CREATION OF EXCITONS AND DEFECTS IN A CSI CRYSTAL DURING PULSED ELECTRON-IRRADIATION

Data presented on the influence of the temperature in the range 80-650 K on the spectral kinetics of the luminescence and transient absorpti on of unactivated CsI crystals under irradiation by pulsed electron be ams ([E]=0.25 MeV, t(1/2)=15 ns, j=20 A/cm(2)). The structure of the s hort-wavelength part of the transient absorption spectra at T=80-350 K exhibits features, suggesting that the nuclear subsystem of self-trap ped excitons (STE's) transforms repeatedly during their lifetime until their radiative annihilation at T greater than or equal to 80 K, alte rnately occupying di-and trihalide ionic configurations. It is establi shed that a temperature-induced increase in the yield of radiation def ects, as well as F and H color centers, and quenching of the UV lumine scence in CsI occur in the same temperature region (above 350 K) and a re characterized by identical thermal activation energies (similar to 0.22 eV). It is postulated that the STE's in a CsI crystal can have a trihalide ionic core with either an on-center or off-center configurat ion; the high-temperature luminescence of CsI crystals is associated w ith the radiative annihilation of an off-center STE with the structure (I-(I(0)I(-)e(-))). (C) 1998 American Institute of Physics.