Extracting the Anharmonic Properties of the G-Band in Graphene Nanoplatelets

We have examined the effect of temperature and pressure on the Raman-active G-band of graphene nanoplatelets with an average thickness of 4 nm. Measuring the Raman mode frequency and width of the G-band as a function of temperature and pressure allowed us to extract the individual factors contributing to the frequency and width of the G-band, i.e. the volumetric (thermal expansion) and anharmonic (phonon-phonon interactions) terms responsible for the Raman shift, and the electron-phonon coupling and anharmonic contributions controlling the width/ lifetime of the G-band. Considering the available literature, the significant role of the anharmonic effects for understanding the G-band physical processes in carbon-based systems is highlighted.