Symmetry, selection rules, and energy levels of Pr3+:Y3Al5O12
Abstract
Absorption, fluorescence, and site-selective excitation spectra of Pr3+: Y3Al5O12 are reported between 0.4 and 6.7 μm at several temperatures between 1.6 and 90 K. The complexity of the spectra indicates that Pr3+ ions occupy several different sites. The most intense spectra, representing the majority of the Pr3+ ions in dodecahedral lattice sites, are analyzed on the basis of electric-dipole selection rules for D2 site symmetry. Weak spectra are reported but not analyzed due to the difficulty in assigning levels to a particular site. Analyses of intense spectra establish the symmetry of 17 Γ1, 12 Γ2, 10 Γ3, and 12 Γ4 Stark levels. These 51 levels are compared with the results of a crystal-field splitting calculation. A Hamiltonian consisting of Coulombic, spin-orbit, and crystal-field (D2 symmetry) terms was diagonalized for all manifolds of the Pr3+ (4f2) configuration. The rms deviation between calculated and experimental levels is 11 cm-1. © 1989.