Regensburg 2025 – wissenschaftliches Programm

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O: Fachverband Oberflächenphysik

O 96: Plasmonics and Nanooptics: Light-Matter Interaction, Spectroscopy II

O 96.9: Vortrag

Freitag, 21. März 2025, 12:30–12:45, H4

Electron Relaxation in Noble Metals: Microscopic Theory of Orientational Relaxation, Thermalization and Cooling — •Jonas Grumm and Andreas Knorr — Institut für Theoretische Physik, Nichtlineare Optik und Quantenelektronik, Technische Universität Berlin, Berlin, Germany

The excitation of electrons in noble metals by light fields with high intensities results in non-equilibrium electron occupations. The relaxation back to thermodynamic equilibrium, proceeding on scales from a few femtoseconds to several picoseconds, depends strongly on these excitation conditions: Typically, during the first tens of femtoseconds after the excitation, momentum polarization induced by the distinct polarization direction of the light field dominates the electron gas.

To address the relaxation dynamics of this momentum polarized state, we solve a kinetic momentum-resolved Boltzmann equation with focus on electron-phonon interaction and introduce orientational relaxation as first temporal step in a sequence of relaxation processes followed by thermalization and cooling. Applying a self-consistent treatment of Maxwell's equations and material dynamics we are able to present results for the optical and thermal properties of plasmonic nanostructures after linear and non-linear optical excitations. Thereby, Pauli-blocking non-linearities in the electron-phonon interaction modify the relaxation dynamics for strong excitations and effect the optical response of the electron gas.

Keywords: Ultrafast electron relaxation; Momentum orientational relaxation; Non-equilibrium dynamics; Plasmon dephasing