Regensburg 2025 – wissenschaftliches Programm
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O: Fachverband Oberflächenphysik
O 67: Ultrafast Electron Dynamics II
O 67.10: Vortrag
Mittwoch, 19. März 2025, 17:15–17:30, H11
Tracing thermal and athermal electrons in laser-excited metals — •Markus Uehlein1, Henry Snowden2, Christopher Seibel1, Tobias Held1, Sebastian T Weber1, Reinhard J Maurer2, 3, and Baerbel Rethfeld1 — 1Department of Physics and Research Center OPTIMAS, RPTU Kaiserslautern-Landau, Germany — 2Department of Chemistry, University of Warwick, United Kingdom — 3Department of Physics, University of Warwick, United Kingdom
Understanding the energy- and time-resolved electronic properties in metals at the initial athermal stage after femtosecond laser irradiation is of fundamental importance for many applications in surface science. In the time domain, where no electron temperature is defined, the non-equilibrium dynamics are usually described with microscopic methods, such as the Boltzmann equation. However, especially when investigating ballistic transport processes, a description with full Boltzmann collision integrals [1] is challenging due to the numerical effort.
We present a model that describes the athermal carriers efficiently.
To that end, we consider thermal and athermal electrons separately.
We use a temperature-based approach for the thermal electrons and the phonons, while we trace the distribution of the athermal electrons explicitly.
Such a separation allows to conserve particles and energy even when a relaxation time approach is applied.
We show the energy-resolved dynamics and find good agreement with time-resolved two-photon photoemission spectroscopy measurements [2].
[1] B. Y. Mueller and B. Rethfeld; Phys. Rev. B 87, 035139 (2013)
[2] F. Kühne et al.; Phys. Rev. Res. 4, 033239 (2022)
Keywords: non-thermal electrons; athermal electrons; nonequilibrium; ultrafast dynamics; femtosecond laser excitation