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.
@article{arxiv.0810.5358,
title = {Raman Spectroscopy of Graphene Edges},
author = {C. Casiraghi and A. Hartschuh and H. Qian and S. Piscanec and C. Georgi and K. S. Novoselov and D. M. Basko and A. C. Ferrari},
journal= {arXiv preprint arXiv:0810.5358},
year = {2009}
}