20 Springer Series in Chemical Physics Edited by Robert Gomer _ _- J ~ Springer Series in Chemical Physics Editors: V. I. Goldanskii R. Gomer F. P. Schafer J. P. Toennies Volume I Atomic Spectra and Radiative Transitions By I. I. Sobelman Volume 2 Surface Crystallography by LEED Theory, Computation and Structural Results By M. A. Van Hove, S. Y. Tong Volume 3 Advances in Laser Chemistry Editor: A. H. Zewail Volume 4 Picosecond Phenomena Editors: C. V. Shank, E. P. Ippen, S. L. Shapiro Volume 5 Laser Spectroscopy Basic Concepts and Instrumentation By W. Demtroder Volume 6 Laser-Induced Processes in Molecules Physics and Chemistry Editors: K. L. Kompa, S. D. Smith Volume 7 Excitation of Atoms and Broadening of Spectral Lines By I. I. Sobelman, L. A. Vainshtein, E. A. Yukov Volume 8 Spin Exchange Principles and Applications in Chemistry and Biology By Yu. N. Molin, K. M. Salikhov, K. I. Zamaraev Volume 9 Secondary Ion Mass Spectrometry SIMS II Editors: A. Benninghoven, C. A. Evans, Jr., R. A. Powell, R. Shimizu, H. A. Storms Volume 10 Lasers and Chemical Change By A. Ben-Shaul, Y. Haas, K. L. Kompa, R. D. Levine Volume 11 Liquid Crystals of One-and Two-Dimensional Order Editors: W. Helfrich, G. Heppke Volume 12 Gasdynamic Laser By S. A. Losev Volume 13 Atomic Many-Body Theory By I. Lindgren, J. Morrison Volume 14 Picosecond Phenomena II Editors: R. Hochstrasser, W. Kaiser, C. V. Shank Volume 15 Vibrational Spectroscopy of Adsorbates Editor: R. F. Willis Volume 16 Spectroscopy of Molecular Excitons By V. L. Broude, E. I. Rashba, E. F. Sheka Volume 17 Inelastic Particle-Surface Collisions Editors: E. Taglauer, W. Heiland Volume 18 Modelling of Chemical Reaction Systems Editors: K. H. Ebert, P. Deuflhard, W. Higer Volume 19 Secondary Ion Mass Spectrometry SIMS III Editors: A. Benninghoven, J. Giber, J. Laszlo, M. Riedel, H. W. Werner Volume 20 Chemistry and Physics of Solid Surfaces IV Editors: R. Vanselow, R. Howe Volume 21 Dynamics of Gas-Surface Interaction Editors: G. Benedek, U. Valbusa Volume 22 Laser Photochemistry By V.S. Letokhov Chemistry and Physics of Solid Surfaces IV Editors: R.Vanselow and R. Howe With 247 Figures Springer-Verlag Berlin Heidelberg New York 1982 Professor RalfVanselow Professor Russel Howe Department of Chemistry and Laboratory for Surface Studies, Thc University of Wisconsin-Milwaukee, Milwaukee, WI 53201, USA Series Editors Professor Vitalii 1. Goldanskii Professor Dr. Fritz Peter Schafer Institute of Chemical Physics Max-Planck-Institut fUr Academy of Sciences Biophysikalische Chemie Vorobyevskoye Chaussee 2-b D-3400 Gottingen-Nikolausberg Moscow V-334, USSR Fed. Rep. of Germany Professor Robert Gomer Professor Dr. J. Peter Toennies The James Franck Institute Max-Planck-Institut fUr Stromungsforschung The University of Chicago BottingerstraJ3e 6-8 5640 Ellis Avenue 0-3400 Gottingen Chicago, IL 60637, USA Fed. Rep. of Germany ISBN-13: 978-3-642-47499-6 e-ISBN-13: 978-3-642-47495-8 DOl: 10.1007/978-3-642-47495-8 Library of Congress Cataloging in Publication Data. Main entry under title: Chemistry and physics of solid surfaces. At head oftitle, v.I: CRe. Vol. 4: editors, R. Vanselow and R. Howe. Heidelberg; New York: Springer-Verlag. (Springer series in chemical physics; v. 20). Includes bibliographical references and indexes. I. Surface chemistry. 2. Solid state chemistry. I. Vanselow, Ralf. II. Tong, S. Y. III. Howe, R. (Russel), 1948-. IV. Chemical Rubber Company. V. Series: Springer series in chemical physics. QD508.C48 541.3'453 77-25890 This work is subject to copyright. All fights are reserved, whether the whole or part of the material is concerned, specifically those of translation, reprinting, reuse of illustrations, broadcasting, reproduction by photocopying machine or similar means, and storage in data banks. Under § 54 of the German Copyright Law where copies are made for other than private use, a fee is payable to "Verwertungsgesellschaft Wort", Munich. © by Springer-Verlag Berlin Heidelberg 1982 Softcover reprint of the hardcover I st edition 1982 The use of 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 and therefore free for general use. OtTset printing: Beltz Offsetdruck, 6944 Hemsbach/Bergstr. Bookbinding: J. Schaffer OHG, 6718 Grlinstadt 2153/3130-543210 Preface At the International Summer Institute in Surface Science (ISISS), which is held bienially on the Campus of the University of Wisconsin-Milwaukee, invited speakers present tutorial review lectures during the course of one week. The majority of the presentations deal with the gas-solid interface, but now and then relevant reviews concerning liquid-solid or solid-solid interfaces are included. The goal of ISISS was outlined in the first ISISS publication: "We recognize that the International Summer Institute in Surface Science should foster mutual understanding and interaction among theorists and experimentalists in the various areas of surface science. Progress can be achieved only when we occasionally peek over the fence into neighboring areas, not so much to amuse ourselves that the grass is greener on the other side as to learn from their progress and, perhaps