Energy Levels of Pr+3 in Pr(NO3)3·6H2O

Abstract

The energy levels of Pr+3 in Pr(NO3)3·6H2O have been determined from optical absorption experiments on single crystals at 77°K. With the exception of three bands, all of the electronic intra-f1 transitions from the ground state multiplet to higher multiplets were observed. The absorption spectrum along with the determined Stark level schemes of the multiplets and their centers of gravity are reported. An expanded “free-ion” Hamiltonian which includes configuration interactions along with spin–other-orbit and spin–spin interactions was used in the analysis of the multiplet centers of gravity. In a least-squares fit calculation the best-fit free-ion parameters found were F2 = 315.44 cm−1, F4 = 51.17 cm−1, F6 = 5.19 cm−1, ζ4f = 741.12 cm−1, α = 18.76 cm−1, β = −756.77 cm−1, γ = 88.05 cm−1, M0 = 0.43 cm−1. The average deviation between the calculated best fit and the experimental “free-ion” energy levels is 27 cm−1. A first-order perturbation calculation was carried out for the Stark levels of the various observed multiplets of the Pr+3(4f2) ion in a crystal field of C1 symmetry. Because of the large number of crystal field parameters involved in the potential, only a tentative set of best-fit B kq parameters were determined from a least-squares calculation.