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 ($\frac{{\ensuremath{\partial}}^{2}V}{\ensuremath{\partial}{z}^{\ensuremath{'}2}}$) and $(\frac{{\ensuremath{\partial}}^{2}V}{\ensuremath{\partial}{x}^{\ensuremath{'}2}})\ensuremath{-}(\frac{{\ensuremath{\partial}}^{2}V}{\ensuremath{\partial}{y}^{\ensuremath{'}2}})$ 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.