Cu Barite

Copper in minerals luminescence is usually considered only as an effective quencher. Nevertheless, it is well known that a bright blue luminescence is emitted from Cu ions in inorganic solids by UV light irradiation. It was found that these materials have potential application to tunable lasers. For example, in CaO-P20s glasses Cu is characterized by luminescence band at 440 nm with half-width of 100 nm and excitation maximum at 260 nm. Decay time of luminescence is approximately 25 ps (Tanaka et al. 1994). Red fluorescence possibly connected with Cu pair is also known (Moine et al. 1991). 

In BaS04 Cu two bands are detected red and violet (Fig. 5.96). The red one peaking at 740 nm at room temperature has half-width of 150 nm and decay time of 350 ps. The violet band peaking at 410 nm has at room temperamre half-width of 35 nm and decay time of 7 ps. At lower temperatures both bands disappear and the new IR one is detected. Such deep red luminescence in natural barite has been described earlier (Gaft et al. 1985) while the possible connection with Cu was not considered. 

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