Elementary processes of photolysis in lead halide crystals

Citation
H. Nakagawa et al., Elementary processes of photolysis in lead halide crystals, RADIAT MEAS, 33(5), 2001, pp. 819-822
Citations number
6
Language
INGLESE
art.tipo
Article
Categorie Soggetti
Apllied Physucs/Condensed Matter/Materiales Science
Journal title
RADIATION MEASUREMENTS
ISSN journal
1350-4487 → ACNP
Volume
33
Issue
5
Year of publication
2001
Pages
819 - 822
Database
ISI
SICI code
1350-4487(200110)33:5<819:EPOPIL>2.0.ZU;2-O
Abstract
Emission spectra from PbCl2 crystals doped with various amount of Tl+ ions have been measured at 4.8 K by varying the excitation photon energy. Two ad ditional emission bands appear in the green region (G(1) at 2.48 and G(2) a t 2.39 eV) with excitation in the low energy tail region of the excitonic a bsorption band. The G(1)- and G(2)-emissions show behavior similar to the i ntrinsic ultraviolet (UV at 3.78 eV) and blue-green (BG at 2.62 eV) emissio n, respectively, in their excitation spectra, temperature dependence and th ermal quenching effect. By quenching the crystal from 620 K to room tempera ture, the intensities of the UV- and G(1)-emissions are diminished drastica lly while those of the BG- and G(2)-emissions are maintained. The G(1)- and G(2)-emissions are related to the [Tl-0(Cl-)(3) + hole] center and the [(P bTl)(2+) + hole] center corresponding to the [Pb+(Cl-)(3) + hole] center fo r the UV-emission and [(Pb-2)(3+) -STEL +hole] center for the BG-emission i n the host crystal, respectively. A well-defined excitation band for the G( 1)-emission is established through spectral decomposition of the observed e mission spectra. This means that the Tl+-related excitons maintain a rather strong localized nature leading to luminescence specific to the doped Tlion. The role of the anion vacancy will be discussed in relation to the lat tice relaxation and the photolysis processes. (C) 2001 Elsevier Science Ltd . All rights reserved.