Inelastic Scattering from Metal Surfaces

Abstract

For a long time it has been recognized that the atom scattering technique has a remarkable potential for obtaining new and interesting information on solid surfaces. However, technical difficulties, in particular for inelastic measurements, have held up progress until recently. Elastic scattering measurements on insulators have now given detailed information on surface structure and interaction potentials. Recently those experiments were extended to the more difficult, but also more rewarding case of metal surfaces |1–2|, and shortly later to the exciting area of metal surfaces with well defined adsorbates |4–6|. In the realm of inelastic scattering experiments, a major breakthrough were the recent results of BRUSDEYLINS, DOAK, and TOENNIES |7,8|, which demonstrate the power of this method to study the low-energy elementary excitations of solid surfaces and showed sharp, detailed spectra for phonon excitation on a Li F crystal face. These exciting results call for an extension to metal surfaces. In fact, a small number of very recent results are available to date, which cannot be regarded conclusive as yet, but clearly demonstrate the power of this approach and indicate the directions for future experimentation. As it appears that we are right now at the threshold of a new and exciting era, the present paper will refrain from reviewing the pioneering earlier results that prepared the way for todays progress, and refer the reader to a number of detailed review articles |9–11|. The present discussion will focus exclusively on current results as well as the prospects and consequences arising from them.