Photoluminescence in C60 solutions

The nonlinear absorptive properties of C60 are of significant interest especially in the near IR. In this paper we describe spectral emission measurements on C60 solutions. In toluene solutions the laser induced emission in the fluence regime of 3 to 1500 J/cm2 excited by nanosecond and picosecond pulses is measured. In C60/toluene solutions a broad double feature is observed with peaks at 692 nm and 732 nm matching the published fluorescence spectra of C60. No evidence for breakdown is apparent in the C60 solutions though there is in the neat toluene. A survey study to determine solvent effects on the electronic states of C60 is reported. Thirteen solvents were chosen from among those in which C60 is soluble to give a wide range of dielectric constant and polarity. The molar extinction coefficient and fluorescence is measured in these solutions. A large solvent induced increase of the near IR molar extinction coefficient is observed in most solvents relative to toluene. Evidence for complex formation is observed. The changes of these spectra relative to that observed for toluene solutions indicate that solvent induced change of the quantum efficiency of triplet production is possible.