ESR of V 3+ in [C(NH 2) 3]V(SO 4) 2 · 6H 2O

Abstract

Electron paramagnetic resonance spectra of V 3+ions in the concentrated salt guanidinium vanadium sulfate hexahydrate (GVSH) and diluted in the isomorphous diamagnetic host guanidinium aluminum sulfate hexahydrate (GASH) have been measured at 21.5 GHz and 4.2 K. The spectra are well-described by a spin Hamiltonian for S = 1 having axial symmetry about the crystalline C 3 axis and a singlet ground state. Small rhombic distortions permit observation of forbidden transitions. For GVSH the measured parameters are g =2.00 ± 0.01, g = 1.91 ± 0.01, D = 3.85 ± 0.01 cm -1. Spectra from the dilute salt exhibit hyperfine splitting from the I = 7 2 51V nucleus with A = (1.01 ± 0.02) × 10 -2 cm -1 and B = (0.72 ± 0.05) × 10 -2 cm -1. Several features of the dilute spectra are not clearly understood, and attempts to observe spectra from interacting pairs of V 3+ ions were inconclusive.