NBSIR 80-2166

Technical Activities 1980

Surface Science Division

Reprinted from NBSIR 80-2132

C. J. Powell, Chief

Surface Science Division

Center for Thermodynamics and Molecular Science

National Measurement Laboratory

National Bureau of Standards

U.S. Department of Commerce

Washington, DC 20234

October 1980

Prepared for; National Bureau of Standards

Department of Commerce

Washington, DC 20234

NBSIR 80-2166

TECHNICAL ACTIVITIES 1980

SURFACE SCIENCE DIVISION

REPRINTED FROM NBSIR 80-2132

C. J. Powell, Chief

Surface Science Division

Center for Thermodynamics and Molecular Science

National Measurement Laboratory

National Bureau of Standards

U.S. Department of Commerce

Washington, DC 20234

October 1980

Prepared for: National Bureau of Standards

Department of Commerce

Washington, DC 20234

U.S. DEPARTMENT OF COMMERCE, Philip M. Klutznick, Secretary

Luther H. Hodges, Jr., Deputy Secretary

Jordan J. Baruch, Assistant Secretary for Productivity. Technology, and innovation

NATIONAL BUREAU OF STANDARDS, Ernest Ambler, Director
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ABSTRACT

This report summarizes technical activities of the NBS Surface

Science Division during Fiscal Year 1980. These activities include

experimental and theoretical research in surface science, the development

of improved measurement methods, the provision of needed data, the

development of reference materials, applications to important scientific

and national problems, and surface-standards work. A listing is given

of publications, talks, professional committee participation, and

professional interactions by the Division staff.

'

Key Words: Surface chemistry; surface physics; surface science;

surface standards

%

i
FOREWORD

This report is a summary of the technical activities of the TIBS Surface Science Division for the period October 1, 1979 to September 30, 198C

The report was prepared as part of the Annual Report of the Center for

Thermodynamics and Molecular Science within the national Measurement

Laboratory of NBS. Much of the writing was done in June and July of

1980 so not all of the actual accomplishments for the year have been

included.

The technical work of the Division is separated formally into a "Surface Measurements Program" and a "Surface Science Competence Program."

The basis for this separation is described briefly in the Introduction

(Section 1) and in the reports for these two programs (Sections 2 and 3).

Within each program are a number of technical projects. Information is

given on project objectives, results obtained during the past year, and

the nature of planned activities.

Sections 4 and 5 of the report contain listings of papers published,

papers submitted for publication, and talks presented during the year.

Talks presented at the Division's seminars at fiBS are given in Section 6.

The involvement of Division staff on professional committees is shown in

Section 7 while internal and external scientific collaborations are described in Section 8. Visiting scientists who have worked in the

Division during the year are identified in Section 9 and the Division

staff is listed in Section 10.

Further information on the activities of the Division can be. obtained

by contacting the scientists identified in each project report or by

writing Dr. C. J. Powell, Chemistry B-248, National Bureau of Standards,

Washington, D.C. 20234.

ii
TABLE OF CONTENTS

ABSTRACT i

FOREWORD i i

1. Introduction 1

2. Surface Measurements Program 5

2.1 Introduction 5

2.2 Characterization of Surface Reactions and Processes ... 5

2.2a Catalytic Chemistry for Synthetic Fuels 5

2.2b Infrared Studies of Chemisorbed Species 6

2.2c Field-ion Microscopy Studies of Stress-Corrosion

Cracking 7

2.3 Physical Characterization of Surfaces 9

2.3a Electron-Stimulated Desorption 9

2.3b Electron Spectroscopy of Surfaces 9

2.3c Ion-Induced Electron Spectroscopy of Surfaces 11

2.3d Liquid-Metal Surfaces 11

2.3e Microcompositional Analysis of Semiconductor Surfaces . . 12

2.3f Investigation of Surface Atomic Structure 12

2.4 Theoretical Descriptions of Surface Processes 13

2.4a Surface Theory 13

2.5 Surface Standards 14

2.5a Measurement of Absolute Ion Sputtering Yields 15

2.5b Development of Prototype Standard Reference Materials . . 15

2.5c Standards Committee Activities 16

2.5d Review Articles and Books 18

iii
3. Surface Science Competence Program 19

3.1 Introduction 19

3.2 Report of Technical Activities 20

3.2a ESDIAD-EELS Studies of the Molecular Structure

of Adsorbed Species 20

3.2b Laser Fluorescence as a Probe of Surface Dynamics . . 21

3.2c Neutron Inelastic Scattering from Adsorbed Species

on Surfaces 22

3. 2d Angle-Resolved Photon-Stimulated Desorption - A New

Tool for Surface Characterization 22

3.2e Photoemission Studies of Materials 23

3.2f Atom-Probe Field-Ion Microscopy of Materials .... 25

3.2g Surface Theory 26

4. Publications 28

5. Talks 35

6. Seminars 45

7. Technical and Professional Committee Participation and

Leadership 49

8. Professional Interactions, Consulting and Advisory

Services 51

9. Visiting Scientists 55

10. Surface Science Division Staff 57

iv
SURFACE SCIENCE DIVISION

C.J. Powell, Chief

SUMMARY OF ACTIVITIES

Fiscal Year 1980

1. INTRODUCTION

(a) Background

Surface science is a rapidly growing, exciting field offering many

scientific and technological challenges. The growth is evident in the

large number of national and local meetings of major professional societies

(e.g., American Physical Society, American Chemical Society, Ajnerican

Vacuum Society), of many other groups (e.g., Pittsburgh Conference on Analytical Chemistry and Applied Spectroscopy, Conference on Metallurgical

Coatings, Materials Research Society, Applied Surface Analysis Symposium,

Physical Electronics Conference, Conference on Plasma-Surface Interactions),

of over a dozen Gordon Research Conferences in 1980 concerned with surface

phenomena, and in both journal and book publications. The excitement in

the field is evident from the enthusiasm of the practitioners, the numerous

articles reporting new phenomena in many different journals (particul arly,

for example, in Physical Review Letters, Chemical Physics Letters), and in

the widespread realization that the availability of new experimental and

theoretical tools offers opportunities to probe, at a fundamental atomic

and molecular level, the physics and chemistry of complex surface processes.

It is also clear that surface characterization is now an integral part of

many technologies and industries (e.g., catalysis, coatings, corrosion,

semiconductors, semiconductor devices, computer, automobile, communications)

for many different applications (e.g., failure analysis, quality control,

process and device development). Characterization of surface properties

and processes is similarly important in many areas of national concern

(e.g., defense, energy, environment, space).

The nature of the required surface characterization in the above areas

varies tremendously. For the more fundamental investigations, it is often

necessary to determine the surface composition, surface atomic structure,

and the surface electronic structure of carefully prepared surfaces (e.g.,

single-crystal samples, single-crystal samples with steps, small clusters

or particles, surfaces with various amounts of adsorbed gases or deposited

atoms or molecules) and to evaluate the physical and chemical properties in

terms of current theories and other knowledge. For the more applied investigations, it is often necessary to determine the surface composition and

surface morphology of an extremely wide range of samples (e.g., catalysts,

polymers, semiconductor devices, metals, alloys, compounds, coatings, thin1
film devices, laser windows, display devices, solar devices, memory devices

contacts, biomaterials, adhesives, seals, wear surfaces, composites,

energy-storage devices, Tokamak-wall parts, building materials, flyash,

automobile parts) and to relate the measured surface properties to other

characteristics of the sample. In many instances, other surface properties

need to be measured for both fundamental and applied work (e.g., roughness,

surface defects, and the mechanisms and kinetics for morphological and

chemical transitions).

Although there have been many successes in surface science and surface

technology, many measurement-related problems and limitations remain.

Among these problems and limitations are: many of the widely used instruments for the measurement of surface composition are not sufficiently

accurate; most analyses of surfaces are qualitative, not quantitative;

there are virtually no standard procedures, reference data, or reference

materials to ensure reliable surface measurements by the commonly used

techniques; there is inadequate knowledge of the "measurement process" for

many methods of surface characterization; the rates of irreversible damage

to a surface during surface characterization are not well established;

structural information can be obtained with some difficulty for ordered

surfaces but methods to obtain short-range atomic structures are not

established; little kinetic data exists for important surface processes

under wel 1 -control 1 ed conditions; and most surface-characterization measure

ments have to be performed in a low-pressure (usually ultrahigh-vacuum)

environment rather than in situ .

(b) Goal and Objectives

The goal of the Surface Science Division is to improve the quality of

existing surface-characterization measurements and to extend the present

capability. Specific objectives of the Division are:

(1) Perform experimental and theoretical research in surface

science to provide a scientific base for surface-measurement

methodology;

(2) Develop measurement methods and provide properties data for

the physical and chemical characterization of surfaces and

surface processes to meet identified needs of industry,

government, and other groups;

(3) Develop standard procedures, calibration data, and reference

materials in cooperation with national and international standards organizations; and

(4) Develop expertise in selected new areas of science in order that

NBS can provide measurement services where needs are anticipated

in the near future.

2
Objectives (1) through (3) are met organizationally through a task

titled "Develop Measurement Methods for Surface Properties." Work performed

during the year for this task is reported in Section 2. Objective (4) is

being met as a result of the recently established MBS Competence Program

through a task titled "Surface Science." A separate report on these

activities is given in Section 3.

(c) Technical Output and Professional Interactions

Sections 4 and 5 of this report contain listings of the publications

and talks, respectively, for the past year by Surface Science Division

staff. Although these listings were prepared before the end of the fiscal

year, the quantity of the technical output is high both in absolute terms

and in comparison with the previous year.

An innovation this year has been the establishment of a joint mailing

list by the Surface Science Division and the MBS Electron Physics Group.

In both December 1979 and June 1980, a listing of recent publications and

of publications in progress was sent to over 800 individuals whose names

and addresses were compiled in an ad hoc way largely from attendance lists

at recent meetings. The response has been extremely gratifying. Over 50%

of those receiving the mailing sent back a postcard requesting copies of

designated publications; other scientists have asked for their names to

be placed on our mailing list while others have indicated that they appreciate receiving listings of the recent work (and make use of the information

in their own libraries). Some 400 responses were received to the first

mailing; there were 100 to 150 requests for copies of each of six review

articles while there were typically 30 to 70 requests for each of most of

the remaining publications. The mailing list has proven to be an effective

means of disseminating the recently published work of the Division to those

who can use it and also provide a means of documenting the fact that a substantial "clientele" exists for the services now being provided by the

Division. The mailing list is also an effective means of publicizing NBS

work in surface science. It is planned to continue these mailings at a frequency of approximately two per year.

Many members of the Division staff hold leadership positions in professional societies and groups, as listed in Section 7. These interactions

not only reflect the professional esteem in which these staff members are

held but provide useful mechanisms for both disseminating the results of

NBS work and for learning of significant measurement problems being faced

by those using surface-characterization equipment.

Much of the Division's work is carried out in collaboration with other

scientists within NBS, within the U.S.A., and internationally. The nature

of these collaborations is shown in Section 8. These collaborations are considered important because they enable a relatively small Division staff

to work synergistically with other experts, they enable us to have access to unique facilities or expertise, and they enable our expertise to be

extended to a larger range of important scientific and technical problems.

3
The Division has been fortunate in having nine visiting scientists

work at NBS for varying periods during the past year, as indicated in

Section 9. These scientists enrich our staff and our projects. A further

enrichment of our programs comes from Postdoctoral Research Associates who

hold 1 to 2 year appointments. In the annual competition for 1980, the

Surface Science Division received 11 applications for Postdoctoral awards

out of about 75 for the entire NBS; two awards to this Division were made.

Interest in surface science and surface characterization at NBS con- tinues to grow. The Division has had an active Seminar program, as indicated

in Section 6, and these seminars have been attended by other NBS staff.

A third one-day course on surface analysis was presented at NBS in February

1980; this course was attended by 36 scientists from 16 different NBS

organizational units. Since this course was first offered in 1978, over

100 NBS scientists have taken the course or expressed interest in it.

Members of the Division staff are consulted on a wide range of NBS problems

such as: fracture mechanisms and crack growth in materials; leaching of

toxic elements from flyash; material transport at the interfaces of electrical contacts; artifacts in eddy-current standards for non-destructive

evaluation of materials; and surface effects on proposed secondary mass standards

(d) Laboratory Automation

During the past year, a number of the experimental projects in the

Division have been interfaced to microcomputer systems and other projects

are being similarly automated. It is believed that these changes will

lead to more efficient operations, more accurate and reliable experimental

data, and to new types of experiments being undertaken that would previously

not have been feasible.

4
2. SURFACE MEASUREMENTS PROGRAM (13 staff years)

2.1 Introduction

The Division's work for the task titled "Development of Measurement

Methods for Surface Properties" is divided into a number of individual

projects. These projects meet Division objectives through the development

of new measurement techniques, improvement of existing techniques, development of theories of the measurement process, applications to important

scientific and national problems, development of measurement procedures,

tests of the measurement system, the development of new concepts, the

provision of needed data, and the development of reference materials. The

reports of the technical projects have been divided into four groups to

provide a clear relationship to different surface-measurement problem

areas and to the Division objectives. It should be recognized, however,

that many of the projects have outputs extending beyond the particular

category in which they have been placed.

2.2 Characterization of Surface

Reactions and Processes

(a) Catalytic Chemistry for Synthetic Fuels - The Hydrogenation of CO

(Yates, Madey, Kelley, Goodman, Kiskinova)

The overall objective of this research is to provide a molecular

understanding of heterogeneous catalytic chemistry in areas of importance

to energy-related technologies, particularly the generation of synthetic

fuels. Among these areas are the catalytic synthesis of hydrocarbons from

carbon oxides and hydrogen on metal surfaces, the mechanism of catalytic

poisoning, and the molecular and electronic nature of chemisorbed species.

Results of past year include:

(1 ) A comparison of the absolute reaction rate of CH^ synthesis on Ni(lOO)

and Ni(lll) has been completed. Within experimental error, both the

rate and activation energy are identical on the two crystal surfaces.

Similar conclusions have also been reached in comparison of two Ru

crystal surfaces for this reaction. This work suggests that structure

factors are unimportant and that for this reaction it is likely that

electronic factors within the catalytic substrate govern the kinetic

behavior.

(2) Quantitative studies of S poisoning and alkali metal promotion have

been carried out. In both cases it appears that electronic effects

govern the behavior of the doped surface, and that major rate changes

may be induced in this manner.

(3) A new method for studying interactional effects on surface binding of

CO to Ni(lOO) has been devised. Desorption of one isotopic species

5
p

of CO into a high flux beam of a second isotope of CO has been directly

employed to observe the effect of elevated CO coverage on the desorption process.

(4) A second high pressure chamber, complete with an Auger spectroscopy

facility for surface analysis, has been completed.

Future plans include the following:

(i) Search for catalytic methanation activity among elements

outside of group VIII. Anong the candidates are: W, Mo,

and Sm.

(ii) , Exploratory studies of classes of catalytic poisons and

their relative influence on the rate of synthesis of CH,

.

Examples are S, N and P.

(iii) Study of the decomposition of organic molecules by surfaces

using isotopic labeling methods, (alcohols, aldehydes), in

order to produce a systematic picture of organic functional

group stabilities on surfaces.

(b) Infrared Studies of Chemisorbed Species (Yates, Cavanagh, Griffin)

Infrared spectroscopy provides a means for gaining structural information about chemisorbed species. It is important in studies of technical

surfaces of catalytic importance and is an important component of an MBS

effort to make comparative studies of chemisorption processes and surface

reactions on three types of substrates: (i) highly dispersed atoms on a support (by IR spectroscopy); (ii) macroscopic single-crystals (by highresolution electron energy-loss spectroscopy; and (iii) high-area practical

catalyst materials (by neutron inelastic-scattering spectroscopy).

