Charge transfer in gemstones

In case of blue sapphire, there exist iron and titanium as impurities. Each of the impurity ions can be presented in two valence states. One is ferrous iron and titanium four valence cation, another is ferric iron and titanium three valence cation as a high level. By light energy, electron transfers from the iron to the titanium. At this time, it produces broad absorption band at the red of spectrum, so we can see deep blue color.

Видео Charge transfer in gemstones канала Gemstones and Jewelry