Radiation processes in frozen aqueous systems

Abstract

Primary events in the radiolysis of liquid and solid water are discussed. It is concluded that in low temperature solids, only H· and ·OH radicals need to be considered. Secondary processes involve reaction between H· and water to give ·OH and H 2, and the formation of H 2O 2 from ·OH radicals, but neither reaction occurs at ca. 4 K. Hence, mass-loss at low temperatures is probably not caused by chemical reactions, since both H· and ·OH are strongly bound into the ice lattice by hydrogen bonds. Possible reasons for blurring effects are considered, together with expectations for the effects of very high doses. Radiation effects in phase-separated aqueous systems, and in aqueous glasses are also discussed, a major new element for the latter being the formation of trapped-electron centres, and consequently also of trapped positive centres (H 3O +). Further chemical reactions in both inorganic and organic glasses are discussed.