15min:

A. SASSARA, G. ZERZA AND M. CHERGUI, Institut de Physique Expérimentale, Université de Lausanne, CH-1015 Lausanne-Dorigny, Switzerland.

Highly structured fluorescence, phosphorescence and fluorescence-excitation spectra of C₇₀ in neon matrices are reported. Fluorescence from both S₁ and S₂ states is observed and these are identified as being of A₂' and E₁' symmetry and have gas phase energies estimated at 15560 and 15725 cm^-1, respectively. A third singlet state is identified in the excitation spectrum and is proposed to be of A₂'' symmetry with an estimated gas phase energy of 16000 cm^-1. Finally, the phosphorescence is dominated by vibrational bands of e₁' symmetry pointing to a lowest triplet state of A₂' symmetry. Its energy lies at 12588 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 E₁' 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.