ELECTRONIC DEFECTS INDUCED BY X-RAYS IN POWDERS OF ALKALINE IODIDES

Color centers obtained in powders of alkaline iodides (KI, RbI, CsI) X-irradiated at room temperature are studied by means of resonant Raman spectroscopy. Electron centers (F, F2. ṫ, Fn) are observed by using a low-energy laser excitation (green, yellow or red). Complementary centers: molecular ions (I-3). molecules associated to molecular ions and molecular aggregates, are selectively detected by using blue, violet or UV laser lines. Color centers created in pure powders are of similar nature than those observed in single crystals. Iodine aggregates (I2)n are obtained in KI while molecular ions I-3, with well-defined spectroscopic parameters, are observed in RbI and CsI. By using a mixture of KI with RbI or CsI, these two types of defects coexist. However, the proportion of (I2)n aggregates is reduced by increasing the concentration of RbI or CsI in the melt. © 1990.