Division of Physics and Applied Physics, School of Physical and Mathematical Sciences, Nanyang Technological University, Singapore 637371.
ACS Nano. 2010 Jun 22;4(6):3175-80. doi: 10.1021/nn100705n.
We report a confocal Raman study on edges of single-layer graphene. It is found that edge orientations could be identified by G mode in addition to D mode. We observe that G mode at the edges of single-layer graphene exhibits polar behaviors and different edges such as zigzag- or armchair-dominated responses differently than the polarization of the incident laser. Moreover, G mode shows stiffening at zigzag-dominated edges, while it is softened at armchair-dominated ones. Our observations are in good agreement with recent theory (Sasaki, K. et al. J. Phys. Soc. Jpn. 2010, 79, 044603) and could be well-explained by the unique properties of pseudospin at graphene edges, which lead to asymmetry of Raman active modes and non-adiabatic processes (Kohn Anomaly) at different types of edges. This work could be useful for further study on the properties of the graphene edge and development of graphene-based devices.
我们报告了对单层石墨烯边缘的共焦拉曼研究。除了 D 模式外，还发现 G 模式可以用于识别边缘方向。我们观察到，单层石墨烯边缘的 G 模式表现出各向异性，不同类型的边缘（如锯齿形或扶手椅形）的响应与入射激光的偏振方式不同。此外，G 模式在锯齿形边缘处变硬，而在扶手椅形边缘处变软。我们的观察结果与最近的理论（Sasaki，K.等人，J. Phys. Soc. Jpn. 2010，79，044603）非常吻合，并且可以很好地用石墨烯边缘的赝自旋的独特性质来解释，这导致了不同类型边缘的拉曼活性模式的不对称和非绝热过程（Kohn 异常）。这项工作对于进一步研究石墨烯边缘的性质和开发基于石墨烯的器件可能是有用的。
