Time-Resolved Two-Photon Photoemission at Metal–Dielectric Interfaces

Abstract. We review the influence of rare-gas layers on image-potential states at metal surfaces. Experiments on Xe, Kr, and Ar on Cu(100) and on Xe/Ru(0001) that use the technique of time-resolved two-photon photoemission are discussed. The energetic position of the electron affinity, the geometry of the adsorbate layer, and dielectric screening are the factors that influence the dynamical and energetic properties of the states. Theories on various levels are compared, including 1- and 3-dimensional models and the GW approximation of many-body theory. We also present new results on buried interface states that exist in the band gaps of both the Cu(100) substrate and a thick adsorbed Ar layer