Regensburg 2019 – wissenschaftliches Programm
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O: Fachverband Oberflächenphysik
O 80: Ultrafast Electron Dynamics at Surfaces and Interfaces I
O 80.8: Vortrag
Donnerstag, 4. April 2019, 12:15–12:30, H16
Ultrafast exciton dynamics in monolayer WS2 probed by femtosecond time-resolved (non-)linear optical spectroscopies. — •Stefano Calati1, Selene Mor1, Sarah King1,2, and Julia Stähler1 — 1Fritz-Haber-Institut der Max-Planck-Gesellschaft, Berlin (DE) — 2University of Chicago, Department of Chemistry, Chicago, USA
Controlling the optical properties of transition metal dichalcogenides (TMDCs) on ultrashort timescale is foundamental for device applications. Our aim is to unveil the foundamental processes responsible for the exciton dynamics of these materials. We present our work on pristine monolayer WS2 using femtosecond time-resolved reflectivity contrast (tr-RC) and electronic sum frequency generation (tr-eSFG) optical spectroscopies [1]. We present tr-RC measurements of monolayer WS2 with unprecedented time resolution. We discover an unexpected transient blueshift of the A excitonic resonance, which depends on the excitation density and photon energy. We identify and discuss the ultrafast processes responsible for the observed dynamics. Furthermore, we report intense eSFG generation from a monolayer WS2. We identify a resonant contribution of the A exciton, and the transient changes are compared to the dynamics observed in the linear optical experiment. These studies provide the basic framework for future studies on energy and charge transfer at TMDC-based hybrid interfaces.
[1] L. Foglia et al., Appl. Phys. Lett. 109, 202106 (2016)