Eur. Phys. J. B (2012) 85: 418
https://doi.org/10.1140/epjb/e2012-30684-x

Regular Article

Theoretical polarization dependence of the two-phonon double-resonant Raman spectra of graphene

¹ Faculty of Physics, University of Sofia, 1164 Sofia, Bulgaria
² Research Center in Physics of Matter and Radiation, University of Namur (FUNDP), 5000 Namur, Belgium

^a e-mail: vpopov@phys.uni-sofia.bg

Received: 25 July 2012
Received in final form: 20 October 2012
Published online: 24 December 2012

Abstract

The experimental Raman spectra of graphene exhibit a few intense two-phonon bands, which are enhanced through double-resonant scattering processes. Though there are many theoretical papers on this topic, none of them predicts the spectra within a single model. Here, we present results for the two-phonon Raman spectra of graphene calculated by means of the quantum-mechanical perturbation theory. The electronic and phonon dispersions, electronic lifetime, electron-photon and electron-phonon matrix elements, are all obtained within a density-functional-theory-based non-orthogonal tight-binding model. We study systematically the overtone and combination two-phonon Raman bands, and, in particular, the energy and polarization dependence of their Raman shift and intensity. We find that the ratio of the integrated intensities for parallel and cross polarized light for all two-phonon bands is between 0.33 and 0.42. Our results are in good agreement with the available experimental data.