Taxonomy of F -Aggregate Centers in NaF

Results of a study of broad and narrow optical absorption bands of F-aggregate color centers in NaF are given in terms of correspondence between optical absorption band and defect model. Comparison is given to previous work. New results or results which modify previous conclusions are reported for F2+, F3+, M′, M, and N centers, as well as for an impurity center which gives rise to a prominent optical absorption band at 312 mμ (300°K). It is proposed that this center consists of an oxygen-impurity–F-center complex. A number of identifications were made possible through use of OH− and O−− dopings, which favor centers with net positive and net negative charges, respectively.