Nonlocal Screening of the Photon Fields in Surface Photoemission from Simple Metals

Abstract

A hydrodynamical model calculation that includes retardation, nonlocal effects within the constitutive equation as well as damping through a constant parameter, has been used to interpret the surface photoemission results for simple metals. Special attention has been paid to the effects that multipole surface modes have in the spectrum. The photon field is screened by the electron gas modeling the vacuum–metal interface with a low density overlayer. A constant initial state for the electron at the Fermi level is assumed. We conclude that the main structure of the photoemission spectrum, a peak at ω0<ωp, is not produced by the generation of multipole modes, and instead these modes produce a secondary structure between ω0 and ωp whose number and position depend on the electronic profile.