Regensburg 2019 – wissenschaftliches Programm
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CPP: Fachverband Chemische Physik und Polymerphysik
CPP 65: Two-dimensional Materials IV (joint session HL/CPP)
CPP 65.2: Vortrag
Freitag, 5. April 2019, 09:45–10:00, H36
Exciton-lattice coupling in monolayer WSe2 investigated by femtosecond electron diffraction — •Shuo Dong1, Daniela Zahn1, Robert Schneider2, Thomas Vasileiadis1, Helene Seiler1, Yingpeng Qi1, Rudolf Bratschitsch2, and Ralph Ernstorfer1 — 1Fritz-Haber-Institut der Max-Planck-Gesellschaft, Faradayweg 4-6, 14195 Berlin, Germany — 2Institute of Physics and Center for Nanotechnology, University of Münster, Wilhelm-Klemm-Straße 10, 48149 Münster, Germany
Exciton-phonon coupling as the essential exciton relaxation mechanism plays a crucial role in transition metal dichalcogenides (TMDC). Besides the bright exciton dynamics, the formation of dark excitons greatly impacts the optoelectronic properties of atomically thin TMDC, which requires spin flip-scattering or phonon-assisted momentum transfer. Here, we investigate the incoherent lattice excitation associated with exciton relaxation in monolayer WSe2 by femtosecond electron diffraction. We discuss the observed structural dynamics in terms of the intra- and inter-valley exciton scattering towards the lower-lying dark states. The direct measurement of lattice motion provides important complementary insights to exciton dynamics.