be obtained only in powdered form. NIST researchers are developing im- proved methods for accurate structure re- finement. A major effort is under way to

relate atomic arrangement and super- conducting properties in high Tc ceramic

superconductors. In addition, a number

of industrial scientists are collaborating

with NIST staff in neutron diffraction studies of inorganic catalysts, new kinds of ionic conductors for small batteries and

fuel cells, improved ceramics for microcircuit substrates and engine components, 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 diffraction 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.

Nondestructive evaluation methods

are used throughout the manufacturing process to monitor important properties and characteristics of materials. To assist in this process, NIST

scientists have developed a new probe

for examining ceramics, composites, and

other nonconductive materials. The

probe is basically an array of capacitive

elements, each of which is essentially a

parallel plate capacitor unfolded so the two electrodes lie in the same plane. A

voltage is impressed across the elec- trodes, and the resultant current flow be- tween them is measured. The array is 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

materials, the array may be embedded in the composite lay up.

Early work with the capacitive array probe shows that it has good sensitivity to both surface and subsurface discontinuities, such as cracks and voids of submillimeter and even micrometer di- mensions. Its capabilities in any given

application depend upon the dielectric constant of the material, as well as geometric parameters, and theoretical efforts are under way to guide further development work. Recent studies indicate that the probe has important potential as a

sensor for monitoring the sintering of ce- ramics and the curing of polymers and

polymer-based composites because

these processes are accompanied by

changes in the dielectric constants.

Contact: H. Thomas Yolken, 8344

Materials BIdg., 301/975-5727.

Nondestructive

Evaluation for

Ceramics and

Composites

48
Polymers

Composites

Processing Fi

'iber-reinforced composites offer, along with otiner advantages, versatility in processing connbined with high strength and stiffness at low weight. For the current growth in the production

of these materials to continue, however, more rapid and reliable processing is needed. To help meet this need, NIST re- searchers are developing new measure- ment tools to study the reactions associated with processing to understand the

relationships among processing parameters, the microstructure of the fabricated

materials, and their performance properties. Such scientific understanding will facilitate both advances in processing

methods and implementation of on-line control and automation. The development of this understanding requires re- searchers to monitor the materials during

the curing process to observe simul- taneously chemistry, morphology

development, flow, molecular network

formation, build-up of residual stresses,

interfacial effects, and wetting and

spreading.

The NiST program currently has 10

different spectroscopic, dielectric, ther- mal, and mechanical techniques avail- able for cure monitoring, and others are under development. This diversity of tools provides a unique capability for evaluating and calibrating new measure- ment methods, for developing process

modeling, and for analyzing model ther- moset systems. For example, through

cooperative projects with NIST, several

industries have selected and developed

monitoring methods for their particular

problems.

Contact: Donald L. Hunston, A209

Polymer BIdg., 301/975-6837.

elastomers, molecular composites, and

fibers to develop improved models of mechanical behavior, characterize structure from the atomic- to fine-texture level, and elucidate relationships between mechanical performance and structure. NIST scientists use a variety of tech- niques to characterize the structure of polymers in the solid state. Nuclear magnetic resonance spectroscopy is used to determine molecular orientation, molecular dynamics, and microstructure on the 1-to 10-nm scale. Microstructural infor- mation is deduced from C-13 lineshapes

obtained with magic angle spinning or by

proton "spin diffusion" experiments in which domain-size information is inferred from the rates at which proton magnetization diffuses in the presence of magnetization gradients. Fourier transform

infrared spectroscopy helps to determine

molecular architecture, orientation, and

molecular processes, such as measure- ment of the amount of chain scission as- sociated with mechanical deformation of polymers. Microstructural features, including spherulytic morphologies, lamellar

texture, fiber structures, and crystallization habits, are elucidated through optical and electron microscopic studies of polymers. NIST scientists are examining

the relationships between mechanical

performance of polymers and fine struc- tures by investigating the morphological

changes that polymers undergo when

they are deformed. Wide- and small- angle x-ray diffraction techniques, which

include the use of position-sensitive

detectors, are also employed in these

investigations.

