Luminescence characteristics of the Rb2CdI4 crystal

Optical reflection spectra of Rb2CdI4 single crystals were measured in the region of exciton creation at temperatures 77-250 K. Band gap width (E-g = 4.927 eV), binding energy (F = 0.390 eV) and radius (r(ex) = 4.43 Angstrom) of excitons were determined. Emission spectra at excitation in the exciton absorption bands and at band-to-band transitions were studied in the temperature region 8-300 K. The pi- and sigma-emission bands of the self-trapped exciton have observed at 3.06 and 3.44 eV, respectively. The temperature dependencies of intensities of excitation bands of Mn2+ centres in the region of intrinsic absorption give evidence of the existence of two additional bands, connected with the localization of excitons near impurity centres. (C) 2000 Elsevier Science B.V. All rights reserved.