Ground term energy states for Nd 3+ in LiYF 4

Abstract

Absorption spectra of Nd 3+ in single-crystal LiYF 4 have been measured at 25 and 85°K for the purpose of establishing the 4I 13 2 and 4I 15 2 ground-term energy levels. These energy levels and those published previously for the 4I 9 2 and 4I 11 2 multiplets were compared with theoretical energy levels where the Hamiltonian H = ∑ 3 n=1 λ n (L · S) n + ∑ km B + km C km was used in the calculations. An r.m.s. deviation of 3·87 cm −1 was obtained between calculated and experimental energy levels using the values, in cm −1, λ 1 = 294·78, λ 2 = −2·42, λ 3 = 0·04, B 20 = 480, B 40 = −973, B 60 = −60·6, B 44 = 1119, ReB 64 = 1051 and ImB 64 = 49. Comparisons of the spin-orbit parameters, the λ n , with earlier work concerning Nd 3+ in CaWO 4 suggests that the λ n adequately describe the splitting of the free ion energy levels. Therefore, these B km values might be expected to describe the effect of the crystal on the Nd 3+ free ion levels. In addition, calculated g factors for all the energy states of the ground term are given. The g ∥ and g ⊥ values for the ground state are within 2 per cent agreement with the experimentally determined values of g ∥ = 1·987 ± 2 and g ⊥ = 2·55 ± 3.