Desorption Induced by Electronic Transitions DIET III: Proceedings of the Third International Workshop, Shelter Island, New York, May 20–22, 1987

303 Pages·1988·11.299 MB·English

by  D. Menzel (auth.), Dr. Richard H. Stulen, Dr. Michael L. Knotek (eds.)

Springer Series in
Surface Sciences
13
Editor: Robert Gomer
Springer Series in Surface Sciences
Editors: Gerhard Ertl and Robert Gomer
Volume 1: Physisorption Kinetics
By H.J. Kreuzer, Z. W. Gortel
Volume 2: The Structure of Surfaces
Editors: M. A. Van Hove, S. Y. Tong
Volume 3: Dynamical Phenomena at Surfaces, Interfaces and
Superiattices
Editors: F. Nizzoli, K.-H. Rieder, R.F. Willis
Volume 4: Desorption Induced by Electronic Transitions, DIET II
Editors: W. Brenig, D. Menzel
Volume 5: Chemistry and Physics of Solid Surfaces VI
Editors: R. Vanselow, R. Howe
Volume 6: Low-Energy Electron Diffraction
Experiment, Theory and Surface Structure Determination
By M. A. Van Hove, W. H. Weinberg, C.-M. Chan
Volume 7: Electronic Phenomena in Adsorption and Catalysis
By V. F. Kiselev, O. V. Krylov
Volume 8: Kinetics ofinterface Reactions
Editors: M. Grunze, H.J. Kreuzer
Volume 9: Adsorption and Catalysis in Transition Metals and Their
Oxides III
By O. V. Krylov, V. F. Kiselev
Volume 10: Chemistry and Physics of Solid Surfaces VII
Editors: R. Vanselow, R. Howe
Volume 11: The Structure of Surfaces II
Editors: J. F. van der Veen, M. A. Van Hove
Volume 12: Diffusion at Interfaces: Microscopic Concepts
Editors: M. Grunze, H.J. Kreuzer, J.J. Weimer
Volume 13: Desorption Induced by Electronic Transitions, DIET III
Editors: R. H. Stulen, M. L. Knotek
R. H. Stulen M. L. Knotek (Eds.)
Desorption Induced by
Electronic Transitions
DIET III
Proceedings of the Third International Workshop
Shelter Island, New York, May 20-22, 1987
With 181 Figures
Springer-Verlag Berlin Heidelberg New York
London Paris Tokyo
Dr. Richard H. Stulen
Surface Science and Chemical Physics, Division 8343,
Sandia National Laboratories, Livermore, CA 94550, USA
Dr. Michael L. Knotek
National Synchrotron Light Source, Brookhaven National Laboratory,
Building 725B, Upton NY 11973, USA
Series Editors
Professor Dr. Gerhard Ertl
Fritz-Haber-Institut der Max-Planck-Gesellschaft, Faradayweg 4-6
D-1000 Berlin 33
Professor Robert Gomer
The James Franck Institute, The University of Chicago, 5640 Ellis Avenue,
Chicago, IL 60637, USA
ISBN-13:978-3-642-73730-5 e-ISBN-13:978-3-642-73728-2
DOl: 10.1007/978-3-642-73728-2
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Preface
These proceedings are the result of the third international workshop on
Desorption Induced by Electronic Transitions, DIET III, which took place
on Shelter Island, NY, May.20-22, 1987. The work contained in this
volume is an excellent summary of the current status of the field and should
be a valuable reference text for both "seasoned" researchers and newcomers
in the field of DIET. Based on the success of the meeting it seems clear
that interest and enthusiasm in the field is strong. It is also apparent, from
the many lively discussions during the meeting, that many unanswered
questions (and controversies) remain to be solved. It was particularly
pleasing to see many new participants from new and rapidly advancing
fields, ranging from gas phase dynamics to semiconductor processing. The
resulting cross-fertilization from these separate but related fields is playing
an important role in helping us understand desorption processes at solid
surfaces.
