Ultrafast electronic and structural response of monolayer MoS2 under intense photoexcitation conditions.

Mannebach, Ehren M; Duerloo, Karel-Alexander N; Pellouchoud, Lenson A; Sher, Meng-Ju; Nah, Sanghee; Kuo, Yi-Hong; Yu, Yifei; Marshall, Ann F et al. · ACS Nano · 2014

basic_science · Level V

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Abstract

We report on the dynamical response of single layer transition metal dichalcogenide MoS2 to intense above-bandgap photoexcitation using the nonlinear-optical second order susceptibility as a direct probe of the electronic and structural dynamics. Excitation conditions corresponding to the order of one electron-hole pair per unit cell generate unexpected increases in the second harmonic from monolayer films, occurring on few picosecond time-scales. These large amplitude changes recover on tens of picosecond time-scales and are reversible at megahertz repetition rates with no photoinduced change in lattice symmetry observed despite the extreme excitation conditions.