Pb Feldspars

Luminescence of monovalent Pb was firstly proposed for explanation of IR luminescence band peaking at 860 nm in emission spectrum of feldspars (Kusnetsov and 

All considerations above for and are also relevant for Tl, which also belongs to s elements (or mercury like). In minerals its UV luminescence peaking at 290 nm was found in microcline, where the isomorphous substitution of for Tl takes place (Kusnetsov and Tarashchan 1978). 

Center Sn belongs to 5s configuration. As impurity in artificial phosphors it is mainly responsible for narrow luminescence bands from UV to red part of the spectrum. Besides that intrinsic luminescence of tin compounds is also known (Donker et al. 1989). 

In order to find impurity responsible for yeUow emission, artificial Sn02 have been studied activated by different impurities such as Ti, Nb, Ta, W, Fe (Gaft et al. 1982). From crystallochemical positions such ions are capable to substitute for Sn . Nevertheless, the correlation of luminescence with any impurity was not found. From the other hand, in nominally pure super pure Sn02 all luminescence bands have been found, which were detected in natural cassiterite (Fig. 5.90). Thus it was concluded that luminescence is connected to intrinsic, namely to Sn of diverse valence, possibly Sn. Blasser et al. (1981) arrived at the same conclusion about intrinsic nature of Sn02 luminescence. 

We studies laser-induced time-resolved luminescence of synthetic BaS04 artificially activated by Sn and found several intensive UV and blue bands evidently connected with Sn emission (Fig. 5.91). Similar bands have been also found in natural barite laser-induced luminescence spectra and we think that their connection with Sn center is quite possible. 

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