Raman Spectroscopy of Graphene Edges
  Graphene edges are of particular interest, since their chirality determines the electronic properties. Here we present a detailed Raman investigation of graphene flakes with well defined edges oriented at different crystallographic directions. The position, width and intensity of G and D peaks at the edges are studied as a function of the incident light polarization. The D-band is strongest for light polarized parallel to the edge and minimum for perpendicular orientation. Raman mapping shows that the D peak is localized in proximity of the edge. The D to G ratio does not always show a significant dependence on edge orientation. Thus, even though edges can appear macroscopically smooth and oriented at well defined angles, they are not necessarily microscopically ordered. 
C. Casiraghi, A. Hartschuh, H. Qian, S. Piscanec, C. Georgi, K. S.   Novoselov, D. M. Basko, A. C. Ferrari