It was noted that the emission and absorption intensities of F3+ color centers in these crystals exhibited unusual behaviors immediately after high-power excitation. The existence of a triplet state was proposed in order to explain their optical cycle. A detailed study of its dynamic characteristics was performed here for the first time at 2K, and the triplet state was also investigated by means of magnetic circular dichroism measurements. The parameters of the optical transitions were calculated, and these explained why the triplet state was able to capture a large fraction of the excited F3+ centers.

G.Baldacchini, M.Cremona, E.De Nicola, R.M.Montereali, V.Kalinov: Materials Science Forum, 1997, 239-241, 703-6