A theoretical study of the influence of Cs adsorbates on the dynamics of Cu(100) image states is reported. It is applied to the coverage range where the Cs adsorbates are randomly adsorbed on the surface. In contrast to an earlier study based on a single adsorbate scattering approach and thus limited to the very low adsorbate coverages, the present work considers the image-state electron scattered by a given adsorbate in the presence of all the others. This allows the treatment of the intermediate coverage range. The core of the present approach consists of defining a coverage dependent potential representing the average interaction between the electron and the adsorbate layer together with a local perturbing potential centered on each adsorbate. A time-dependent study of electron scattering associated to a many-body treatment of inelastic interactions with bulk electrons yields the rates for population and coherence decay of the image-state electron. This leads to a discussion of the coverage dependence of the decay and dephasing rates, which exhibit a complex variation due to the simultaneous interactions of the image-state electron with many adsorbates on the surface.

• Received 8 January 2007

DOI:https://doi.org/10.1103/PhysRevB.75.235412