title: Momentum-resolved lifetimes of image-potential States on cu(100).
abstract: The dependence of the inelastic lifetime of electrons in the image-potential states of Cu(100) on their momentum parallel to the surface has been studied experimentally by means of time- and angle-resolved two-photon photoemission and theoretically by evaluating the electron self-energy within the GW approximation. The pronounced decrease of the n = 1 lifetime from 40 fs at normal emission (k(parallel) = 0) to 20 fs for k(parallel) = 0.33 A(-1) cannot be accounted for by interband decay processes to bulk states. We show that intraband transitions within the image-state band give a contribution to this decrease comparable in magnitude with the interband channel.
authors.affiliation: Fachbereich Physik und Zentrum für Materialwissenschaften, Philipps-Universität, D-35032 Marburg, Germany.
authors.forename: W
authors.initials: W
authors.lastname: Berthold
authors.forename: U
authors.initials: U
authors.lastname: Höfer
authors.forename: P
authors.initials: P
authors.lastname: Feulner
authors.forename: E V
authors.initials: EV
authors.lastname: Chulkov
authors.forename: V M
authors.initials: VM
authors.lastname: Silkin
authors.forename: P M
authors.initials: PM
authors.lastname: Echenique