Crystal spectrum of promethium 3 + in LaCl3

The absorption spectrum of Pm³⁺ in LaCl₃ was measured between 12 000 and 28 000 cm⁻¹ for both sigma and pi polizations. Free ion crystal field energy level calculations were made and the line groups ⁵F₁, ⁵F₂, ⁵F₃, ⁵S₂, ⁵F₄, ⁵F₅, ³K₆, ⁵G₃, and ⁵G₂ identified. Crystal field parameters were determined from the energy splittings in the first four line groups. Their values are $B_0^2\text{=145\hspace{0.17em}}{\mathrm{cm}}^{\text{−1}}$ , $B_0^4\text{=−320\hspace{0.17em}}{\mathrm{cm}}^{\text{−1}}$ , $B_0^6\text{=−650\hspace{0.17em}}{\mathrm{cm}}^{\text{−1}}$ , and $B_6^6\text{=450\hspace{0.17em}}{\mathrm{cm}}^{\text{−1}}$ . For these groups the exact free ion energy levels were calculated and the free ion parameters determined. Their values are F₂ = 412.5 cm⁻¹, F₆ = 7.6 cm⁻¹, and ζ = 977 cm⁻¹.