Quasi-particle lifetimes on noble metal surfaces studied by ARPES and STM Original Research Article

The energy dependence of quasi-particle lifetimes of electronic states contains a variety of information about many-particle interactions in solids. We discuss the capabilities that angle-resolved photoemission and scanning tunneling microscopy and spectroscopy have for studying the contributions to lifetime broadening due to electron–electron, electron–phonon and electron–defect scattering. Using noble metal surfaces as model systems, we compare the energy and temperature dependence of quasi-particle lifetimes of two- and three-dimensional states to theory. In many cases the contribution to lifetime broadening due to Auger decay can not be described by Fermi liquid theory for free-electron-like systems. The symmetry and the localization of the states involved in the decay have to be considered when calculating the phase space available for decay. The advantages of the different experimental techniques and the possible applications to complex materials are also discussed.