The effect of temperatures of 80 to 650K upon the spectral kinetics of the luminescence and transient absorption of unactivated crystals under irradiation by pulsed electron beams (0.25MeV, 15ns, 20A/cm2) was studied. The structure of the short-wavelength part of the transient absorption spectra at 80 to 350K exhibited features which suggested that the nuclear sub-system of self-trapped excitons transformed repeatedly, during their lifetime, up to radiative annihilation at above 80K; alternately occupying di- and trihalide ionic configurations. It was established that a temperature-induced increase in the yield of radiation defects, as well as of F and H color centers, and a quenching of the ultra-violet luminescence occurred within the same temperature range (above 350K) and were characterized by identical thermal activation energies of about 0.22eV. It was suggested that the self-trapped excitons could have a trihalide ionic core, with either an on-center or off-center configuration; with the high-temperature luminescence being associated with the radiative annihilation of an off-center self-trapped exciton with the structure: (I–(I0I–e–))*.

Creation of Excitons and Defects in a CsI Crystal during Pulsed Electron Irradiation. E.S.Gafiatulina, S.A.Chernov, V.Y.Yakovlev: Physics of the Solid State, 1998, 40[4], 586-90