ELECTRON EMISSION SPECTROSCOPY

ELECTRON EMISSION SPECTROSCOPY

ELECTRON EMISSION SPECTROSCOPY PROCEEDINGS OF THE NATO SUMMER INSTITUTE HELD AT THE UNIVERSITY OF GENT, AUGUST 28 - SEPTEMBER 7, 1972 Edited by W. DEKEYSER, L. FIERMANS, G. V ANDERKELEN and J. VENNIK State University, Gent D. REIDEL PUBLISHING COMPANY DORDRECHT-HOLLAND I BOSTON-U.S.A.

First printing: December 1973 Library of Congress Catalog Card Number 73-83559 ISBN-13: 978-94-010-2632-1 e-isbn-13:978-94-01o-2630-7 DOl: 10.1007/978-94-010-2630-7 Published by D. Reidel Publishing Company, P.O. Box 17, Dordrecht, Holland Sold and distributed in the U.S.A., Canada, and Mexico by D. Reidel Publishing Company, Inc. 306 Dartmouth Street, Boston, Mass. 02116, U.S.A. All Rights Reserved Copyright 1973 by D. Reidel Publishing Company, Dordrecht-Holland Softcover reprint of the harcover 1st edition 1973 No part of this book may be reproduced in any form, by print, photoprint, microfilm, or any other means, without written permission from the publisher

T ABLE OF CONTENTS PREFACE C. B. DUKE / ELECTRON SCATTERING BY SOLIDS I. The Structure of Solid Surfaces 2. Elastic Electron-Solid Scattering: General Features 3. Elastic Low-Energy Electron Diffraction (ELEED) 4. Surface Crystallography 5. Inelastic Low-Energy Electron Diffraction (ILEED) 6. Synopsis VII 1 2 19 35 82 116 145 C. s. FAD LEY / THEORETICAL ASPECTS OF X-RAY PHOTOELECTRON SPECTROSCOPY 1. Introduction 2. Core Electron Binding Energies 3. Valence Electron Binding Energies 4. Multiplet Splittings and Multi-Electron Processes 5. Relative Intensities and Angular Distributions 151 151 156 111 181 201 R. P. GUPTA AND S. K. SEN / CRYSTAL FIELD THEORY AND CALCULATION OF THE INNER SHELL VACANCY LEVELS 225 I. Crystal Electric Potential 225 2. Multiplet Splitting in Crystalline Potential 233 3. Sternheimer Effect 250 E. LINDHOLM / MOLECULAR PHOTOELECTRON SPECTROSCOPY 259 1. Historical Development 259 2. Instruments 263 3. Diatomic Molecules: Photoelectron Spectra and Potential Energy Diagrams 265 4. Intensities in Photoelectron Spectra 214 5. Polyatomic Molecules 218 6. Vibrational Structure of the Photoelectron Bands 280 7. Theoretical Calculation of Orbital Energies 283 8. Approximate Calculation of Orbital Energies 287 9. The Study of Large Molecules with Molecular Photoelectron Spectroscopy 289 10. The Dissociation of the Molecular Ion 292

VI TABLE OF CONTENTS J. C. TRACY / AUGER ELECTRON SPECTROSCOPY FOR SURFACE ANALYSIS 295 1. Introduction 295 2. Secondary Electron Energy Distributions 296 3. The Auger Process 306 4. Electron Excitation of Auger Spectra 317 5. Experimental Considerations 329 6. Auger Spectroscopy for Surface Analysis 341 Bibliography compiled by D. T. Hawkins 352 D. T. CLARK / CHEMICAL ASPECTS OF ESCA 373 1. Introduction to ESCA, Applications to Chemical Analysis and Surface Studies 373 2. Application of ESCA to Studies of Structure and Bonding in Organic Molecules 409 3. Application of ESCA to Studies of Structure and Bonding in Inorganic Chemistry 443 4. Application of ESCA to Structure and Bonding in Polymers 480

