Browsing by Author "Bassman, Lindsay"

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    Ultrafast non-radiative dynamics of atomically thin MoSe2
    (Springer Nature, 2017) Lin, Ming-Fu; Kochat, Vidya; Krishnamoorthy, Aravind; Bassman, Lindsay; Weninger, Clemens; Zheng, Qiang; Zhang, Xiang; Apte, Amey; Tiwary, Chandra Sekhar; Shen, Xiaozhe; Li, Renkai; Kalia, Rajiv; Ajayan, Pulickel; Nakano, Aiichiro; Vashishta, Priya; Shimojo, Fuyuki; Wang, Xijie; Fritz, David M.; Bergmann, Uwe
    Photo-induced non-radiative energy dissipation is a potential pathway to induce structural-phase transitions in two-dimensional materials. For advancing this field, a quantitative understanding of real-time atomic motion and lattice temperature is required. However, this understanding has been incomplete due to a lack of suitable experimental techniques. Here, we use ultrafast electron diffraction to directly probe the subpicosecond conversion of photoenergy to lattice vibrations in a model bilayered semiconductor, molybdenum diselenide. We find that when creating a high charge carrier density, the energy is efficiently transferred to the lattice within one picosecond. First-principles nonadiabatic quantum molecular dynamics simulations reproduce the observed ultrafast increase in lattice temperature and the corresponding conversion of photoenergy to lattice vibrations. Nonadiabatic quantum simulations further suggest that a softening of vibrational modes in the excited state is involved in efficient and rapid energy transfer between the electronic system and the lattice.