F-19 ENDOR MEASUREMENTS OF TRANSFERRED HYPERFINE INTERACTIONS IN CSCDF3-GD3+ AND CSCAF3-GD3+

The transferred hyperfine interaction parameters have been measured at 4. 2 K by ENDOR for five shells of **1**9F neighbors around Gd**3** plus in CsCdF//3:Gd and CsCaF//3:Gd. The parameters for the octahedrally coordinated ligands are rather different from those previously determined from the transferred hyperfine structure of EPR spectra at 300 K by Buzare and co-workers. Our own EPR measurements show that the separations of the transferred hyperfine-structure lines are rather smaller than those predicted using the ENDOR data. They are only just consistent for CsCdF//3, and they are slightly outside the estimated uncertainty of the EPR data for CsCaF//3. There is no evidence of temperature dependence of the separation of the transferred hyperfine-structure lines in the EPR spectrum. Local distortions are deduced from **1**9F second-shell parameters and these distortions and the ligand-shell parameters are compared with those for octahedrally coordinated **1**9F ligands in CaF//2 and CdF//2.