Nuclear Quadrupole Interactions in Two Tutton's Salts

This paper reports results of nuclear induction experiments on two isomorphic single crystals of Tutton's salts, ${\mathrm{Rb}}_2$Mg${\left(\mathrm{S}{\mathrm{O}}_4\right)}_2$·6${\mathrm{H}}_2$O and ${\mathrm{Cs}}_2$Mg${\left(\mathrm{S}{\mathrm{O}}_4\right)}_2$·6${\mathrm{H}}_2$O, belonging to crystal class $\frac{P{2}_1}{a}$. The splittings, due to nuclear electric quadrupole interactions, of the nuclear magnetic resonance spectra of ${\mathrm{Rb}}^{87}$ and ${\mathrm{Cs}}^{133}$ observed in these experiments are analyzed by using perturbation theory. Analysis of the data yields a quadrupole coupling constant for ${\mathrm{Rb}}^{87}$ of $\left|\frac{\mathrm{eQq}}{h}\right|=3141\mathrm{}\pm 35$ kc/sec, and the asymmetry of the field gradient at the nuclear site is $\eta =\frac{({\phi }_{\mathrm{xx}}-{\phi }_{\mathrm{yy}})}{{\phi }_{\mathrm{zz}}}=0.47\mathrm{}\pm 0.01$. The principal axis of the field gradient is directed toward the nearest sulfate ion but no correlation of asymmetry and near neighbor locations is observed.