Table Of ContentSpringer Series in
Surface Sciences
3 5
Editor: Gerhard Ertl
SpringerSeries in Surface Sciences
Editors: G. Ertl, R. Gomer and D. L. Mills Managing Editor: H.K.V. Lotsch
Physisorption Kinetics 20 Scanning Tunneling Microscopy I
By H. I. Kreuzer, Z. W. Gortel General Principles and Applications to Clean
and Adsorbate-Covered Surfaces
2 The Structure of Surfaces
Editors: H.-I. Giintberodt, R. Wiesendanger
Editors: M. A. Van Hove, S. Y. Tong
3 Dynamical Phenomena at Surfaces, Interfaces 21 Surface Phonons
and Superlattices Editors: W. Kress, F. W. de Welte
Editors: F. Nizzoli, K.-H. Rieder, R. F. Willis 22 Chemistry and Physics of Solid Surfaces VIII
4 Desorption Induced by Electronic Transitions, Editors: R. Vanselow, R. Howe
DIETD 23 Surface Analysis Methods in Materials
Editors: W. Brenig, D. Menzel Science
5 Chemistry and Physics of Solid Surfaces VI Editors: D. I. O'Connor, B. A. Sexton,
Editors: R. Vanselow, R. Howe R. St. C. Smart
6 Low-Energy Electron Diffraction 24 The Structure of Surfaces DI
Experiment, Theory Editors: S. Y. Tong, M. A. Van Hove,
and Surface Structure Determination K. Takayanagi, X. D. Xie
By M. A. Van Hove, W. H. Weinberg, C.-M. Chan 25 NEXAFS Spectroscopy
7 Electronic Phenomena in Adsorption By I. Stohr
and Catalysis
26 Semiconductor Surfaces and Interfaces
By V. F. Kiselev, O. V. Krylov
ByW.Monch
8 Kinetics of Interface Reactions
27 Helium Atom Scattering from Surfaces
Editors: M. Grunze, H. I. Kreuzer
Editor: E. Hulpke
9 Adsorption and Catalysis on Transition Metals
28 Scanning Tunneling Microscopy II
and Their Oxides
Further Applications
By V. F. Kiselev, O. V. Krylov
and Related Scanning Techniques
10 Chemistry and Physics of Solid Surfaces VII Editors: R. Wiesendanger, H.-I. Giintberodt
Editors: R. Vanselow, R. Howe
29 Scanning Tunneling Microscopy m
11 The Structure of Surfaces II Theory of STM
Editors: I. F. van der Veen, M. A. VanHove and Related Scanning Probe Metbods
12 Diffusion at Interfaces: Microscopic Concepts Editors: R. Wiesendanger, H.-I. Giintberodt
Editors: M. Grunze, H. I. Kreuzer, J. I. Weimer 30 Concepts in Surface Physics
13 Desorption Induced by Electronic Transitions, By M. C. Desjonqueres, D. Spanjaard
DIETm
31 Desorption Induced by Electronic Transitions,
Editors: R. H. Stulen, M. L. Knotek
DIET V
14 Solvay Conference on Surface Science Editors: A. R. Bums, E. B. Stechel,
Editor: F. W. de Wette D. R. Iennison
15 Surfaces and Interfaces of Solids 32 Scanning Tunneling Microscopy
By H. Liitb and Related Techniques
16 Atomic and Electronic Structure of Surfaces By Ch. Bai
Theoretical Foundations 33 Adsorption on Ordered Surfaces
By M. Lannoo, P. Friedel of Ionic Solids and Thin Films
17 Adhesion and Friction Editors: H.-I. Freund, E. Umbach
Editors: M. Grunze, H. I. Kreuzer 34 Surface Reactions
18 Auger Spectroscopy and Electronic Structure Editor: R. J. Madix
Editors: G. Cubiotti, G. Mondio, K. Wandelt
35 Applications of Synchrotron Radiation
19 Desorption Induced by Electronic Transitions, High-Resolution Studies of Molecules
DIET IV and Molecular Adsorbates on Surfaces
Editors: G. Betz, P. Varga Editor: W. Eberhardt
w.
Eberhardt
(Ed.)
