Abstrakt
Surface-enhanced Raman spectroscopy is a valuable tool for inspection of trace concentrations of various molecules; hence, this method has a great potential for characterization of functionalised graphene. However, to make this method a reliable analytical tool, the influence of the metal-graphene interactions on Raman spectra of the graphene must be understood.
Here, the surface-enhanced Raman spectra of exfoliated single-layer graphene covered with gold or silver thin layers were studied. The metal-graphene interactions resulted in the broadening of the G mode and the 2D mode of graphene.
A change of the 2D mode dispersion was also observed. The effects were found to be weaker for the silver layer; however, the Raman signal enhancement of the graphene features was found to be significantly stronger in case of the silver layer.
Various scenarios of the observed effects are discussed: graphene-plasmon interaction, charge transfer between the metal and graphene, and selective enhancement at the lattice and topographic defects.