A PHOTOLUMINESCENCE STUDY OF FULLERENES - TOTAL LUMINESCENCE SPECTROSCOPY OF C-60 AND C-70

Two-dimensional luminescence and luminescence excitation spectra of C6 0 and C70 fullerenes were recorded in glassy toluene solutions, polycr ystalline toluene, and benzene matrices and in a Shpolskii type n-hexa ne matrix at 77 K. The energies of the lowest excited singlet states o f C60 and C70 as well as of the lowest triplet state Of C70 were deter mined experimentally and compared with respective values calculated us ing a modified INDO method. The calculated S1-S2 energy difference in C70 was found to be quite large and the S1-T1 splitting in both C60 an d C70 very small. The spectra exhibit a pronounced dependence on the n ature of the solvent used.