Assignment of the Lowest Excited States of C70 and Evidence for Fluorescence from the S2 State

Highly structured fluorescence, phosphorescence, and fluorescence−excitation spectra of C 70 in neon matrixes are reported. Fluorescence from both S 1 and S 2 states is observed, and these are identified as being of A 2 ‘ and E 1 ‘ symmetry and have gas-phase energies estimated at 15 560 and 15 725 cm -1, respectively. A third singlet state is identified in the excitation spectrum and is proposed to be of A 2 ‘‘ symmetry with an estimated gas-phase energy of 16 000 cm -1 . Finally, the phosphorescence is dominated by vibrational bands of e 1 ‘ symmetry pointing to the lowest triplet state of A 2 ‘ symmetry. Its energy lies at 12 588 cm -1 above that of the ground state in the neon matrix. From a comparison with data from the literature, the existence of a second triplet state of E 1 ‘ character is inferred, which lies about 165 cm -1 above the lowest triplet state, i.e., with the same energy separation as the lowest two singlet states.