Applications of
Synchrotron Radiation
High-Resolution Studies of Molecules
and Molecular Adsorbates on Surfaces
With Contributions by
A.M. Bradshaw W. Eberhardt H.-J. Freund
F.M. Hoffmann H. Kuhlenbeck N. Martensson
D. Menzel A. Nilsson G.P. Williams
D.P. Woodruff W. Wurth
With 170 Figures
Springer-Verlag
Berlin Heidelberg New York London Paris
Tokyo Hong Kong Barcelona Budapest·
Professor Dr. Wolfgang Eberhardt
Institut fUr Festkiirperforschung,
KFA Jiilich,
52425 Jiilich, Germany
Series Editors
Professor Dr. Gerhard Ert!
Fritz-Haber-Institut der Max-Planck-Gesellschaft, Faradayweg 4-6,
14195 Berlin, Germany
Professor Robert Gomer, Ph.D.
The James Franck Institute, The University of Chicago, 5640 Ellis Avenue,
Chicago, IL 60637, USA
Professor Douglas L. Mills, Ph.D.
Department of Physics, University of California,
Irvine, CA 92717, USA
Managing Editor: Dr. Helmut K.V. Lotsch
Springer-Verlag, Tiergartenstrasse 17,
69121 Heidelberg, Germany
ISBN-13 :978-3-642-79026-3 e-ISBN -13 :978-3-642-79024-9
DOl: 10.1007/978-3-642-79024-9
Library of Congress Cataloging-in-Publication Data. Eberhardt, W. (Wolfgang), 1950- Applications of
synchrotron radiation: high-resolution studies of molecules and molecular adsorbates on surfaces/W.W. Eber
hardt. p. cm. - (Springer series in surface sciences; 35) Includes bibliographical references and index.
ISBN-13:978-3-642-79026-3 1. Surfaces
(Physics) 2. Synchrotron radiation-Industrial applications. 3. Surface chemistry. 4. Molecular dynamics.
5. Adsorption. I. Title. II. Series. QCI73.4.S94E24 1994 530.4'17--dc20 94-12947
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microfilm or in any other way, and storage in data banks. Duplicl!tion of this publication or parts thereof is
p"rrnitted only under the provisions of the German Copyright Law of September 9, 1965, in its current version, and
permission for use must always be obtained from Springer-Verlag. Violations are liable for prosecution under the
German Copyright Law.
© Springer-Verlag Berlin Heidelberg 1995
Softeover reprint of the hardcover 1st edition 1995
The use of general descriptive names, registered names, trademarks, etc. in this publication does not imply, ,even in
the absence of a specific statement, that such names are exempt from the relevant protective laws and regulations
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Typesetting: Macmillan India Ltd., Bangalore-25
SPIN: 10092384 54/3140/SPS -- 5 4 3 2 I 0 - Printed on acid-free paper
Preface
Both, the fundamental interest in understanding the chemisorption bond and
the dynamics of molecular interactions on and with surfaces as well as the
obvious connection to the technological application in catalysis have provided
an important stimulus for the research on molecules and molecular adsorption
systems. A major impact in the understanding of model chemisorption systems
on single-crystal surfaces originated from the application of synchrotron radi
ation based experimental techniques like angle-resolved photoemission, high
resolution studies of core-electron excitations, photoemission and core-hole
decay processes, and infrared reflection absorption spectroscopy. These ex
periments have revealed new insight into the static and dynamic electronic
interactions and simultaneously also provided new and more accurate informa
tion about the chemisorption geometries.
As the third-generation synchrotron-radiation facilities, offering vastly
improved source characteristics for these kind of studies, are coming online at
many places around the globe it seems appropriate to step back and evaluate
these experimental techniques and to discuss their potential for future appli
cations. Foremost among these capabilities are improvements in spectral and
spatial resolution and in intensity for the study oflow-yield secondary processes.
The trend to explore the dynamics in the electronic interactions as well as the
dynamically introduced changes of the molecular geometry, ranging from the
excitation of vibrational modes to desorption and dissociation, is obvious in
some of the most recent work. Together with spatially-resolved "spectro
microscopy" experiments the exploration of the dynamics seems to be one of the
'new horizons' in this field of research.
This quasi-monograph provides a survey of various experimental tech
niques, as they are applied to the study of molecules and molecular adsorption
systems. The extension of the application of these experimental techniques to
other systems like semiconductor surfaces and heterostructures or epitaxial
growth of metallic thin films and overlayers is obvious and straightforward.
Therefore this book should also be of interest to the general community of
researchers and students working with synchrotron radiation in the area of
materials science and information technology.
