Color centers in heavily irradiated CsI(Tl) crystals

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• 作者：V. Yakovlev ; A. Meleshko ; L. Trefilova
• 关键词：Thallium-doped cesium iodide ; Color center ; Luminescence ; Energy transfer
• 刊名：Journal of Luminescence
• 出版年：2008
• 期刊代码：54_00222313
• 类别：ch
• 出版时间：September 2008
• 卷：128
• 期：9
• 页码：1447-1453
• 文件大小：338 K

摘要

The absorption and luminescence properties of CsI(Tl) crystals colored by irradiation are studied by the method of the time-resolved spectroscopy. The scheme of the electron transitions in CsI(Tl) crystal is suggested to explain the appearance of the color centers under exposure to the near-UV light. It is established that either of the two types activator color centers holds the charge carrier with opposite sign. The model of the hole Tl²⁺v_c⁻ activator color center is suggested. According to the model the positive charge of Tl²⁺ ion is compensated by the negative charge of a close cation vacancy v_c⁻. The color center emission reveals in the cathode-luminescence spectrum of the colored CsI(Tl) crystal. The high-dose irradiation of CsI(Tl) crystal results in the reduction of the decay time of the near-thallium self-trapped excitons (STE) emission. The decay kinetics of Tl²⁺v_c⁻ emission contains the time components typical for the decay kinetics of near-thallium STE emission. The reason of the observed effects is the energy transfer from the near-thallium STE excitons to the color centers via the inductive-resonant mechanism.