Regensburg 2019 – wissenschaftliches Programm

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O: Fachverband Oberflächenphysik

O 45: Poster Tuesday: Ultrafast Processes

O 45.7: Poster

Dienstag, 2. April 2019, 18:00–20:00, Poster D

Band Occupation and Optical Response of Gold far from Equilibrium — •Pascal D. Ndione1, Sebastian T. Weber1, Dirk O. Gericke2, and Baerbel Rethfeld11Department of Physics and OPTIMAS Research Center, TU Kaiserslautern, Germany — 2Centre for Fusion, Space and Astrophysics, Department of Physics, University of Warwick, UK

Short laser pulses drive materials into a nonequilibrium state. Then due to diverse scattering processes, a new thermodynamic equilibrium is reached. It is important to understand the transient changes of the optical properties which strongly depend on the nonequilibrium electrons dynamics within the bands.
This contribution investigates the band occupation and the optical properties in gold upon excitation with a short laser pulse. We propose two different models depending on the photon energy of the applied excitation. With optical pulses, only d and sp-band electrons can be excited and electrons might be promoted into states above Fermi energy. The subsequent dynamics are calculated in a two-band model. On the other hand, X-ray light allows accessing deeper bands like the f-shell. In that case, more kinetic processes are at play and more bands are needed. Our model with three active bands allows tracing the occupation numbers for VUV excitation. With the bands’ occupation, we are able to calculate the transient optical properties and make a comparison to experimental data.

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