Jiilich, September 1994 Wolfgang Eberhardt
Contents
1. Introduction
W. Eberhardt 1
References . . . . 7
2. Band-Structure Determination of Adsorbates
H.-J. Freund and H. Kuhlenbeck (With 42 Figures) . . . . . . . . . . .. 9
2.1 Historical Introduction. . . . . . . . . . . . . . . . . . .. 9
2.2 CO Adsorbates. . . . . . . . . . . . . . . . . . . . . . . 12
2.2.1 Symmetry Considerations
and CO-Substrate Interactions . . 12
2.2.2 Ordered Overlayers. . . . .. . ...... . 15
2.3 Ethylene Adsorbates. . . . . . . . . . . . ..... . 39
2.3.1 Symmetry Consideration
and Ethylene-Substrate Interaction. . . 40
2.3.2 Ordered Ethylene Overlayers . . . . 43
2.4 Benzene Adsorbates . . . . . . . . . . . . . 47
2.5 Co-Adsorbates 58
2.6 Synopsis. . . . 60
References . . . . . 60
3. High-Resolution Core-Level Photoelectron Spectroscopy
of Surfaces and Adsorbates
N. MlJrtensson and A. Nilsson (With 39 Figures) . . . 65
3.1 Background. . . . . 65
3.2 Instrumentation . . . . . . . . . . .. ....... 71
3.3 Core-Level Shifts. . . . . . . . . . . . . . . . . . . . 73
3.3.1 Initial and Final State Effects . . . . . . . . . 73
3.3.2 Equivalent Core or Z + 1 Approximation. . . . . . . . . 75
3.4 Adsorbate Core-Level Shifts. . . . . . . . . . . . . . . . . . . . 76
3.4.1 Final State Effects. . . . . . . . . . . . . . . . . . . . . . . 77
3.4.2 Chemical Shifts Between Inequivalent Atoms. . . . . . . .. 80
3.4.3 Adsorption Site-Dependent Shift in CO. . . . . . . . . . .. 81
3.4.4 Molecular Orientation and Site-Dependent Shifts in NO.. 85
3.4.5 Physisorption-Induced Shifts in O 87
2 ••••••••••••••
VIII Contents
3.5 Surface Core-Level Shifts. 89
3.5.1 Clean Metals. . . . . 89
3.5.2 Adsorbate-Induced Shifts 92
3.6 Core-Level Line Shapes .... . 96
3.7 Vibrational Effects ....... . 98
3.7.1 The Franck-Condon Principle 99
3.7.2 Vibrational Broadening in Adsorbates. 100
3.8 Shake-up Satellites. . . . . . . . . . . . . . . . 107
3.8.1 General Aspects . . . . . . . . . . . . . . 108
3.8.2 Substrate Excitations for Adsorbed Argon 110
3.8.3 Local Excitations in Strongly Chemisorbed Atoms 113
3.8.4 Chemisorption-Induced Excitations
in Adsorbed CO and N 2 116
References . . . . . . . . . . . . . . . . . . . . . 122
4. Structure Determination of Molecular Adsorbates
Using Photoelectron Diffraction
A.M. Bradshaw and D.P. Woodruff(With 26 Figures). 127
4.1 Introductory Comments . . . . . . . . . . 127
4.2 Basis of the Technique and Its Potential. . . . . . 131
4.3 Examples . . . . . . . . . . . . . . . . . . . . . . . . 140
4.3.1 Forward-Scattering Photoelectron Diffraction (XPD):
CO on Ni (110) . . . . . . . . . . . . . . 140
4.3.2 Experimental Methodology
and Qualitative Site Sensitivity in PhD 143
4.3.3 Quantitative Structural Analysis with PhD. 150
4.3.4 Chemical-Shift Photoelectron Diffraction. 159
4.4 Concluding Remarks 165
References . . . . . . . . . . . . . . . . . . . . . . . . . 167
5. Near Edge X-Ray Absorption and Decay Dynamics
of Adsorbed Molecules
W. Wurth and D. Menzel (With 16 Figures) 171
5.1 Background. . . . . . . . . . . 171
5.2 X-Ray Absorption ...... . 173
5.2.1 Physisorbed Molecules. 173
5.2.2 Chemisorbed Molecules 181
5.3 Decay Dynamics. . . . . . . . 187
5.3.l Physisorbed Molecules. 188
5.3.2 Chemisorbed Molecules 192
5.4 Desorption and Dissociation. 195
5.5 Conclusions. 198
References . . . . . . . . . . . . . . 198
Contents IX
