Ultraviolet Raman spectroscopy of graphene and transition-metal dichalcogenides

Here, we overview Raman spectroscopy of graphene and transition- metal dichalcogenides as a function of laser excitation energy EL, especially in the ultraviolet (UV) region. The double resonance G' (or 2D) band of graphene is calculated for the laser energy range up to 7 eV. The intensity of the G' band is proportional to E-L(-1) for E-L = 5 eV. We also discuss electronic Raman spectra and the asymmetric Breit- WignerFano lineshape of the G band in graphene for UV light. Finally, transition- metal dichalcogenide materials show a strong optical absorption of the UV light at the M point at which we expect a two- dimensional van Hove singularity of density of states. The double- resonance Raman spectra for the UV light can be assigned to a combination or overtone phonons at the M point. [GRAPHICS] (C) 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim