Fluorescence of Tm doped Li2B4O7 glass

Lithium tetraborate (Li2B4O7) is mainly used in dosimetry as thermoluminesc ent material. This study is an overview of optical studies made with Tm dop ed Li2B4O7 in glassy state. An energy level diagram of Tm3+ in Li2B4O7 was obtained from the fluorescent spectra. Optical absorption measurements, bet ween 2850 nm and 300 nm, showed bands due to the presence of Tm-3+(4f(12)) in the glassy matrix because of its characteristic electronic transitions. Optical intensities determined at room temperature, for 455 nm absorption w avelength after different Co-60 gamma rays irradiation doses, show the redu ction of Tm3+ to the Tm2+ state. The reconversion from Tm2+ to the Tm3+ sta tes is shown by the fluorescence emission intensity at 455 nm due to a post -irradiation heating of the samples.