Dresden 2026 – wissenschaftliches Programm

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O: Fachverband Oberflächenphysik

O 98: Ultrafast electron dynamics at surface and interfaces IV

O 98.6: Vortrag

Freitag, 13. März 2026, 11:00–11:15, TRE/MATH

Competition of electron-electron and electron-phonon scattering in thermalization of laser-excited electrons — •Christopher Seibel, Tobias Held, Markus Uehlein, Sebastian T. Weber, and Baerbel Rethfeld — Department of Physics and Research Center OPTIMAS, RPTU University Kaiserslautern-Landau, 67663 Kaiserslautern, Germany

When an ultrashort laser pulse irradiates a metal, electrons are excited to a state of strong nonequilibrium. According to the common picture, they thermalize subsequently towards a hot Fermi distribution on a femtosecond timescale and transfer energy to the still cold lattice on a picosecond timescale. Often these two processes are considered to be independet and driven by different interactions. Electron-electron scattering is considered responsible for the thermalization, whereas electron-phonon scattering is considered responsible for the energy transfer to the lattice. However, there are indications that these two processes influence each other and can act on similar timescales.

We use a kinetic description based on full Boltzmann collision integrals to trace the dynamics of the electron distribution during the thermalization after ultrashort laser excitation. We show that electron-electron and electron-phonon scattering have different effects on the distribution, which both lead to thermalization. Comparing various excitation fluences, we find that the thermalization times of the two processes exhibit an opposite fluence dependence and can become comparable for weak excitations.

Keywords: Ultrafast dynamics; electron-electron scattering; electron-phonon scattering; Boltzmann equation