Accomplishments of the past year include:

(1 ) Identification of atomically dispersed Rh sites on an A1 20^ support.

These sites exhibit different chemi sorptive properties from Rh sites

present in crystalline Rh.

(2) Development and use of methods for controlling the distribution of the

two classes of Rh sites.

(3) Discovery of an infrared spectroscopic method for observing the electrostatic interaction of a surface dipolar oscillator with its image in

the underlying substrate.

(4)

Extension of infrared spectroscopy to the investigation of electronic

analogs to CO and establishment of a firm linkage between transition

metal chemisorption and organometall ic chemistry (isocyanide chemisorption)

6
(5) Demonstration of the concept that anchor ligands may be used to orient

functional groups to surfaces in a controlled manner.

(6) Study of through-metal electronic interactions between adsorbed

species.

(7) Direct spectroscopic observation of ligand-induced displacement

effects between coadsorbed species.

(8) Study of the spillover of chemisorbed hydrogen atoms produced on metal sites to the oxide support.

(9) Correlation of IR and thermal desorption techniques for hydrogen

chemisorption on a ZnO surface.

It is planned to continue IR work in the following areas:

(i) Study of phenyl isocyanide chemisorption with the objective of

anchoring an ultraviolet-absorbing chromophase for possible use

in surface photolytic studies.

(ii) Exploratory studies of the effect of solvents on the infrared

behavior of adsorbed molecules as they are covered. This could

lead the way to IR studies of electrode surfaces exposed to the

electrolyte.

(iii) Search for a transient intermediate in the desorption of CO from

a Rh surface, i.e., Rh(C0)2 [Rh(CO)] .

(c) Field-Ion Microscopy Studies of Stress-Corrosion Cracking (Melmed,

Carrol 1

)

The objective of these studies is to examine on an atomic scale the

early stages of stress-corrosion cracking, a phenomenon leading to premature

failure of metals under apparently innocuous conditions. Surface chemistry

as well as defect properties are important factors to be understood in the

interplay between stress-assisted cracking and crack promoting agents, such

as hydrogen.

The work carried out in the past year sought to extend the application

of field ion microscopy (FIM) to new alloy systems and pure metals with the

aim of examining the occurrence of hydrogen/stress-induced metal defects.

Results of the past year include:

(1) Work with three titanium-palladium alloys resulted in an evaluation

of their susceptibility to stress-corrosion cracking. The FIM results

indicated that the susceptibility to stress-corrosion cracking in

titanium was not reduced by the addition of palladium.

7
(2) Work with vanadium resulted in the observation of an unexpected effect

due to the interaction with hydrogen under stress. Field ion micrographs indicate that the material's normally-imaged impurities were

removed in the top-most 10-15 layers by exposing specimens to hydrogen

imaging conditions at temperatures less than 30 K. The technique may

be adaptable to larger, single crystal vanadium samples where the

attainment of clean vanadium surfaces in the past proved to be a formidable achievement.

(3) Work was started with a high purity aluminum-5. 5% zinc-2. 5% magnesium

alloy to study the initial stages of its hydrogen embrittlement behavior

Previous SEM studies have shown that the aluminum matrix contains

aggregated constituent phases with a wide distribution of sizes.

Field ion micrographs indicate that this distribution contains clusters

as small as a few atoms. In addition, and perhaps more importantly,

micrographs indicate that the aluminum matrix has a high distribution

of a defect structure (tentatively identified as partial dislocation

pairs) that sometimes are as little as five layers deep.

(4) The first clear field ion micrographs of alpha-uranium were obtained

that show atomic details of many orthorhombic crystal planes. Micrographs indicate that a surface hydride phase is formed readily under

hydrogen imaging conditions; some micrographs indicate possible hydride

particle precipitation at a major crystal defect boundary. No evidence

was found, however, of hydrogen/stress-induced surface cracks.

Future studies will be directed toward obtaining FIM characterizations

of:

(i) the Al-Zn-Mg alloy charged with hydrogen sufficient to promote

hydrogen embrittlement to determine whether there is a positive

or negative correlation between the observed dislocation pairs

and the initial stages of crack formation.

(ii) a wide range of electroless nickel-phosphorous alloys and their

interaction with hydrogen and stress.

Future atom-probe FIM investigation should provide chemical identification of corrosion products at surface crack sites in zirconium and titanium

and in Ti-Pd and Al-Zn-Mg alloys.

8
2.3 Physical Characterization of Surfaces

(a) Electron-Stimulated Desorption (Madey, Houston)

A key problem in surface science is the determination of the structures

of molecules on surfaces, particularly in the absence of long range order.

The goal of this project is to provide a di rect determination of the

structures of adsorbed molecules using the Electron Stimulated Desorption

Ion Angular Distribution (ESDIAD) method, and to characterize the fundamental electronic excitations resulting in the stimulated desorption of

ions. ESDIAD has the advantage of being sensitive to the local bonding

geometry of adsorbed molecules, even in the absence of long range order

in the adsorbed layer.

During the last year, progress has been made in the following areas:

(1 ) We have completed a detailed study of the influence of surface

structure on molecular bonding geometry, by examining the adsorption

of CO on both planar surfaces and on surfaces containing monatomic

steps. The data demonstrate that there are profound differences in

molecular bonding at step sites compared to adsorption on flat

surfaces.

(2) We have probed the mechanisms of electron-stimulated desorption (ESD)

by studying the enhancement of ion desorption yields at energies above

deep-core excitation thresholds in surface molecules.

(3) We have initiated a study of MH^ adsorption on Mi (111) to compare

ESDIAD-determi ned structures with the structure determined using

angle-resolved ultraviolet photoemission spectroscopy . The results

indicate that there are differences in the methods which require

detailed investigation.

Future plans include:

Study orientational order-disorder processes.

Probe the mechanism of ESD by assessing the effect of deep core ionization on ion desorption from adsorbed molecules.

Measure yields and angular distributions of negative ions.

Examine the relationshiTi between surface bond angle and ion

desorption angle with adsorbed molecules of "known" structure.

(b) Electron Spectroscopy of Surfaces (Powell, Jach)

The objective of this project is to apply and extend techniques of

electron spectroscopy for the determination of surface composition, other

surface properties, and the dynamics of electron-surface interactions.

(i)

(ii)

(iii)

(iv)

9
Activities of the past year include:

(1 ) The L^VV Auger-electron spectra of Ni and Cu have been measured as a function of incident-electron energy near the threshold for ionization

of electrons in the L^-subshell. At the lower incident energies,

the observed spectra are shown to be substantially free of perturbing

satellites. The L^VV spectrum of Ni consists of two features, one

due to atomic final states and the other due to band effects. Shifts

in the position of the LoW Auger features as a function of incident

energy imply a systematic difference in core-electron binding energies

measured under adiabatic and sudden conditions. One cannot therefore

directly use "absolute" binding energies determined by appearancepotential spectroscopy for calibration of x-ray photoelectron spectroscopy instruments.

(2) Measurements have been made of the electron energy-loss spectra

associated with excitation of the 2p and 3p core levels of Ni and Cu.

Although Ni and Cu have very different band structures, the Ni and Cu

3p loss spectra are very similar in shape, the Ni and Cu 2p loss

spectra show similarities near the threshold for excitation, while

there is a considerable difference in the 3p and 2p loss spectra for

each metal. In addition, weak features in the 3p loss spectra of Ni

and Cu change as a function of incident electron energy in the range

150 to 1000 eV.

(3) Thirteen types of intraocular lenses manufactured for human implantation

were examined by x-ray photoelectron spectroscopy (XPS) in a search

for possible surface contaminants that could be harmful; Apart from

signals due to carbon and oxygen, the only other elements detected

were chlorine on one sample and nitrogen on another.

(4) Extensive XPS measurements have been made of a series of pollutant

particles both after insertion into the instrument and after’ varying

periods of ion bombardment to remove layers of sample material. Many

elements have been detected and it has been found that the relative

concentrations of most elements vary as a function of depth from the

original surface. Comparisons of XPS data with average bulk compositions show that some elements (e.g., Sb, As, V, P, and Cl) can be

located close to the virgin surface.

(5) In collaboration with scientists in the NBS Polymer Science and

Standards Division, Auger-electron spectroscopy studies have been

made of dental alloys to understand wear mechanisms and of polymer

films to optimize procedures for uniform film deposition and to

develop protective polymer coatings.

10
Future work includes:

(i) Further studies of core-level electron energy-loss spectra (e.g.,

Co, Zn, Ag, An) to identify excitation mechanisms.

(ii) Studies of surface phase changes on stepped crystals of magnetic

materials near the Curie temperature.

(iii) Use of secondary-ion mass spectroscopy to identify trace elements

in pollutant particles and to detect ionic fragments from different

individual particles excited by an incident electron beam.

(c) Ion-induced Electron Spectroscopy of Surfaces (Fine, Andreadis)

The collision of energetic ions ( 1 keV) with solid surfaces gives

rise to a number of interactions within the solid which result in the

ejection of atoms, ions, photons, and electrons. Ejected atoms and ions

have been used extensively to monitor sputtering and secondary-ion emission

processes but there has been very little work to correlate the ejected

electrons with these collision processes. Although the kinetic ejection

of electrons by ions and the ejection of Auger electrons are recognized

effects, little is known about the interactions which generate them.

Measurements have been recently made of the total secondary-el ectron

yield and the secondary-electron energy distribution in the 0-200 eV range

for Ga , Ge, In, and Sn samples bombarded by 0.5-5 keV argon ions. These

energy distributions show the onset of a collisional process which is

capable of producing secondary electrons of rather high energy (greater

than 100 eV); these electrons are not Auger electrons. It se'ems likely

that these electrons are the result of an ion (atom)-atom collision in the

target rather than one between an ion (atom) and the target conduction

atoms

Future work will include:

(i) Secondary-electron energy-distribution measurements of additional

elements excited by different ions to identify various atomic

excitation mechanisms.

(ii) .Similar measurements with higher ion energies (up to 20 keV) and

with ions of metallic elements.

(d) Liquid-Metal Surfaces (Fine,^Andreadis)

A collaborative project is underway with the NBS Metallurgy Division

to examine surface properties of liquid metals and, in particular, to

correlate measurements of surface tension with amounts of surface impurities.

11
1

A new way has been found in initial test measurements to generate a clean liquid gallium surface. It has been found that a smal 1 -diameter

(1 mm) argon-ion beam can effectively remove impurity precipitates from a large surface area (about 50 mm'^). Impurity particles can be seen to flow

into the ion-impact region from distances of many millimeters. This cleaning method may be a useful means for cleaning other liquid surfaces.

An uhv instrument dedicated to surface-tension measurements and with

the capability for Auger-el ectron spectroscopy is being assembled. Surfacetension measurements of elemental liquid metals and of liquid-metal alloys

will be correlated with processes such as surface segregation and the

growth of solid oxide overlayers.

(e) Microcompositional Analysis of Semiconductor Surfaces (Melmed)

An outstanding problem in semiconductor characterization is the

measurement of impurity concentrations at low levels (e.g., 1 ppm of carbon).

It is believed that the time-of-fl ight atom-probe field ion microscope

(APFIM) could be utilized to determine impurity or dopant concentrations

at these low levels.

In a collaboration with scientists at the Pennsylvania State University,

the practical upper limit of resistivity for semiconductor analysis has been

from about 10 ohm cm with commonly used APFIM instruments to about

ohm cm. This development allows the full analytical capability of

the APFIM to be applied to a wide range of semiconductor materials.

(f) Investigations of Surface Atomic Structure (Melmed)

The atomic structure of a surface is an important parameter for understanding surface properties. For many materials, the surface atomic

structures have been shown not to be simple continuations of the bulk

atomic structure; in such cases, the surface is said to be reconstructed.

In collaboration with scientists at the University of Pennsylvania,

it has been found

(1 ) Similar to previous work on the W[001] surface, it has been found

with field-ion microscopy (FIM) that the Mo [001] surface is recon- structed over a wide temperature range (15-500 K) . This result is

consistent with recent low-energy electron diffraction (LEED) measurements except that no evidence has been found for a structural phase

transition in this temperature range.

(2) In contrast to the results for W and Mo, FIM observations of a Mb [001]

surface show no evidence of reconstruction (again over a wide temperature range). LEED measurements with a Nb[001] sample are in progress

for comparison with the FIM results.

extended

12
It is planned to examine other metals and semiconductors and other

crystal planes to determine the systematics of reconstruction phenomena.

2.4 Theoretical Descriptions of Surface Processes

(a) Surface Theory (Gadzuk)

The theoretical physics projects of the Division are focused on understanding both static and dynamic behavior of atoms, molecules, solids,

surfaces, radiation and their mutual interactions. This understanding

comes from consideration of the microscopic atomic-scale properties of

individual entities as well as from larger-scale statistical properties

of ensembles. Based upon our studies, phenomenological or model theories

are constructed which relate to the chemical physics and statistical

mechanical behavior and to the intrinsic properties of relevant physicochemical systems. In addition, a significant effort is invested in the

study of the role of an actual measurement process in determining observed

quantities in different surface spectroscopies. Ways in which measurementprocess-specific quantities such as lineshapes, satellite structures, etc.

provide additional information on system dynamics are of considerable

interest.

.j Recent accomplishments include:

(1 ) A significant goal of surface science is to provide insights needed

to control reaction rates in a desired way. We have initiated a large scale theoretical study into the modelling of reaction dynamics

at metallic surfaces which include, in a very fundamental and necessary

way, intrinsic non-adiabatic effects due to the electronic excitations

of the substrate. Model studies in which analogies are drawn with

deep level spectroscopies of solids have demonstrated the important

role of substrate-excited states in determining reaction rates. In

addition to model studies, a formal reaction theory has been constructed

from which well-defined specific simplifications can be made.

(2) Semi-classical scattering theory, based upon some trajectory approximations has been an extremely useful tool for describing gas-phase

molecular-collision events involving non-adiabatic electronic behavior.

We have developed theoretical techniques for applying such theory to

problems associated with the coupled electron-nuclear motion behavior

of atomic or molecular scattering from surfaces. We have constructed

a trajectory-like theory for^ such encounters in which the quantized

nature of the "classical trajectory" can be treated within a "FranckCondon-like" picture. Applications of this theory to the problem of

atom sticking to surfaces has been carried out. Ways in which stateof-the-art infrared and electron energy-loss vibrational spectroscopy

can provide necessary input into such a description of surface collisions has been detailed.

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(3) An extremely transparent theory for a generic class of time-dependent

quantum-mechanical problems has been developed which should enable

experimentalists to do certain theoretical analyses without theorists.

The class of problems involves an initial excitation and the subsequent decay of a portion of a quantum system. While in the excited

state, the coupling of the subsystem to the remainder of the system

is altered and, depending upon the excitation lifetime of the intermediate state, this altered coupling can significantly affect

experimental observables. The single theory has been applied to

gas-phase resonance Raman spectroscopy, shape resonances in molecular photoionization, XPS-Auger coincidence electron energy

distributions, resonance photoionization lineshapes, stimulated

desorption, and atom sticking probabilities. By drawing attention

to the common link in this diverse collection of physical phenomena,

workers in one field should be better able to avail themselves of

relevant information provided by research output in the other fields.

Work planned for the future includes:

(i) Continuation of work in the significant new area of reaction dynamics

with near term emphasis on the interrelationship between substrate

electronic excitations and surface vibrational structure. Incorporation of vibrational data into trajectory-based semi -cl assical

scattering theory and path-integral formulations of surface-rate

processes is anticipated.

(ii) Model field theories with prescribed dynamical coupling constants

will be explored. Work in progress includes a theory for substrate

electron-hold pair renormalization of adsorbed i ntra-mol ecul ar vibrational ly excited states in which level shifts and widths will

be deduced and models capable of treating stimulated desorption

over the entire dynamic range, adiabatic to sudden, in the excitation process will be developed.

