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O: Fachverband Oberflächenphysik
O 16: Ultrafast Electron Dynamics at Surface and Interfaces II
O 16.6: Talk
Monday, March 27, 2023, 16:30–16:45, TRE Phy
Band-resolved relaxation of laser-excited gold. — •Tobias Held1, Pascal D. Ndione1, Sebastian T. Weber1, Dirk O. Gericke2, and Baerbel Rethfeld1 — 1RPTU, Kaiserslautern, Germany — 2CFSA, University of Warwick, Coventry, UK
Irradiation of gold with visible light may excite d-band electrons into the free sp-electron states. This process increases the energy content of the electron system and induces an occupational nonequilibrium. Since the particle exchange is significantly slower than the energy transfer between the electron subsystems, the nonequilibrium band occupation persists long after a temperature can be well defined. Subsequently, density equilibration and the electron-phonon relaxation need to be considered consistently. In Ref. [1], we have simulated the non-equilibrium band occupation with electron density-resolved rate equations and coupled them with a two-temperature model to include the energy transfer from the electrons to the lattice. The results are sensitive to the electron-phonon coupling parameter applied.
Here, we investigate the electron-phonon coupling strength in more detail. We describe the interaction of the d- and sp-electrons with the lattice by complete Boltzmann collision integrals and show that the extracted electron-phonon coupling parameters strongly depend on the band occupation. Consequently, we incorporate this aspect into the simulation by assigning different temperatures to these bands and couple them separately to the phonons.
[1] Ndione, Weber, Gericke, and Rethfeld. Sci Rep, 12(1), 2022