Over the past few years, there has been a growing awareness of the vibratio nal properties of solid surfaces and adsorbates due to a steady growth in the number of experimental techniques which have evolved with sufficient resolution and surface sensitivity. An understanding of the surface vibratio nal modes is of fundamental importance in many areas of the physics and chemistry of surfaces, most notably in the field of heterogeneous catalysis on metals and alloys. The present volume derives from a one day meeting of invited lectures, held under the auspices of the Thin Films and Surfaces Section of the Insti tute of Physics in the Cavendish Laboratory, University of Cambridge, 13 December 1979. The object was to bring together specialists from various diverse fields who would examine the wide variety of methods currently avail able for studying surface adsorbate vibrations. Since these methods cover several scientific disciplines, it was subsequently felt that it would be useful to provide a permanent record of the talks as a source lor future reference by workers in what is rapidly becoming an expanding field of',inter est in an increasing number of laboratories. The contributions, however, are not in any way meant to constitute exhaustive reviews.

The observation of the vibrational spectra of adsorbed species provides one of the most incisive methods for und erst an ding chemical and physical phenomena on surfaces. At the present time, many approaches may be applied to studies of molecular vibrations on surfaces. Some of these are used on high-area solids of technological importance (e.g., heterogeneous catalysts) while others are applied to single-crystal substrates to gain better understanding under conditions of controlled surface structure. This book has attempted to bring together in one place a discussion of the major methods used to measure vibrational spectra of surface species. The emphasis is on basic concepts and experimental methods rather than a current survey of the extensive literature in this field. Two introductory chapters describe the basic theoretical aspects of vibrational spectroscopy on surfaces, dealing with normal modes and excitation mechanisms in vibrational spectroscopy. The remaining seven chapters deal with various methods employed to observe surface vibra tions. These are arranged in an order that first treats the use of various methods on surfaces that are not of the single-crystal type. It is in this area that the field first got started in the late 1940s with pioneering work by Terenin and others in the Soviet Union, and by Eisehens and others in the United States in the 1950s. The last four chapters deal with relatively recent methods that permit vibrational studies to be made on single crystal substrates.

Over the past few years, there has been a growing awareness of the vibratio nal properties of solid surfaces and adsorbates due to a steady growth in the number of experimental techniques which have evolved with sufficient resolution and surface sensitivity. An understanding of the surface vibratio nal modes is of fundamental importance in many areas of the physics and chemistry of surfaces, most notably in the field of heterogeneous catalysis on metals and alloys. The present volume derives from a one day meeting of invited lectures, held under the auspices of the Thin Films and Surfaces Section of the Insti tute of Physics in the Cavendish Laboratory, University of Cambridge, 13 December 1979. The object was to bring together specialists from various diverse fields who would examine the wide variety of methods currently avail able for studying surface adsorbate vibrations. Since these methods cover several scientific disciplines, it was subsequently felt that it would be useful to provide a permanent record of the talks as a source lor future reference by workers in what is rapidly becoming an expanding field of',inter est in an increasing number of laboratories. The contributions, however, are not in any way meant to constitute exhaustive reviews.

This volume contains most of the invited and contributed papers presented at the second international conference devoted to the general topic "Vibrations at Surfaces" and which took place from 10 to 12 September 1980 at the Facu1tes Notre-Dame de 1a Paix in Namur, Belgium. The conference was organized to review the large amount of information gathered in this field over the late seventies as a result of th~ rapid improvements and dissemination of surface spectroscopic technique such a electron energy loss, infrared and Raman surface spectroscopies. Much time was devoted to Raman spectroscopy of adsorbed mo1e 'cu1es. After several years of vivid debate over the causes of the observed large enhancement of Raman cross section, a clearer pic ture emerges from the papers presented here: the actual value of the enhancement factor does depend in a complicated manner on long range surface roughness, atomic-scale roughness and the dielectric properties of the substrate as well as on the electronic structure of the molecule in its adsorbed state. Less controversial are the results obtained with electron energy loss spectroscopy (EELS) and several sessions of the con ference were devoted to the approach. As witnessed by the growing number of laboratories using the technique, EELS is now a mature spectroscopic tool for the characterization and analysis of the chemisorption bond.

Studies in Surface Science and Catalysis 14: Vibrations at Surfaces documents the proceedings of the third International Conference on ""Vibrations at Surfaces"" held at Asilomar, California, from September 1-4, 1982. Almost all of the 102 papers presented at the meeting are published in this volume. The topics chosen for the eight sessions held over a span of three days were: (I) Vibrational Frequency Shifts and Widths-Lateral Interactions; (II) Dynamical Processes at Surfaces; (III) and (IV) Electron Loss Spectroscopy; (V) Raman and Surface Enhanced Raman Scattering; (VI) Infrared Absorption and Reflection Spectroscopy; (VII) Beam Surface Scattering Surface Phonons; (VIII) Electron Tunneling Spectroscopy - Surface Enhanced Raman Studies in Electrochemistry. In addition, C. B. Duke presented an introductory keynote surveying progress in the field since the last meeting. In the final session H. Ibach and T. Grimley presented conference overviews and future prospects for the field from an experimental and theoretical perspective. Also included in the Proceedings are four literature surveys on Energy Loss, Inelastic Tunneling, Infrared and Raman (SERS) papers.