The appearance of fine structure in the phosphorescence spectra of organic molecules in solid solutions under T 1 ← S 0 laser excitation

Abstract

Phosphorescence spectra of coronene. 1,2-benzypyrene and chrysene in bromobutyl at 4.2 K under laser excitation directly in the region of the T 1 ← S 0 transition have been studied. Under these conditions, the phosphorescence spectra acquire a line structure. Vibrational analysis of the spectra has been performed and the frequencies of the normal vibrations of the investigated molecules in the S 0 state have been determined. A “multiplet” structure of the phosphorescence spectra appearing for monochromatic excitation to vibrational sublevels of the T 1 state has been studied. It is shown that the frequencies of the molecular vibrations in a triplet state can be found from an analysis of this structure.