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

The vibrational properties of oxygen-free C-60 films indicate the near ly ideal molecular nature of solid C-60 Numerous sharp Raman lines (si milar to 98) and infrared lines (similar to 98) were observed and assi gned 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 mo de frequencies of a C-60 molecule. Irradiation of oxygen-free C-60 fil ms with visible or ultraviolet light phototransformed C-60 to a new po lymeric phase. We present experimental evidence which suggests the for mation of covalent C-C bonds between C-60 molecules in the polymeric p hase. Furthermore, the rate for thermal dissociation of these intermol ecular bonds is found to follow an Arrhenius' type behavior with an ac tivation energy E(a) = 1.25 eV. Our experimental results will also be compared to recent theoretical calculations and connected with the pho tophysical behavior of C-60.