Energy Levels and Crystal Field of LaCl3:Gd3+

Abstract
The optical‐absorption spectra of Gd3+ in single crystals of 2% and 5% GdCl3 in LaCl3 at 1.7° and 77°K are given. The 8S7/2 ground state has no resolved structure in the field‐free spectra. Absorption to all Stark components of the 6P and 6I multiplets are observed, as well as for the higher 6D7/2 and 6D9/2 levels. Fluorescence from 6P7/2 and 6I7/2 is observed. A crystal‐field analysis gives values of B20=97.4 cm−1, B40=−42 cm−1, B60=−30 cm−1, B66=290 cm−1 for the crystal‐field parameters, based on intermediate coupling free‐ion calculations for the 6P and 6D multiplets. Hydrogenic ratios of the Slater parameters were assumed.