VIBRATIONAL-MODES IN C-60 AND C-60 POLYMER

The vibrational properties of oxygen-free C-60 films indicate the nearly ideal molecular nature of solid C-60 Numerous sharp Raman lines (similar to 98) and infrared lines (similar to 98) were observed and assigned to first-order modes, or combination and overtone intramolecular mode frequencies of C-60. Analysis of these vibrational modes yields a complete, self-consistent set of the 46 fundamental intramolecular mode frequencies of a C-60 molecule. Irradiation of oxygen-free C-60 films with visible or ultraviolet light phototransformed C-60 to a new polymeric phase. We present experimental evidence which suggests the formation of covalent C-C bonds between C-60 molecules in the polymeric phase. Furthermore, the rate for thermal dissociation of these intermolecular bonds is found to follow an Arrhenius' type behavior with an activation energy E(a) = 1.25 eV. Our experimental results will also be compared to recent theoretical calculations and connected with the photophysical behavior of C-60.