Unusual chemically-induced dynamic electron polarization of electrons produced by photoionization

ESR polarizations of e{sub aq}{sup {minus}} produced by photoionization of phenoxide and thiophenoxide were observed in laser photolysis experiments to be absorptive and emissive, respectively. In both cases, random encounters in radiolysis experiments lead to emission. These observations can best be explained if the ionizing states are singlet and triplet, respectively, and the exchange interaction is positive (triplet lower) in encounters of the radical pairs. The anion radical of benzoate behaves like e{sub aq}{sup {minus}} in reactions with phenoxyl and phenylthiyl radicals while that from p-acetylbenzoate behaves normally. A reason for the positive exchange interaction is suggested. 22 refs., 4 figs.