In general, the topics covered during the course of the workshop over
lapped those of both DIET I and DIET II. However, clear advances have
been made and in general there is a much more sophisticated understand
ing of the physics and chemistry of stimulated desorption. Of particular
note in this regard is the gas phase research highlighted in this workshop
by the work of Nenner et al., where new results indicate that in the gas
phase, photodissociation can precede or compete strongly with autoion
ization and other electronic relaxation pathways. Although we do not
yet have any direct experimental evidence that this occurs for adsorbates
on surfaces, it is certainly possible that such effects may be important,
for example, in the desorption of hydrogen isotopes from larger molecular
species that are only weakly coupled to an underlying surface. Other gas
phase results presented at this workshop underscore the tremendous ad
vances in electron-ion and ion-ion coincidence experiments that are now
being used to elucidate the important photo dissociation pathways and re
lated electronic excitations in molecules. The understanding that these
experiments provide will give us a valuable conceptual framework for un
derstanding DIET at surfaces. Condensed phase studies (of rare gases
and other physisorbed molecules) provide a link between the gas phase
experIments and DIET from more strongly bound chemisorbed molecules.
v
There is now a new generation of complex experimentation utilizing
lasers, synchrotrons, digital ESDIAD, and neutral detection. Applica
tions of these tools will no doubt give us a much clearer picture of the
desorption dynamics and relevant excited states. The work of Burns et al.
shows that we are now able to look at internal state distributions following
desorption, and as a result theory is now being developed to understand
the dynamics of DIET including electronic and nuclear effects. With these
and similar results in hand, current theoretical studies continue to push
ahead in understanding relaxation, screening, and deexcitation effects fol
lowing initial excitation at the surface. In the area of ESDIAD there have
been significant advances in instrumentation, providing new capabilities
and resulting in dramatic new observations. Measurements by Yates et
al. have elucidated the nature and energetics of complex hindered rotor
adsorbate-adsorbate interactions, which opens the way for significant new
areas of exploration in the dynamics of molecules on surfaces. The insights
drawn from these measurements would be exceedingly difficult to derive
with any other experimental probe.
As the modelling of the mechanisms of DIET has matured, the impor
tance of relaxation and screening mechanisms which govern the lifetime
of the excitations which produce desorption has become more apparent.
Charge transfer (CT) processes are the most effective of relaxation mech
anisms and are also the most difficult to understand. Measurements and
modelling by Cowin and co-workers have given us new insight into the
dynamics of CT for generalized adsorbate-surface systems, and the effect
it can have on electronically induced phenomena on surfaces. The work of
Rabalais et al. is extending the ideas in DIET to chemical sputtering phe
nomena by relating chemical effects in sputtering to electronic interactions
important to bonding.
Finally, we feel a few comments and conjectures about future directions
in DIET are appropriate. Broady speaking, the work presented in this and
past DIET workshops represents a mixture of basic and applied. As the
field matures there will be greater emphasis on directing the techniques
described in these proceedings to new areas in technology. Applications of
DIET spectroscopy are now found in areas ranging from biological systems
to semiconductor processing, and they are having an important impact in
the areas concerned with radiation effects on surfaces, such as tokamaks,
storage rings, and glasses for high-power laser applications. As new ma
terials technology moves toward the use of radiation-enhanced chemistry
in semiconductor processing, plasma materials processing, and diamond
coatings, this body of knowledge from DIET will become critical in un
derstanding and optimizing processing variables.
Most importantly, we would like to express our gratitude to Brookhaven
National Laboratory, the Office of Naval Research through Dr. L.R.
Cooper, and the Air Force Office of Scientific Research through Dr. L.W.
VI
Burggraf for providing the financial support which made this workshop
possible. We also thank Sandia National Laboratories and the National
Bureau of Standards for providing administrative services during the prepa
ration of the workshop and proceedings.
Shelter Island, NY M.L. Knotek
January 1988 R.H. Stulen
VII
Contents
Part I Introductory Lecture
Some Recent Developments in DIET
By D. Menzel (With 5 Figures) ......................... 2
Part II Gas Phase
Photodissociation and Photoionization Processes of Core Excited
Molecules: The CH3Br Case
By I. Nenner, P. Morin, M. Simon, P. Lablanquie,
and G.G.B. de Souza (With 14 Figures) ................... 10
Auger Electron-Ion Coincidence Studies on Free Molecules
By W. Eberhardt and R. Murphy (With 3 Figures) .......... 32
Electron-Stimulated Desorption of D;t Clusters from Condensed
Deuterium Layers on Pd(111) Between 5 and 20K
By R.H. Stulen (With 5 Figures) ........................ 39
Desorption Processes in Planetary Science
By R.E. Johnson. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 47
Atom Selective Photochemistry with Monochromatic Soft X-Rays
By D.M. Hanson. . . . . . . .. . . . . . . . . . . . . . . . . . . . . . . . . . . . 50
Part III Neutrals and Negatives
Photon Stimulated Desorption of Neutrals by Synchrotron
Radiation from Chemisorbed, Physisorbed, and Condensed Layers
By P. Feulner, S. Auer, T. Miiller, A. Puschmann, and D. Menzel
(With 7 Figures) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 58
Rovibrational Laser Spectroscopy of ESD Neutrals from
Chemisorbed Species
By A.R. Burns, E.B. Stechel, and D.R. Jennison (With 5 Figures) 67
IX
Electron Stimulated Desorption of Excited Hydrogen Atoms from
an Alkali Promoted Surface
By P.D. Johnson, X. Pan, J. Tranquada, S.L. Hulbert,
and E. Johnson (With 2 Figures) ........................ 73
Dissociative Attachment in ESD from Condensed Molecules
By L. Sanche (With 8 Figures) ......................... 78
Image Charge, Coherent Scattering, and Symmetry Effects in
Electron Stimulated Desorption: 0 - from O2 Condensed on
Metals
By D.E. Ramaker and H. Sambe (With 6 Figures) ........... 85
Techniques for the Detection of Photodesorbed Negative Ions
By C.E. Young, E.L. Schweitzer, M.J. Pellin, D.M. Gruen,
z.
