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O: Fachverband Oberflächenphysik

O 8: Surface State Spectroscopy I

O 8.1: Vortrag

Montag, 7. März 2016, 10:30–10:45, H4

One-step theory of two-photon photoemission — •Jürgen Braun¹, Roman Rausch², Michael Potthoff², Jan Minar¹, and Hubert Ebert¹ — ¹LMU München — ²Universität Hamburg

A general theoretical framework for the description of pump-probe photoemission is presented. The approach is based on a general formulation using the Keldysh formalism for the lesser Green function to describe the real-time evolution of the electronic degrees of freedom in the initial state after a strong pump pulse that drives the system out of equilibrium. The final state is represented by a time-reversed low-energy electron diffraction (LEED) state. The formalism allows for a quantitative calculation of the time-dependent photocurrent that results from core or valence-band excitations, and is applicable to simple metals or more complex materials like topological insulators. Our approach covers as a special case the two-photon photoemission (2PPE) scenario where both the pump-pulse and the probe pulse are weak in intensity. We present as a first application of our fully relativistic implementation within the Munich SPR-KKR package [2] calculated 2PPE spectra from Ag(100), where the first image state serves as intermediate state to probe the occupied bandstructure below the Fermi level [3].

1. J. Braun, R. Rausch, M. Potthoff, J. Minar, H. Ebert, Phys. Rev. B 91, 035119 (2014)

2. H. Ebert et al., The Munich SPR-KKR package, version 6.3, http://olymp.cup.uni-muenchen.de/ak/ebert/SPRKKR (2012)

3. J. Braun, R. Rausch, M. Potthoff, J. Minar, H. Ebert, submitted