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E-Journal of Chemistry
Volume 7 (2010), Issue 2, Pages 425-432
http://dx.doi.org/10.1155/2010/971465

Optical Studies on KBr:Tl and KCl-Br:Tl Mixed Crystals

P. Eswaran,1 A. Anbagi,2 and S. Nagarajan2

1Department of Physics, SMK Fomra Institute of Technology, Kelambakkam, Thaiyur, Chennai, Tamilnadu-603 103, India
2Department of Physics, Pondicherry Engineering College, Puducherry-605 014, India

Received 18 August 2009; Accepted 10 October 2009

Copyright © 2010 Hindawi Publishing Corporation. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

Optical absorption spectra of KBr:Tl+ (0.0125 mol%) single crystals shows A, B and C bands around 258, 220 and 210 nm respectively. In KCl0.1Br0.9 :Tl+ (0.0125 mol%) mixed crystals exhibit slightly broadening of the A-band towards lower wavelength side. The broadening of the absorption spectra are suggested to be due to some complex Tl+ centers involving Br- and Cl- ions formed in the mixed crystals. When excited at A, B and C-bands of Tl+ ions, PL of KBr:Tl+ showed emission band around 320 with a prominent shoulder around 365 nm. In KCl0.1Br0.9 mixed crystals the shoulder around 365 nm is not prominent due to the perturbing influence of Cl- ions. Addition bands in the excitation spectra are attributed to the presence of Tl+ dimmers. PSL observed in X-ray irradiated crystals resembled their respective PL emissions indicating that PSL in them is due to Tl+ ions.