Contact: Bruno M. Fanconi, A305

Polymer BIdg., 301/975-6769.

Polymer Structure

Ki

nowledge of the relationships be- tween mechanical properties of ^polymers and polymer structure is important to the design and processing

of materials for optimal performance. Re- searchers at NIST are studying semicrystalline polymers, polymer glasses.

M

odern dental and medical materials utilize numerous substances

in an array of combinations. NIST

has a comprehensive program aimed at increasing basic understanding of the causes for failure or poor performance of these materials, proposing and testing new material systems, and transferring the resultant science and technology to industry. The program has the active participation of researchers from the Ameri- can Dental Association, the National

Institutes of Dental Research, dental

industries, and universities.

Dental and

Medical Materials

49
Polymers

Researchers are working in a number

of areas. For example, in a tribology

study, scientists are examining wear and

degradation of materials in various en- vironments, and in a bioadhesion project,

they are making new monomers for adhesion to tissues. In addition, improved

resins are being synthesized to produce

polymers that have improved properties,

such as wear resistance, higher strength,

resistance to oral fluids, or x-ray opacity.

Researchers have developed an in- mouth shield for cancer patients undergoing radiation therapy to protect their healthy tissues from secondary radiation emitted from metallic restorations. With

regard to infection control, a unique

method that uses gas plasmas to sterilize dental instruments has been shown to be

highly effective.

In an effort to improve the strength of dental systems, different combinations of materials are being designed and tested,

including ceramic-metal, resin matrix composites, metal-cement, cement-tooth.

John A. Tesk sterilizes clinical instruments with a new

microwave-generated gas plasma method. The new technique may reduce the damage to expensive instruments

caused by repeated exposure to time-consuming, traditional

sterilization methods.

and composite-adhesive-tooth materials. Weibull statistical analysis is employed to

identify the weakest links, and finite- element analysis is applied to define

stress states within systems. Scientists working in the area of precision metal

casting processes have designed a

unique casting monitor that can be used

for rapidly solidified alloys.

Contact: John A. Tesk, A143 Polymer

BIdg., 301/975-6801,

NIST is conducting a number of studies on the electrical properties

of polymers. The research focuses on dielectric measurements, fundamentals and applications of piezoelectric and

pyroelectric polymers, measurement of space charge distribution within polymer

films, and electro-optic properties of polymers.

Scientists at the Institute have

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 dielectric constant, and an acoustic im- pedance close to water make piezoelectric 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 applications or to assist in measuring the properties of new piezoelectric polymers or composites.

The scientists also have designed in- strumentation and data analysis tech- niques to measure the charge or polari- zation distribution across the thickness of polymer film by analyzing the transient charge response following a pulse of energy on one surface of the film. This technique has been used to detect the 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.

Electrical

Properties

50
Polymers

Molecular

Networks

Organic molecules with highly

delocalized n-conjugated electrons offer great potential in the field of nonlinear optics (NLO) due to their relatively large

second-order susceptibilities and their picosecond response times. Polymers

with highly delocalized electrons (such as polydiacetylenes) are being designed, synthesized, and characterized

for their NLO properties. Other polymers

are being investigated as a medium in which NLO-active molecules can be dis- solved, processed, oriented, and maintained in an oriented configuration for use in NLO devices.

Contact: George T. Davis, B320 Polymer

BIdg., 301/975-6725.

Ti

"hermoset resins are used extensively in practical applications, especially polymer-based composites.

However, knowledge of the basic structural entity of these resins, i.e., their molecular network structure, is very

limited. NIST researchers have

developed a neutron-scattering tech- nique that can be used to determine

quantitatively characteristics of the net- work, including the average distance be- tween crosslinks, the rigidity of the network, the molecular weight distribution between crosslinks, and the topological

heterogeneity of the network structure. Current NIST research focuses on

developing correlations among chemical

compositions, processing conditions,

and resulting network structure for epoxytype polymers. To establish processingstructure-property relationships, these

materials are then evaluated to determine

performance properties, such as fracture behavior. The neutron-scattering tech- nique is also being used to study how

the molecular network deforms when the

material is placed under load. These

studies help industry by providing guidelines for designing and processing poly- mers for optimal performance.

