Optical absorption (OA) bands in fluorites by heavy gamma irradiation

Optical absorption spectra of heavily irradiated Brazilian fluorite have been obtained. Radiation exposures (60Co-γ-rays) up to 2.58.103 C/kg induce absorption bands at 225, 260, 335, 400, 580, 780 and 1450 nm, the two last ones being in the infrared region. Since several authors found 225, 335, 400 and 580 nm in both undoped and doped CaF2, suggestions are made that the defects responsible for these bands are the so-called modified Vk-centers contrary to the proposed model according to which the above bands are due to the f to d transitions induced in divalent rare-earths ions. (orig.)