RESONANT NONLINEAR-OPTICAL PROPERTIES AND EXCITED-STATE DYNAMICS OF PRISTINE, OXYGEN-DOPED, AND PHOTOPOLYMERIZED C-60 IN THE SOLID-STATE

The resonant nonlinear optical (NLO) response and excited-state dynamics of pure and photochemically modified C60 are studied at 590.5 nm by time-resolved degenerate four-wave mixing and nonlinear transmission. The magnitude of the NLO response for C60 is largely unaffected by photopolymerization or oxygen doping. The presence of molecular oxygen shortens the unimolecular lifetime of the participating excited states while photopolymerization appears to alter the character of the fluence-dependent kinetics. Bimolecular decay via exciton-exciton annihilation dominates the temporal response at high-fluence for C60, poly-C60 and C60-O2 films. The bimolecular rate coefficient k2 determined for C60 and C60-O2 films is 7×10-9 cm3/s with an uncertainty on the order of a factor of 2. © 1995 The American Physical Society.