Contact: Wen-li Wu, A209 Polymer BIdg.,

301/975-6839.

Blending polymers has become an

effective method for producing

high-performance engineering poly- mers. The fundamental data required to design a manufacturing process include

the equilibrium phase diagram, the energetic interaction parameter (compatibility) between the blend components, dif- fusion coefficients, and the interfaciai tension. At NIST small-angle neutron scattering has been used to measure the in- teraction parameter and phase diagram

of polymer blends. NIST scientists have

developed forced Rayleigh scattering

and temperature-jump light-scattering

techniques to measure polymer-polymer

diffusion and other parameters which

control phase separation kinetics and

morphology.

Currently, Institute researchers are

testing various kinetic theories of phase

separation and late-stage coarsening

and are studying the control of mor- phology and mechanical properties of microphase-separated polymer blends. As part of this program, they are working

with industry to study the homogenization

and phase coarsening of rubber blends.

Contact: Charles C. Han, B210 Polymer

BIdg., 301/975-6771.

Small-angle x-ray scattering (SAXS)

is used to characterize structural elements of polymers, ceramics,

and metals in the 1-nm to 100-nm size range. This technique has been used

successfully at NIST to study phase separation, crystallite morphology, molecular

dimensions, void formation, pore characteristics, and other elements. A state-of- the-art 10-meter SAXS facility has been

constructed at NIST for such studies and

is available for cooperative research.

This SAXS facility uses a 12-kW rotating

anode source, pinhole collimation, and a two-dimensional position-sensitive detector to provide high resolution and simul- taneous recording of all scattering data

over the entire small-angle region. In addition, a computer-assisted interactive data reduction and analysis program is available with color graphics display for the two-dimensional image. Structural and dimensional information can be extracted using available model analysis

and curve-fitting procedures.

Polymer Blends

Small-Angle

X-Ray Scattering

51
Polymers Radiation Research

The small-angle x-ray scattering facility is used by NISTpoly- mer physicist John Barnes to obtain information on the microstructures of polymer blends to develop polymer alloy phase

diagrams.

Additional equipment is available for characterizing the crystallite orientation

distribution of semicrystalline polymers

using pole figure techniques. Workers

from Mobil Chemical Company's re- search and development laboratory have

used the SAXS and pole figure facilities to characterize their processes for pro- ducing tear-resistant polyethylene films.

Contact: Charles C. Han, B210 Polymer

BIdg., 301/975-6771.

Fluorescence

Monitoring N

1ST researchers are evaluating

iuorescence spectroscopy, which

is used to characterize the structural and dynamic properties of polymer

molecules. Fluorescence quenching is employed, for example, to monitor the

uniformity of mixing in polymer blends

and in particle-filled polymer melts. In addition, excimer fluorescence is utilized to monitor the cure of thermoset resins, while fluorescence anisotropy is used to monitor the non-Newtonian flow of poly- mer solutions and melts. At NIST, the measurements are carried out with a

spectrofluorimeter and a nanosecond

spectrofluorimeter. In combination with

optical fibers, which are used to get the

exciting light into the interior of a composite part, the fluorescence techniques

are attractive for process monitoring of composites.

Contact: Francis W. Wang, B320

Polymer BIdg., 301/975-6726.

Luminescence techniques have

broad application in virtually every

scientific field, including radiation measurement, remote sensing, quantitation of biomolecules by intrinsic lumines- cence and immunoassay techniques,

and characterization of laser, semiconductor, and superconductor materials. 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- ometry provide the accuracy base for the spectral and quantum efficiency

measurements. Luminescent phenomena

under investigation at NIST are photo-,

chemi-, thermo-, electro-, and bio- luminescences. These designations

usually indicate the source of the excitation energy. The NIST researchers are conducting luminescence radiometric

research in the near-ultraviolet, visible, and near-infrared spectral regions and

are developing accurate standards

and measurement procedures for these

regions. Facilities available for this research are various laser and lamp

sources, the NIST reference spectrofluorimeter, and a low-light-level spectroradiometer now under construction.

