Luminescent and photochemical processes in CdBr2 : AgCl crystals

Time dependence of the luminescence intensity in CdBr2: AgCl,PbBr2 crystals under N2-laser excitation at room temperature

“…The results of CdBr 2 : AgCl,PbBr 2 optical studies confirm that photoinduced absorption in this material (as well as in CdBr 2 : AgCl [15,16]) is caused by the photodissociation of the matrix [11] and by photochromic transformations of silver centres [15,16]. Considering the results of [20][21][22][23] one can assume that in case of the activation of melt-grown CdBr 2 with AgCl, (Ag + Cd ) − impurity, single-charge acceptor centres are formed as the dopant: Ag + ion substitutes Cd 2+ ion in the regular lattice sites.…”

“…The influence of silver impurity on the opticalluminescent characteristics of CdBr 2 crystals has been studied in [15,16]. In the photoluminescence spectra of low-doped transparent CdBr 2 : AgCl (measured at 85 K under N 2 -laser excitation), an intensive band around 630 to 640 nm and less pronounced band at 490 to 505 nm have been reported.…”

“…In heavily doped crystal an additional emission band peaked at 465 nm is also observed. The origin of these bands and photochemical processes during the irradiation of the crystal have been discussed in details by Novosad et al [16].…”

“…Such structural arrangement, on the one hand, determines strongly anisotropic mechanical, electrical and optical properties and, on the other hand, provides favorable conditions for the creation of impurity centres localized at different crystallographic lattice sites. CdBr 2 crystals doped with copper and silver impurities exhibit photochromic properties [9][10][11][12][13][14][15][16][17]. Therefore, it is interesting to study optical and luminescent properties of photochromic crystals derived from cadmium bromide and investigate electronic processes that are responsible for the photochromic behavior.…”

“…Moreover, the material shows weak luminescence at room temperature when excited by N 2 -laser and this luminescence is further diminished during photochemical reactions. Restoring of the luminescence properties of silver-doped cadmium bromide crystals after thermal or optical bleaching is explained by Novosad et al [16] by the decay of colloidal nAg 0 centres, which can be regarded as release of carriers from trapping centres related to silver impurity.…”