ESR STUDY OF NA-COLLOIDS IN HEAVILY IRRADIATED NACL - SIZE EFFECTS AND INTER-PRECIPITATE INTERACTIONS

Compared with other materials, the radiolysis processes in alkali hali des and in particular NaCl have been investigated extensively. From th ese investigations we have obtained a rather clear picture of the radi olysis processes in these model materials. During irradiation of NaCl crystals at 50-150 degrees C Na and Cl-2 precipitates are formed. At l ow doses the F-center ESR signal and the optical F-band are found. Wit h increasing dose a rapid transition from F and F-aggregates to colloi ds occurs. We have observed colloids showing Curie paramagnetism, a Cu rie-Pauli cross-over (both due to size effects) and normal Pauli behav ior. In heavily damaged samples we have observed anomalous behavior of the intensity and line-width as a function of temperature. Our observ ations have important consequences for the understanding of the radiol ysis processes in heavily damaged NaCl. Copyright (C) 1996 Elsevier Sc ience Ltd