Luminescence of V-Type Centers in Potassium and Rubidium Iodide Crystals

Luminescent Associates of Pb2+vc− Dipoles with Interstitial Iodine Atoms in KI:PbI2 Crystals

“…Thus, if this interpretation of the spectra of X-irradiated KI: P b crys;als is correct it means that the intra-centre luminescence connected with the processes in the excited state of the molecular ion (or the so-called H, centre) has been first observed in [5]. According to [19] the RES of an X; molecular ion have no stable minima, consequently, they cannot emit.…”

“…The emission spectrum exhibits two bands with peaks at 0.805 and 0.734 eV and half-widths of (0.056 & 0.003) and (0.039 0.003) eV, respectively. The excitation spectra of both bands are the same and consist of two intense bands peaking at 2.82 and 3.54 eV and of one weak band at 1.55 eV, tentatively denoted in [5] as VLl, VLZ, V,, bands, respectively. The peaks of the excitation spectra correspond well to those of the absorption spectrum3).…”

“…The infrared luminescence excited in any of the V, bands, has been observed in [5]. The emission spectrum exhibits two bands with peaks at 0.805 and 0.734 eV and half-widths of (0.056 & 0.003) and (0.039 0.003) eV, respectively.…”

“…It has been shown in [l, 41 that optical bleaching of [IiIaaavc-centres at 77 K by 4.55 eV light results in the formation of new centres (tentatively referred to as V, centres [5]) which induce absorption bands peaking near 2.88 and 1.55eV. Thermal decay of V, centres occurring at about 110 K is accompanied by the formation of the initial [I;Iaaavc-centres.…”

“…The optical and thermal properties of V, centres produced in KI and RbI crystals, are very similar. It has been suggested that the V, centre may involve a neutral iodine atom [5] or a cation vacancy [l, 3, 41. In KI crystals doped with divalent (A2') ions (A2+ : Mg2+, Ca2+, Sr", Ba'', Pb2+) and containing cation vacancies necessary for the compensation of the excess charge of A' ' ions, the X-irradiation at 140 K produces centres designated as V, , centres [6] with three absorption bands, which are analogous to the V, bands described above. With the increase of X-irradiation dose their intensity grows at the first stage of coloration parallel with the rise of the F absorption band.…”