Signature of electronic excitations in the Raman spectrum of graphene

Inelastic light scattering from Dirac-type electrons in graphene is shown to be dominated by the generation of the interband electronic modes which are odd in terms of time-inversion symmetry and belong to the irreducible representation A2 of the point group C6v of the honeycomb crystal. At high magnetic fields, these electron-hole excitations appear as peculiar n−→n+ inter-Landau-level modes with energies n=2 2n v / B and characteristically crossed polarization of in/out photons.