Color Centers in Additively Colored CaF₂ and BaF₂

Abstract

Abstract The electron spin resonance method is applied to the study of the structure of color centers in additively colored CaF 2 and BaF 2 crystals. Together with optical absorption measurements and bleaching experiments the results indicate that the α‐band in CaF 2 and the 6600 Å band in BaF 2 are due to an electron trapped in an F − vacancy. The hyperfine interactions between the unpaired electron and the surrounding nuclei are discussed and compared with the results obtained for F‐centers in alkali fluoride crystals. Furthermore, the optical bleaching experiments lead to probable models for other absorption bands in CaF 2 .