Line Strengths for ${\mathrm{Gd}}^{3+}$ at a $C_{4v}$ Site in Sr${\mathrm{F}}_2$

Oscillator strengths of the transitions from ${}_{}{}^8{}_{}{}^{}S_{\frac{7}{2}}^{}{}_{}{}^{}$ to some of the ${}_{}{}^6{}_{}{}^{}P$, ${}_{}{}^6{}_{}{}^{}I$, and ${}_{}{}^6{}_{}{}^{}D$ multiplets at a $C_{4v}$ symmetry site in Sr${\mathrm{F}}_2$: ${\mathrm{Gd}}^{3+}$ have been measured experimentally and compared with calculations using the Ofelt-Judd theory. Calculations using crystal-field wave functions for the ${}_{}{}^6{}_{}{}^{}P_{\frac{7}{2}}^{}{}_{}{}^{}$ and ${}_{}{}^6{}_{}{}^{}P_{\frac{5}{2}}^{}{}_{}{}^{}$ spectra showed that $J$ mixing is negligible and, in agreement with Zeeman measurements, the transitions are predominantly magnetic dipole. The ${}_{}{}^6{}_{}{}^{}I$ transitions are predominantly electric dipole and the intensities are in good agreement with theory. The line-strength parameters $T_{\lambda }$ are 3.4 ± 0.1, 1.05 ± 1.05, and 12.2 ± 0.05 cm × ${10}^{10}$ for $\lambda =2,4\mathrm{}$, and 6, respectively.