Properties of the phosphorescent state of 1,2,4,5-tetrabromobenzene as determined by optically detected magnetic resonance

Abstract

The optically detected magnetic resonance (ODMR) and phosphorescence microwave double resonance (PMDR) spectra of 1,2,4,5-tetrabromobenzene in durene are reported. The results show that the phosphorescence originates from an undistorted 3B 1u (ππ*) state. The sign and magnitude of the zero-field parameters are discussed in terms of spin dipolar interactions in the 3B 1u state and large spin-orbit contributions to the zero-field splitting. Finally, the excited triplet state values for the 79Br and 81Br nuclear quadrupole coupling constants are obtained from an analysis of the zero-field ODMR.