Spectra, energy levels, and transition line-strengths for Sm3+:Y3Al5O12

Optical spectra and energy levels of the sextet, quartet, and doubler states of Sm3+ (4f(5)) incorporated into single crystals of Y3Al5O12 (Sm3+:YAG), where YAG denotes yttrium aluminum garnet, are reported and analyzed at wavelengths between 560 and 280 MI. The analysis of energy (Stark) levels is based on a model Hamiltonian consisting of Coulombic, spin-orbit, and interconfigurational terms for the 4f(5) atomic configuration of Sm3+ and crystal-field terms in D-2 symmetry (the: site symmetry of the Sm3+ ions in the garnet lattice). The Hamiltonian also includes contributions arising from:the spin-correlated crystal field. Because of the strength of the crystal field, the entire energy matrix is diagonalized within the complete 4f(5) SLJM(J) basis set representing 73 LS states, 198 L-2S + I(J) multiplets, and 1001 doubly degenerate crystal-quantum states. In D-2 symmetry, all Stark levels are characterized by the same irreducible representation ((2)Gamma(5)). Optimization between 314 calculated-to-observed Stark levels was carried out with a final rms deviation of 10 cm(-1). Eigenvectors obtained from the crystal-field splitting analysis are used to calculate transition line strengths originating from the ground-state Stark level to Stark levels in excited manifolds. The calculated line strengths are compared with experimental line strengths obtained from the absorption spectrum at 3.8 K. The line-strength analysis is useful in identifying individual excited Stark levels associated with sextet, quartet, and doublet states strongly mixed by the crystal field. [S0163-1829(99)09347-9].