Visible photoluminescence in coloured Lithium Fluoride under ultra-violet continuous wave excitation

H.J. Kalinowski, R.M. Monterali, M.A. Vincenti, R.N. Nogueira

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Abstract

The γ-coloured Lithium Fluoride crystals visible fluorescence at room temperature was measured under excitation with ultra-violet continuous wave light at λ 244 nm from a frequency-doubled Ar+-ion laser. The excitation wavelength lies close to the peak of the F-centre absorption band for LiF, and the visible luminescence spectrum consists of two broad emission bands, assigned to F+3and F2centres in LiF. The luminescence spectrum changes in a short time after start of illumination. The main effect of 244 nm laser illumination is the observed change in the F2emission band intensity, which is strongly and permanently bleached by the CW UV light at 244 nm as soon as it illuminates the crystal. The time evolution of the fluorescence signals can be measured, and the corresponding curves were fitted by a single exponential decay, resulting in characteristic time constants of 9 s and 30 s for the F2and F+3bands, respectively. The reported effects support previous work about UV laser illumination in the F-band absorption peak as an effective method to control the ratio of F2to F+3centres in LiF, due to permanent bleaching of the former ones. © 2010 IOP Publishing Ltd.
Original languageEnglish
DOIs
Publication statusPublished - 2010
Externally publishedYes

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All Science Journal Classification (ASJC) codes

  • Physics and Astronomy(all)

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