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 tempe rature 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 d ependencies of intensities of excitation bands of Mn2+ centres in the regio n 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.