Spectroscopic studies on naphthalene in the vapor phase. II. Fluorescence quantum yields from single vibronic levels in the first excited singlet state—behavior of higher excited singlet states

Abstract

Fluorescence quantum yields for a variety of single vibronic levels in the first excited singlet state of naphthalene-h8 and -d8 were measured under collision-free conditions. The interpretation of the data is given in terms of the present theory of intersystem crossing. The experimental results suggest that in cases of accidental degeneracy between vibronic levels in S1 and higher triplet states T2, T3 a resonance crossing mechanism is dominant. Fluorescence as well as intersystem crossing quantum yields were also measured on irradiation into higher singlet states. The results indicate that at higher photon energy a new decay channel opens up which is not intersystem crossing.