Contact: Ambler Thompson, B306

Metrology BIdg., 301/975-2333.

NIST researchers are investigating the use of thermal imaging cameras as a temperature-measuring

tool. These devices may prove to be very

useful in determining the quality of products and in investigating changes in different processes. Research projects

under way involve the development of large-area blackbodies, use of Pt-Si as

detector standards, and the characterization of thermal imaging cameras. Equipment available at NIST includes

several heat-pipe blackbodies, a Pt-Si camera, and an infrared radiometer.

Contact: Robert Saunders, A221 Physics

BIdg., 301/975-2355.

Luminescence

Spectral

Radiometry

Thermal

Radiometry

52
Radiation Research

UV Radiometry

T:

Accelerator

Research

"he measurement of terrestrial solar irradiance in the UV-B spectral re- gion is being investigated by NIST

researchers in order to provide improved

techniques and standards in this region. Their work is of importance not only to scientists studying biological effects but

to researchers investigating the aging of materials by uv light. Specific projects in- clude the development of a reference

spectral radiometer, broadband detectors, and source standards in the region.

A high-accuracy spectrometer, standard

detectors, and standard sources are

available for this research.

Contact: Robert Saunders, A221 Physics

BIdg., 301/975-2355.

"he NIST accelerator research pro- gram is aimed at developing advanced particle accelerators for applications in free-electron lasers

(FEL's), production of monoenergetic

X rays, and dosimetry .The program

focuses on designing, constructing, and

commissioning the NIST racetrack microtron (RTM), which will accelerate elec- trons in a continuous train of pulses to energies of up to 185 MeV by recirculation through a 12-MeV, continuous-wave

linac. Results of preliminary evaluations surpass the design goals of beam quality

by almost a factor of two. The unique characteristics of the RTM

beam—±20-keV full-energy spread,

±10-keV energy stability, normalized emittance, 100-percent macroscopic duty factor, and 100-kW average

power—open up a range of innovative

applications. The major planned application is to drive the NIST free-electron

laser (FEL), an intense source of radiation with wavelengths tunable between

200 nm and 10 ^m. Researchers are developing a new, continuously pulsed,

5-MeV injector with several amps of peak

current to facilitate lasing. They also are

studying, both theoretically and experimentally, beam breakup in the RTM. Im- proved techniques for measuring the properties of high-quality, relativistic electron beams will be developed. Completion of construction and performance

tests at full energy are scheduled for 1990.

Recent advances in electron accelerators have provided high-quality,

continuously pulsed electron beams without using storage rings, opening up a host of possibilities for new

types of intense, coherent x-ray sources.

Insertion devices are presently used in highly expensive, multi-GeV storage

rings for coherent production of x rays. Despite small electron-beam dimensions,

the need to maintain the lifetime of the stored beam necessitates large clear apertures and precludes interception of the beam. However, these restrictions do

not apply if the beam is not reused. In this case, much smaller structures, even

interceptive ones, can be used to pro- duce coherent x rays at beam energies

well below 1 GeV.

The racetrack microtron (RTM) under

construction at NIST provides a unique

opportunity to develop such innovative sources.The expected beam size and

divergence at 185 MeV are ±160 |im and

±160 )irad. X-ray production mechanisms

accessible with a beam of this quality in- clude radiation from miniature undulators, transition radiation, channeling

radiation, and parametric x-ray generation. Although the full range of beam energies will not be available until 1990,

researchers are using the IZ-MeV beam

now available for an experiment with an

undulator with a submillimeter magnetic

period.

Contact: Philip Debenham, B119

Radiation Physics BIdg., 301/975-5602.

