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Emission, excitation, and polarization spectra as well as decay kinetics are studied at 4.2 to 500 K for the luminescence of BC' + centres in two crystals (KC1 and CaO) with strongly different electron-phonon interaction. It is concluded that three bands at -2.5, 3.11, and -1.5 eV, observed in the emission spectrum of the KC1 : Bi, S crystal belong to the same centre, but arise from states of different origin. The splitting of the 2.5 eV band, caused by the presence of a defect (S2-) near a Bi'+ ion is detected. Besides the well-known triplet 3.3 and 3.1 eV bands, a new 4.15 eV emission is found in CaO :Bi crystal, which is ascribed to transitions from the singlet excited state of the Bi3+ ion. The structure and the parameters of the relaxed excited states are determined and the models of the corresponding BiJt centres are discussed.

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The thermoluminescence of ultraviolet- (250 nm) and X-ray-irradiated KCl:Eu2+ is investigated. The peaks are located in the same positions independent of the radiation used to excite the sample, with differences only in the peak intensity ratios. Thermal and optical bleaching methods allow us to relate the thermoluminescence peaks located in the low-temperature region (320-425 K) to Fz centres and those in a higher-temperature region (425-530 K) to F centres.