Phosphorescence spectra of bromobenzene in highly viscous glassy matrices

Phosphorescence spectra of bromobenzene have been observed in glycerol, 3-methyloctane and 4-methylheptane glassy matrices. The phosphorescence quantum yield has been determined to be ca. 0.03 in glycerol at 77 K. The phosphorescence is composed of two emissions, from 3ππ∗ and 3πσ∗ to the ground state. The phosphorescence radiative lifetime is 14 times shorter than that of chlorobenzene and this shortening has been explained by the internal heavy atom effect. The non-radiative rate constants were independent of the solvent species but depended only on the solvent viscosity. The non-radiative decay rate constant was 102 times larger than that of chlorobenzene.