Lyoluminescence and spin trapping

Abstract

The chemical origin of lyoluminescence has been probed using spin trapping techniques. Radicals derived from amino acids and saccharides by γ-irradiation in the solid state have been identified after trapping with aliphatic and aromatic nitroso compounds. Most of the radicals trapped were secondary alkyl radicals. Reaction of peroxyl radicals derived therefrom are thought to produce the emitting species (excited carbonyl compound and/or singlet oxygen). The effect which thermal annealing of the solids after γ-irradiation has on (a) the concentration of radicals in the solid, (b) the concentration of trapped radicals, and (c) the light yield has been investigated. One new water-soluble spin trap has been prepared.