Crystal-Field Splitting of Ho3+ and Tm3+ J Levels in Hydrated Chloride Salts

Abstract

The crystal-field splitting of Ho3+ in HoCl3· 6H2O was calculated for the ground-state 5I8 and 10 excited J levels and compared to the observed splitting. In order to carry out the crystal-field splitting calculation, a systematic procedure was developed to obtain crystal-field parameters from a knowledge of the polarization of observed optical transitions. The crystal-field parameters for HoCl3· 6H2O resulting from a fit of 10 J levels with 84 Stark components are as follows: A20=108, A22=195, A2−2=−340, A40=−63, A42=−200, A4−2=275, A44=220, A4−4=220, A60=−4.5, A62=−117, A6−2=50, A64=240, A6−4=−80, A66=260, A6−6= −200. All parameters are in units of cm−1. By means of a least squares fit, the crystal-field parameters determined from an analysis of the holmium spectrum were used to determine the 15 crystal-field splitting parameters for Tm3+ in TmCl3· 6H2O. The crystal-field parameters for both crystals were found to agree in sign and to be close in magnitude. The calculated crystal-field splitting of J levels for both ions Ho3+ and Tm3+ agrees very well with the observed splitting. The calculated crystal-field wavefunctions for Tm3+ in TmCl3· 6 H2O were used to explain the magnetic properties of this particular salt.