equally fruitfully, from their limitations and setbacks. In addition, it is an important task in any field of science to assess, take count of what is done and, what is more important, to point in future directions." Since the foundation of ISISS in 1973, the invited speakers - internation ally recognized experts in their area of specialization - have been asked to write review articles too. We wanted in this way to ensure that the largest possible group of scientists could benefit from the special review concept. The collected articles from past Institutes were published by the CRC Press, Boca Raton, Florida, USA, under the following titles: Surface Science: Recent Progress and Perspectives, Critical Reviews in Solid-State Sciences 4, 124-559 (1974), and Chemistry and Physics of Solid Surfaces, Vol. I (1976), Vol. II (1979), Vol. III (1982). It is not intended that anyone volume will offer a complete state-of-the art report on the whole field of gas-solid interactions, an impossible task given the rapidly expanding scope of the field. Instead, recent developments VI in selected areas are presented, providing up-to-date supplements to exis ting textbooks on surface science. Each volume also contains an extensive subject index, vital for the usefulness of a review series. It has become a tradition to start each volume with a historical review. Distinguished scientists such as P.H. Emmet, E.W. MUller, F.C. Tomkins, and G.-M. Schwab have provided their services in the past. The authors of this volume are led by William E. Spicer, who was recently named "Scientist of the Year" by the journal "Industrial Research and Development." It is no easy decision to change the publisher for an established book series. Technical reasons, however, did not leave us any choice. We are con vinced that the long experience of the Springer-Verlag and its expertise in the area of surface science will ensure continuing success of "Chemistry and Physics of Solid Surfaces." We hope that this fourth volume, with its new format, will be as well received as its forerunners. Finally, we would like to thank our faithful sponsors: The Air Force Office of Scientific Resear.ch and the Office of Naval Research (Grant No. NOOOI4-81-G-0059), as well as the College of Letters and Science and the Graduate School at UvJt1. Milwaukee, January 1982 R. Vanselow R. Howe Contents 7. Development of Photoemission as a Tool for Surface Science: 7900-7980 By W.E. Spicer (With 4 Figures) ................................... 1 1.1 I ntroducti on .................................................. 1 1.2 The Einstein Era: 1900-1930 ................................... 5 1.3 The Period of Misguided Quantum Mechanics: 1930-1945 ..... ..... 8 1.4 The Development of the Correct Fundamental Understanding of the Photoemission Process: 1945-1960 .... ....... .......... ..... 10 1.5 The Development of Photoemission Spectroscopy: 1960-1970 . ..... 12 1.6 The Explosive Era in Which Photoemission Spectroscopy Was Successfully Applied to the Study of Surfaces: 1970-1980 . ..... 15 1. 7 Conclusions................................................... 15 References ........................................................ 16 2. Auger Spectroscopy as a Probe of Valence Bonds and Bands By D.E. Ramaker (With 19 Figures) ................................. 19 2.1 Introduction... .... ... ...................... ............. ..... 19 2.2 Lineshape Description - One-Electron Model.............. ...... 22 2.2.1 Atomic Auger Matrix Elements.. ........ .................. 24 2.2.2 Local or Mulliken Populations... ........ ............ .... 26 2.3 Localization.. ...... .... ........ ..... ...... ........... .... .... 28 2.4 Screeni ng ..................................................... 34 2.5 Outlook....................................................... 39 2.5. 1 ESDI PSD ................................................. 39 2.5.2 AES in the Gas Phase and Chemisorbed Systems .... ... ..... 41 2.5.3 AES in the Bulk and at Interfaces .. ........ ..... ........ 45 2.6 Summary ....................................................... 46 References ........................................................ 46 3. SIMS of Reactive Surfaces By W.N. Delgass, L.L. Lauderback, and D.G. Taylor (Uith 16 Figures) 51 3.1 Introduction.................................................. 51 3.2 Single Crystal Metal Surfaces................................. 52 3.2.1 Characteristics of SIMS ............ ..................... 52 3.2.2 CO and 02 on Ru{OOn ................................... 55 3.2.3 Classicdl Dynamics Modelling...................... ...... 60 3.2.4 Structure from Angle Dependence.......... .... ........ ... 62 3.2.5 Reactive Intermediates.................................. 64 3.3 Molecular SIMS................................................ 66 3.3.1 SIMS of Molecular Solids................................ 66 3.3.2 Thiophene on Silver..................................... 68 3.3.3 Inorganic Complexes..................................... 69 VIII 3.4 Complex Surfaces.............................................. 69 3.4.1 Proximity.... ....................... .................... 