Electron Spin Relaxation of Cu(II) Ions in ZnGeF₆·6H₂O Crystal with Strong Jahn-Teller Effect

Abstract

Cu2+ ions doped to ZnGeF6 · 6H2O substitute the host Zn 2+ ions and undergo a strong Jahn-Teller effect producing nearly axial elongation of the Cu(H 2 O) 6 octahedra with equal population of the three possible deformations at low temperatures as shown by the EPR spectra. Reorientations between these distorted configurations are observed as a continuous shift of EPR lines leading to averaging of the g-and A-tensors. The full averaging is observed at the phase transition temperature 200 K. Electron spin relaxation was measured up to 45 K only, where the electron spin echo signal was detectable. Electron spin-lattice relaxation is governed by the Raman two-phonon process allowing to determine the Debye temperature as Θ D = 99 K. There is no contribution of the Jahn-Teller dynamics to the spin-lattice relaxation rate. Electron spin echo decay is strongly modulated by dipolar coupling to the 1 H and 19 F nuclei. The phase memory time is governed by instantaneous diffusion at helium temperatures and then by spin-lattice relaxation processes and excitation to the first vibronic level of energy ∆ = 151 cm −1 .

Investigations on the local structure and the EPR parameters for the tetragonal Cu2+center in ZnSeF6·6H2O crystal

“…and MF 6 octahedra and its site symmetry is C 3i [1,2]. It is believed that the local crystal structure around an impurity in doped crystals may be unlike the corresponding structure in the host crystals.…”

Crystal Structure and EPR Investigation of Pyrazinamide Containing Copper (II) 2-Nitrobenzoate Single Crystal

“…It is used to raise the salicylate level in blood and is used in miticides, contrast media in urology, and in the manufacture of pharmaceuticals [3]. Electron paramagnetic resonance (EPR) technique is widely applied to transition ions, especially to Cu(II) ions, to identify the magnetic properties, local symmetry, and spin dynamics of the complexes [4][5][6].…”