Four bands which were associated with the main Tl centers were detected in the emission spectra of Tl-doped crystals. Their spectral, polarization and kinetic characteristics were studied at temperatures of between 0.45 and 360K. It was shown that a new model for the relaxed excited state structure of the luminescence center in Tl-doped CsI crystals was also applicable to the present materials. Two ultra-violet emission bands, which were excited mainly in the A absorption band of Tl+ centers, were attributed to electronic transitions from trigonal and tetragonal Jahn-Teller minima of the relaxed excited state of Tl+. Two visible bands, which were excited mainly in the higher-energy absorption bands, were attributed to 2 different off-center configurations of a self-trapped exciton that was perturbed by the Tl+ ion. The mixing of impurity and halogen excited states was shown to decrease markedly in the sequence: I-  Br-  Cl-.

E.Mihokova, V.Nagirnyi, M.Nikl, A.Stolovich, G.P.Pazzi, S.Zazubovich, V.Zepelin: Journal of Physics - Condensed Matter, 1996, 8[23], 4301-14