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O: Fachverband Oberflächenphysik

O 13: Ultrafast Electron Dynamics at Surfaces and Interfaces II

O 13.9: Talk

Monday, March 18, 2024, 17:15–17:30, MA 041

Band-resolved relaxation of laser-excited gold — •Tobias Held, Stephanie Roden, Pascal D. Ndione, Sebastian T. Weber, and Baerbel Rethfeld — Department of Physics and Research Center OPTIMAS, RPTU Kaiserslautern-Landau

When a noble metal is irradiated with a short-pulsed laser in the visible spectrum, sp- and d-electrons are excited into energetically higher free states while the phonons are not directly affected. This process increases the energy content of the electron system, alters the partial electron densities and induces non-equilibrium electron distributions. We investigate how the non-equilibrium evolves in the individual bands towards Fermi distributions using the Boltzmann equation with full Boltzmann collision integrals for the excitation, electron-electron scattering and electron-phonon scattering, respectively.

Following the fully kinetic stage, when a temperature description is valid, an occupational non-equilibrium can still persist between sp- and d-electrons [1]. We investigate how this occupational non-equilibrium affects the electron-phonon coupling parameter, finding a strong dependence of the coupling strength on the band occupation [2]. We also observe signatures of features of the partial densities of states in the coupling parameter.

[1] P. D. Ndione, S. T. Weber, D. O. Gericke and B. Rethfeld,

Scientific Reports 12, 1 (2022)

[2] T. Held, S. T. Weber and B. Rethfeld, arXiv:2308.01067 (2023)

Keywords: Boltzmann; band-resolved; nonequilibrium; laser excitation; femtosecond dynamics