Coherent nanoscale optical-phonon wave packet in graphene layers
Coherent nanoscale optical-phonon wave packet in graphene layers
复制标题
石墨烯层中的相干纳米级光学声子波包
DOI：
10.1103/physrevb.88.245406
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发表时间：
2013
影响因子：
3.7
通讯作者：
and M. Kitajim
中科院分区：
文献类型：
--
作者：
I. Katayama;K. Sato;S. Koga;J. Takeda;S. Hishita;H. Fukidome;M. Suemitsu;and M. Kitajim
使用 7.5-fs 超短激光激发石墨烯层中的相干大波矢量声子，并通过波长分辨泵浦探针瞬态反射光谱进行观察。由石墨烯层中的边缘和缺陷介导的狄拉克锥间电子散射驱动布里渊区的狄拉克点（点）附近的大波矢量相干模声子。与通过一阶拉曼过程产生的正常相干声子相反，观察到声子啁啾，并且幅度和频率根据探测波长而强烈变化。基于双共振拉曼散射过程讨论了结果，证明生成模式相干声子可以作为纳米级光学声子波包传播。
Coherent large-wave-vector phonons in graphene layers were excited by using a 7.5-fs ultrashort laser, and observed by wavelength-resolved pump-probe transient reflectivity spectroscopy. Inter-Dirac-cone electron scattering mediated by edges and defects in graphene layers drives large-wave-vector coherent-mode phonons near the Dirac point (point) of the Brillouin zone. In contrast to the normal coherent phonons generated with first-order Raman process, phonon chirp is observed, and amplitude and frequency strongly change depending on the probed wavelength. The results are discussed on the basis of doubly resonant Raman scattering process, demonstrating that generated-mode coherent phonons can propagate as nanoscale optical-phonon wave packets.