DEPTH PROFILES OF INTERSTITIAL HALOGEN DEFECTS IN HIGH-ENERGY ION-BOMBARDED ALKALI IODIDES BY MICRO-RAMAN SPECTROSCOPY

Halogen aggregates created in alkali iodides by high energy ions consi st of I-3(-), I-n(-) and (I-2)(n) as evidenced by Raman spectroscopy. By extending our studies to micro-Raman measurements. it has been poss ible to determine the depth profiles of the formation of halogen aggre gates. It is shown that I-n(-) clusters are created with an enhanced c oncentration in the region of large excitation density near the Bragg peak at the expense of the I-3(-) defects. Several factors monitor the relationship between I-3(-) and I-n(-) clusters. At saturation within the ion tracks, these respective numbers critically depend on their m utually coupled kinetics, their dose dependence and the degree of ion track overlap. It is shown for example that I-3(-) defects are progres sively enhanced with increasing fluences all along the ion tracks. Res ults are compared to those obtained by X-ray irradiations.