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Regular paper[OPTICAL REVIEW Vol. 6, No. 1 (1999) 82-87] Decay Time of 2.09 eV Luminescence of S2−-Vacancy Centers and Their Optical and Thermal Stability in NaCl:S2 CrystalsRongbin YE, Koji OHTA, Mamoru BABA* and Kazume NISHIDATE Department of Electrical and Electronic Engineering, Faculty of Engineering, Iwate University, 4-3-5, Ueda, Morioka, 020-8551 Japan (Received September 30, 1998; Accepted November 9, 1998) An investigation was carried out on decay time of the 2.09 eV emission of S2−-vacancy pair centers in NaCl crystals. When the crystal was excited by a pulsed 337 nm light from an N2 laser, the 2.09 eV yellow luminescence principally decayed with the lifetime of 14.2 μs at low temperatures, and exhibited a weak thermal quenching with an activation energy of 51.3 meV above about 150 K. Such S2−-vacancy pair centers responsible for the 2.09 eV luminescence were thermally stable at room temperature, and not bleached even when exposed to ultraviolet lights below about 5 eV. Thus, the 2.09 eV emission center possibly can be used as a solid-state laser active center working at room temperature. Key words: sodium chloride, sulfur, photoluminescence, decay time, nonradiative transition, laser active center, solid-state laser |
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