Polarized laser selective excitation and Zeeman infrared absorption of C-4v and C-3v symmetry centers in Eu3+-doped CaF2, SrF2, and BaF2 crystals

Laser selective excitation and Zeeman infrared-absorption spectroscopy have been employed to study Eu3+ centers in CaF2, SrF2, and BaF2 crystals. At low dopant concentrations (less than or equal to0.1 mol%), the dominant center for both CaF2 and SrF2 crystals is the well-established C-4v(F-) center that consists of a Eu3+-F- dipole oriented along the [100] crystallographic directions. The dominant center for BaF2:Eu3+ and a second center in SrF2:Eu3+ has C-3v symmetry with the charge compensating F- ion residing in an interstitial position along the [111] directions. In all three crystals, nonlocally charge-compensated cubic symmetry centers are also present. Zeeman measurements of the infrared absorption transitions to the Eu3+7F6 multiplet reveal interesting nonlinear Zeeman splittings as a function of the applied magnetic field. Crystal-and magnetic-field analyses of the C-4v(F-) and C-3v(F-) centers give crystal-field parameters that are in agreement with those of other rare-earth ions and that well account for the measured Zeeman splittings.