Geminate recombination kinetics of triplet radical ion paris on porous glass: Magnetic field effect

Abstract

Geminate recombination kinetics of radical ion pairs formed by electron transfer from triphenylamine or tri(4-bromophenyl)amine to triplet 9,10-anthraquinone adsorbed onto optically transparent porous glass have been studied, using the laser flash technique. The kinetics are described by the sum of two exponentials, ascribed to the existence of two kinds of “supercages” on the surface. Introduction of a heavy Br atom leads to acceleration of the geminate recombination; application of an external magnetic field results in retardation. These effects are due to the contribution of the recombination route through the separated radical ion pair, where the hyperfine coupling mechanism of spin evolution is active, and intersystem backward electron transfer.