Dresden 2020 – wissenschaftliches Programm

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DS: Fachverband Dünne Schichten

DS 32: Poster: Optical Analysis of Thin Films

DS 32.3: Poster

Mittwoch, 18. März 2020, 15:00–18:00, P1A

Transient Scattering Microscopy and Non-Linear Raman response of Single-Layer Graphene — •Lucas Lange, Veit Giegold, Richard Ciesielski, and Achim Hartschuh — Department of Chemistry and CeNS, LMU Munich, Germany

We investigate the ultrafast response of graphene using transient scattering and non-linear Raman microscopy. In general, high electronic temperatures reached for pulsed excitation cause a partial Pauli-blocking of optical transitions. This leads to reduced transient absorption and hence enhanced reflection. Importantly, the transient reflectivity signal detected at different time delay and energy detuning between pump and probe pulse features pronounced spatial inhomogenities in as prepared single-layer graphene. We discuss the decay dynamics of this transient response based on complementary Raman spectra. In addition, the hot electronic temperatures reached upon pulsed excitation are found to cause a partial Pauli-blocking of interfering quantum pathways contributing to resonant Raman scattering in graphene. As a consequence, the signal of the two dominant Raman bands G and 2D together with their ratio strongly depend on the laser intensity and result in a super-linear and sub-linear increase of the G band and 2D band intensity, respectively.