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 surfaces contain a wealth of information about many-body effects in the electron system. However, an analysis of experimental data depends on a very detailed understanding of the contributions to line width due to various other effects. This report reviews photoemission line shape studies 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 the vicinity of the Fermi level. Different channels of photohole decay like Auger processes, phonon creation and elastic scattering at surface defects and impurities are discussed along with high-resolution spectra from surface states. We discuss to which extent the various effects can be distinguished experimentally. Information can also be extracted from experimental data concerning properties of the many-electron system at elevated temperature.