Transformation of defects arising in CsI(Tl) crystals under daylight

The part played by the activator in delocalization of the excitation and defect formation in a CsI(Tl) crystal has been studied. Basing on the investigation of the long term afterglow kinetics for CsI(Tl) crystals with various activator concentrations, it has been found that the cation substituted Tl+ions participate in the process of the charge carriers delocalization in CsI(Tl) crystals under daylight. Non-radiative decay of electronic excitations with the F center formation is stimulated by oxygen containing anions. The subsequent destruction of the F centers is accompanied by both, luminescence of the excitons localized near Tl + and activator defect formation. The luminescence of Tl + centers is reabsorbed by the stable activator defects arising in CsI(Tl) crystals under irradiation. As a result, a sensitized luminescence of activator defects appears along with Tl + luminescence. (copyright 2005 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)