The optical isotropy of cubic garnet was overcome by crystal-site-selective polarized excitation and fluorescence spectroscopy. By this method the energies and the symmetries of the crystal-field components of the free-ion states ${}_{}{}^7{}_{}{}^{}$${\mathit{F}}_{\mathit{J}}$ (J=0,...,6), and ${}_{}{}^5{}_{}{}^{}$${\mathit{D}}_{\mathit{J}}$ (J=0,...,3) could be determined. On this basis a crystal-field analysis was performed to derive the crystal-field parameters for the ${\mathrm{Eu}}^{3+}$ replacing the ${\mathrm{Y}}^{3+}$ ions on the ${\mathit{D}}_2$ sites. Most of the transitions were either of electric- or magnetic-dipole character. For a number of transitions mixed electric- and magnetic-dipole character was found, and the mixing ratios were determined.

• Received 22 March 1993

DOI:https://doi.org/10.1103/PhysRevB.48.9264