Nuclear magnetic resonance of63Cu in dimeric cupric ions of copper acetate monohydrate

Abstract

⁶³Cu N.M.R. transitions of divalent copper ions have been detected for the first time in Zeeman perturbed quadrupole levels in the exchange coupled pair of copper acetate monohydrate at the temperatures 20 to 60 K. The electric quadrupole coupling tensor at the Cu nuclear site at 20 K was determined to be e ² Qq = 117 ± 2 MHz and η = 2·8 ± 0·1 per cent from the anisotropy of resonance frequency by means of third-order approximation in Zeeman interaction. The temperature dependence of the spin-lattice relaxation rate along the x-axis is proportional to the triplet spin population, which is compatible with the model that the relaxation is brought about by the fluctuation of hyperfine coupling via triplet spins. The second-order perturbation of the static part of the hyperfine coupling results in indirect nuclear spin coupling in the exchange coupled pair. Splitting into quartet with equal spacing of 9·6 gauss due to the I-I coupling was observed along the z-axis.