engleski

Temporal stages of elecron scattering from adsorbates in image potential bands: Calculations of total scattering cross-sections for comprison with two-photon-photoemission data

We present a theoretical assessment of electron scattering processes in the first image potential band on Cu(100) surface that are induced by randomly distributed adsorbates and observed by two-photon photoemission (2PPE)[1]. Employing the quasiparticle propagator formalism developed earlier[2] we establish the electron self-energy expansion in terms of contributions that are linear in the concentration of adsorbates and ascending in the powers of dipolar electron-adsorbate potential. The total adsorbate induced electron scattering section measured in 2PPE experiments is obtained from the imaginary part of the thus calculated self energy divided by the initial electron current. By studying the properties of the various contributions to the self-energy series and introducing a simple scattering pseudopotential approach we obtain the quasiparticle decay rates and scattering cross sections that are in excelent agreement with the experimental data[1]. General implications of these results on the ultrafast electron dynamics in image potential bands during the intermediate stage of two-photon photoemission from surfaces are discussed. [1] K. Boger, Th. Fauster and M. Weinelt, New J. Phys. 7 (2005) 110. [2] B. Gumhalter et al., Phys. Rev. B 78 (2008) 155410.

Surface electronic bands; Electron scattering from adsorbates; Electron decoherence; Two-photon photoemission

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