HALOGEN DEFECT AGGREGATION IN KI IRRADIATED BETWEEN 195-K AND 295-K

Annealing experiments, in conjunction with optical absorption and Raman scattering measurements, have been undertaken previously on KI, X- or gamma-irradiated at 195 K and 295 K, in order to study the mechanism of halogen interstitial aggregation. Irradiation at 195 K resulted in the prominent formation of I3- clusters whereas at 295 K large molecular aggregates (I2)n were preferentially formed. The present studies at the intermediate temperatures of irradiation, 233 K and 273 K have provided important information clarifying the progressive nature of halogen cluster development. At these temperatures I3-, I(n)- and (I2)n clusters are formed. The (I2)n clusters become increasingly dominant as the temperature of irradiation is raised. The role of the I(n)- clusters is examined.