Observation of Low-Frequency Combination and Overtone Raman Modes in Misoriented Graphene
Observation of Low-Frequency Combination and Overtone Raman Modes in Misoriented Graphene
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定向错误石墨烯中低频组合和泛音拉曼模式的观察
DOI：
10.1021/jp411573c
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发表时间：
2014-02
影响因子：
3.7
通讯作者：
Zhang Jin
中科院分区：
文献类型：
--
作者：
Wu Juanxia;Xu Hua;Mu Weihua;Xie Liming;Ling Xi;Kong Jin;Dresselhaus Mildred S.;Zhang Jin
堆积无序将显著改变少层石墨烯的光学性质和层间耦合伸长。在此，我们报道了在SiO_2/Si衬底上观察到错取向的几层石墨烯在100-200 cm(-1)的低频范围内的拉曼呼吸模。确定了两个主要的拉曼模式。约120 cm(-1)处的声子呼吸模被指认为面内剪切和离面光学声子呼吸模的E-g+ZO‘组合模。在182 cm(-1)附近的另一个峰被鉴定为泛音模式2ZO‘。不同扭角下这些拉曼模式的出现表明，少层石墨烯中的堆积无序显著地改变了拉曼特征，特别是对于那些包含层间呼吸模式的组合模式。进一步的研究表明，这两个拉曼振动模(类似于120和类似于182 cm(-1))与激发激光的能量是强耦合的，但它们的频率与折叠前的石墨烯层数无关。本工作为研究错误取向石墨烯薄膜的声子色散、电子-声子相互作用和电子能带结构提供了一种灵敏的方法。
Stacking disorder will significantly modify the optical properties and interlayer coupling stretch of few-layer graphene. Here, we report the observation of the Raman breathing modes in the low-frequency range of 100-200 cm(-1) in misoriented few-layer graphene on a SiO2/Si substrate. Two dominant Raman modes are identified. The one at similar to 120 cm(-1) is assigned as the E-g + ZO' combination mode of the in-plane shear and the out-of-plane interlayer optical phonon breathing modes. Another peak at similar to 182 cm(-1) is identified as the overtone mode 2ZO'. The appearance of these Raman modes for different twist angles indicates that stacking disorder in few-layer graphene significantly alters the Raman feature, especially for those combination modes containing the interlayer breathing mode. Further investigation shows that the two Raman vibrational modes (similar to 120 and similar to 182 cm(-1)) are strongly coupled to the excitation laser energy, but their frequencies are independent of the number of graphene layers before folding. The present work provides a sensitive way to study the phonon dispersion, electron-phonon interaction, and electronic band structure of misoriented graphene layers.
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通讯作者：
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