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Laser selective excitation and optical absorption of deuterated SrF2:0.05% Er3+ crystals have revealed eight Er3+ ion centers involving D- ion charge compensation, nine new Er3+–F- centers not associated with D- ions and several approximately cubic symmetry Er3+ centers. In contrast to the trigonal symmetry of the principal F- center, the dominant arrangements in the D- ion charge compensation case are derived from a tetragonal symmetry center. Detailed spectroscopic results for the new centers are presented. Fluorescence polarization ratios are listed for three centers ( J, B, and G1) present in either SrF2:Er3+ or CaF2:Er3+ and crystal-field analyses of these, based on assumed trigonal symmetry, are also reported. [ABSTRACT FROM AUTHOR]

Laser selective excitation and optical absorption studies of hydrogenated CaF2:0.05% Er3+ crystals have revealed 16 Er3+ ion sites involving H- or D- ion charge compensation. The relative occurrence of these sites can be controlled over a wide range by varying the duration of the hydrogenation treatment. The hydrogenic nature of these sites is established by the observation of local mode absorption lines in the infrared, Er3+ ion electronic line isotope shifts and associated local mode vibronic lines involving the H- and D- ions. Local mode infrared absorption frequencies of four sites are reported for most rare-earth ions. Five new Er3+-F- sites were identified in the laser selective excitation study. For <100> and <111> oriented crystals the fluorescence spectra of several of the sites exhibit well-defined polarization which determines their Er3+ ion site symmetries. Symmetry confirmations are also established for the two previously reported single Er3+ ion sites involving fluoride ion compensation. Eleven of the hydrogenic sites reported here are classified into two families, each derived from a single Er3+ ion site of the parent crystal, while three others are attributed to sites of nearly cubic Er3+ ion symmetry. Detailed spectroscopic results for these sites are presented, together with a crystal-field analysis for the C4v symmetry sites and some model assignments. [ABSTRACT FROM AUTHOR]