Datolite luminescence

The narrow band at 455 nm with a decay time of 750 ns in the datolite luminescence spectrum belongs to Eu " luminescence (Fig. 4.16b), which was also detected by steady-state spectroscopy (Gaft et al. 1979). Besides that, narrow lines appear in the orange part of the spectrum with the main one at 610 nm (Fig. 4.16c) with a long decay time, which confidently may be ascribed to Eu ". ... 

Datolite is caldiun borosilicate with a monoclinic structure (2/m) and space group P2i/c. It consists of superimposed complex sheets of linked oxygen and O, OH tetrahedra around silicon and boron atoms respectively the Si04 and B(0,0H)4 tetrahedra alternate, forming rings of four and eight tetrahedra. The natural datolite in our study consisted of seven samples from a variety of geologic environments. Concentrations of potential luminescence impurities in one sample are presented in Table 4.8. 

Fig. 4.16. a-d Laser-induced time-resolved luminescence spectra of datolite demonstrating Mn, Ce, Eu and Eu centers... 

Fig. 5.22. Luminescence and excitation spectra of in danburite and datolite (Gaft and Gorobets 1979)...

Characteristic bands of Mn + well studied by steady-state luminescent spectroscopy (Tarashchan 1978 Gorobets and Rogojine 2001) have been found in time-resolved luminescence spectra of calcite (Fig. 4.14a), fluorite (Fig. 4.10d), datolite (Fig. 4.16d), wollastonite (two bands at 555 and 603 nm Fig. 4.42a,c), and spodumen (Fig. 4.61a). 

Ce in the Ca2 site in two different natural samples. Other minerals showed similar Ce bands, notably zircon (355 nm), anhydrite (320 and 340 nm), barite (330 and 360 nm), danburnite (346 and 367 nm) and datolite (335 and 360 nm), with Ce " presumably substituting at a Ca site in all cases except zircon. In these samples, the Eu " emission bands were always at longer wavelengths, and thus distinctive. As the Ce luminescence transition is from the lowest level of the 5d manifold to a spin-orbit coupling split 4/... 

Luminescence centers Eu, Yb " and Mn, characterize steady-state spectra of datolite (Gaft et al. 1979). By using laser-induced time-resolved spectroscopy we were able to detect and the following emissirm centers Mn, Ce, Eu ", Eu ", Sm -", Dy (Fig. 4.29). 

Table 8.4 Results of datolite CaB(Si04)(OH) ore laser luminescent sorting...

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