6. Spectroscopy and Dynamics of the Electronic Decay
of Core Electron Excitations in Isolated and Chemisorbed Molecules
W. Eberhardt (With 29 Figures) . . . . . . . . . . . . . . . . . . . . .. 203
6.1 Deexcitation Electron Spectroscopy ................. . 204
6.1.1 Historical Development . . . . . . . . . . . . . . . . . . . . . 204
6.1.2 Development of an Empirical Assignment ......... . 207
6.1.3 Relationship Between Photoemission and DES ..... . 210
6.2 Probing the Local Electronic Structure and Response. . . . . . 213
6.2.1 Deexcitation . . . . . . . . . . . . . . . . . . . . . . . . . . . 213
6.2.2 Basic Parameters of the Spectator Shift . . . . ...... . 219
6.3 A Detailed Probe of Electron Correlation . . . . . ..... . 221
6.3.1 The Difference Between n* and Rydberg Excitations
in N2 ......................... . 221
6.3.2 Threshold Behaviour in CO2:
'There is No Threshold at the XPS-Threshold' . . 227
6.3.3 Identification of the Primary Excitation
Through the Decay Spectra (0 233
2) •••••••••••••••
6.4 Dynamics of Core-Electron-Excited States ........... . 239
6.4.1 Coherence and Interference . . . . . . . . . . . . . . . . . 239
6.4.2 Theoretical Description of the Interference Profiles .. 240
6.4.3 Vibrational Resolution in Excitation and Decay (N2) • 245
6.4.4 Time Development of the Eigenstates
on the FS Time Scale (0 249
2). • • • • • • • • • •••
6.5 Direct Observation of Charge Transfer
and Screening Processes . . . . . . . . . . . . . . . . . 253
6.5.1 Deexcitation of Transition Metal Carbonyls
and CO Chemisorbed on Surfaces ........ . 253
6.6 Summary and Outlook . . . . . . . . . . . . . . . 258
References . . . . . . . . . . . . . . . . . . . . . . . . . 260
7. Synchrotron Radiation in the Far Infrared:
Infrared Reflection Absorption Spectroscopy
F.M. Hoffmann and G.P. Williams (With 18 Figures) .. 263
7.1 IR Spectroscopy at Surfaces ................. . 264
7.2 Synchrotron Radiation in the Far Infrared ........ . 267
7.3 Examples ................................ . 272
7.3.1 Resonant Adsorbate-Substrate Interactions
for CO Adsorbed on Cu(I00) ................. . 272
7.3.2 Potassium - Oxygen Bond Formation ......... . 279
7.4 Conclusion - Outlook ...................... . 283
References . . . . . . . . . . . . . . . . . . . . . . . . . 284
Index of Molecules and Adsorbate Systems. . . . 287
Subject Index . . . . . . . . . . . . . . . . . . . . . 289
Contributors
A.M. Bradshaw
Fritz Haber Institute, Faradayweg 4-6,
14195 Berlin, Germany
W. Eberhardt
Institut fur Festk6rperforschung, KF A Jiilich,
Postfach 1913, 52425 Jiilich, Germany
H.-J. Freund
Physikalische Chemie, Ruhr-UniversiHit,
UniversiHitsstr. 150, 44801 Bochum, Germany
F.M. Hoffmann
Exxon Research and Engineering,
Annandale, NJ 08801, USA
H. Kuhlenbeck
Physikalische Chemie, Ruhr-Universitiit,
Universitiitsstr. 150,44801 Bochum, Germany
N. Martensson
Department of Physics, Uppsala University, Box 530,
75121 Uppsala, Sweden
D.Menzel
Physik Department E20, Technische Universitiit Munchen,
85748 Garching, Germany
A. Nilsson
Department of Physics, Uppsala University, Box 530,
75121 Uppsala, Sweden
XII Contributors
G.P. Williams
Brookhaven National Laboratory, Upton, NY 11973, USA
D.P. Woodruff
Physics Department, University of Warwick,
Coventry CV4 7AL, UK
W. Wurth
Physik Department E20, Technische Universitiit Miinchen,
85748 Garching, Germany
