OPTICAL-PROPERTIES OF PRESSURE-POLYMERIZED C-60

We report Raman, infrared (IR), and photoluminescence (PL) studies of several polymeric phases of solid C-60 synthesized under high pressure and temperature conditions. The structure and dimensionality of bondi ng in the polymer depend on the conditions of synthesis. Relative to p ristine C-60, the Raman and IR spectra of these polymers exhibit numer ous lines which are shifted to low frequencies and are also broadened. These changes are consistent with the loss of the original icosahedra l C-60 symmetry and an increase in the strength of intermolecular bond ing due to polymerization. PL features are also broadened significantl y and are redshifted compared to those of pristine C-60 which is consi stent with the usual trend that polymerization decreases the HOMO-LUMO gap. The pressure-induced shift of the PL bands in the rhombohedral f ullerene polymer is about five times smaller than that reported for so lid C-60.