Peculiarities of the decay of cation excitons in alkali halide crystals

The decay channels of cation excitons in alkali halide crystals are discuss ed. The excitation spectra of intrinsic and impurity emissions have been me asured, using synchrotron radiation of 6-36 eV, for NaCl, NaBr and NaI crys tals at 8 K and room temperature. Photons of 32 eV form three, four and fiv e electron-hole pairs each in NaCl, NaBr and NaI, respectively. An anion ex citon is created instead of one electron-hole pair at the decay of the 2p(5 )3s Na+ cation exciton formed by a 33-34 eV photon in these crystals. (C) 2 001 Elsevier Science Ltd. All rights reserved.