(iii) Analysis will be made, whenever possible, of novel experimental

results. Current work includes a study of the vibrational structure

and lineshape in photoionization spectra of shape resonances in

diatomic molecules.

2.5 Surface Standards

The term "surface standards" is intended to cover a broad range of

activities that are directed to improving the quality of surface-characterization measurements.
(a) Measurement of Absolute Ion Sputtering Yields (Fine, Andreadis)

The principal aim of this work is to obtain absolute sputtering

yields of 1-5 keV ions on wel 1 -characterized elemental samples in order

to improve the accuracy of depth-profiling measurements by current surfaceanalysis methods. The accuracy of depth-profiling measurements is at

present limited by the unavailability of accurate, reliable sputtering

yield data and by the lack of knowledge of the topographical and morphological effects produced by ion bombardment.

A dynamic method of maki.ng sputtering-yield measurements has been

developed that will allow in situ measurements of sputtering yield as a function of ion dose. As a result of some difficulties encountered with

previous quartz-oscillator microbalance measurements of sputter yields,

new oscillator design parameters have been chosen to assume greater

stability and a new set of quartz crystals has been fabricated. These

crystals were specially polished to produce the ultrasmooth surfaces

(with an rms surface roughness 1 nm) needed to eliminate initial surfacetopography effects on the yield. It is planned to calibrate the crystals

by means of neutron activation analysis. With the particular quartzcrystal oscillator head that has been designed, it is possible to monitor

concurrently mass change as well as total ion dose. Both of these measurements are made with frequency counters which have recently been interfaced

to a small computer that has been programmed to output yield and total

dose data continuously. This data will be correlated with Auger-electron

spectra and x-ray yield data as thin-film samples are sputtered.

It is planned to measure absolute sputter yields of gold, silver,

nickel, and chromium bombarded by 0.5-5 keV argon ions in the near future.

(b) Development of Prototype Standard Reference Materials (Fine, Andreadis)

The objective of this project is to develop standard reference materials

that would allow convenient determinations of ion-beam sputter-removal

rates in commonly used surface-analysis instrumentation. Thin film reference

materials of known thickness would be used to calibrate ion-gun current

densities for particular operating conditions. This information together

with sputtering-yield data for a range of materials would establish depth

scales in the measurement of depth profiles.

We are presently preparing two prototype sets of reference materials.

One of these reference materials will be a thin film ('^.70 nm) Ta^Or sputter

deposited onto a polished silicon crystal; the outer surface will Be protected by a very thin layer (-^^lO nm) of sputter deposited amorphous silicon.

The other reference material will be a multi-layered metal thin film

structure (A B A B ... sandwich) also to be sputter deposited onto a silicon substrate. The metals selected, Ni and Cr, have reported sputtering yields which are very similar and thus there should be minimal

effects of preferential sputtering. The choice of these reference materials

15
T

I

was decided upon as a result of inputs from ASTM Committee E-42 on Surface

Analysis and the Surface Analysis Reference Committee in Europe (SARCE).

The fabrication of these specimens will be a part of a new collaborative research project under a new joint U.S ./Yugosl avia program between

J. Fine at NBS and B. Navinsek at the J. Stefen Institute in Ljubljana.

The laboratory in Yugoslavia has a sputter-deposition apparatus capable

of producing very uniform thin films under good vacuum conditions and we

plan to fabricate our reference materials in this apparatus. The materials

will be characterized and calibrated at L’BS by means of Auger depth-profile

analysis, the quartz oscillator weight-loss method, and x-ray fluorescence.

Other groups may participate in the calibrations.

We expect that in the development of such Standard Reference .‘Materials

that the measured depth profiles should correlate with the "true" layer

structures. However, the effect of ion bombardment on the depth resolution

at interfaces is not now completely understood. One approach to learning

more about this depth resolution effect is through computer modelling of

the sputtering process. As part of a Cooperative Program with the University of Maryland, the sputtering of multiple layered materials is being

modelled using a Monte-Carlo code. These results should allow a more complete analysis to be made of our depth profile -measurements.

(c) Standards-Committee Activities (Powell, Fine, Kelley)

Three staff members hold offices on ASTM Committees E-42 on Surface

Analysis and 0-32 on Catalysts. Participation in the activities of these

committees not only provides an efficient means to disseminate our expertise

to those who need it and to exert a leadership role in important areas

but provides us with current information on significant measurement problems facing those who are using surface-analysis equipment (E-42) or who

are characterizing catalyst properties (0-32).

Recent activities have included:

(1) The development of Standard Practices. Draft documents concerning

Auger terminology, specimen handling, qualitative elemental identification in Auger-electron spectroscopy, energy calibration in x-ray

photoelectron spectrometers, and specifying the performance of

electrostatic electron spectrometers will be ballotted in August,

1980. Other documents concerning electron-beam damage effects,

identification of chemical states by Auger-electron spectroscopy,

measurement of performance oY electron spectrometers, ESCA terminology

and quantification in Auger spectroscopy and ESCA are being discussed.

(2) Surveys to determine desirable characteristics of prototype standard

reference materials. Information has been collected recently concerning

reference materials for the calibration of depth scales in depth16
profile measurements with surface-analysis instrumentation. One

class of useful reference materials has been identified: electrochemically analyzed oxides on metals. These oxides have the virtue

of being easily fabricated but there is not now available a set of

procedures for preparing high-purity metal oxides. Work has started

on assembling and evaluating a set of procedures in order to prepare

a document on recommended thin-film anodization methods.

(3) Contacts have been made with a small group of European scientists

who have formed a Surface Analysis Reference Committee in Europe

(SARCE) that is loosely associated with the Bureau Committee de

Reference, an official part of the European Economic Community.

Efforts will be made to coordinate the activities of the ASTM E-42

Committee on Surface Analysis with the SARCE group to increase the

effectiveness of both groups and to minimize possible duplications

of effort. The SARCE group was formally established at a Symposium

on Quantitative Surface Analysis in London in October, 1979; at this

meeting a survey of the attendees showed a strong desire for the

development of a broad range of surface standards (e.g., calibration

and operating procedures, reference materials, reference data, recommended procedures for data analysis, methods for quantification).

(4) Organization of an Evening Workshop on Quantitative Surface Analysis

at the 1980 Pittsburgh Conference on Analytical Chemistry and Applied

Spectroscopy. This workshop involved discussion between a panel of

invited speakers who gave presentations to an earlier formed Symposium

and the audience on key questions which affect the accuracy of practical

surface analyses (e.g., specific practical problems with particular

analysis techniques, problems with the associated methodology, needs

for additional reference data and materials, extent of sample damage

during analysis, and sources of errors and mistakes). The workshop

was judged successful by many of the attendees and a similar format

and program are planned for forthcoming Pittsburgh Conferences.

(5) Recommended methods have been developed for the analysis of base-metal

and precious-metal catalysts and for the determination of catalystsurface areas. An NBS-analyzed Co-Mo catalyst have been employed as

a standard for calibration of analytical procedures.

Similar activities will continue in the coming year.

(i) One planned activity is a test of the transmission properties of a limited number of x-ray photoel ectron spectrometers of the same type.

As a followup to the recently conducted ESCA roundrobin, tests will be

made to determine the extent of differences in analyzer transmission

properties for instruments that have been as carefully checked,

aligned, and operated as possible. Such measurements will provide a baseline for comparisons with other instruments of the same type and

from the other manufacturers.

17
(ii) Another planned activity is the sputter depth profile characterization of a multi-layered thin film (sandwich-type) structure

in order to establish a method for calibrating sputtering rates

for depth profile analysis. The use of such a layered structure

should enable the user to eliminate the uncertainty of initial

surface contaminants on the ion-erosion rate and should therefore

provide a practical means for converting absolute sputtering yield

data into a sputter depth measurement.

(d) Review Articles and Books

Review articles are an excellent means of disseminating information

on measurement methods and reference data in selected areas. Although

the preparation of a good review article is time-consuming, it is clear

from the response to the division's mailing list (Section 1) that such

articles are considered valuable.

A good example of the utility of review articles is the recent

selection of a 1971 review article by T. E. Madey and J. T. Yates as a "citation classic" by the publisher of the Science Citation Index.

This article, "Electron-Stimulated Desorption as a Tool for Studies of

Chemisorption: A Review," was prepared at a time when electron-stimulated

desorption (ESD) was of scientific interest for characterizing the

nature of adsorbed species on surfaces and was of practical importance

in affecting the accuracy of pressure measurements in the ultrahigh vacuum regime. Since then, electron-beam methods such as low-energy

electron diffraction and Auger-electron spectroscopy have grown appreciably in use as surface-characterization techniques and ESD and related

electron-damage effects have been recognized as a factor limiting the

accuracy of measurement for many types of samples.

Review articles by Division staff that have been published since

1979 include;

(1 ) "Electron Spectroscopy and Chemical Bonding," T. N. Rhodin and

J. W. Gadzuk, in The Nature of the Surface Chemical Bond , ed. by

G. Ertl and T. N. Rhodin ( North-Hol 1 and , 1 979).

(2) "Chemical Information in Auger Spectroscopy," R. R. Rye, J. E. Houston,

D. R. Jennison, T. E. Madey, and P. H. Holloway, Ind. Eng. Chem.

Prod. Res. Dev., 1_8, 2 (1 979).

(3) "Recent Progress in the Quantification of Surface Analysis Techniques,"

C. J. Powell, Appl . Surface Sci., 4, 492 (1980).

(4) "Prospect! ves for Surface Chemistry," J. T. Yates, and T. E. Madey,

Proc. of Fourth Symposium on Fluid/Solid Interactions (Naval Research

Laboratory, 1980).

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Review articles in the course of publication include:

(5) "Nitric Oxide Reduction," W. F. Egelhoff, in The Chemical Physics

of Solid Surfaces and Heterogeneous Catalysis , ed. by D. A. King

and D. P. Woodruff.

(6) "The iMethanation Reaction," R. D. Kelley and D. W. Goodman, in

The Chemical Physics of Solid Surfaces and Heterogeneous Catalysis , ed. by D. A. King and D. P. Woodruff.

(7) "The Thermal Desorption of Adsorbed Species," J. T. Yates, in

Methods of Experimental Physics , ed. by R. L. Park.

(8) "Experimental Methods in Electron and Photon Stimulated Desorption,"

T. E. Madey in Methods of Experimental Physics , ed. by R. L. Park.

(9) "Electron Beam Damage in Auger Electron Spectroscopy," C. G. Pantano

and T. E. Madey, to be published in Applications of Surface Science.

While there are many books and review articles on different aspects

of surface science and its applications, there is a dearth of information

on how to make reliable surface-characterization measurements. There is,

in essence, a large information gap between review articles in which the

latest scientific advances are discussed and manufacturers handbooks in

which the operation of commonly used surface-characterization equipment is

described. Negotiations are currently underway with a commercial publisher

to produce a series of books which will address this need. Three NBS

staff members (Powell, Madey, Yates) and two other scientists will con- stitute an editorial board that will oversee the production. Current

plans call for several books that will include extensive descriptions

of the commonly used methods of surface analysis, the practice of ion

sputtering to obtain depth-profile information, specimen preparation,

and vibrational -spectroscopy methods of characterizing surface molecules.

3. SURFACE SCIENCE COMPETENCE PROGRAM (9 staff years)

3.1 Introduction

The Surface Science Competence Program is a part of the recently

established NBS "Competence Program." The NBS program was introduced

to provide long-term support for the establ isl^nent and maintenance of

areas of excellence in science and technology contributing to the NBS

mission and the projected needs of' the NBS clientele.

The initial plans for the Surface Science Competence Program envisaged new research activities in three areas: (a) chemical dynamics on surfaces, (b) ion interactions with surfaces, and (c) surface properties

of novel materials; there will, however, be appreciable overlaps among

these areas and with other Division projects. Specific projects have

19
been selected based on a judgement of their scientific merit and on assessments of impacts with other NBS Divisions and of the future scientific and technical challenges requiring NBS expertise and action. Our

strategy has been to involve the existing Division staff in the new activities to the maximum extent possible, to attract additional highquality staff to NBS, to seek staff at both junior and senior levels,

to implement both new experimental and new theoretical activities, and

to retain flexibility to meet future needs by filling some positions on

a non-permanent basis.

3.2 Reports of Technical Activities

Details are given here of projects which have been initiated.

Other projects are currently being developed.

(a) ESDIAD-EELS Studies of the Molecular Structure of Adsorbed Species

(Yates, Madey, Ceyer)

The determination of the local bonding geometry of adsorbed species

on surfaces is of fundamental importance to the development of a conceptual

basis of surface chemistry. Fundamental studies of adsorbate structures

on single crystals are just beginning to give baseline information of

importance to technologies such as heterogeneous catalysis, corrosion

prevention, electrochemistry, and semiconductor design.

We are constructing an instrument to combine two powerful techniques

for studying adsorbate structures - ESDIAD (Electron Stimulated Desorption

Ion Angular Distribution) and EELS (Electron Energy Loss Spectroscopy).

The two-level apparatus, magnetically shielded, is almost ccm’pleted.

The EEL-spectrometer is operating at optimal resolution and tpeam current

and has been tested at resolutions as low as 4.5 meV (36 cm ) in the

direct beam. When finished the apparatus will have provision for molecular beam dosing of the crystal with adsorbates (to maintain high purity).

Auger spectroscopy, thermal desorption spectroscopy , angular dependent

EELS, and ESDIAD, including mass spectrometric detection of the ionic

fragments. It will be a unique experimental facility for structural

studies on surfaces. The areas of planned research include:

(i) Study of and 0^ chemisorption and interaction on Ag surfaces

(ii) Study of the catalytic reduction of chemisorbed oxygen by hydrogen on Rh surfaces searching for adsorbed OH intermediates

(iii) The influence of substrate crystallography on the bonding of CO

to transition metals

(iv) Exploratory studies of laser-induced dissociation of chemisorbed

molecules

20
(v) study of the orientation and vibrational spectrum of the CH^NC

molecule on Rh surfaces. Preliminary IR studies on dispersed

Rh indicate the molecule chemisorbs via the NC group (as expected)

and this mode of bonding provides an anchor for CH^ groups. It

is planned to study the CH^ orientation and its freedom to rotate

about the axis.

(vi) Study of CO bonding at ZnO single crystal surfaces, to correlate

with recent photoemission studies, as well as recent IR studies

at NBS.

(b) Laser Fluorescence as a Probe of Surface Dynamics (Yates, Cavanagh)

Surface science has long been concerned with understanding the

kinetics of thermal desorption. To date, no complete studies of the

distribution of internal energy (vibration, rotation) in desorbing molecules have been done. Such information is of importance in modeling

desorption at the quantum mechanical level, and will be important to

the understanding of a crucial step in catalysis (desorption of the

product molecule).

Laser fluorescence techniques are well known' to be useful for

studies of the internal energy distribution of free molecules. In

collaboration with Drs. J. Stephenson and D. King of the NBS Molecular

Spectroscopy Division, we have designed an experiment for determining

the internal energy distribution of molecules desorbed thermally from

surfaces. Particular care has been taken to ensure that the laser

excites molecules desorbing from the sample rather than returning from

the apparatus walls.

The ultrahigh vacuum optical cell has been built and tested. It

has been shown that a single desorption state of NO from Ru(OOl) occurs

at 480 K in agreement with earlier thermal desorption studies elsewhere.

The optical portion of the experiment is currently under test.

We plan initially to study the thermal desorption of NO from Ru(OOl).