PREFACE Electron emission spectroscopy became recently a major tool for the study of molecules and solids. These volumes contain a rather complete review of the state of the art in this field. Both the physical and chemical aspects are covered extensively by wellknown specialists. Different modes of excitation are used in electron emission spectroscopy. The electron-solid scattering is covered in detail by C. B. Duke, from a theoretical point of view. Elastic and inelastic low energy electron diffraction are extensively discussed in relation to the geometrical, electronic and vibronic structure of solid surfaces. Auger electron emission spectroscopy (AES) is covered by J. C. Tracy. The technique is discussed from the point of view of surface research. This part also contains a complete literature list concerning the application of AES up to the middle of 1972. Electron emission produced by X-ray impact, is covered by C. S. Fadley, D. T. Clark, R. P. Gupta and S. K. Sen. The contribution by C. S. Fadley, entitled Theoretical Aspects of X-Ray Photoelectron Spectroscopy', is an up to date discussion of core electron binding energies, valence electron binding energies, multiplet splittings and multi-electron processes. R. P. Gupta and S. K. Sen's contribution provides an introduction to crystal field theory and its application to electron energy level determination. D. T. Clark deals with the more chemical aspects of X-ray photoelectron spectroscopy, i.e. the study of chemical shifts and the relation to the bonding characteristics in molecules. Finally, E. Lindholm considers the UV excitation in electron emission spectroscopy, a branch known as 'Molecular Photoelectron Spectroscopy'. These surveys are the rearranged and extended versions of six out of the nine sets of lecture notes of the NATO Advanced Summer Institute held at Gent from August 28 to September 7, 1972. The editors are grateful to the lecturers of this school for providing extended lecture notes and particularly to those who accepted to publish them. In some cases this involved a major rewriting task in order to cover the subject as completely as possible. The support of the NATO Science Committee is gratefully acknowledged. Our gratitude also goes to the following editors of books and periodicals and authors who granted permission to reproduce figures, diagrams or other material, i.e. Accounts of Chemical Research; American Chemical Society; American Institute of Physics; Analytical Chemical Research; Applied Spectroscopy; Bulletin des Societes Chimiques Belges; Chemical Physics Letters; Faraday Division of the Chemical Society; Institute of Physics (London); Journal of the American Chemical Society; Journal of Chemical Physics; Journal of the Chemical Society; Journal of Electron

VIII PREFACE Spectroscopy; Journal of Physical Chemistry; Journal of Polymers Science; North Holland Publishing Co.; Nova Royal Society Uppsala; Physical Society of Japan; Plenum Publishing Corporation; Review of Modern Physics; Robert A. Welch Foundation Research Bulletin; Royal Society (London); Royal Society of Sciences of Uppsala; Royal Swedish Academy of Sciences; Solid State Communications; Zeitschrift fur Naturforschung; Zeitschrift fur Physik; J. Wiley and Sons Publishing Co; I. Adams; S. Aksela; D. A. Allison; A. Bagchi; M. Barber; T. Bergmark; S. A. L. Bergstrom; G. K. Bohn; H. P. Bonzel; G. Broden; C. R. Brundle; J. M. Burkstrand; C. W. Caldwell Jr; T. A. Carlson; J. C. Carver; P. H. Cutler; D. W. Davis; R. Ditchfield; A. R. Du Charme; C. B. Duke, D. E. Eastman; C. S. Fadley; A. Fahlman; R. W. Finck; C. T. Foxon; T. E. Gallon; U. Gelius; R. L. Gerlach; J. Gerstner; A. M. Gibbons; E. J. McGuire; C. Glupe; K. Hamrin; S. B. M. Hagstrom; E. Hasilbach; D. M. Hercules; K. Hirabayshi; P. O. Heden; J. Hedman; B. W. Hilland; J. M. Hollander; J. E. Houston; D. A. Huchital; L. D. Hulett; D. W. Jespen; G. Johansson; W. L. Jolly; E. R. Jones; J. Jones; R. C. Jopson; B. A. Joyce; S. Karlsson; J. T. McKinney; M. O. Krausse; A. B. Kunz; G. E. Laramore; U. Landman; M. G. Lagally; B. Lindberg; I. Lindgren; H. Lofgren; P. M. Marcus; H. Mark; N. Mehlhorn; W. E. Moddeman; J. H. Neave; T. C. Ngoe; R. Nordberg; C. Nordling; C. Norris; T. Novakov; G. A. Olah; P. W. Palmberg; R. L. Park; L. G. Parrat; M. Pelavin; F. M. Propst; E. G. McRae; H. Rosencwaig; D. A. Shirley; K. Siegbahn; D. L. Smith; L. C. Snydes; W. E. Swartz; C. D. Swift; N. J. Taylor; T. D. Thomas; J. C. Tracy; C. W. Tucker; M. B. Webb; G. W. Wertheim.