Absorption spectra, energy levels, and crystal-field analysis of trivalent neodymium in the γ phase of neodymium sesquisulfide (γ-Nd2S3)

Abstract

We report absorption spectra of Nd³⁺ in the γ phase of Nd₂S₃. Energy levels of all manifolds from the ground state (⁴I_9/2) through ²H_11/2 (15 616 cm⁻¹) were determined from the spectra. A best least‐squares fit of the experimental levels was made with a crystal‐field Hamiltonian of S₄ symmetry, resulting in the following crystal‐field parameters B_km (in cm⁻¹): B₂₀=−209, B₄₀=402, B₄₄=1236, B₆₀=−774, RB₆₄=−423, and IB₆₄=103. The rms deviation between calculated and experimental levels is 8.7 cm⁻¹. A total of 50 levels was included in the fit (out of a possible 53 within the manifolds considered). The results are shown to be consistent with an effective point‐charge model for the γ‐Nd₂S₃ lattice in which Nd³⁺ vacancies are distributed randomly.