Parametric analysis of the energy levels of Nd3+ in frozen dilute aqueous solutions of neodymium chloride

A parametric analysis of the Stark-split spectra of Nd³⁺ in frozen dilute aqueous solutions of neodymium chloride has been carried out.The similarity of the spectra of Nd³⁺ in frozen dilute solutions and in crystals, where the ion is nine-fold coordinated and of approximate D_3h symmetry (Nd³⁺: LaCl₃, neodymium ethylsulfate and bromate), was used to obtain initial parameter values. Simultaneous diagonalization of the free ion and crystal field hamiltonians resulted in a r.m.s. deviation σ of 11 cm^?1 for 50 levels. The resulting crystal field parameters are B²₀ = 278 ± 19, B⁴₀ = ?201 ± 39, B^b₀ = ?946 ± 55 and B⁶₆ = 663 ± 43 cm^?1. Selection rules for D_3h are approximately obeyed. The small value of σ, the number of levels accounted for and the fact that the final parameters are not very different from those in the crystals indicate a nine-fold coordination of approximate D_3h symmetry for Nd³⁺ in frozen aqueous solutions. The spectra of liquid solutions show by their similarity to the spectra of frozen solutions that the same surroundings exist in the liquid.