Dresden 2026 – scientific programme

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O: Fachverband Oberflächenphysik

O 14: Ultrafast electron dynamics at surface and interfaces I

O 14.4: Talk

Monday, March 9, 2026, 16:00–16:15, TRE/MATH

Tracking ultrafast exciton-polariton propagation and coherent energy exchange in thin WSe₂ films — •Tobias Eul^1,2, Kai Rossnagel^2,3,4, and Michael Bauer^2,3 — ¹Institute of Physics, University of Augsburg — ²Kiel Nano, Surface and Interface Science KiNSIS, Kiel University — ³Institute of Experimental and Applied Physics, Kiel University — ⁴Deutsches Elektronen-Synchrotron DESY, Hamburg

Efficient charge transfer of electrons and holes after photogeneration is fundamental for light-induced energy conversion. The propagation of bound electron-hole pairs, i.e., excitons, can enhance this efficiency by reducing non-radiative losses before charge separation and extraction. A promising approach to improve exciton propagation is via exciton-polaritons, quasiparticles formed by the strong coupling of excitons and photons. In these hybrid states, the excitation coherently oscillates between exciton and photon character, enabling the photonic component to transport energy over extended distances. Using photoemission electron microscopy, we visualize the propagation of exciton-polaritons in a thin WSe2 film by observing the ultrafast energy exchange between excitons and photons.

Keywords: Exciton-Polaritons; Ultrafast Photoemission Electron Microscopy