Determination of the Parameters of the Electric Field Gradient Tensor for Nuclei with Half Integral Spin from Zeeman-Split NQR Spectra

Abstract

A new method is proposed for determining the magnitude of the coupling constant, the asymmetry parameter and the orientation of the principal axes of the electric field gradient tensor at the site of a quadrupole nucleus with half integral spin. A function is constructed from the first order splitting of the nuclear quadrupole resonance absorption line produced by a small magnetic field. The parameters of the EFGT are determined from the behaviour of this function for rotation of the crystal around certain axes. A goniometer has been constructed for effecting these rotations and measurement have been made on a single crystal of Ba(ClO₃)₂, H₂O at the site of chlorine nuclei. It has been found that the chlorines in the unit lattice can be grouped in two sets with two different EFGT having the same value of eqQ=58.6873±.0001 MHz and η=0.027±.007 but different orientations of the principal axes.