69 3.4.2 Prospects for Catalysis............... .................. 71 3.5 Conclusions................................................... 73 References ........................................................ 74 4. Chemisorption Investigated by Ellipsometry By G.A. Bootsma, L.J. Hanekamp, and O.L.J. Gijzeman (With 18 Figures) ................................................. 77 4.1 Introduction.................................................. 77 4.2 Principles of Ellipsometry......... ......... .................. 78 4.3 (Sub)Monolayer Models......................................... 82 4.4 Clean Metal Surfaces.......................................... 86 4.5 Spectroscopic Ellipsometry of Overlayers ......... ............. 90 4.6 Kinetic Studies of Chemisorption..................... ......... 95 4.6.1 Coverage Cali brati on .................................... 95 4.6.2 Initial Stages of Oxidation.......... ................... 97 4.6.3 Reacti ons of Adsorbed Oxygen ............................ 101 References ........................................................ 104 5. The Implications for Surface Science of Doppler-Shift Laser Fluorescence SRectroscopy By D.M. Gruen, A.R. Krauss, M.J. Pellin, and R.B. Wright (With 11 Figures) ................................................. 107 5.1 Introduction.................................................. 107 5.2 Charge Transfer Processes at Surfaces ......................... 109 5.3 Laser Fluorescence Spectroscopic Measurements of Fluxes and Energy Distributions of Sputtered Particles ................... 113 References ........................................................ 121 6. Analytical Electron Microscopy in Surface Science By J.A. Venables (With 9 Figures) ................................. 123 6.1 Introduction .................................................. 123 6.2 Analytical Electron Microscopy Techniques ..................... 125 6.3 Scanning Electron Microscopy of Surfaces ...................... 127 6.4 Surface Spectroscopies and Microscopy ......................... 132 6.4.1 Auger Electron Spectroscopy and Microscopy .............. 132 6.4.2 Secondary Electron Spectroscopy and Work Function Imaging................................................. 135 6.4.3 Photoemission and Energy-Loss Spectroscopy .............. 136 6.5 Diffraction Techniques and Microscopy ......................... 138 6.5.1 Transmission Electron Diffraction and Microscopy ........ 138 6.5.2 RHEED and Refl ecti on Mi croscopy ......................... 140 6.5.3 LEED and Low-Energy Microscopy .......................... 142 References ........................................................ 143 7. He Diffraction as a Probe of Semiconductor Surface Structures By M.J. Cardillo (With 15 Figures) ................................ 149 7.1 Introduction .................................................. 149 7.2 Si{lOO}: Disordered Dimer Array ............................... 151 7.2.1 Si{100} Periodicity..................................... 151 7.2.2 Diffraction Scans and Qualitative Features of the Si{100} Surface......................................... 154 7.2.3 Specular Intensities .................................... 156 7.2.4 Structural Models for Si{100} ........................... 157 IX 7.3 Ga/\s {110} .................................................... 158 7.3.1 Diffraction Scans ....................................... 159 7.3.2 Specular Intensity Scans ................................ 160 7.3.3 Rigorous Calculation of Diffraction Intensities ......... 162 7.3.4 The Original of the He/GaAs Potential ................... 163 7.3.5 Computation of Rarified Charge Densities ................ 164 7.3.6 Summary ................................................. 165 7.4 Si{111} (7x7) ................................................. 165 7.4.1 Diffraction Scans ....................................... 166 7.4.2 Specular Intensity Interference ......................... 166 7.4.3 A Model of the Si{111} (7x7) ............................ 169 7.4.4 Summary ................................................. 171 References ........................................................ 172 8. Studies of Adsorption at Well-Ordered Electrode Surfaces Using Low-Energy Electron Diffraction By P.N. Ross, Jr. (With 19 Figures) ............................... 173 8.1 Introduction .................................................. 173 8.2 Thermodynamics of Electrodeposition ........................... 174 8.3 Experimenta 1 Methods .......................................... 177 8.4 Underpotential States of Hydrogen on Pt ....................... 180 8.4.1 Isotherms for Hydrogen on {1l1} and {l00} Pt ............ 181 8.4.2 Hydrogen at Stepped Surfaces ............................ 185 8.5 Underpotential States of Oxygen on Pt ......................... 188 8.6 Underpotential States of Metals on Metals ..................... 191 8.7 Relation of the Underpotential State to the Chemisorbed State in Vacuum ..................................................... 194 References ........................................................ 