INVESTIGATION OF LINE-SHAPES AND LINE-INTENSITIES BY HIGH-RESOLUTION UV-PHOTOEMISSION SPECTROSCOPY - SOME CASE-STUDIES ON NOBLE-METAL SURFACES

Line shapes in angle-resolved photoemission spectra from solid surface s contain a wealth of information about many-body effects in the elect ron system. However, an analysis of experimental data depends on a ver y detailed understanding of the contributions to line width due to var ious other effects. This report reviews photoemission line shape studi es of bulk-and surface-emission peaks measured on noble-metal surfaces and their interpretation in terms of electron and photohole lifetimes , electron-phonon interaction and defect scattering. Special attention is focussed on the possibility to measure the photohole lifetime in t he vicinity of the Fermi level. Different channels of photohole decay like Auger processes, phonon creation and elastic scattering at surfac e defects and impurities are discussed along with high-resolution spec tra from surface states. We discuss to which extent the various effect s can be distinguished experimentally. Information can also be extract ed from experimental data concerning properties of the many-electron s ystem at elevated temperature.