Lowest Triplet State of Substituted Benzenes. I. The Optically Detected Magnetic Resonance of para-Dichlorobenzene

Abstract

The optically detected magnetic resonance (ODMR) of para‐dichlorobenzene in its first ³ππ^* state is reported. The structures of the three zero‐field transitions are interpreted in terms of a Hamiltonian incorporating the electron spin—spin, chlorine nuclear quadrupole, and chlorine hyperfine interactions. It is concluded from an analysis of the spin‐Hamiltonian parameters that the triplet spin density in the chlorine out‐of‐plane orbitals is small, the chlorine electric field gradient is significantly reduced in the ³ππ^* state as compared to the value for the ground state, and that the molecule most likely is distorted.