The activation energy for desorption is about 10000 cm^^ while the vibrational frequency of the free molecule is about 1900 cm" , and we will

determine whether the desorbing molecule is vibrational ly or rotational ly

hot. Since the initial state of the chemisorbed NO is known (site location, vibrational dynamics), the determination of the internal energy

distribution of the desorbing malecule in its "final state" should permit

a detailed theoretical description of the dynamics of the desorption

process to be constructed. NO desorbing from a molecular NO state on Ru(OOl) will be compared with NO desorbing from recombination of N(ads)

and O(ads) on Ir(lOO). In addition, transient species in catalytic

reactions on surfaces may possibly be detected by laser fluorescence

studies in the gas phase (i.e., 0H(g) from H(ads) + O(ads) on the surface),

and exploratory studies in this direction are planned.

21
(c) Neutron Inelastic Scattering from Adsorbed Species on Surfaces

(Madey, Kelley, Cavanagh)

An important challenge to surface science is the characterization

of surfaces in their working environments, e.g., high temperature and

high pressure. To this end we are developing neutron inelastic scattering

(NIS) at the NBS 10 MW Reactor as a tool for determining the vibrational

spectra of hydrogen-containi ng molecules on the surfaces of high-area

transition-metal catalysts. Neutron scattering is particularly sensitive

to hydrogen vibrations, is ideally suited for optically opaque samples,

and is useful under high pressure conditions as an in situ surface

characterization tool.

Dr. J. J. Rush and his colleagues in the NBS Reactor Radiation

Division have constructed a new neutron analyzer/detector system to provide a factor of 6 increase in signal -to-background over our initial

measurements. A new cryostat and portable uhv system permit adsorption

studies to be carried out over a wide temperature range. Using these

facilities, we have studied the adsorption and decomposition of

over Raney Ni in the range 77-300 K; this is the first reported use^of

NIS for studying hydrocarbon chemisorption by a metal surface.

./ Future plans include;

(i) Study of the adsorption and decomposition of small hydrocarbon

molecules on Raney Ni catalysts; use these data to help identify

intermediates in CO hydrogenation reactions.

(ii) Examine low-frequency torsional modes of -CH^ and -CH^ ligands.

These non-optical 1 y active modes cannot be easily detected using

other methods and their presence or absence is essential to structural assignments of molecular fragments on surfaces.

(d) Angle-Resolved Photon-Stimulated Desorption - A New Tool for Surface

Characterization (Madey, Stockbauer)

NBS surface scientists have collaborated in a crucial and successful

test of a recent theory by Knotek and Feibelman in which ion desorption

from surfaces was postulated to be initiated by core-hole ionization of

surface atoms. The first measurements of angular anisotropy in the

photon-stimulated desorption (PSD) of positive ions from adsorbed layers

on a metal surface have been made in a joint effort between the NBS

group and scientists from IBM and Yorktown Heights. These experiments

were conducted with soft x-rays from the University of Wisconsin Synchrotron Radiation Facility in Stoughton, Wisconsin and with a unique

display-type energy analyzer designed by Dr. D. E. Eastman of IBM. In

the collaborative experiments, the NBS/IBM group extended the range of

the analyzer (originally designed for angular resolved photoelectron

emission) to detect the PSD of 0 ions from an adsorbed oxygen monolayer

22
on a tungsten (111) oriented single crystal surface. PSD ion angular

distributions, energy distributions, and photon excitation spectra for

0 desorption from W{111) have been measured for oxygen coverages ranging

from a fractional monolayer to a multilayer oxide, and for photon energies

in the range 8 to 120 eV. A direct comparison of PSD with ESD revealed

identical angular distributions indicating that the excitation mechanisms

are the same in each case. This work confirms the Knotek-Fei belman theory,

which postulates that ion desorption is initiated by core-hole ionization

of surface atoms, whether ionization is produced by electron or photon

bombardment.

The use of photon excitation rather than electron excitation for

the desorption of ions has the advantage that the ion signal can be

identified with a particular bond. By tuning the photon energy, it is

possible to correlate a photon-energy threshold for the emergence of a particular ion signal with a specific bond (e.g., for ions emerging

from a composi;^e surface). In the recent experiments, the angular distribution of 0 ions and the ion yields as a function of photon energy

provided detailed information about the directions of surface bonds and

the site from which desorbing ions originated. Angle-resolved PSD thus

offers an exciting new means of characterizing the electronic and geometric properties of specific surface bonds. Similar experiments are being initiated at the NBS SURF II facility in collaboration with

Dr. R. P. Madden and his colleagues of the MBS Radiation Physics Division.

The collaboration with the IBM scientists is continuing. Planning has

also been initiated for related work at the Brookhaven National Synchrotron

Light Source.

Plans for the next year include:

(i) PSD of covalently bonded surface species to assess the role of

valence-type excitations in ion desorption (CO, hydrocarbons

adsorbed on transition-metal surfaces)

(ii) Application of PSD to oxygen adsorption and oxide formation on metals known to be catalytical ly active; characterization of the

structure and bonding of OH groups on oxides using angle-resolved

PSD

(e) Photoemission Studies of Materials (Egelhoff)

A series of photoemission experiments is in progress with basically

two different goals. One goal i? to gain a deeper understanding of the

physical phenomena that govern the characteristics of the photoemission

process itself. This work has yielded a better understanding of electronic

processes and electron dynamics in the rare-earth elements from analysis

of photoemission resonances. The other goal is to use photoemission as

a tool to study novel surface properties of materials. Among the properties under consideration are the electronic and geometric structure

23
of monolayer and submonolayer metal overlayers on metal substrates,

changes in the electronic structure for surface atoms, and information

on the electronic structure of small metallic particles ranging in size

from single atoms to several hundred atoms.

The following experiments are in progress:

(1 ) The study of materials by photoemission using synchrotron radiation

is at present a rapidly growing field. One phenomena of particular

interest recently has been photoemission resonances. These resonances

can be used, for example, to establish differences in valence

between surface and bulk rare-earth atoms. Our aim has been to

gain a deeper understanding of the general principles governing

these resonances. Prior to our work it was not understood why the

intensity profile of the photoemission resonances in the lanthanideseries rare-earth elements was directly proportional to the photon

absorption coefficient.

Experiments have been conducted at the Stanford Synchrotron Radiation

Laboratory in collaboration with Dr. G. G. Tibbets of the General Motors

Research Laboratories and Mr. M. H. Hecht and Prof. I. Lindau of Stanford

University. Measurements have been made of photoemission spectra of

thulium in the 150 to 250 eV photon-energy range. The results indicate

the 4d 4f absorption cross section is directly proportional to the

strength of an autoionization resonance which is thus believed to be the

predominant decay channel associated with excitation from the 4d shell.

Decay by the alternative channel of escape of an excited electron does

not occur readily because of a significant angular-momentum barrier

constraining the 4f electrons to the atom core.

It is believed that similar behavior will be observed in other

rare-earth elements and compounds. Further experiments are planned at

Stanford and at the new Brookhaven National Synchrotron Light Source to

examine the dynamics of electron excitation.

(2) Recent breakthroughs in the use of binary alloys as industrial

catalysts demonstrate the need for an improved understanding of

the chemical physics of adatoms on one metal on a substrate of

another metal. It is planned to make careful studies of the properties of Ni, Co, Fe, Cu, Pt, and Pd evaporated onto single-crystal

surfaces of Fe, Ni , A1 , and ^Cu. The surface geometry will be studied

by low-energy electron diffraction with an emphasis on surface-phase

transitions, ordered overlayers, and diffusion into the bulk. The

electronic structure will be studied by x-ray photoemission with

an emphasis on gaining an understanding of effects produced by

changes in the geometric structure. The effects of gases such as CO, NO, and hydrocarbons adsorbed on binary alloy surfaces will

also be studied. By investigating such systems under carefully

controlled conditions, we anticipate the development of a set of

24
general principles for the electronic and geometric structures

binary-alloy catalyst surfaces. It is noteworthy in this context

that no one to date has applied photoemission to study an ordered

overlayer of one metal on a single-crystal surface of another metal.

(3) The subject of ultrasmall metallic particles is currently receiving

considerable attention due to established and anticipated novel

surface properties. We plan to use photoelectron spectroscopy to

investigate changes in the valence-electronic structure for metallic

particles as a function of particle size. Metallic particles,

particularly rare-earth elements such as Eu, Sm, and Yb, will be

produced by evaporation onto an amorphous carbon substrate with

the average size being controlled by the substrate temperature and

subsequent annealing. Particular attention will be paid to possible

changes in 4f-shell occupancy as a function of size. Further studies

will be made of changes in electronic structure as the particles are exposed to different gases. Such experiments should be very illuminating as the surface atoms of the particle can be an appreciable

fraction of the total and as structural changes could be visible

through changes in molecular-bonding configurations.

Extensive modifications and additions have been made to an existing

x-r.ay photoelectron spectrometer for experiments in the second and third

categories above. A sample-preparation chamber has been designed in

which a range of samples can be prepared by vacuum evaporation and

characterized by low-energy electron diffraction. The samples can then

be transferred to the spectrometer.

(f) Atom-Probe Field-Ion Microscopy of Materials (Melmed, Martinka)

We are constructing an Atom-Probe Field-Ion Microscope (APFIM)

facility which will enable microscopic determinations of composition

and atomic structure to be made on a wide range of materials in both

surface and bulk regions of the sample. There are three types of atom- . probe instruments, namely time-of-fl ight (ToF), imaging, and magnetic

sector, which each have specific advantages and limitations. The magneticsector type appears to have few applications in the microanalysis of

solid materials so it has been decided to build a facility of ToF and

imaging atom-probe instruments.

The ToF APFIM is designed with an energy-compensation stage to have

a mass resolution A M/M = 1/2000 in the mass range of most metallic

elements. The main application of this instrument will be the surface

analysis and depth-profile analysis of small areas and volumes, respectively, of solid materials. The spatial resolution in surface analysis

will be variable from 15 nm to an atomic spacing while a depth resolution

of one atomic layer over a depth range of ly m will be attainable.

25
The imaging APFIM produces displays of the spatial distribution

of selected elements on a sample surface. The mass resolution of the

instrument is about 1/50 and the lateral resolution is about 0.3 nm.

It is also possible to use the imaging instrument in the ToF mode with

a mass resolution of about 1/150.

The ToF and imaging APFIM instruments are currently under construction.

Both instruments incorporate a number of novel features. The instruments

will be fully computerized to enable rapid data acquisition and real-time

data analysis.

We plan to use the APFIM instruments for a wide range of surface

and bulk materials problems:

(i) Composition and structure: microanalysis of new materials,

platings, metallic glasses, alloys, etc.

(ii) Segregation: al loy consti tuents , gas, grain-boundary diffusion.

(iii) Radiation Implantation: surface damage, dopant penetration.

(iv) Corrosion: hydrogen interactions, aqueous media damage.

(v) Gaseous adsorption: site-specific adsorption, reaction-product

identification.

(g) Surface Theory (Gadzuk, Girvin, Matthew, Metiu)

Theoretical research is conducted in areas judged useful for the

experimental program and to develop a conceptual base for surface properties, processes, and interactions.

The Division has been fortunate to have as visiting scientists

during the 1980 summer Prof. J.A.D. Matthew from the Physics Department,

University of York, England and Prof. H. I. Metiu from the Chemistry

Department, University of California at Santa Barbara. Each visitor

gave three tutorial lectures which were appreciated by large audiences.

While at NBS, Prof. Matthew worked on a comparative study of Augerelectron spectra excited by ions, electrons, and photons. Prof. Metiu

has investigated mechanisms of electron-stimulated desorption of adsorbates

from surfaces and the role of roughness in surface spectroscopies.

Other accomplishments include:

(1 ) A theory for molecular reaction-rate processes at surfaces has been

developed. A paper presenting the formal theory of surface rate

processes together with model examples has been completed. Another

paper emphasizing the role that vibrational spectroscopy can play in

the reaction-rate theory has also been written.

26
(2) The photoemission and Auger spectra of a material is often directly

interpretable in terms of a one-body density of states. In some instances, however, one must consider the many-body dynamics of the

measurement process in detail. Striking examples of the latter are the resonant satellites in several d-band materials which have been

observed in photoemission near the photon-energy threshold for corehole production. Near threshold, the Auger decay spectrum of the

core-hole may be significantly modified by the presence of the

spectator electron which is a by product of the creation of the

core hole. A clarification of the physics of this phenomenon and

its possible relationship to observed photoemission satellites

has been made and an approximate analytic solution for a model

describing the dynamics of the process has been obtained.

A general program of study of the statistical mechanics of adsorbed

layers is underway. The capability to determine orientation of

molecules by ESDIAD (Electron-Stimulated Desorption of Ion-Angular

Distribution) has prompted a study of orientational ordering in

adlayers on substrates of various symmetries. Another area of

.investigation is the analytic study and numerical Monte-Carlo

simulation of interaction effects in the thermal desorption

spectroscopy of adlayers. A general investigation of equilibrium

phase transitions in two dimensions is planned.

27
4. PUBLICATIONS

(a) Publications of Past Year

Carroll, J. J., Melmed, A. J., and Kruger, J., Technical Report to ONR,

"Hydrogen Interactions with Stressed Titanium-Palladium Alloys

and Stressed Vanadium Explored with Field Ion Microscopy."

Carroll, J. J., Klein, R., and Melmed, A. J., "Thorium Field-ion Microscopy," Surface Science, L93-L97 (1980).

Duncan, T. M. , Yates, J. T., Jr., and Vaughan, R. W., "13p - NMR Studies

of CO Chemisorbed on Rh dispersed on Al^Oo," J. Chem. Phys., 71,

3129 (1 979). -

Dunlap, B. I. and J. W. Gadzuk, "Surface Plasmon Relaxation Energies for

CO Adsorbed on Jellium," Surf. Sci . , 89 (1980).

Gadzuk, J. W., "Hole Recoil, Vibrational Shake-up, and Photoelectron

Lineshapes," Phys. Scripta, 570 (1 980).

Goodman, D. W. , Kelley, R. D., Madey, T. E., and Yates, J. T., Jr.,

"Kinetics of the Hydrogenation of CO over a Single Crystal Nickel

Catalyst," J. Catal . , 63, 226 (1 980).

Goodman, D. W., Madey, T. E., and Yates, J. T., Jr., "Interaction of Hydrog

Carbon Monoxide, and Methanol with Ni(lOO)," Surface Science, 93,

L135 (1 980).

Goodman, D. W., Kelley, R. D., and Madey, T. E., "Kinetics of Carbon

Deposition from CO on Ru(llO) and Ni(lOO)," J. Vac. Sci. Tech.,

U, 143 (1 980). ~

Goodman, D. W., and White, J. W., "Measurement of Active Carbon on Ru(llO): Relevance to Catalytic Methanation ," Surface Science, 90,

201 (1 979).

Holloway, P. H., Madey, T. E., Campbell, C. T., Rye, R. R., and Houston,

J. E.y "Electron Spectroscopy of Condenseti Multilayers: Line Shape

Changes due to Beam Damage and Excitation .^tode," Surface Science,

88, 121 (1979).

X Kelley, R. D., and Goodman, D. W., "Catalytic Methanation • over Single

Crystal Nickel and Ruthenium: Reaction Kinetics on Different

Crystal Planes," Division of Fuel Chemistry, ACS, Vol . 25, #2,

March, 1980.

Madey, T. E., Yates, J. T., Jr., Bradshaw, A. M., and Hoffman, F. M.,

"Evidence for "Inclined" CO on Pd(210)," Surface Science, 89,

370 (1979).

28
Madey, T. E. , "The Role of Steps and Defects in Electron StimulatedDesorption: Oxygen on Stepped W(llO) Surfaces," Surface Science,

9±, 483 (1980).

