Koivistoinen Juha, Myllyperkiö Pasi, Pettersson Mika
Nanoscience Center, Department of Chemistry, University of Jyväskylä , P.O. Box 35, Jyväskylä FI-40014, Finland.
J Phys Chem Lett. 2017 Sep 7;8(17):4108-4112. doi: 10.1021/acs.jpclett.7b01711. Epub 2017 Aug 18.
We report dynamics of the G-mode in graphene probed with time-resolved coherent anti-Stokes Raman scattering measurements. By applying BOXCARS excitation geometry with three different excitation wavelengths, various nonlinear processes can be selectively detected due to energy and momentum conservation and temporal sequence of the pulses. The Raman signal due to resonant coherent excitation of the G-mode shows exponential decay with lifetime of ∼325 ± 50 fs. This decay time is shorter than expected based on the line width of the G-mode in the Raman spectrum. We propose that the unexpectedly short dephasing time is a result of dynamic variation of nonadiabatic coupling of the photoexcited electron distribution and the G-mode.
我们报道了利用时间分辨相干反斯托克斯拉曼散射测量探测石墨烯中G模的动力学。通过应用具有三种不同激发波长的BOXCARS激发几何结构，由于能量和动量守恒以及脉冲的时间序列，可以选择性地检测到各种非线性过程。由于G模的共振相干激发产生的拉曼信号呈现指数衰减，寿命约为325±50飞秒。这个衰减时间比基于拉曼光谱中G模线宽的预期要短。我们认为，意外短的退相时间是光激发电子分布与G模的非绝热耦合动态变化的结果。
