Fluorescence spectra of isolated C60 molecules in neon and argon matrixes: assignment of the lowest emitting states

Highly structured fluorescence is reported for C60 mols. isolated in Ne and Ar matrixes. Their excitation spectra are similar to the gas-phase 2-photon ionization spectrum of C60. Most of the bands seen in emission can be attributed to Herzberg-Teller or Jahn-Teller active modes and to combinations of these modes. The intensity distribution of the fluorescence bands is compared with calcd. intensities and shows that the emission is of mixed singlet T1g and T2g character in Ne matrixes in nearly equal proportions and of mixed singlet T1g and Gg character in Ar matrixes, in a proportion of 4 to 1 in favor of the T1g state. The band frequencies show that these 3 states are degenerate to within exptl. uncertainty and the authors est. their gas-phase energy at 15,695 +- 5 cm-1. The assignment of ground-state vibrational band frequencies are rediscussed. [on SciFinder (R)]