SITE-SELECTIVE SPECTROSCOPY OF CAF2-HO-3+

Using selective laser excitation, the crystallographic sites arising from fluoride compensation of Ho3+ doped into CaF2 have been investigated. Two sites are found corresponding to single-Ho3+ -single-fluoride-interstitial pairs. These sites are suspected to be the tetragonal and trigonal sites observed in the similar CaF2: Er3+ system. Two sites and a family of similar sites are found to be dimers and/or higher-order clusters. These sites exhibit upconversion and energy-transfer-assisted decay characteristics of the closely coupled rare-earth ions. This phenomenon was used to observe energy transfer between an Er3+ and a Ho3+ in a double-doped crystal, and therefore show the equivalency of the respective sites in each of the ion's individual spectra. © 1979 The American Physical Society.