ESR and ENDOR studies of the main radical created by gamma irradiation at 300 °K in the imidazole crystal

Abstract

ESR studies of room-temperature gamma irradiated single crystals of imidazole and of its derivatives deuterated in several different positions have permitted us to identify the main radical produced by such irradiation. It is a π radical formed by the addition of one hydrogen atom on a carbon of the ring. Moreover, we show that the hydrogen atom which is added to form the radical comes from hydrogens involved in the hydrogen bond chains. The subsequent ENDOR study enables us to deduce the spin density distribution in the radical from the determination of all the proton hyperfine tensors.