Melmed, A. J., Tung, R. T., Graham, W. R., and Smith, G.D.W., "Evidence

for Reconstructed [001] Tungsten Obtained by Field- Ion Microscopy,"

Phys. Rev. Letters, 1521 (1979).

Melmed, A. J., and Carroll, J. J., "El lipsometry Data Analysis Aided

by Derivative Plots in N,K-Space," Applied Optics, ^9 (1980)

1735-1736.

Powell, C. J., Recent Progress in Quantification of Surface Analysis

Techniques, Appl. of Surf. Science, 4, 492 (1980).

Powell, C. J., "Application of Auger-Electron Spectroscopy and X-ray

Photoelectron Spectroscopy to the Characterization of Pollutant

particles," Characterization of Particles , edited by K.F.J. Heinrich,

NBS Special Technical Publication 533, p. 131, (1980).

Powell, C. J., Erickson, N. E., and Madey, T. E., "Results of a Joint

Auger/ESCA Round Robin Sponsored by ASTM Committee E-42 on Surface

Analysis, Part I." ESCA Results J. Elect. Spect., ]7_, 361 (1979).

Thiel, P. A., Yates, J. T. , Jr., and Weinberg, W. H., "The Interaction

of Oxygen with the Rh(lll) Surface," Surface Science, 22 (1979).

Thiel, P. A., Yates, J. T., Jr., and Weinberg, W. H., "The Co-Adsorption

of Oxygen and Hydrogen on Rh(lll)," Surface Science, 121 (1979).

Thiel, P. A., Williams, E. D. , Yates, J. T. , Jr., and Weinberg, W. H.,

"The Chemisorption of CO on Rh(lll)," Surface Science, 199 (1979).

Thiel, P. A., Weinberg, W. H., and Yates, J. T., Jr., "A Determination

of Adsite Symmetry on Surfaces via Electron Energy Loss Spectroscopy

Co-Adsorption of CO and NO on Ru(OOl)," J, Chem. Phys., 71_» 1643

(1979).

Thiel, P. A., Weinberg, W. H., and Yates, J. T., Jr., "The Adsorption

of Nitric Oxide on Ru(OOl)," Chem. Phys. Letters, 67_y 403 (1979).

West, J. B. , Parr, A. C., Cole, B. E-j Ederer, D. L., Stockbauer, R. , and

Dehmer, J. L., "Shape-Resonance-Induced Non-Franck-Condon Vibrational

Intensities in 3 photoionization of N-," Journal of Physics B Letters;

Atom. Molec. Phys., 1_3, L105 (1980).

Williams, E. D. , Thiel, P. A., Weinberg, W. H., and Yates, J. T., Jr.,

"Segregation of Co-Adsorbed Species - Hydrogen and Carbon Monoxide

on the (111) Surface of Rh," J. Chem. Phys., 72, (1980) 3496-3505.

29
Yates, J. T. , Jr., Thiel, P. A., and Weinberg, W. H., "The Catalytic

Reaction between Adsorbed Oxygen and Hydrogen on Rh{lll)," Surface

Science, 82^, 45 (1979).

Yates, J. T. , Jr., Duncan, T. M. , Worley, S. D. , and Vaughan, R. W.,

"Infrared Spectra of Chemisorbed CO on Rh," J. Chem. Phys., 7^,

121 9 (1979).

Yates, J. T. , Jr., Worley, S. D. , Duncan, T. , and Vaughan, R. W.,

"Catalytic Decomposition of Formaldehyde on Single Rhodium Atoms,"

J. Chem. Phys., 7£ 1225 (1979).

Yates, J. T. , Jr., Zinck, J. J., and Weinberg, W. H., "Preparation and

Purity Measurement of Extremely Pure Helium Gas," Review of

Scientific Instruments, 5£, 132 (1979).

Yates, J. T. , Jr., Zinck, J. J., Sheard, S., and Weinberg, W. H., "Search

for Vibrational Activation in the Chemisorption of CH-," J. Chem.

Phys., 70, 2266 (1 979).

^

Yates, J. T. , Jr., Williams, E. D., Weinberg, W. H., "Does Chemisorbed

Carbon Monoxide Dissociate on Rhodium?", Surface Science, ^ (1980)

562-570.

Yates, J. T. , Jr., Duncan, T. M. , and Vaughan R. W., "Infrared Spectroscopic Study of Activated Surface Processes: CO Chemisorption on Supported Rh," J. Chem. Phys., 71_, 3908 (1979).

Yates, J. T. , Jr., Thiel, P. A., and Weinberg, W. H., "The Chemisorption

of Hydrogen on Rh(lll)," Surface Science, 427 (1 979).

(b) Publications in Progress

Antoniewicz, P. R. , Cavanagh, R. R. , and Yates, J. T. , Jr., "Temperature

Effects on the Infrared Spectrum of Chemisorbed CO," J. Chem. Phys.,

accepted.

Carroll, J. J., Madey, T. E. , Melmed, A. J., and Sandstrom, D. R.,

"The Room Temperature Adsorption of Oxygen, Hydrogen and Carbon

Monoxide on (1120) Ruthenium: An El 1 i psometry-LEED Characterization,

To be published in Surface Science ^August 1 980.

Cavanagh, R. R., and Yates, J. T.,'Jr., "Hydrogen Spill-over on Alumina - A Study by Infrared Spectroscopy, J. of Catalysis, accepted.

Cavanagh, R. R., and Yates, J. T. , Jr., "Site Distribution Studies of

Ph supported on A1 20^ - An Infrared Study of Chemisorbed CO,"

J. Chem. Phys., in press.

Cavanagh, R. R. , and Yates, J. T. , Jr., "Infrared Spectra of Methyl

Isocyanide Chemisorbed on Rhodium," Surface Science, accepted.

30
Cole, B. E., Ederer, D. L. , Stockbauer, R., Codling, K. , Parr, A. C.,

West, J. B., Poliakoff, E. D. , and Dehmer, J. L. , "Wavelength and

Vi brational -State Dependence of Photoelectron Angular Distributions.

Resonance Effects in 5 Photoionization of CO," J. Chem. Physics,

to be published.

Egelhoff, W. F. , "Nitric Oxide Reduction," in The Chemical Physics of

Solid Surfaces and Heterogeneous Catalysis , King, D. A., and

Woodruff, D. P. , editors, Elsevier, London, in press.

Fine, J., "Absolute Sputtering Yield Measurement Methods - A Review,"

Proceedings of the Tenth Symposium on the Physics of Ionized

Gases, Dubrovnik, Yugoslavia (1980).

Fine, J. , Hardy, S. C. , and Andreadis, T. D. , "The Generation of Clean

Liquid Gallium Surfaces by Ion Bombardment," Contributed Papers of

the Tenth Symposium on the Physics of Ionized Gases, Dubrovnik,

Yugoslavia (1 980).

Gadzuk, J. W., and Metiu, H., "Theory of Electron-Hole Pair Excitations in

Unimolecular Processes at Metal Surfaces. I. X-ray Edge Effects,"

Phys. Rev. B, in press.

Gadzuk, J. W., and Metiu, H., "Aspects of Reaction Dynamics at Metal

Surfaces," Proc. of IVth Int. Conf. on Solid Surfaces, Cannes,

France, September, 1980.

Girvin, S. M. , and Jonson, M. , "Dynamical Electron-Phonon Interaction

and Conductivity in Random Metal Alloys," Phys. accepted.

Girvin, S. M. , and Penn, D. R. , "Theory of Coherence Effects in Photoinduced Auger Events: Resonant Satellites in Metals with Filled

d-Bands," to be published in Phys. Rev. B.

Goodman, D. W., Kelley, R. D., Madey, T. M. , and White, J. M. , "Measurement

of Carbide Buildup and Removal Kinetics on Ni(lOO)," Catal . , accepted.

Jach, T. J,, and Powell, C. J., "L^VV Auger-Electron Lineshapes and Peak

Positions for Near-Threshold Electron Excitation in Nickel and Copper,"

submitted for publication, Phys. Rev. Letters.

Jach, T. J., and Powell, C. J., "Application of X-ray Photoelectron Spectroscopy and Auger-Electron Spectroscopy for the Surface Characterization

of Pollutant Particles," to be published in the Summary Report of the

DOE Program Review on Physics and Chemistry of Atmospheric Pollution,

Harpers Ferry, W. Va., May 28-30, 1980.

Kelley, R. D. , Cavanagh, R. R., Rush, J. J., and Madey, T. E., "Neutron

Inelastic Scattering Study of C

2

H^ Adsorbed on Raney Nickel,"

Surface Science, accepted.

31
Kelley, R. D. , and Goodman, D. W., "Catalytic Methanation over Single

Crystal Nickel and Ruthenium: Reaction Kinetics on Different

Crystal Planes," Division of Fuel Chemistry, ACS, Vol . 25, #2,

March, 1980.

Klein, R. , and Fine, J., "Desorption of Cesium from Molybendum (111);

Positive Ion Thermal Desorption Spectroscopy and Neutral Lifetime

Measurements," Proceedings of the Eighth International Vacuum

Congress and Fourth Inti. Conference on Solid Surfaces, Cannes,

France (1980).

Lehwald, S., Yates, J. T. , Jr., and Ibach, H., "Adsorption and Dissociation of MO on fJi(lll)," Proceedings of Fourth International

Conference on Solid Surfaces, to be published in Le Vide .

Madey, T. E. , Goodman, D. W., Fisher, G. B., and Yates, J. T. , Jr.,

"Structure and Kinetics of Surface Species," Proceedings Fourth

Symposium on Fluid-Solid Surface Interactions, in press.

Madey, T. E., "Determination of the Structures of Surface Molecules

Using ESDIAD (Electron Stimulated Desorption Ion Angular Distribution),

to be translated into German and published in "Nova Acta Leopoldina."

Madey, T. E. , Stockbauer, R., van der Veen, J. F., and Eastman, D. W.,

"Angle Resolved Photon Stimulated Desorption of Oxygen Ions from a W(lll) Surface," Physical Review Letters, accepted.

Madey, T. E. , Houston, J. E., and Dahl berg, S. C. , "Bonding Geometry of

CO on Planar and Stepped Single Crystal Surfaces," Le Vide , (Proceedings of 4th International Conference on Solid Surfaces,

Cannes, France, September 1980).

Melmed, A. J., Sakurai, T. , Kuk, Y., and Givargizov, E. I., "Feasibility

of ToF Atom-Probe Analysis of Silicon," submitted for publication.

Surface Science.

Metiu, H., and Gadzuk, J. W., "Theory of Rate Processes at Metal Surfaces.

II. The Role of Substrate Electronic Excitations," J. Chem. Phys .

,

to be published.

Parr, A. C., Stockbauer, R. , Cole, B. E., Ederer, D. L. , Dehmer, J. L.

,

and West, J. B., "An Angle Resolved Photoelectron Spectrometer for

Atoms and Molecules," Nucl . Iqstrum. Methods, to be published.

Williams, E. D. , Thiel, P. A., Weinberg, W. H. , and Yates, J. T. , Jr.,

"Two Dimensional Phase Separation - Coadsorption of Hydrogen and

Carbon Monoxide on Rh(lll)," Conference on Surface Dynamics,

La Jolla (1 979), accepted.

Yates, J. T. , Jr., and Cavanagh, R. R., "Vibrational Spectroscopic

Studies of Chemisorbed Species on Metals," Proceedings of Fourth

International Conference on Solid Surfaces, to be published in

Le Vide.

32
Yates, J. T., Jr., and f^adey, T. E. , "Prospectives for Surface Chemistry,"

in Proceedings of Fourth Symposium on Fluid-Solid Surface Interactions,

(1978).

(c) Recent Publications of New Staff Members (Cavanagh, Egelhoff, Girvin,

Griffin, and Stockbauer) describing Work in Previous Positions

Cavanagh, R. R. , Altman, R. S., Herschbach, D. R. , and Klemperer, W.,

"Molecular Beam Electric Deflection Analysis of (SN)^ Vapor.

Evidence for a Nonpolar Tetramer," J. Am. Chem. Soc., 101 4734

(1979).

Egelhoff, W. F. , Jr., and Tibbetts, G. G., "Valence Changes in a YtterbiumAluminum Alloy During Autoionization and Auger Electron Emission,"

Phys. Rev. Lett. 4^, 482 (1980).

Girvin, S. M. , and Mahan, G. D., "Thermoelectric Power in Half-filled

Bands," Phys. Rev. B 1_9» 1302 (1 979).

Girvin, S. M. and Mahan, G. D. , "Exact Results for the Quantum Diffusion

of Many Particles in a Stochastic Medium," Phys. Rev. B 20, 4896

(1 979).

Griffin, G. , and Andres, R. P., "Microscopic Capillarity Approximation:

Free Energies of Small Clusters," J. Chem. Phys. 71_, 2522 (1 979).

Griffin, G. , and Andres, R. P. , "Microscopic Capillarity Approximation:

Appl ication to Homogeneous Nucleation Theory," J. Coll, and Interface

Science, accepted.

Inghram, M. G., Hanson, G. R., and Stockbauer, R. , "The Fragmentation

of C

2 Fg+," Int'l J. I!ass Spectrom. Ion Phys. 253 (1 980).

Jonson, M. , and Girvin, S. M. , "Electron-Phonon Dynamics and Transport

in Random Metal Alloys," Phys. Rev. Lett. 1447 (1979).

Parr, A. C. , Jason, A. J., and Stockbauer, R., "Photoionization and

Threshold Photoelectron - Photoion Coincidence Study of Cyclopropene from Onset to 20 eV," Int'l J. Mass Spectrom. Ion Phys.

33, 243 (1 980).

Parr, A. C., Jason, A. J., Stockbauer, R., and McCulloh, K. E.,

"Photoionization and Fragmentation Study of Cyclopropene,"

Advances in Mass Spectrometry Vol . 8, Proceedings of 8th International Mass Spectrometry Conference, 12-18 August 1 979, Oslo,

Norway, to be published.

Rosenstock, H. M. , Stockbauer, R. , and Parr, A. C. , "Kinetic Shift in

Chlorobenzene Ion Fragmentation and the Heat of Formation of the

Phenyl Ion," J. Chem. Phys. 71, 3708 (1 979).

33
Rosenstock, H. M. , Stockbauer, R, , and Parr, A. C., "PhotoelectronPhotoion Coincidence Study of Benzonitrile," Journal de Chimie

Physique, to be published.

Rosenstock H. M. , Stockbauer, R. , and Parr, A. C. , "PhotoelectronPhotoion Coincidence Study of The Bromobenzene Ion," J. Chem. Phys .

,

to be published.

Stockbauer, R. , "The Formation of High Vibrational States of Ions by

Photoionization," Advances in Mass Spectrometry Vol . 8, Proceedings

of 8th International Mass Spectrometry Conference, 12-18 August

1 979, Oslo, Norway, to be published.

Stockbauer, R. , "Observation of the OH"^ Fragment Threshold in the Threshold Photoelectron Spectra of Water," Journal Chemical Physics,

to be published.

Tibbetts, G. G., and Egelhoff, W. F., Jr., "Mixed Valent Ytterbium - Aluminum Films," J. Vac. Sci . Technol . , 1_7, 458 (1 980).

Zhdan, P. A., Schepelin, A. P., Boronin, A. I., Boreskov, G. K.,

Weinberg, W. H., and Egelhoff, W. F. , Jr., "Photoelectron Spectroscopic Evidence for the Oxidation of Ir(lll)," "J. Catal . 6^

180 (1980).

Zhdan, P. A., Boreskov, G. K., Boronin, A. I., Schepelin, A. P.,

Egelhoff, W. F. , Jr., and Weinberg, W. H., "Nitric Oxide Adsorption

and Decomposition on the (111) and (110) Surfaces of Iridium,"

J. Catal. 60, 93 (1 979).

34
5. TALKS

Cavanagh, R. R. , "Infrared Spectra of Chemisorbed Isocyanide Species

on Rhodium," Staff of the Office of Naval Research and Contractors,

Case Western Reserve University, Cleveland, Ohio, f'ay, 1980.

