Charge-transfer bands in alkaline-earth fluoride crystals doped by Eu3+ or Y b3+ ions

High resolution emission spectra of Eu-doped CaF2 and SrF2 crystals excited into CT1 and CT2 bands were measured. Under excitation into CT1 bands, all present Eu sites (C4v, Oh and some aggregates) were observed in emission spectra. While under excitation into CT2 bands, only the emission of C4v sites was observed.