The Interaction of Nuclear Electric Quadrupole Moments with Molecular Rotation in Asymmetric-Top Molecules. I

Abstract

The theory of the interaction of nuclear electric quadrupole moments with molecular rotation is extended to asymmetric-top molecules containing one or two quadrupolar nuclei. The first-order theory is developed in detail, and in a form which makes use of published numerical tables of line strengths of asymmetric-top pure rotation transitions, and involves the second derivatives of the electrostatic potential $V$ taken along the three principal axes of inertia. Only two of these are independent, and ($\frac{{\partial }^{2}V}{\partial z^{\prime 2}}$) and $\left(\frac{{\partial }^{2}V}{\partial x^{\prime 2}}\right)-\left(\frac{{\partial }^{2}V}{\partial y^{\prime 2}}\right)$ are a convenient choice of the parameters of the problem. A general formulation of the theory, which includes higher order effects, is given. In case a molecule contains only one quadrupolar nucleus, the structure of the quadrupole multiplets should be sufficient to identify pure rotation transitions.