Spectroscopy and photophysics of C60H18 and C60H36

Ground and triplet state spectroscopic and photophysical properties of C60H18 and C60H36 have been studied using the complementary techniques of nanosecond pulse radiolysis and laser flash photolysis to determine triplet-triplet (T-T) absorption spectra, triplet lifetimes, T-T molar absorption coefficients and triplet quantum yields, in particular for C60H18. The spectroscopic and photophysical properties of C60H18 are similar to those of an sp(2) network species such as C-60, whereas those of C60H36 resemble benzene. No T-T absorption was observed for C60H36 at lambda > 300 nm, so that its triplet state parameters could not be measured. The most probable assignment of the C60H36 samples studied, on the basis of vibrational and electronic spectra and structure, is to an S-6 symmetry isomer, but the lowest energy T and D-3d isomers are not entirely excluded, Our partially hydrogenated fullerene samples were prepared by a transfer hydrogenation method. Other preparation techniques may have produced other isomers of these species, thus accounting for some differences in reported spectroscopic results.