ELECTRONIC SPECTRUM AND ENERGY LEVELS OF GD3+ IN LAF3

The optical-absorption and fluorescence spectra of Gd3+ in crystals of LaF3, pure GdF3, and mixed crystals of 50% CaF2: 50% GdF3 are given. Absorption has been observed in all the states of the P6, I6, and D6 multiplets, with the exception of D126 state. Fluorescence from the components of the P726 state has been observed. A least-squares fit of 14 barycenters, with the inclusion of configuration interactions, gave a mean error of 43 cm-1 between the calculated and experimental barycenters, with the parameter values F2=419.1 cm-1, F4=56.54 cm-1, F6=6.006 cm-1, ζ4f=1486 cm-1, and α=21.78 cm-1. With the inclusion of spin-other-orbit and spin-spin effects, the mean error was reduced to 32 cm-1. The intermediate-coupling free-ion calculation was carried out assuming nonhydrogenic ratios of the Slater parameters. © 1969 The American Physical Society.