▎ 摘　　要

A study of resonant Raman spectroscopy of the as-grown graphene on copper foils is presented. Different laser energies have been used to excite the sample, in order to obtain the dependence of the Raman features (intensities, frequencies and line widths) on the laser energy. We show that the normalised spectra acquired using green laser lines are more intense, with a maximum around 2.3 eV. Moreover, the results show a broader 2D (or G') band when a UV laser is used to excite the sample, which is explained by the manifestation of the trigonal warping effect in the dispersion of electrons and phonons around the Dirac point. (C) 2012 Elsevier Ltd. All rights reserved.