Cavanagh, R. R., "Spectroscopic Comparison of CO and Isocyanide Chemisorption on Supported Metal Catalysts," ACS Meeting, Houston,

TX, March, 1980; Phillips Petroleum, Bartlesville, OK, May, 1980;

ONR, Cleveland, Ohio, May, 1980; General Motors, Warren, Michigan,

May, 1980; Bell Labs, Murray Hill, New Jersey, June, 1980.

Ceyer, S., "Dynamics of Gas-Surface Scattering," IBM Research Labs,

San Jose, CA, Feb., 1980; Dept, of Chemistry, Harvard University,

Cambridge, MA, March, 1980; Dept, of Chemistry, M.I.T., Cambridge,

MA, June, 1980.

Egelhoff, W. F. , Jr., "Electronic Effects in Nitric Oxide Adsorption on Tin Oxide," Northeast ESCA Users Group Meeting, Brookhaven, MY,

November, 1979.

Egelhoff, W. F. , Jr., "Photoelectron Spectroscopies- Studies Using

Resonance Lamp and Synchrotron Radiation of Thulium, Ytterbium,

and an Aluminum Ytterbium Alloy," Physics Dept., College of William

and Mary, Williamsburg, VA, April, 1 980.

Egelhoff, W. F. , Jr., "Photoemission Studies on a Yb-Al Alloy," Sixth

International Vacuum Ultraviolet Radiation Physics Conference,.

Charlottesville, VA, June, 1980.

Fine, J., "Measurement Methods and Calibration Techniques for Making

Absolute Sputtering Yield Measurements at MBS," Boris Kidric

Institute, Belgrade, Yugoslavia, October, 1979.

Fine, J., "Absolute Sputtering Yields for Depth Profile Analysis," and

"Visual Ion Beam Images Produced by Electron and Ion Beam Interaction on Surfaces," J. Stefan Institute, Ljubljana, Yugoslavia,

October, 1979.

Fine, J., "Sputtering and Surface Analysis," Short Course in Surface

Analysis organized by C. J. Powell, given at NBS , February, 1980.

Fine, J., "Absolute Sputtering Yield Measurement Methods - A Review,"

Tenth Symposium on the Physics of Ionized Gases, Dubrovnik,

Yugoslavia, August, 1980.

Fine, J., "The Generation of Clean Liquid Gallium Surfaces by Ion Bombardment," Tenth Symposium on the Physics of Ionized Gases,"

Dubrovnik, Yugoslavia, August, 1980.

35
Fine, J., "Desorption of Cesium from Molybdenum (111); Positive Ion

Thermal Desorption Spectroscopy and Neutral Lifetime Measurements,"

Eighth International Vacuum Congress and Fourth International

Conference on Solid Surfaces, Cannes, France, September, 1980.

Gadzuk, J. W. , "An Introduction to the Theory of Atomic and Molecular

Sticking at Metal Surfaces," Conference on "The Chemisorption Bond:

Electronic Structure and Formation Mechanisms," Aspenasgarden

,

Sweden, October, 1979.

Gadzuk, J. W., "Relaxation Effects in Electron Spectroscopies of Molecules,

Solids, and Surfaces," Physics Colloquium, Rice University, Houston,

TX, November, 1979.

Gadzuk, J. W., "Theory of Electron-hole Pair Excitations in Unimolecular

Processes at Metal Surfaces," Institute fiir Theoretical Physics of

University of Hamburg, Hamburg, W. Germany, January, 1980; Rudor

Boskovic Institute, Zagreb, Yugoslavia, January, 1980.

Gadzuk, J. W., "Surface Science as Practiced at NBS," P. N. Lebedev

Physics Institute, Moscow, USSR, January, 1980.

Gadzuk, J. W., "Basic Principles for Phenomenological Modeling of

Dynamical Processes in Molecules, Solids and Surfaces; Dynamical

Relaxation Effects in Photoelectron Spectroscopy of Molecules,

Surfaces and Adsorbates; Dynamics of Irreversible Unimolecular

Processes at Metallic Surfaces," Institute for Catalysis,

Novosibirsk, USSR, January, 1980.

Gadzuk, J. W., (co-author H. Metiu) "Theory of Electron-Hole Pair

Excitations in Unimolecular Processes at Metal Surfaces," American

Physical Society Meeting, New York, NY, March, 1980.

Gadzuk, J. W., "Dynamical Processes at Solid Surfaces," M.I.T.,

Cambridge, Mass., April, 1980.

Gadzuk, J. W. , "Role of Electron-Hole Pair Excitations in Unimolecular

Processes at Metal Surfaces," Cornell University, Ithaca, NY,

May, 1 980.

Gadzuk, J. W., "Why do Atoms Stick to Surfaces?" Interdepartmental

Catalysis Colloquium, Argonne National Laboratory, Argonne, IL,

June, 1980.

Gadzuk, J. W., "Time Dependent Quantum Mechanics Made Simple," and

"Theory of Reaction Rates at Metallic Surfaces," Institute of

Theoretical Physics, Chalmers University of Technology, Goteborg,

Sweden, September, 1980.

36
Gadzuk, J. W., "The Role of Molecular Vibrations and Franck-Condon Factors

j in Surface Reaction Dynamics," International Conference on Vibrations

at Surfaces, Namur, Belgium, September, 1980.

Gadzuk, J. W., "Aspects of Reaction Dynamics at Metal Surfaces," Fourth

:i! International Conference on Solid Surfaces, Cannes, France,

j! September, 1 980.

,1

I Girvin, S. M. , "Electron-phonon Dynamics and Transport Anomalies in

|: Random Metal Alloys," University of Virginia, Charlottesville, VA,

I September, 1979.

'j Girvin, S. M. , "Transport in Random Metal Alloys," American Physical Society,

ij New York, NY, March, 1980.

j Girvin, S. M. , "Theory of Transport Anomalies in Random Metals," University

of Maryland, College Park, MD, May, 1980.

j Goodman, D. W., "The Kinetics of Carbon Deposition From CO on Ru(llO) and

j Ni(lOO)," 26th AVS Symposium, New York, NY, October, 1979.

1 Goodman, D. W., "Surface Science and Catalysis," Auburn University,

I Auburn, AL, November, 1979.

Goodman, D. W., "Methanation Over Single Crystal Catalysts," Columbia

University, Mew York, NY, November, 1979.

Goodman, D. W., "Hydrogenation of CO over Single Crystal Catalysts,"

Exxon Research and Engineering, Linden, NY, November, 1979.

Goodman, D. W., "Methanation over Single Crystal Catalysts," Sandia

Laboratories, Albuquerque, NM, December, 1979.

Goodman, D. W., "Hydrogenation of CO over Single Crystal Catalysts,"

Ninth Symposium, American Vacuum Society, Tampa, Florida,

February, 1980.

Goodman, D. W., "Single Crystals as Models for Catalytic Studies,"

16th American Vacuum Society Symposium, Santa Fe, New Mexico,

May, 1980.

Goodman, D. W., "Single Crystals as Models for Catalytic Studies,"

Bell Telephone Labs, Murray Hill, NJ, May, 1980.

Griffin, G. L., "Combined Temperature Programmed Desorption and IR Study

of Hp Adsorption on ZnO," 180th /'merican Chemical Society Meeting,

San Francisco, CA, August, 1980.

37
Jach, T. , "Dependence of Auger-Electron Lineshapes on Incident Electron

Energy near Threshold," American Physical Society Meeting,

New York, NY, March, 1980.

Jach, T. , "LoVV Auger Electron Lineshapes and Peak Positions for NearThreshofd Electron Excitation in Nickel and Copper," Gordon Conference on Electron Spectroscopy, Wolfeboro, MY, July, 1980.

Kelley, R. D. , "Catalytic Methanation over Single Crystal Nickel and

Ruthenium: Reaction Kinetics on Different Crystal Planes,"

Symposium on Catalytic Reactions Involving Synthesis Gas and 179th

American Chemical Society Meeting, Houston, TX, March, 1980.

Kelley, R. D. , "Synthesis Gas Reactions over Single Crystal Ni and Pu

Effect of Pressure and H^/CO Ratio on Kinetics, Product Distribution,

and Surface Carbon Concentration," New England Catalysis Society,

M.I.T., Cambridge, MA, May, 1980.

Kelley, R. D. , "Neutron Inelastic Scattering (NIS) from Molecular Species

Chemisorbed on a Catalyst Surface: Potential for NIS in Catalysis,"

Joint Chemistry-Physics Colloquium, University of Rhode Island,

Kingston, RI, May, 1980.

Kelley, R. D., "Synthesis Gas Reaction Over Single Crystal Nickel and

Ruthenium: Effect of Pressure and H

2 /CO Ratio on Kinetics, Product

Distribution, and Surface Carbon Concentration," 19th Annual Spring

Symposium, Pittsburgh Catalysis Society, Monroeville, PA, May, 1980.

Kelley, R. D., "Inelastic Neutron Scattering as a Probe of Catalytic

Reactions on Raney Nickel," Solid State Seminar, Brookhaven National

Laboratory, Upton, NY, June, 1980.

Madey, T. E., "Electron Stimulated Desorption Phenomena: Relationship

to the Structure of Surface Molecules," Surface Physics Dept.,

Bell Laboratories, Murray Hill, MJ, November, 1979.

Madey. T. E., "An Overview of Surface Science and Vacuum Technology in

the Soviet Union," Rocky Mountain Chapter of American Vacuum

Society, Denver, CO, December, 1979.

Madey, T. E., "Use of Electron Stimulated Desorption for Determining

Structures of Adsorbed Molecules," Electrical Engineering Department,

University of Minnesota, Minneapolis, MN, January, 1980.

Madey, T. E., "Use of Electron Stimulated Desorption for Determining

Structures of Adsorbed Molecules," Dept, of Chemistry, Brown University, Providence, RI , February, 1980.

38
Madey, T. E., "Electron Stimulated Desorption and its Relation to Surface

Molecular Structure," Florida Chapter of the American Vacuum Society,

Tampa, FL, February, 1930.

Madey, T. E., "Electron Stimulated Desorption, Relation to Surface Molecular Structure," American Physical Society Meeting, New York, NY,

March, 1980.

Madey, T. E., "Electron and Photon Stimulated Desorption," National

Research Council, Ottawa, Canada, April, 1 980.

Madey, T. E., "Structure of Molecules and Molecular Complexes at Surfaces,"

International Seminar on Catalysis and Catalytic Phenomena, Institute

Mexicano del Petroleo, Mexico City, flexico. May, 1980.

Madey, T. E., "Catalytic Processes as Studied by Modern Kinetic & Spectroscopic Methods," International Seminar on Catalysis and Catalytic

Phenomena, Institute Mexicano del Petroleo, Mexico City, Mexico,

May, 1980.

Madey, T. E., "Catalyst Characterization Using Electron Spectroscopies,"

International Seminar on Catalysis and Catalytic Phenomena,

Institute Mexicano del Petroleo, Mexico City, Mexico, May, 1980.

Madey, T. E., "Angle Resolved Electron and Photon Stimulated Desorption:

Relation to Surface Structure," Physics Department Colloquium,

University of Wisconsin, Milwaukee, WI, May, 1980.

Madey. T. E., "Surface Characterization Using Angle Resolved Electron

and Photon Stimulated Desorption," Department of Physics,

University of Wisconsin, Milwaukee, WI, May, 1980.

Madey. T. E., "Determination of Surface Molecular Geometry Using Angle

Resolved Electron and Photon Stimulated Desorption," IBM,

Yorktown Heights, NY, June, 1980.

Madey. T. E., "Electron and Photon Stimulated Desorption," University

of Wroclaw, Wroclaw, Poland, September, 1980.

Madey. T. E., "Physical Principles of Electron and Photon Stimulated

Desorption," Conference on Inelastic Ion-Solid Collisions," Munich,

W. Germany, September, 1980.

^ Madey. T. E., "Bonding Geometry of CO on Planar and Stepped Single Crystal

Surfaces," 4th International Conference on Solid Surfaces, Cannes,

France, September, 1980.

39
Melmed, A. J., (co-authors: R. B1 aszczyszyn , M. B1 aszczyszyn , R. Meclewski,

and T. E. Madey, "Interactions of Sulfur and Nickel: Preliminary

Observations," Fifth Seminar on Surface Physics, Karpacz, Poland,

April , 1 980.

Melmed, A. J., (co-authors: R. T. Tung, and W. R. Graham) "Evidence for

Reconstructed (001 )W and (001 )Mo Obtained by FIM," 40th Conference

on Physical Electronics, Cornell University, Ithaca, NY, June, 1980.

Melmed, A. J., "A History of Field Emission Microscopy," 27th International Field Emission Symposium, Tokyo, Japan, July, 1980.

Melmed, A. J., (co-authors: M. B1 aszczyszyn , R. Blaszczszyn, R. Meclewski,

and T. E. Madey) "Interactions of Sulfur and Nickel: Preliminary

FEM Observations," 27th International Field Emission Symposium,

Tokyo, Japan, July, 1980.

Melmed, A. J., (co-authors: M. Martinka, T. Sakurai, and Y. Kuk),

"Analysis of High Resistivity Silicon in an Energy-Compensated

ToF Atom-Probe," 27th International Field Emission Symposium,

Tokyo, Japan, July, 1980.

Powell, C. J., "Progress of the ASTM Committee E-42 on Surface Analysis,"

International Conference on Quantitative Surface Analysis, National

Physical Laboratory, London, England, October, 1979.

Powell, C. J., "Shapes and Shifts of Auger Lines," Physics Department,

Technical University of Munich, West Germany, October, 1979.

Powell, C. J., "Quantitative Surface Analysis by Auger-Electron Spectroscopy and X-ray Photoelectron Spectroscopy," Institute of Interface

Science and Vacuum Physics, Kernforschungsanlage, Julich, Germany,

October, 1979.

Powell, C. J., "Quantification of X-ray Photoelectron Spectrosc ooy and

Auger-electron Spectroscopy," Eighteenth Eastern Analytical Symposium,

New York, NY, November, 1979.

Powell, C. J., "Introduction to Surface Analysis," "X-ray Photoelectron

Spectroscopy," "Auger-Electron Spectroscopy," and "Comparisons of

Surface-Analysis Techniques," Surface Analysis Course, NBS

February, 1980.

Powell, C. J., "Recent Progress in Quantification of Surface Analysis

Techniques," Symposium on Modern Spectroscopies in Surface and SolidState Chemistry, Chemistry Dept., Case Western Reserve University,

Cleveland, OH, May, 1 980.

40
Powell, C. J., "Angular Resolved Electron and Photon Stimulated Resorption: Work in the Surface Science Division," Contractors and Staff

of the Office of Naval Research, Case Western Reserve University,

Cleveland, OH, May, 1980.

Powell, C. J., "Application of X-Ray Photoelectron Spectroscopy and Auger

Electron Spectroscopy for the Surface Characterization of Pollutant

Particles," (co-author T. J. Jach) Program Review on the Physics & Chemistry of Atmospheric Pollution, Harpers Ferry, W.Va., May, 1980.

Powell, C. J., "Comparative Observation of the 2p and 3p Electron Energy

Loss Features in Nickel, Copper, and Gallium," (co-authors:

T. J. Jach, J. Fine, and T. Andreadis), Physical Electronics Conference, Cornell University, Ithaca, NY, June, 1980.

Powell, C. J., "Recent Progress in the Quantification of Surface Analysis

Techniques," Aspen Symposium of the Rocky Mountain Chapter of the

American Vacuum Society, Aspen, CO, June, 1980.

