Vibrational signatures of fullerene oxides

Abstract

Raman and IR spectra of C₆₀, C₆₀O, C₁₂₀O and C₁₂₀O₂, measured at room temperature, are discussed using geometric structures, normal modes, Raman and IR intensities from density functional-based tight-binding (DF-TB) calculations. An assignment of the most important vibrational modes is given. In the studied compounds the splitting of the C₆₀ modes is explained by the removal of degeneracy and the vibrational coupling between the C₆₀ cages. Strong IR absorptions of both dimeric oxides between 950 and 1150 cm^-1 are assigned to the furan-like structures connecting the buckyballs. The inter-ball Raman lines below 200 cm^-1 are shown to be dependent on the bonding strength between the cages. Both the bridge-based IR absorptions and the inter-ball Raman modes are suitable for the identification of the nature and number of bridging structures in oligomeric fullerene oxides.