Photostimulated Reorientation of H (Pb²⁺) Centres in a KCl:PbCl₂ Crystal

Abstract

Temperature dependences of polarization and kinetic characteristics of luminescence are investigated for Pb2+ ions perturbed by a (nnn) cation vacancy and an interstitial chlorine atom (Hkoo1](Pb2+) centres) in a KCI: PbCl, crystal. At T > 110 K the reorientation of these centres in the triplet excited state of the Pb2+ ion stimulated by polarized UV radiation becomes evident in the polarization spectra and decay kinetics of the AT emission. It results neither in the depolarization of the emission nor in the "alignment" of the centres. Most probably the effect can be explained by a strong covalent interaction between the excited Pb2+ ion and an interstitial, and it is caused by the dissociation of the two-component defect near the Pba+ ion and the following jump of the interstitial chlorine atom into one of the (100)

Decay Kinetics and Polarization of the AT Emission of Pb2+ Centres of Different Structure in KBr:PbBr2

“…On absorption of linearly polarized light by the Pb2+ ion a dissociation of the complicated defect occurs with the subsequent reorientation of the centre. The mechanism of this phenomenon is discussed in detail in [4]. It should be emphasized that the reorientation takes place only after the thermal equilibrium between radiative and metastable minima has been achieved and thus only the slow decay component displays the corresponding peculiarities.…”

“…I t is shown in [4] that photostimulated reorientations of Hioo1J(Pb2+) centres in KCI : PbC1, occur after the thermal equilibrium between the radiative and metastable minima of the triplet excited state of Pb2+ ion has been achieved. Therefore, they reveal themselves in the polarization characteristics of SC only.…”