Charge transfer processes in CsI: Tl using near-UV light

V. Yakovlev, L. Trefilova, A. Meleshko, V. Alekseev, N. Kosinov

Research output: Contribution to journalArticlepeer-review

5 Citations (Scopus)


This paper studies charge transfer processes in CsI:Tl crystals by analyzing the bulk photo-conductivity spectra, the temperature behavior of the bulk photo-conductivity current and the shape and intensity of the activator emission pulse excited by an electron pulse beam and/or laser pulse emission at temperatures between 80 and 400 K. The Tl concentration in CsI:Tl crystals varies from 10-3-10-1 mass%. It has been determined that near-UV light induces a bulk conductivity in CsI:Tl crystals only when the Tl concentration is greater than 3×10-3 mass%. A mechanism is proposed to explain the charge transfer processes with photons whose energy is approximately half the width of the CsI band gap. Near-UV light causes charge transfer from I- to Tl+ ions, forming Tl0 centers in the 6p2P1/2 ground and 6p2P 3/2 excited states. The electron, assisted by phonons, leaves the Tl0 center from either the 6p2P1/2 or 6p 2P3/2 states and overcomes the 0.13 or 0.30 eV energy barrier, respectively, and subsequently populates the activator conduction sub-bands, which are found inside the band gap of CsI:Tl. The formation of activator sub-bands is possible only above the threshold Tl concentration, i.e., above 3×10-3 mass%.

Original languageEnglish
Pages (from-to)79-83
Number of pages5
JournalJournal of Luminescence
Publication statusPublished - 1 Jan 2014

ASJC Scopus subject areas

  • Biophysics
  • Atomic and Molecular Physics, and Optics
  • Chemistry(all)
  • Biochemistry
  • Condensed Matter Physics

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