Host-Sensitized Luminescence in CdBr2: I

Luminescence in CdBr2: I single crystals has been investigated with UV・light excitation in the intrinsic absorption region of CdBr2・Theemission spectra were determined in detai1 for different concentration of 1-in the temperature region between liquid herium and room tempera ture. Two emission bands，having their maxima at 2.11eV and 2.52eV were observed above liquid nitrogen temperature. They are known to be the intrinsic one of CdBr2 and that due to I-in CdBr2，respectively. It was found that the intensity of the 2.52 eV emission band relative to the total emission intensity enhances with increase of the 1-concentration or of the temperature. This means that the excitation energy is transfered from the host lattice to the 1-site and that the efficiency of the energy transfer increases with increasing temperature. It is proposed that the thermal hopping of relaxed excitons is most likely among various types of energy transfer in CdBr2・ With decreasing temperature below liquid nitrogen temperature，it was found that other emission bands enhance around 3.3eV，w hi1et he 2.11eV and 2.52eV bands diminish. These emission are supposed to arise from the relaxed excited states of excitons shallower than those giving rise to the 2.11eV and 2.52eV emlSSlon