Selective site excitation of europium-doped monoclinicGd2O3

Monoclinic crystals of ${\mathrm{Eu}}^{3+}$:${\mathrm{Gd}}_2$ ${\mathrm{O}}_3$ were studied at 80 K with the use of fluorescence spectra to interpret the energy levels. A tunable dye laser was used to selectively excite levels of the ${}_{}{}^5{}_{}{}^{}D_{0,1,2}^{}{}_{}{}^{}$ manifolds. Three distinct crystallographic sites for Eu${\mathrm{o}}^{3+}$ ions were identified for a majority of the Stark levels of the ${}_{}{}^7{}_{}{}^{}F_{0,1,2,3,4}^{}{}_{}{}^{}$ and ${}_{}{}^5{}_{}{}^{}D_{0,1}^{}{}_{}{}^{}$ multiplets. Comparisons of the fluorescence spectra from different sites were used in this energy-level assignment. Several fluorescence-lifetime measurements were also recorded.