The energy levels of ${\mathrm{Gd}}^{3+}$ in the $^{6}\mathrm{P}$ , $^{6}\mathrm{I}$ , and $^{6}\mathrm{D}$ 4 ${f}^{7}$ configuration in cubic, tetragonal, and cluster sites in ${\mathrm{CaF}}_{2}$ have been excited by two-photon absorption. The relative two-photon intensities and polarization dependence show behavior which is similar to that previously observed for ${\mathrm{Gd}}^{3+}$ : ${\mathrm{LaF}}_{3}$ and ${\mathrm{Eu}}^{2+}$ : ${\mathrm{CaF}}_{2}$ and which requires higher-order perturbation theory in the virtual intermediate 4${f}^{6}$5d configuration.The energy levels of ${\mathrm{Gd}}^{3+}$ in the $^{6}\mathrm{P}$, $^{6}\mathrm{I}$, and $^{6}\mathrm{D}$ 4${f}^{7}$ configuration in cubic, tetragonal, and cluster sites in ${\mathrm{CaF}}_{2}$ have been excited by two-photon absorption. The relative two-photon intensities and polarization dependence show behavior which is similar to that previously observed for ${\mathrm{Gd}}^{3+}$:${\mathrm{LaF}}_{3}$ and ${\mathrm{Eu}}^{2+}$:${\mathrm{CaF}}_{2}$ and which requires higher-order perturbation theory in the virtual intermediate 4${f}^{6}$5d configuration.

Physical review. B, Condensed matterApr 15, 198510 citations

The energy levels of

{\mathrm{Gd}}^{3+}

in the

^{6}\mathrm{P}

^{6}\mathrm{I}

, and

^{6}\mathrm{D}

{f}^{7}

configuration in cubic, tetragonal, and cluster sites in

{\mathrm{CaF}}_{2}

have been excited by two-photon absorption. The relative two-photon intensities and polarization dependence show behavior which is similar to that previously observed for

{\mathrm{Gd}}^{3+}

{\mathrm{LaF}}_{3}

and

{\mathrm{Eu}}^{2+}

{\mathrm{CaF}}_{2}

and which requires higher-order perturbation theory in the virtual intermediate 4${f}^{6}$5d configuration.