ESR study of Na-colloids in heavily irradiated NaCl: Size effects and inter-precipitate interactions

Compared with other materials, the radiolysis processes in alkali halides and in particular NaCl have been investigated extensively. From these investigations we have obtained a rather clear picture of the radiolysis processes in these model materials. During irradiation of NaCl crystals at 50–150°C Na and Cl2 precipitates are formed. At low doses the F-center ESR signal and the optical F-band are found. With increasing dose a rapid transition from F and F-aggregates to colloids occurs. We have observed colloids showing Curie paramagnetism, a Curie-Pauli cross-over (both due to size effects) and normal Pauli behavior. In heavily damaged samples we have observed anomalous behavior of the intensity and line-width as a function of temperature. Our observations have important consequences for the understanding of the radiolysis processes in heavily damaged NaCl.