Abstract
The contributions of the two-dimensional phonon dispersion to the double-resonant Raman scattering process in graphene is determined from the line shape of the two-phonon combination mode around . This mode is usually referred to as or . By combining Raman experiments with excitation energies up to eV and a full two-dimensional calculation of the double-resonant Raman process based on fourth-order perturbation, we can describe in detail the composition of this two-phonon mode and explain the asymmetry on the high-frequency side. The asymmetry directly reflects phonon contributions with wave vectors away from the high-symmetry lines in the Brillouin zone. The main peak of this mode originates from the K high-symmetry line highlighting and supporting two important findings: first, the existence of so-called processes and, second, the dominant contribution along the high-symmetry line.
- Received 20 September 2012
DOI:https://doi.org/10.1103/PhysRevB.87.075402
©2013 American Physical Society