Powell, C. J., "Comparison of the ESCA with other Surface-Analysis

Techniques," Seventh Annual Meeting of the Federation of Analytical

Chemistry and Spectroscopy Societies, Philadelphia, PA, Sept., 1980.

Stockbauer, R. L., "Shape Resonance and Autoionization Effects in Molecular Photoionization. Results from the Triply Differential Photoelectron Experiment at SURF II," Center for Thermodynamics and

Molecular Science Seminar, NBS, January, 1980.

Stockbauer, R. L., "Shape Resonance and Autoionization Effects in Molecular Photoionization," Joint Physics-Chemistry Seminar, Polytechnic

Institute of Brooklyn, Brooklyn, MY, May, 1980.

Stockbauer, R. L. , (co-authors: H. M. Rosenstock and A. C. Parr), "Photo

el ectron-Photoion Coincidence Study of the Bromobenzene Ion,"

Twenty-eighth Annual Conference on Mass Spectrometry and Allied

Topics, New York, NY, May, 1980.

Stockbauer, R. L., (co-authors: A. C. Parr, J. L. Dehmer, B. E. Cole,

D. L. Ederer, and J. B. West), "Triply Differential Photoionization

Studies of Small Molecules," Twenty-eighth Annual Conference on Mass

Spectrometry and Allied Topics, New York, NY, May, 1980.

Stockbauer, R. L., (co-authors: H. M. Rosenstock and A. C. Parr),

"Recent Photoelectron-Photoion> Coincidence Studies on Benzonitride

and Pyridine Fragmentation," Twenty-eighth Annual Conference on Mass

Spectrometry and Allied Topics, New York, NY, May, 1980.

41
Stockbauer, R. L., (co-authors: A. C. Parr, J. L. Dehmer, B. E. Cole,

D. L. Ederer and J. B. West), "An Angle Resolved Photoelectron

Spectrometer for Triply Differential Photoionization Studies,"

Sixth International Conference on Vacuum Ultraviolet Radiation

Physics, Charlottesville, VA, June, 1980.

Stockbauer, R. L. , (co-authors: A. C. Parr, J, L. Dehmer, B. E, Cole,

D. L. Ederer, J. B. West, and K. Codling), "Perturbation of Vibrational Intensity and Angular Distributions by Autoionization in

Molecular Photoionization," Sixth International Conference on Vacuum Ultraviolet Radiation Physics, Charlottesville, VA,

June, 1980.

Stockbauer, R. L. , (co-authors: K. Codling, J. B. West, A. C. Parr,

J. L. Dehmer, B. E. Cole, D. L. Ederer), "Partial Cross Sections,

Vibrational Branching Ratios, and Angular Distributions in the

570-600 A Window Resonances in O

2

," Sixth International Conference

on Vacuum Ultraviolet Radiation Physics, Charlottesville, VA,

June, 1980.

Stockbauer, R. L., (co-authors: J. L. Dehmer, A. C. Parr, J. B. West,

K. Codling, D. L. Ederer, B. E. Cole, E. D. Poliakoff), "Effects of

Shape Resonances on Vibrational Branching Ratios and Photoelectron

Angular Distributions in Molecular Photoionization," Sixth International Conference on Vacuum Ultraviolet Radiation Physics,

Charlottesville, VA, June, 1980.

Stockbauer, R. L., (co-authors: H. M. Rosenstock and A. C. Parr),

"Photoelectron-Phdtoion Coincidence Studies of Chlorobenzene and

Bromobenzene ," Sixth International Conference on Vacuum Ultraviolet

Radiation Physics," Charlottesville, VA, June, 1980.

Stockbauer, R. L. , (co-authors: T. E. Madey, J. F. van der Veen, and

D. E. Eastman), "Angle Resolved Photon Stimulated Desorption of

Oxygen Ions from a W(lll) Surface," Sixth International Conference

on Vacuum Ultraviolet Radiation Physics, Charlottesville, VA,

June, 1980.

Yates, J. T., Jr., "Spectroscopic Correlations in Catalytic Chemistry on Single Crystal and on Dispersed Metal Substrates," Advances in

Catalytic Chemistry Symposium, University of Utah, Snowbird, Utah,

October, 1979.

Yates, J. T., Jr., "Spectroscopic and Other Structural Studies of Chemisorbed Species on Metal Single Crystals and on Dispersed Metal

Substrates," 3M Research Center, St. Paul, MN, January, 1980.

42
Yates, J. T. , Jr., "Spectroscopic Correlations in Surface Chemistry,"

Dept, of Chemical Engineering, Stanford University, Palo Alto,

CA, February, 1 980.

Yates, J. T. , Jr., "Spectroscopic Correlations in Surface Chemistry,"

Department of Chemistry, University of California, Berkely, CA,

February, 1980.

Yates, J. T. , Jr., "Spectroscopic and Other Structural Studies of Chemisorbed Species on Metal Single Crystals and on Dispersed Metal

Substrates," Exxon Research and Development Laboratories, Baton

Rouge, LA, March, 1980.

Yates, J. T. , Jr., "Spectroscopic Methods for Studying Chemisorption

and Catalysis," Union Carbide Corporation, Charleston, W.VA.,

March, 1980.

Yates, J. T., Jr., "Spectroscopic Correlation in Surface Chemistry on Single Crystal and Dispersed Metal Substrates," Joint Interdisciplinary Seminar , National Science Foundation, Washington, D.C.,

March, 1980.

Yates, J. T., Jr., "Spectroscopic and Other Structural Studies of

Chemisorbed Species on Metal Single Crystals and on Dispersed Metal

Substrates," Southv/est Texas Catalysis Symposium, Houston, TX,

March, 1980.

Yates, J. T. , Jr., "The Rate of Isotopic Mixing Between CO Molecules on Ni(lOO)," 179th American Chemical Society Meeting, Houston, TX,

March, 1980.

Yates, J. T. , Jr., "Spectroscopic Correlation in Surface Chemistry - Forging a Relationship between Chemisorption on Supported Metals,

on Single Crystals, and to Bonding in Organometall ic Chemistry,"

Tri State Catalysis Club, Charleston, W.VA., March, 1980.

Yates, J. T., Jr., "Spectroscopic Methods for Studying Surface Species

as a Means of Understanding Heterogeneous Catalysis at the Molecular

Level," Frontiers in Chemistry Lecture Series, State University of

New York, New Platz, NY, April, 1 980.

Yates, J. T. , Jr., "Spectroscopic Methods for Studying Surface Species

as a Means of Understanding Heterogeneous Catalysis at the Molecular

Level," Philadelphia Catalysis Society, Philadelphia, PA, April, 1980.

Yates, J. T. , Jr., "Spectroscopic and Other Structural Studies of Chemisorbed Species on Metal Single Crystals and on Dispersed Metal

Substrates," Pittsburgh Catalysis Symposium, Monroeville, PA,

May, 1980.

43
Yates, J. T., Jr., 1. "Kinetics of Chemical Processes on Single Crystal

Surfaces;" 2. "The Vibration of Molecules in the Adsorbed Layer;"

3. "Molecular Dynamics and Fundamental Excitation in Surface

Reactions;" International Seminar on Catalysis and Catalytic Phenomena, Institute Mexicano del Petrol eo, Mexico City, Mexico, May, 1980.

Yates, J. T. , Jr., "Vibrational Properties of Chemisorbed Molecules on

Metal Surfaces," Department of Chemistry, Northwestern University,

Evanston, IL, May, 1980.

Yates, J. T., Jr., "Vibrational Properties of Chemisorbed Molecules on Metal Surfaces," Materials Science Colloquium, M.I.T., Cambridge,

MA, May, 1980.

Yates, J. T., Jr., "Spectroscopic Studies of CO Chemisorption on Transition Metals and Studies of the Kinetics of CH^ Synthesis," Conference

on Chemistry and Physics of Coal Utilization, University of West

Virginia, Morgantown, W.VA., June, 1980.

Yates, J. T. , Jr., "Spectroscopic Correlation in Surface Chemistry - Forging a Relationship Between Chemisorption on Supported Metals,

on Single Crystals and to Bonding in Organometall ic Chemistry,"

1st Whitney Symposium, General Electric Corporation, Schnectady, NY,

June, 1 980.

Yates, J. T. , Jr., "Electron Stimulated Desorption - A Review," 180th

American Chemical Society Meeting, San Francisco, CA, August, 1980.

Yates, J. T., Jr., "Vibrational Spectroscopy of Adsorbed Molecules on Metals," International Conference on Solid Surfaces, Cannes,

France, September, 1980.
6. SURFACE SCIENCE DIVISION SEMINARS

Brenner, A., Wayne State University, Detroit, MI, "Supported Organometallics: The Frontier between Traditional, Homogeneous and

Heterogeneous Catalysts," April, 1980.

Bryant, G. W., Washington State University, Pullman, WA, "Quadratic

Shakeup Satellites in Core Level Spectroscopy ," April, 1980.

Cini, M. , Lab Ricerche di Base, Snamprogetti , Rome, Italy, "Optical

Properties of Small Particles," March, 1980.

Cohen, G., Metallurgy Division, National Bureau of Standards, "Laboratory

EXAFS and Surface EXAFS; NBS Plans for the Brookhaven Synchrotron ,"

May, 1980.

Cole, M., Penn State University, University Park, PA, "Bound State

Resonances in Atomic Scattering from Surfaces," February, 1980.

D'Andrea, A., C.N.R., Laboratory Methodol ogie , Avanzate Inorganiche-Roma,

Italy, "The (e,2e) Reactions Near Surfaces," November, 1979.

D'Andrea, A., C.N.R., Laboratory Methodologi e , Avanzate Inorganiche-Roma,

Italy, "Polaritons in Semi-infinite Crystals and in Thin Slabs:

Microscopic Calculations," February, 1980.

Davenport, J., Brookhaven National Laboratory, "Infrared Intensity and

the CO Molecule," December, 1979.

Dehmer, J., Argonne National Laboratory, Argonne, IL, "Connections

between Electron-Molecule Scattering and Molecular Photoionization:

Shape Resonances and Vibrational Effects," April, 1980.

Egelhoff, W. F. , Surface Science Division, NBS, "Photoemission Studies of

Materials: Background and Planned Research," January, 1980.

Einstein, T. L., University of Maryland, "Extended Appearance Potential

Fine Structure: A New Probe of Interatomic Spacings at Surfaces,"

November, 1 979.

Fain, S. C., Jr., Physics Department, University of Washington, Seattle,

Washington, "Low Energy Electron Diffraction Study of Physi sorbed

Monolayers on Graphite," March^ 1980.

Feldman, L. C., Bell Telephone Lab., Murray Hill, NJ , "Structural Studies

of the W(OOl) and Si(OOl) Surfaces Using MeV Ion Scattering," April,

1980.

45
f

Fink, J., Kernforschungszentrum Karlsruhe Institut fur Angewandte Kernphysik, "The Layered Materials SnS

2

, SnSe^, NbSp and Intercalates:

Investigation by High Energy Electron Loss Spectroscopy," June, 1980.

Flodstrom, S. A., Linkoping Institute of Technology, Sweden, "Oxidation

of Simple Metals as Studied by Electron Spectroscopy," August, 1980.

Girvin, S.M., Surface Science Division, National Bureau of Standards,

"Orientational Order/Disorder Transitions in Surface Adlayers,"

January, 1980.

Hecht, M. H., Stanford University, Palo Alto, CA, "Subshell Cross

Sections for Synchrotron Radiation Studies in the Solid State,"

June, 1980.

Herman, K., Institute fur Theoretical Physik der Technischen, University

of Clausthal , W. Germany, "Cluster Models for the Interpretation

of Photoemission Spectra from Adsorbed Molecules," May, 1980.

Houston, J. E., Sandia Laboratories, Albuquerque, NM, "Chemical Information in Auger Lineshapes," February, 1 980.

Jonson, M. , Physics, Dept., Indiana University, Bloomington, IN, "The

Dynamical Image Potential for Tunneling Electrons," April, 1980.

Kiskinova, M. , Surface Science Division, National Bureau of Standards,

"Interaction of Oxygen and Alkali Metals with the Ni(lOO) Surface,"

July, 1980.

Kolb, D. M. , Fritz-Haber-Institut der Max-Pl anck-Gesel 1 schaft , Faradayweg

4-6, Berlin, W. Germany, "Reflectance Spectroscopy in the Study of

the Electrode-Electrolyte Interface," October, 1 979.

Legally, M. G. , Dept, of Metallurgical and Mineral Engineering, University

of Wisconsin, Madison, WI, "Local Densities of States in Compound

Semiconductor Surfaces from Auger Lineshapes," December, 1979.

Larkins, F. P., Chemistry Dept., Monash University, Australia, "A Theoretical Study of Satellites in Atomic Photoelectron Spectra," July,

1980.

Matthew, J.A.D., Physics Department, University of York, Heslington,

York, England, "Relaxation Energies for Core Holes in Atoms, Vapours

and Solids," July, 1980.

Matthew, J.A.D., Physics Department, University of York, Heslington,

York, England, "Autoionisation versus Auger Emission in Rare Earths,"

August, 1980.

46
Matthew, J.A.D., Physics Department, University of York, Heslington,

York, England, "Ion Excited Auger Spectra - A Critical Review,"

August, 1980.

Metiu, H., Chemistry Department, Univesity of California at Santa Barbara,

’’A Microscopic Theory of Thermal Desorption," July, 1 980.

Metiu, H., Chemistry Department, University of California at Santa Barbara,

"Raman Spectroscopy at Metal Surfaces," July, 1980.

Metiu, H., Chemistry Department, University of California at Santa Barbara,

"El ectrodynamics at Metal Surfaces," July, 1980.

Monkenbusch, M. , Kernforschungsanlage Julich Qnbh, Julich, W. Germany,

"Neutron Scattering Study on Benzene and Toluene on Graphite Basal

Planes," June, 1 980.

Navinsek, B. J., Stefan Institute, University of Ljubljana, Ljubljana,

Yugoslavia, "Surface Changes Induced by Medium Energy Ion Bombardment,"

May, 1 980.

Neiuwenhuys, B. E,, Gorlaeus Laboratories, State University at Leiden,

Netherlands, "Adsorption and Catalysis on Metal- and Alloy Surfaces,"

October, 1 979.

Ramaker, D. , Naval Research Laboratory, VJashington, D.C., "Hole-hole

Correlation Effects on Auger Line Shapes and Electron Stimulated

Desorption," June, 1980.

Rowe, J;, Bell Telephone Laboratories, Murray Hill, NJ , "Roughness and

Coverage Dependence of Surface Enhanced Raman Scattering," December,

1979.

Salaneck, W. R. , Molecular and Organic Materials Area, Xerox Webster

Research Center, Webster, NY, "Photoelectron Spectroscopy of Molecular Solids," March, 1980.

Schonhammer, K. , Institute for Theoretical Physics, University of Hamburg,

Hamburg, W. Germany, "Deep-Level Spectroscopy from Adsorbates,"

July, 1980.

Semancik, S., Physics Department, Brown University, Providence, RI

,

"CO Dissociation on Mo (100)," December, 1979.

Thiel, P. A., Dept, of Chemical Engineering, California Institute of Technology, Pasadena, CA, "Vibrational Spectroscopy of H^O Adsorbed on Ru(OOl)," April, 1 980.

^

47
Tighe, N., Fracture and Deformation Division, National Bureau of Standards,

"Scanning Transmission Electron Microscopy - An Overview," June,

1980.

Tolk, N., Bell Telephone Laboratori es , Murray Hill, NJ, "Quantum Interference in Ion-Atom and Ion-Surface Collisions," May, 1980.

van der Veen, J. F. , IBM, Thomas J. Watson Research Center, Yorktown

Heights, NY, "Electronic and Geometrical Structure of Some Transition Metal Surfaces," March, 1979.