200 9. Low-Energy Electron Diffraction Studies of Physically Adsorbed Films By S.C. Fain, Jr. (~Iith 7 Figures) ................................ 203 9.1 Introduction .................................................. 203 9.2 Background .................................................... 203 9.3 LEED Instrument ............................................... 205 9.4 Krypton on Graphi te ........................................... 207 9. 5 Ar~on on Graphit~ ............................................. 210 9.5.1 Rotational Epitaxy of an Incommensurate Monolayer ....... 210 9.5.2 Thermodynamics of an Incommensurate Monolayer ........... 212 9.5.3 Overlayer-Substrate Spacing for an Incommensurate Monolayer ............................................... 214 9.6 Nitrogen on Graphite .......................................... 214 9.7 Conclusions ................................................... 215 References ............................................... ,........ 216 70. Monte Carlo Simulations of Chemisorbed Overlayers By L.D. Roelofs (With 15 Figures) ................................. 219 10.1 Introduction ................................................. 219 10.2 Motivation for Monte Carlo Simulation of Surface Systems ..... 220 10.2.1 Introduction to the Monte Carlo Method ................ 221 10.2.2 Results Obtainable via Monte Carlo .................... 223 10.2.3 Comparison to Other Methods for Treating Statistical Systems ............................................... 225 10.3 Monte Carlo t1ethods for La tti ce Gases ........................ 227 10.3.1 Simulation Mode ....................................... 228 10.3.2 Microscopic Dynamics .................................. 229 10.3.3 Order of Transitions .................................. 230 x 10.4 Monto Carlo Simulation Results .............................. 232 10.4.1 Square Lattice Simulations ........................... 232 10.4.2 Rectangular Lattice Simulations ...................... 235 10.4.3 Triangular Lattice Simulations ....................... 237 10.4.4 Hexagonal Lattice Simulations ........................ 239 10.5 Summary and Discussion ...................................... 246 References ....................................................... 247 77. Critical Phenomena of Chemisorbed Over/ayers By T.L. Einstein (With 8 Figures) ................................ 251 11.1 I ntroducti on ................................................ 251 11.2 Important Concepts .......................................... 252 11.2.1 Lattice Gas Model .................................... 252 11.2.2 Critical Exponents and Scaling Laws .................. 254 11.2.3 Corrections to Scaling ............................... 255 11.2.4 Crossover Phenomena [11.221 .......................... 256 11.2.5 Fisher Renormalization ............................... 258 11.3 Universality Classes for Atoms on a 2-d Lattice ............. 259 11.3.1 Order Parameters ..................................... 259 11.3.2 Universality Classes ................................. 259 11.3.3 Landau Theory for Adlayers ............................ 260 11.3.4 Catalogue of Transitions .............................. 262 11.3.5 Percolation .......................................... 266 11.4 LEED on Single Crystal Faces ................................ 266 11. 4.1 Measurement of Exponents ............................. 266 11.4.2 Surface Defects ...................................... 269 11.5 Case Study: O/Ni{lll} ....................................... 270 11.6 Conclusions and Exhortations ................................ 276 References ....................................................... 278 72. Structural Defects in Surfaces and Over/ayers By M.G. Lagally (With 23 Figures) ................................ 281 12.1 Introduction ................................................ 281 12.2 The Effect of Defects on the Intensity Distribution in Reci proca I Space ............................................ 283 12.3 Surface Defect Studies Using Low-Energy Electron Diffraction ·299 12.4 Surface Defect Studies by Alternative Diffraction Techniques .309 12.5 Summary ..................................................... 311 References ....................................................... 311 73. Some Theoretical Aspects of Metal Clusters, Surfaces, and Chemisorption By R.P. Messmer (With 10 Figures) ................................ 315 13.1 Intrinsic Properties of Metal Clusters ...................... 315 13.1.1 Cluster Density of States ............................ 317 13.1.2 Cluster Magnetism .................................... 321 13.2 The Interaction of CO with Cu Clusters ...................... 323 13.2.1 CugCO Calculations .................................... 329 13.2.2 Discussion of Core Level Spectra ..................... 335 References ....................................................... 339 74. The Inelastic Scattering of Low-Energy Electrons by Surface Excitations; Basic Mechanisms By D.L. Mills, and S.Y. Tong (With 5 Figures) .................... 341 14.1 Introduction ................................................ 341 14.2 Small-Angle Dipole Scattering '" ............................ 345