Spinel luminescence

The emission of natural spinel exhibits a great deal of fine structure, which was ascribed to Cr luminescence (Tarashchan 1978 Mohler and White 1995). The natural spinel in our study consisted of three samples. The laser-induced time-resolved technique enables us to detect Cr and possibly Mn " emission centers (Fig. 4.51). 

Fig. 4.51. Laser-induced time-resolved (a) and steady state (b) luminescence spectra of spinel demonstrating Cr " and possibly Mn " centers...

An identihcation of the nature of Cr luminescence in synthetic spinel by the line narrowing technique enabled to distinguish up to 25 different Cr + sites (Deren et al. 1996). Laser-induced time-resolved spectroscopy enables us to see typical for spinel emission of Cr ", while the different broadness of the spectral lines at different time windows demonstrates that different Cr " sites are present also in natural spinel (Fig. 4.51). 

Fig. 4.120 (a-d) Laser-induced CW luminescence spectra of natural and synthetic spinels (http // rruff.info)... 

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