Answers are grounded in this paper and cite their sources.
The authors report on an intense blue emission centered at 420nm under ultraviolet excitation from pentavalent tantalum ion-doped silicate glasses. The blue emission is distinctly different from emission due to defects in silica glass, which is also reflected in both absorption spectrum and remarkably enhanced emission. The authors suggest that localized Ta 5d0 energy level is responsible for the blue emission.
No takes yet. Share an insight, caveat, or question.
Meng et al. (2006) studied this question.
Synapse has enriched 10 related papers. Consider them for comparative context: