Notes on the classical derivation of the nuclear quadrupole energy levels for half-integral spin systems

Abstract

The derivation of the energy levels for nuclear quadrupole (n.q.r.) spectra is critically examined. The interpretation of the experimental results in terms of parameters which characterize the two interacting systems, the nuclear charge and the electronic charges, is discussed, and found to be inaccurate. An accurate quadrupole moment which corresponds to that measured in other fields of research is larger than the one defined in n.q.r, and related to it by a function of spin I. This relationship is found using the transformation properties of the nuclear quadrupole tensor and referring it to the coordinate system of its own principal axis. The importance of this relationship in evaluating the properties of both the nucleus itself and the electron bonding in the molecule, described by the field gradient and its asymmetry, is discussed.