Berlin 2012 – wissenschaftliches Programm

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O: Fachverband Oberflächenphysik

O 88: Electronic structure II

O 88.1: Vortrag

Freitag, 30. März 2012, 10:30–10:45, MA 043

The XPS-limit in Hard X-ray Angle Resolved Photo emission — •Jürgen Braun, Jan Minar, and Hubert Ebert — Universität München, Department Chemie, Butenandtstr. 5-13, D-81377 München, Germany

A brief introduction to the theory of angle-resolved photo electron spectroscopy (ARPES) of solid materials is given with an emphasis on the so-called one-step-model of photo emission that describes excitation, transport to the surface and the escape into the vacuum in a coherent way. The main aspects of the theory and its implementation within the Munich SPR-KKR program package [1] will be reviewed. As a new feature we present a model that accounts for finite temperatures when calculating photo emission spectra on the basis of the Coherent Potential Approximation (CPA) alloy theory (alloy analogy model). Our method goes well beyond the simple, but standard Debye-Waller approach to photo emission by including in particular the temperature dependence of the effective photo emission matrix elements as well. This allows among others to reproduce the so called XPS- or density of states limit in angle-resolved photo emission which occurs for high photon energies and/or high temperatures due to a full Brillouin zone averaging caused by phonon scattering. To illustrate the applicability of the new formalism examples of soft- and hard X-ray ARPES calculations for W(110), Pt(111) and Au(111) will be presented.

1. H. Ebert et al., The Munich SPR-KKR package, version 5.4, http://olymp.cup.uni-muenchen.de/ak/ebert/SPRKKR (2009)