Walls, J. M., Physics Department, Loughborough University of Technology,

England, "Composition-Depth Profiling in Surface Analysis," June,

1980.

48
7. TECHNICAL AND PROFESSIONAL COMMITTEE

PARTICIPATION AND LEADERSHIP

W. F. Egelhoff, Jr.

Surface Science Division Safety Officer

J, Fine

Chairman, ASTM Subcommittee E-42.09 on Standard Reference Materials

Member, NBS Metrology Users Group on Noise Policy

J. W. Gadzuk

Treasurer, General Committee of the Physical Electronics Conference

Member, Program Committee for Nordic Institute for Theoretical Atomic

Physics Conference "The Chemisorption Bond: Electronic Structure and

Formation Mechanisms," Aspenasgarden , Sweden, 1979

Member, Local Committee for Second International Conference on Solid

Fil ms and Surfaces, College Park, MD., 1981

D. W. Goodman

Treasurer, Division of Colloid and Surface Science of The American

Chemical Society

R. D. Kelley

Chairman, ASTM Subcommittee D-32.03 on Chemical Analysis

T. E. Madey

U. S. Representative to Surface Science Division Steering Committee

of the International Union of Vacuum Science, Techniques and Applications; Secretary of Committee

Member of Welch Scholarship Committee of the International Union of

Vacuum Science, Techniques, and Applications

President-elect, American Vacuum Society

Member, ASTM Committee E-42 on Surface Analysis

A. J. Melmed

Secretary, Steering Committee of the International Field Emission

Symposium '

C. J. Powell

General -Chairman, Physical Electronics Conference

Chairman, ASTM Committee E-42 on Surface Analysis

49
Vice Chairman, 1980 Gordon Research Conference on Electron Spectroscopy

Member, NBS Radiation Safety Review Task Force

Member, Editorial Board, "Applications of Surface Science"

Member, Editorial Board, "Surface and Interface Analysis"

Invited Participant, Workshop on Basic Research Needs and Opportunities in Interfaces in Solar Materials, Solar Energy Research

Institute, June 30-July 3, 1980

J. T. Yates, Jr.

Chairman, Division of Colloid and Surface Chemistry, American

Chemical Society

Chairman, Steering Committee for the Industrial Fellowship Program

in Surface Chemistry and Surface Physics, American Chemical Society

Member, ad hoc Surface Science Subcommittee, Committee on Planning

for the Automobile of the Future, Department of Transportation

Member, Materials Research Division Evaluation Committee, Lawrence

Berkeley Laboratory, University of California

Member, Board of Directors, Catalysis Society

Vice-Chairman, 1981 Gordon Research Conference on Dynamics of

Surface Processes

Member, ASTM Committee D-32 on Catalysis

Member, ASTM Committee E-42 on Surface Analysis

Member, Solid State Sciences Committee, National Academy of Sciences

Chairman, MBS Research Advisory Committee

Vice-Chairman, CTMS Safety Committee

50
8. PROFESSIONAL INTERACTIONS, CONSULTING

AND ADVISORY SERVICES

(1) R. R. Cavanagh and J. T. Yates, Jr., are collaborating with

J. Stephenson and D. King of the NBS Molecular Spectroscopy

Division on laser fluoresence studies of the internal energy

distribution of thermally desorbed molecules. This is a new measurement method for studying the details of the dynamics

of gas-solid interactions.

(2) R. R. Cavanagh, R. D. Kelley, and T. E. Madey are collaborating

with J. J. Rush of the NBS Reactor Radiation Division on neutron

inelastic scattering, measurements of hydrogen and hydrogenic

species adsorbed on Raney nickel catalyst material.

(3) S. T. Ceyer is collaborating with Prof. G. A. Somorjai and

students at the University of California at Berkeley on surfacemolecular beam scattering experiments.

(4) W. F. Egelhoff, Jr. is collaborating with G. G. Tibbetts of the

General Motors Research Laboratories and I. Lindau of the

Stanford Radiation Laboratory on photoemission studies of

rare-earth metals and alloys.

(5) J. Fine is collaborating with Prof. M. Roush of the University

of Maryland on computer simulations of ion bombardment and

sputtering phenomena in which the effects of impurity concentration gradients as well as interfaces between layered materials

are considered.

(6) J. Fine is collaborating with Prof. B. Navinsek of the J. Stefan

Institute, Ljubljana, Yugoslavia on the effect of surface topography on measurements of ion sputtering yields as well as on depth resolution at interfaces. This collaboration is conducted

under the auspices of the U.S. -Yugoslavia Agreement for Cooperation

in Science and Technology.

(7) J. Fine is collaborating with S. C. Hardy and J. Manning of the

NBS Metallurgy Division on studies of surface impurities on liquid metals and the effect of ion beam bombardment mass transfer mechanisms for producing clean liquid metal surfaces.

(8) J. Fine is collaborating with G. Candela of the NBS Electron

Devices Division on a stu(5y of diffusion depths of metals in

Si 02 thin films on silicon.

51
(9)

J. Fine is collaborating with J. E. Houston of Sandia Laboratory,

New Mexico (presently at MBS as a guest worker) on the analysis

of the Auger spectra of liquid and solid gallium.

(10) J. W. Gadzuk is collaborating with M. Sunjic of the Rudor Boskovic

Institute and the University of Zagreb, Yugoslavia under the

auspices of the U.S .-Yugoslavia Agreement for Cooperation in

Science and Technology, on theories of electron spectroscopies

of solids and surfaces.

(11) J. W. Gadzuk is collaborating with theoretical and experimental

physicists at Chalmers University, Gothenburg, Sweden, on theories of dynamical processes near surfaces under the auspices

of a NORDITA (Nordic Institute of Theoretical Atomic Physics)

visiting professorship.

(12) J. W. Gadzuk is collaborating with Prof. Seb Doniach and a graduate student at Stanford University on theories of resonance

lineshapes in photoelectron spectroscopy.

(13) S. M. Girvin is collaborating with D. R. Penn of the MBS

Electron Physics Group on theories of resonant photoemission

satellites and other many body effects.

(14) S. M. Girvin is collaborating with M. Jonson of Indiana University and Chalmers Tekniska Hagskola, Goteborg, Sweden, on studies of transport anomalies in highly disordered metal

alloys and metallic glasses.

(15) T. J. Jach is collaborating with W. Grant and R. Dehl of the

MBS Polymer Science and Standards Division on studies of wear

in dental materials using Auger-electron spectroscopy.

(16) T. J. Jach is collaborating with J. Hamilton of the MBS

Electron Physics Group on studies of the surface properties of

magnetic materials near the Curie temperature.

(17) T. E. Madey and R. Stockbauer are collaborating with D. E. Eastman and J. F. van der Veen of IBM on experiments to characterize the angle resolved photon stimulated desorption of ions

from chemisorbed molecules on metal surfaces.

(18) T. E. Madey is collaborating with R. Poliak of IBM, Yorktown

Heights and J. Houston of Sandia Laboratories on experiments

to compare electron and x-ray excited Auger spectra.

52
(19) T. E. Madey and R. Stockbauer are collaborating with R. P.

Madden of the NBS Radiation Physics Division and S. A. Flodstrom

of Linkoping University, Sweden on photoelectron spectroscopy

and photon stimulated desorption studies of adsorbed molecules

on surfaces using the NBS SURF II facility.

(20) T. E. Madey and A. J. Melmed are monitors of a PL-480 project

between NBS and R. Meclewski and R. Blaszczyszyn of the

University of Wroclaw, Poland concerning the diffusion of

catalytic poisons on a nickel surface.

(21) A. J. Melmed and M. Martinka are collaborating with S. Sakurai

and Y. Kuk of the Pennsylvania State University on the analysis

of high resistivity silicon in an electrically pulsed EnergyCompensated ToF atom-probe field-ion microscope.

(22) A. J. Melmed and J. J. Carroll are collaborating with J. Kruger,

J. J. Ritter, and J. R. Ambrose of the NBS Chemical Stability

and Corrosion Division on stress-corrosion measurements,

characterization of oxide films, and studies of electro plates.

(23) A. J. Melmed is collaborating with Prof. W. R. Graham of the

University of Pennsylvania on a project entitled, "High

Resolution Microscopy of Surface Interactions" which has been

funded (for 3 years) by NSF. A. J. Melmed is a co-principal

investigator. We intend to use FIM to investigate the atomic

structure of (001) crystal planes of Mo, Ta , Nb and V and (111)

planes of Si and Ge, and to survey other major crystal planes ^ of these materials for the occurrence of reconstruction.

(24) C. J. Powell and T. J. Jach are collaborating with D, E. Newbury

and J. E. Small of the NBS Gas and Particulate Science Division

on surface and bulk characterizations of pollutant particles

from the atmosphere.

(25) R. Stockbauer is collaborating with A, C. Parr and D. L. Ederer,

NBS Radiation Physics Division, J. L. Dehmer, Argonne National

Laboratory, K. Codling, Reading University, U. K., and J. B. West,

Daresbury Synchrotron Radiation Laboratory, U. K. , on studies

of gas-phase molecules using triply differential photoelectron

spectroscopy with synchrotron radiation from the NBS SURF II

facility. ^

(26) R. Stockbauer is collaborating with P. M. Dehmer, E. D. Poliakoff

and J. L. Dehmer of the Argonne National Laboratory on studies of

cluster molecules using photoelectron-photoion coincidence

techniques.

53
(27) R. Stockbauer is collaborating with H. M. Rosenstock and

A. C. Parr of the NBS Radiation Physics Division on measurements

of the fragmentation of molecules using photoelectron-photoion

coincidence techniques.

(28) J. T. Yates, Jr. is collaborating with Profs. R. M. Martin and

H. Metiu of the University of California at Santa Barbara on a study of the interaction of metastable inert gas atoms with

surfaces under an NSF grant awarded jointly. This project is

designed to explore a new measurement method for studying the

electronic character of surfaces and adsorbed molecules on surfaces

.
9. VISITING SCIENTISTS

The Surface Science Division has been host during the past year to

a number of scientists who have worked with the Division staff on problems

of mutual interest.

(1) A. D' Andrea of the Consiglio Nazionale delle Ricerche, Rome,

Italy has spent ten months at NBS as a guest worker studying

(a) the (e,2e) coincidence experiment with solid targets,

(b) the spin-orbit splitting of surface resonances in the interaction of low-energy polarized electrons with surfaces, and

(c) the use of more realistic surface potentials in describing

the transport of optically-excited excitons in silicon.

(2) T. D. Andreadis, a graduate student at the University of

Maryland, has worked at NBS during the past year under a cooperative agreement (a) participating in laboratory measurements on sputtering phenomena and liquid-metal characterization

(b) developing and using a i^tonte Carlo program for studying

sputtering phenomena in solids (c) interfacing two frequency

counters with a small calculator for the MBS sputter-yi eld

experiment, and (d) programming a microcomputer facility for

Auger-electron spectroscopy

(3) D. K. Hoffman of Iowa State University has spent the equivalent

of several weeks at NBS as a guest worker studying statistical

mechanical effects in adsorbed layers while on assignment to

the NSF.

(4) J. E. Houston of Sandia Laboratories has spent a year at NBS

as a guest worker and visiting scientist (a) applying the ESDIAD

method to studies of adsorption on planar and stepped surfaces,

(b) studying the enhancement of ion desorption yields for electron

energies above core-electron excitation thresholds, (c) analyzing

Auger-electron and electron energy-loss lineshapes in several

experiments, and (d) making a critical comparison of various

deconvolution schemes used in Auger lineshape analysis.

(5) S. H. Kim of the National Industrial Research Institute, Seoul,

Korea spent five weeks at NBS as a guest worker familiarizing

himself with experimental methods used to deduce reaction

mechanisms and kinetic^ in studies of the catalytic methanation

reaction.

(6) M. Kiskinova of the Institute of Physical Chemistry, Bulgarian

Academy of Sciences, Sofia, Bulgaria has spent six months at

NBS as a guest worker under the auspices of the International

Research and Exchange Board studying (a) physisorption on zeolites and (b) the effects of poisons and promoters in the

catalytic methanation reaction under controlled conditions.

55
1

(7) J.A.D. Matthew of the University of York, England, is spending

two months at NBS as a visiting scientist making a comparative

study of the mechanisms of Auger-electron emission from sur- faces under excitation by electrons, photons, and ions.

(8) H. Metiu of the University of California at Santa Barbara is

spending two months at NBS as a visiting scientist studying

(a) surface spectroscopies on rough metal surfaces and

(b) mechanisms of electron-stimulated desorption.

(9) C. W. Seabury of Cornell University spent three weeks at NBS as a guest worker using ESDIAD to study the structure of

ammonia on Ir(lll) and Ni(lll) surfaces.

1

56
10 . SURFACE SCIENCE DIVISION STAFF

As of June 30, 1980, the Surface Science Division v/as staffed

follows;

C. J. Powell , Chief

S. K. Brereton, Administrative Aid

D. M, Keating, Secretary

J. J. Carroll

R. R. Cavanagh*

S. T. Ceyer

W. F. Egelhoff, Jr.

J. Fine

J. W. Gadzuk

S. M. Girvin

D. W. Goodman

G. L. Griffin*

T. J. Jach

R. D. Kelley

T. E. Madey

M. Marti nka*

' A. J. Melmed

A. Pararas

I. W. Price

R. Stockbauer

J. T. Yates, Jr.

*NBS-NRC Postdoctoral Research Associate
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BIBLIOGRAPHIC DATA

SHEET

1. PUBLICATION OR REPORT NO. NBSIR 80-2166

2. Gov't. Accession No. 3. ReclDient's Accession No,

.X .' 'V-Xv.. . ' " ‘ 'y' /

4. TITLE AND SUBTITLE

Technical Activities 1980

Surface Science Division

Reprinted from NBSIR 80-2132

5. Publication Date

6. Performing Organization Code

7. AUTHOR(S)

C. J. Powell , editor

8. Performing Organ. Report No.

9. PERFORMING ORGANIZATION NAME AND ADDRESS

NATIONAL BUREAU OF STANDARDS

DEPARTMENT OF COMMERCE

WASHINGTON, DC 20234

10, Project/Task/Work Unit No.

11. Contract/Grant No.

12. SPONSORING ORGANIZATION NAME AND COMPLETE ADDRESS csfreer. City, State, ZIP) 13. Type of Report & Period Covered

Final

14. Sponsoring Agency Code

15. SUPPLEMENTARY NOTES

I I Document describes a computer program; SF-185, FIPS Software Summary, is attached.

16. ABSTRACT (A 200“word or less factual summary of most significant information. If document includes a significant bibliography or

literature survey, mention it here.)

^

This report summarizes technical activities of the MBS Surface Science Division

during Fiscal Year 1980. These activities include experimental and theoretical

research in surface science, the development of improved measurement methods, the

provision of needed data, the development of reference materials, applications to

important scientific and national problems, and surface-standards work.. A listing

is given of publications, talks, professional committee participation, and

professional interactions by the Division staff.

17* KEY WORDS (six to twelve entries; alphabetical order; capitalize only the first letter of the first key word unless a proper name;

separated by semicolons)

Surface chemistry; surface physics; surface science; surface standards

18. AVAILABILITY [^Unlimited

I I For Official Distribution. Do Not Release to NTIS Q Order From Sup. of Doc., U.S. Government Printing Office, Washington, DC

20402, SD Stock No. SN003-003- Q Order From National Technical Information Service (NTIS), Springfield, VA. 22161

19. SECURITY CLASS

(THIS REPORT)

UNCLASSIFIED

21. NO. OF

PRINTED PAGES

20. SECURITY CLASS 22. Price (THIS PAGE)

UNCLASSIFIED

USCOMM-OC
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