Theory of Core Hole Decay Dynamics of Adsorbate on Metal Surfaces

Abstract

A comparative study of a core hole decay dynamics is made for an adsorbate on a metal surface. On the basis of the available experimental results for a CO molecule chemisorbed on Cu(110) as a prototype system, we investigate the elementary processes of the core hole decay via various new Auger channels open for adsorbates, i.e., the crossed Auger transition and the participation of an electron in the initially unoccupied level of the adsorbate created by charge transfer from the substrate before core hole decay or resonant core excitation. We calculate the valence Auger spectrum and deexcitation spectrum following resonant excitation. These spectra are compared with the direct valence photoemission, in particular with a single valence hole state screened by charge transfer from the metal. Absence of shake-up satellite in the deexcitation spectrum following resonant core to bound (e.g., 2π* of a CO molecule) level excitation and the mismatch of the binding energy of the screened final state between direct photoemission or normal Auger spectrum and resonantly excited Auger spectrum are explained in terms of the relaxation processes of the excited state before the Auger decay of the core hole.