Analysis of the Spectrum of the Nd+++ Ion in the Bromate Crystal

Abstract

The absorption spectrum of single crystals of Nd(BrO₃)₃·9H₂O was photographed in the visible and near infrared and ultraviolet in σ and π polarizations. Empirical energy level diagrams are presented for some of the groups of lines, and in this way it is found that the ⁴I_9/2 ground state is split in the electric field into five levels at 0, 115, 184, 363, and 382 cm⁻¹. An analysis is made of the spectrum based on a Russell‐Saunders coupling model and a knowledge of the expected splitting of the levels of the free Nd⁺⁺⁺ ion in the electric field of the crystal. The electrostatic interaction energies of terms arising from f³ electrons were computed by the Slater method and the results agree with those previously given by Racah. The Landé interval factors were also computed in order to predict the multiplet splitting. Trial values of the parameters were first found by extrapolation mainly from Pr⁺⁺⁺. Selection rules for transitions in an electric field of C_3v symmetry are presented, and the results applied to the neodymium bromate spectrum indicate that the transitions are not purely electric dipole, quadrupole, or magnetic dipole alone.