SPIN POLARIZATION GENERATED IN THE TRIPLET DOUBLET INTERACTION - HYPERFINE-DEPENDENT CHEMICALLY-INDUCED DYNAMIC ELECTRON POLARIZATION

We studied CIDEP (chemically induced dynamic electron polarization) generated by the interaction between doublet radicals and triplet molecules. CIDEP signals showed significant hyperfine dependence in addition to net emissive signals. Net emissive CIDEP was explained by the avoided crossing of \Q-3/2> and \D1/2> states of a triplet-doublet encounter complex on the potential surfaces followed by the vanishing of the doublet spin states of this system through triplet quenching. The hyperfine dependence of CIDEP was interpreted by the mixing of \Q1/2> and \D1/2> states and that of \Q-1/2> and \D-1/2> states in the region of zero exchange interaction. This mixing is due to the hyperfine interaction between triplet and doublet molecules followed by the exchange interaction by the reencounter. The observed spectrum of the free radical was well reproduced by the simulated spectrum assuming those two mechanisms.