Ultrafast non-radiative dynamics of atomically thin MoSe2

作者：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^*

来源：Nature Communications, 2017, 8(1): 1745.

DOI：10.1038/s41467-017-01844-2

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.

• 出版日期2017-11-23