IDENTIFICATION OF DEFECT STRUCTURES IN EU-3+-CAF2 BY SITE SELECTIVE SPECTROSCOPY OF RELAXATION DYNAMICS

The different charge compensated Eu3+ sites in CaF2 have been identified by creating a nonequilibrium distribution of sites and following the kinetics of the return to equilibrium by site selective laser spectroscopy. The nonequilibrium distribution is created by rapidly quenching the crystals so a high temperature distribution is frozen in the lattice. The absolute concentrations of the four dominant sites are measured during the re-equilibration at a lower temperature. Analysis of the kinetics by standard techniques shows that the site distribution is controlled by dimers and trimers in which an extra fluoride interstitial ion has been scavenged. Studies of doubly doped crystals confirm the identification of the two sites as clusters.