EPR STUDIES OF STRONG JAHN-TELLER COUPLING SYSTEMS CDCL2-AG2+ AND CDBR2-AG2+

The EPR spectra of Ag 2+ ions in CdCl2and CdBr2 are investigated in the temperature range from 4.2 K to 306 K. Low temperature spectra, exhibiting static tetragonal Jahn-Teller distortions, are observed below 77 K. The transition from the low temperature spectra to the motionally averaged high temperature ones is observed between 97 K and 170 K for CdCl 2: Ag 2+ and between 98 K and 213 K for CdBr2: Ag 2+. The transition temperature for CdCl2: Ag2+ depends on the orientation of the crystal and on the position of the super hyperfine line in question, which is explained by the motional averaging model. The anisotropy of the g-value of the low temperature spectrum of CdBr2: Ag 2+ is found to be extraordinarily small (g // =2.072, g ⊥ =2.067 at 77 K). The reasons for this small anisotropy of the g-value are discussed. © 1979, THE PHYSICAL SOCIETY OF JAPAN. All rights reserved.