Regensburg 2019 – wissenschaftliches Programm

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O: Fachverband Oberflächenphysik

O 63: Poster Wednesday: Ultrafast Processes

O 63.1: Poster

Mittwoch, 3. April 2019, 17:45–20:00, Poster B1

Electron dynamics in MoS₂ after resonant optical excitation probed with different light polarizations — •Lasse Münster, Robert Wallauer, Johannes Reimann, Jens Güdde, and Ulrich Höfer — Fachbereich Physik und Zentrum für Materialwissenschaften, Philipps-Universität, 35032 Marburg

We will report on the application of time- and angle-resolved two photon photoemission (2PPE) with a high harmonic probe for the investigation of electron dynamics of MoS₂ in momentum space. For this purpose, we combined a high-repetition rate high-harmonic source with tunable femtosecond pump pulses and a 3D (k_x, k_y, E) electrostatic electron spectrometer [1].

We used this setup to study the electron dynamics in the conduction band of MoS₂ after resonant optical excitation at the K-point with different polarizations of pump- and probe pulses. In addition to the excitation into the conduction band, we observe non-resonant 2PPE from the valence band which can be suppressed by using cross-polarized pump and probe pulses. Within our time-resolution of better than 50 fs, we observe an instantaneous occupation of the conduction band at K followed by an ultrafast transfer to the conduction band minimum at Σ.

[1] R. Wallauer et al., Appl. Phys. Lett. 109, 162102(2016).