Optical evidence for paired Mn2+ centers was detected in Mn-doped material by means of time-resolved laser spectroscopy. The paired Mn2+ center was associated with a peak shift, of the Mn2+ emission, towards longer wavelengths and with fast (500) and slow (48ms) decay components which were due to a single Mn2+ ion. It appeared that this center formed a Mn2+ plus F-center plus Mn2+ complex when the material was irradiated with  rays. This complex was associated with a thermoluminescence peak near to 360C, and an optical absorption band near to 300nm. Conversion from a Mn2+ plus F-center plus Mn2+ complex to an F-center plus Mn2+ complex was detected in photo-transferred thermoluminescence and photo-bleached optical absorption spectra.

K.Chakrabarti, J.Sharma, V.K.Mathur, J.H.Barkyoumb: Physical Review B, 1995, 51[23], 16541-8