Coherent Lattice Vibrations in Mono- and Few-Layer WSe2
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- 作者：Tae Young Jeong ; Byung Moon Jin ; Sonny H. Rhim ; Lamjed Debbichi ; Jaesung Park ; Yu Dong Jang ; Hyang Rok Lee ; Dong-Hun Chae ; Donghan Lee ; Yong-Hoon Kim ; Suyong Jung ; Ki Ju Yee
- 刊名：ACS Nano
- 出版年：2016
- 出版时间：May 24, 2016
- 年：2016
- 卷：10
- 期：5
- 页码：5560-5566
- 全文大小：432K
- 年卷期：0
- ISSN：1936-086X
文摘
We report the observation of coherent lattice vibrations in mono- and few-layer WSe<sub>2sub> in the time domain, which were obtained by performing time-resolved transmission measurements. Upon the excitation of ultrashort pulses with the energy resonant to that of A excitons, coherent oscillations of the A<sub>1gsub> optical phonon and longitudinal acoustic phonon at the M point of the Brillouin zone (LA(M)) were impulsively generated in monolayer WSe<sub>2sub>. In multilayer WSe<sub>2sub> flakes, the interlayer breathing mode (B<sub>1sub>) is found to be sensitive to the number of layers, demonstrating its usefulness in characterizing layered transition metal dichalcogenide materials. On the basis of temperature-dependent measurements, we find that the A<sub>1gsub> optical phonon mode decays into two acoustic phonons through the anharmonic decay process.