Probing substrate effects in the carbon-projected band structure of graphene on Pt(111) through resonant inelastic x-ray scattering

The unoccupied and occupied \ensuremath{\sigma} and \ensuremath{\pi} bands of graphene on Pt(111) were measured using near-edge x-ray absorption spectroscopy (XAS) and resonant inelastic x-ray scattering (RIXS) at the carbon $K$ edge. Elemental specificity and crystal-momentum conservation allows for detection of the dispersive band structure. In addition to features arising from the band structure of free-standing graphene, signatures of symmetry breaking were identified in XAS and in RIXS for excitation around the Fermi level. These additional features are proposed to derive from weak graphene-substrate interactions which manifest as substrate hybridization and surface umklapp processes due to Moir\'e superlattice vectors.