Absorption, Fluorescence, and Energy Levels of Ho3+ in LaF3

Optical absorption and fluorescence spectra of Ho³⁺ in LaF₃ have been obtained between 2500 and 21 000 Å. From an analysis of the data, it was possible to assign $\text{2J\hspace{0.17em}+\hspace{0.17em}1}$ Stark components to the observed states below 26 000 cm⁻¹. A least‐squares fit of 22 assigned $J$ levels, with the inclusion of configuration interaction, gave a rms deviation of 29 cm⁻¹ between the calculated and experimental barycenters with the parameter values $F_2\text{\hspace{0.17em}=\hspace{0.17em}423.9}{\mathrm{cm}}^{\text{−1}}{\mathrm{,\; F}}_4\text{\hspace{0.17em}=\hspace{0.17em}63.37}{\mathrm{cm}}^{\text{−1}}{\mathrm{,\; F}}_6\text{\hspace{0.17em}=\hspace{0.17em}6.817}{\mathrm{cm}}^{\text{−1}}{\mathrm{,\; \zeta }}_{\text{4f}}\text{\hspace{0.17em}=\hspace{0.17em}2144}{\mathrm{cm}}^{\text{−1}}\text{, α\hspace{0.17em}=\hspace{0.17em}20.34}{\mathrm{cm}}^{\text{−1}}\text{, β\hspace{0.17em}=\hspace{0.17em}−\hspace{0.17em}578.5}{\mathrm{cm}}^{\text{−1}},\mathrm{and}\text{γ\hspace{0.17em}=\hspace{0.17em}1267}{\mathrm{cm}}^{\text{−1}}$ . The observed line groups above 30 000 cm⁻¹ agree with the calculated free‐ion levels.