X‐ray luminescence and thermally stimulated processes in CsI crystal

X‐ray luminescence spectra, thermally stimulated luminescence and thermally stimulated conductivity of undoped CsI crystal were investigated in order to reach better understanding of the factors which govern the emission processes in this material. X‐ray luminescence spectra were recorded in the temperature range from 15 to 293 K. The low energy band at 2.2 eV emerging at heating above 120 K has been assigned to the emission of residual impurities. Other two bands peaking at 3.6 and 4.3 eV at 15 K were attributed to the intrinsic emission of CsI due to the self‐trapped excitons. The parameters of the peaks observed in the thermally stimulated luminescence and conductivity of CsI crystal were calculated. Investigations of the thermally stimulated processes in CsI lead to the conclusion that the increase of luminescence of 4.3 eV observed above 70 K is due to release of trapped electrons, which subsequently interact with Vk‐centers and form on‐center STEs. The considerable ionic conductivity observed above 250 K can be explained by influence of the uncontrolled impurities of divalent metal atoms as well as Na+ ions.This article is protected by copyright. All rights reserved.