Afree-electron laser (FEL) facility under construction at NIST will be

operated as a user facility for re- search in physics, chemistry, biophysics,

material sciences, and medical sciences.

The electron source for the FEL is the NIST racetrack microtron (RTM). Be- cause the RTM will provide a continuous

train of pulses and will have a wide

energy range, the FEL will have unique

characteristics. It will be tunable over the range of 200 nm to 10 |im with average

power of 1 0 W to 200 W, and the temporal structure will be a continuous train of 3-ps pulses at 66 MHz.

Coherent X-Ray

Sources Based

on High-Quality

Electron Beams

Free-Electron

Laser

Contact: Mark A. Wilson, B119 Radiation

Physics BIdg., 301/975-5605.

53
Radiation Research

Spectral

Radiometry

Collaborative opportunities exist in both the development and the use of the FEL. The FEL will have sufficient smallsignal power gain to lase in the ultraviolet, but the lower wavelength limit of 200 nm to 300 nm will depend strongly on mirror performance. NIST researchers

will be investigating the development of low-loss, high-power mirrors; laser diagnostics and stabilization; optimization of harmonic radiation (for wavelengths as low as 30 nm); Q-switched

mode of operation; and optical pulse

compression. They are especially inter- ested in dynamical studies which exploit the temporal structure of the FEL.

Contact: Ronald G. Johnson, B110

Radiation Physics BIdg., 301/975-5568.

Ri

I esearch and development pro- grams at NIST span a broad speci trum of activities associated with the measurement of optical radiation, in- cluding spectral radiance measurements

and new techniques for spectrophotometric measurement of dense optical

media. These activities cover the ultraviolet spectral region from 200 nm to the far infrared region and include the development of appropriate detector methodology to perform the measurements and

relate them to the U.S. radiometric measurement base. Specific research and

development projects involve low background infrared calibrations in a cryo- genic environment, solid-state photodiode 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.

Toenhance quality-control methods

used in industrial radiation processing of foods and in the production

and use of medical devices, electronic components, and polymers, NIST re- searchers are developing standardization and measurement assurance methods related to industrial high-dose

applications of ionizing radiation. As part

of this program. Institute scientists are in- vestigating radiation chemical mechanisms and kinetic studies applied to chemical dosimetry systems in the con- densed phase, including liquids, gels,

thin films, and solid-state detectors. They also plan to examine sensor

materials such as doped plastics, solid- state matrices, fiber optics, organic dye

solutions, semiconductors, scintillators, biopolymers, amino acids, metalloporphyrins, and organic or inorganic aqueous

solutions and gels. A number of analyti- cal methods will be used, including trans- mission and fluorescence spectrophotometry, electron spin resonance

spectrometry, and chemiluminescence

spectrophotometry as well as fiber optics

analysis, microcalorimetry, pulse radiolysis, laser-induced photochemistry, and

conductivity measurements. Various

Radiation

Processing

On the automated spectral comparator facility, physicists

Jeanne Houston and Chris Cromer align the silicon photodiode light traps that are used in photodetector research and

calibration.

54
Radiation Research

Autoxidation/

Antioxidants

x-ray and gamma-ray sources and electron accelerators with energies in the

0.1- to 10-MeV range are used in this work. Conventional ultraviolet, visible, and infrared spectrophotometers and

spectrofluorimeters, high-intensity

gamma-ray sources, pulsed and continuous beam electron accelerators, and

organic-chemical analytical equipment

are also available.

Contact: William L. McLaughlin, C209

Radiation Physics BIdg., 301/975-5559.

