ELECTRONIC EXCITATIONS LOCALIZED IN KBR AND KI CRYSTALS NEAR VACANCY DEFECTS OF DIFFERENT SIZES

The luminescence and excitation spectra of electronic excitations localized near a single anion vacancy (e(alpha)), a divacancy (e(d)), and a vacancy quartet (e(q)) are investigated. The shifts of spectral characteristics of these excitations with respect to those of the excitations in regular lattice sites (e(r)) have regular behavior. It turned out that the charge of vacancy defects is the main perturbing factor for e(alpha), e(d), and e(q) creation and the dimension of vacancy defects is the main perturbing factor for the radiative decay e(alpha), e(d), and e(q). The peculiarities of c(alpha), e(d), and e(q) relaxation are discussed in terms of strong and weak off-centers for e(r) in KBr and KI, respectively.