Electron Spin Resonance Studies of Elementary Processes in Radiation- and Photo-chemistry: Part 8.—Thermal and Photochemical Annealing of y-irradiated Glycine

Abstract

E.s.r. studies of y-irradiatcd single crystals of a-glycinc and glycine-d3 between 77 and 403 K show that the primary radical anions are the only species trapped at 77 K. These arc converted to a mixture of radicals NH3CHCOO' and CH.COOH (or ND^CHCOO" and CH2COOD) 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-dcuterated samples arc observed: these arc thought to have their origin in small differences in crystal parameters. Ultra-violet irradiation of y-irradiated crystals at 77 K produces radicals of structure HNCH2COOH (or DNCH2COOD) apparently by loss of molecular hydrogen.