TI t

'he kinetic and mechanistic aspects

of autoxidation in foods, organic materials, and biochemical systems;

the design of appropriate antioxidants to prevent the deleterious effects of oxygen;

and the extension of the lifetime of chemical and biochemical systems are important to many food, drug, and medical

industries. NIST researchers are investi- gating the free-radical chemistry of or- ganic molecules and biochemicals

susceptible to autoxidation and free- radical mechanisms and reaction rates

of oxidants, particularly key components

of foodstuffs and other life-supporting

substances. In addition, the effects of oxygen pressure, temperature, additives,

and concentrations on the optimization of these parameters and the development

of products less sensitive to oxidation are being studied. NIST researchers are seeking in- dustrial collaboration in the analysis of short- and long-term intermediate species in pulse-irradiated oxygenated or- ganic and aqueous solutions; derivation

of kinetic data and unraveling of auto- and radiation-stimulated oxidation proc- esses; and design of new antioxidants to protect against food spoilage, carcinogenesis, atherosclerosis, and nitrosa- mine formation in foods. Kinetic and

analytical chemical technologies, such

as GC/MS, HPLC, spectroscopy, chromatography, electrophoresis, and ESR spectroscopy; high-intensity gamma-ray

sources, and pulsed- and continuousbeam electron accelerators; and various

organic-chemical analytical equipment

are also available.

Contact: Michael G. Simic, C214

Radiation Physics BIdg., 301/975-5558.

The use of penetrating radiation for imaging is one of the most powerful

investigative techniques available to industry for maintaining or improving the

quality of products. Designers, aware of

this, are creating components that facili- tate such nondestructive testing. Re- search is under way at NIST to allow

better quantification of radiographic im- ages. Particularly relevant to image eval- uation are computer-based systems that permit pseudo three-dimensional images

and the implementation of image proc- essing on these or traditional images in real time or near real time. The NIST research focuses on image

processing for improved imaging of low

contrast for noisy images; adaption of tomographic equipment to industrial needs and measurement of the perform- ance characteristics of such systems;

and development of reliable techniques

for image storage and retrieval. Available

equipment includes x-ray sources, low- energy electron accelerators, gamma-ray

sources, and state-of-the-art radiologic

imaging devices.

Contact: Charles E. Dick, C215

Radiation Physics BIdg., 301/975-5580.

NIST researchers are studying in- dustrial applications of neutron

fluence and dose determination in the neutron energy region from thermal to 20 MeV. They are developing effective methods to transfer personnel protection

technology to the private sector. This re- search provides a basis for standardizing personnel protection control procedures in nuclear reactor and in high-energy accelerator operations.

Specific research involves the measure- ment of reference standard neutron reaction cross sections; characterization of reference fission deposits; development

of neutron detectors with fast timing; and

calibrations using standard neutron and

gamma-ray fields. Equipment available includes a 100-kV ion generator-based

2.5-MeV neutron source, a 3-MV pulsed

positive-ion accelerator, and a 20-MW

nuclear reactor.

Contact: Oren A. Wasson, B1 1

1

Radiation Physics BIdg., 301/975-5567.

Industrial

Radiologic

Imaging

Neutron Fluence

Measurement

and Neutron

Physics

55
Standard Reference Data

Computerization

of Standard

Reference Data U

sing computers to provide timely

and inexpensive access to reliable chemical, physical, and materials data contributes greatly to increased productivity and lower manufacturing costs

of industrial operations. The NIST Standard Reference Data program works

closely with industry to develop the tools and standards necessary for computerizing industrial technical data—the numbers, 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 materials properties data. The NIST Standard 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 combines expertise in the physical sciences

with specialized knowledge in computer

science. Areas of activity include preparation of databases of evaluated data

and predictive software for use on per- sonal computers, conversion and combination of published data compilations

into searchable databases, standardization of formats for scientific and en- gineering information, development of expert systems, and establishment of distributed systems linking scientific databases. The computer and telecommunications 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.

Jeffrey Fuhr (left), a physicist in the NIST Atomic Transition

Probabilities Data Center, demonstrates the wall-stabilized arc to W.L. Wiese, head of the data center. The arc is used to measure atomic transition probabilities for use in plasma

modeling and analysis, including fusion research as well as

laser physics and astrophysics.

Contact: Malcolm W. Chase, A323

Physics BIdg., 301/975-2200.

56