Self-energy and inelastic lifetimes of surface-state electrons and holes in metals

A metal surface generates electron states that do not exist in a bulk metal . These so-called surface states can be classified into two categories, cry stal-induced (intrinsic) states and image-potential-induced (image) states. Here we present. a survey of current investigations on the origin of the d ecay of these surface states. Inelastic lifetimes are obtained from the kno wledge of the quasiparticle self-energy, which we compute, within the GW ap proximation of many-body theory, by going beyond a free-electron descriptio n of the surface. Surface-state lifetimes in noble metal surfaces are prese nted. Our results show that actual lifetimes are highly sensitive to the de tails of the surface response and to the presence of the intrinsic surface state itself.