It was recalled that (F2+)H centers in OH--doped samples of this halide had long been known to be bleached at 77K by intense infra-red laser light. This bleaching was usually attributed to reorientation effects. Absorption and emission data unambiguously showed that, in addition to reorientation, significant destruction was involved in the bleaching process. Thus, the (F2+)H centers were transformed into other, so-called C, centers which did not absorb within the same wavelength domain. It was found that the conversion of (F2+)H centers into C-centers was easily and completely reversed by irradiation, at 77K, using visible or near-ultraviolet light.

A.Konaté, E.Kawa, J.L.Doualan, P.Le Boulanger, J.Margerie: Journal of Physics - Condensed Matter, 1996, 8[8], 8041-56