COLOR-CENTERS IN IRRADIATED NAF-MN++ CRYSTALS

The effects of thermal and optical bleaching of color centers in NaF: Mn++ crystals are studied. Thermal treatment of γ‐colored crystals produces a new optical absorption band at 630 nm, accompained by an emission at 580 nm. Undoped crystals irradiated to the same dosage give emission bands at 410 and 620 nm under he same thermal treatment. The 580 nm emission in the doped system is characteristic of the dopant ion and corresponds to four excitation bands at 310, 385, 465, and 535 nm. Four glow peaks are observed at 156, 225, 302, and 360°C at a heating rate of 110°C per min. Partial thermal cleaning followed by photostimulation of F centers generates a new glow peak at 135°C and a new band having an absorption peak at 310 nm. Copyright © 1990 WILEY‐VCH Verlag GmbH & Co. KGaA