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SYED: Symposium Electron-driven processes: Atomic-scale insights from theory and experiment

SYED 1: Symposium Electron-driven processes

SYED 1.1: Hauptvortrag

Donnerstag, 19. März 2020, 09:30–10:00, HSZ 01

Ultrafast electron dynamics at laser-irradiated surfaces — •Baerbel Rethfeld — Department of Physics and Research Center OPTIMAS, Technische Universitaet Kaiserslautern, Erwin-Schroedinger-Strasse 46, 67663 Kaiserslautern, Germany

When a femtosecond laser pulse of moderate intensity irradiates a solid surface, the energy is mainly absorbed by the electrons within the crystal. We calculate numerically the transient distribution function of laser-excited electrons with help of full Boltzmann collision integrals. Based on their density of states, we can trace different materials’ response to an ultrafast stimulus of photonic excitation, as well as the interplay of electron-electron and electron-phonon interaction. Our results show that the initial characteristic signatures of the energy absorption are thermalized on a timescale of a few femtoseconds up to tens of femtoseconds. However, the cooling of the heated electron system by the cold phonons induces a further nonequilibrium, persisting on picosecond timescales [1].

We present possible consequences of the electron-phonon interaction on the energy distribution of hot electrons in dependence on material properties like band gap or particular features of the density of states.

[1] S.T. Weber and B. Rethfeld, Phys. Rev. B 99, 174314 (2019)