Electronic Raman Spectrum and Crystal Field of the Terbium Ion in Terbium Aluminum Garnet

Abstract

Electronic Raman transitions of ${\mathrm{Tb}}^{3+}$ in ${\mathrm{Tb}}_3$ ${\mathrm{Al}}_5$ ${\mathrm{O}}_{12}$ (garnet) within the ${}_{}{}^7{}_{}{}^{}F_6^{}{}_{}{}^{}$ ground-state components and to the excited states of the ${}_{}{}^7{}_{}{}^{}F_5^{}{}_{}{}^{}$ components have been observed. From the polarization properties of the Raman transitions, the symmetry of some of the states of the ${\mathrm{Tb}}^{3+}$ ions in this crystal has been determined. A Zeeman-Raman experiment has been performed. Relations between the observed components of the scattering tensors of cubic symmetry and the tensors for transitions of the ions in the orthorhombic site symmetry have been established. Based on these results, the justification of the cubic and tetragonal approximations of the crystal field in this compound is discussed.