Nuclear Quadrupole Coupling in Polar Molecules

The quadrupole moment induced in various ions by the nuclear electric quadrupole moment $Q$ has been recalculated to higher accuracy than in a previous paper. Values are presented for the ratio ${\gamma }_{\infty }$ of the induced moment to $Q$ for the ${\mathrm{Na}}^{+}$, ${\mathrm{Cl}}^{-}$, ${\mathrm{Cu}}^{+}$, ${\mathrm{Rb}}^{+}$, and ${\mathrm{Cs}}^{+}$ ions. These values of ${\gamma }_{\infty }$ enter into the quadrupole coupling of polar molecules, which is given by $q\cong \frac{2e(1+|\mathrm{}{\gamma }_{\infty }\mathrm{}\left|\right)\mathrm{}}{R^3}$ ($R=\mathrm{internuclear}\mathrm{distance}$) provided that the exchange repulsion of the ions can be neglected. The calculated values of ${\gamma }_{\infty }$ are of order 10-100, in agreement with experimental evidence from the measured values of $q$ for several polar molecules.