Hurych, P. Soukiassian, M.H. Bakshi, and A.S. Bommannavar
(With 3 Figures) ... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 94
Part IV Electron Stimulated Desorption Ion Angular
Distribution (ESDIAD)
Observation of Molecular Rotors on Surfaces by ESDIAD: Studies
of PFa and NHa Chemisorption on Ni Surfaces
By J.T. Yates, Jr., M.D. Alvey, M.J. Dresser, A.-M. Lanzillotto,
and K.J. Uram (With 8 Figures) ........................ 100
The Influence of Surface Structure on Mechanisms of Stimulated
Desorption
By R.L. Kurtz, R. Stockbauer, and T.E. Madey (With 5 Figures) 109
DIET in the Second Layer: An ESDIAD Study of NHa on a CO
Layer on Ni(l11) and Ni(110)
By M.J. Dresser, A.-M. Lanzillotto, M.D. Alvey,
and J.T. Yates, Jr. (With 3 Figures) ..................... 115
ESDIAD of Small Molecules on Surfaces: A Few Caveats
By T.E. Madey, M. Polak, A.L. Johnson, and M.M. Walczak
(With 5 Figures) ... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 120
An Ellipsoidal Mirror Analyzer for the Study of Photon Stimulated
Desorption
By R. Stockbauer, R.L. Kurtz, and T.E. Madey (With 1 Figure) 126
Digital Video Data Acquisition/Analysis for Existing ESDIAD
Apparatus
By A.L. Johnson, R. Stockbauer, D. Barak, and T.E. Madey
(With 3 Figures) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 130
x
Part V Theory
Dynamics in Neutral DIET from Chemisorbed Molecules
By E.B. Stechel, D.R. Jennison, and A.R. Burns (With 3 Figures) 136
The Nature of Repulsive States and the Role of Nuclear Dynamics
in Desorption Induced by Electronic Transitions
By Ph. Avouris, R. Walkup, R. Kawai, D.M. Newns,
and N.D. Lang (With 7 Figures) ........................ 144
The Dynamics of 0+ Desorption from Ti02
By R.E. Walkup and R.L. Kurtz (With 4 Figures) ........... 160
DIET and the Electronic Structure of Chemisorbed Molecules and
Physisorbed Rare Gases
By D.R. Jennison, E.B. Stechel, and A.R. Burns. . . . . . . . . . . .. 167
Theory of Desorption of Neutrals by Temporary Ionization of
Physisorbed Species at Metal Surfaces
By Z.W. Gortel, H.J. Kreuzer, P. Feulner, and D. Menzel
(With 6 Figures) ... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 173
The Magnitude of Secondary Electron Contributions in Photon
Stimulated Desorption
By D.E. Ramaker, T.E. Madey, R.L. Kurtz, and H. Sambe 182
Interatomic Auger Rates for the Sodium Fluoride Crystal
By T.A. Green and D.R. Jennison ........ ,.............. 185
Part VI Spectroscopy
Ultraviolet Surface Photochemistry and Charge Transfer
By E.P. Marsh, F.L. Tabares, M.R. Schneider, and J.P. Cowin
(With 3 Figures) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 190
Chemically Induced Desorption of Nickel Oxide and Carbide by 5-
200 eV C + and 0 + Ion Bombardment
By H. Kang, S.R. Kasi, O. Grizzi, and J.W. Rabalais
(With 6 Figures) ............................ . . . . . . .. 196
PSID SEXAFS Studies of Silicon Surface Chemistry
By G. Thornton, D.R. Warburton, R. McGrath, LT. McGovern,
and D. Norman (With 3 Figures) ........................ 205
Photon Stimulated Desorption from Oxidized Al(llO)
By E.D. Johnson, R.F. Garrett, M.L. Knotek, and F. Sette
(With 9 Figures) ... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 210
XI