Electron spin resonance studies of elementary processes in radiation- and photo-chemistry. Part 8.—Thermal and photochemical annealing of γ-irradiated glycine

Abstract

E.s.r. studies of γ-irradiated single crystals of α-glycine and glycine-d3 between 77 and 403 K show that the primary radical anions are the only species trapped at 77 K. These are converted to a mixture of radicals NH+3ĊHCOO– and ĊH2COOH (or ND+3ĊHCOO– and ĊH2COOD) below 113 K which change in relative proportions on further annealing. The carboxymethyl radicals disappear only at temperatures approaching 370 K. Differences in the relative stabilities of the two types of radicals in the deuterated and non-deuterated samples are observed: these are thought to have their origin in small differences in crystal parameters.Ultra-violet irradiation of γ-irradiated crystals at 77 K produces radicals of structure HNCH2COOH (or DNCH2COOD) apparently by loss of molecular hydrogen.