Nuclear Double Resonance Study of Na First-Order Quadrupole Splittings in a NaF-LiF Mixed Crystal

Abstract

A nuclear magnetic double resonance experiment has been performed to measure the high-field first-order quadrupole splittings of ${\mathrm{Na}}^{23}$ nuclei located in the vicinity of ${\mathrm{Li}}^{+}$ substitutional impurities in a single crystal of NaF. The observed quadrupole-shifted frequency of those ${\mathrm{Na}}^{23}$ nuclei located at (1,0,1)-type sites [relative to the ${\mathrm{Li}}^{+}$ impurity at the (0,0,0) lattice site] was $\frac{{e}^{2}\mathrm{qQ}}{h}=\ifmmode\pm\else\textpm\fi{}(544\ifmmode\pm\else\textpm\fi{}10)$ kHz with an asymmetry parameter $\ensuremath{\eta}=0.65\ifmmode\pm\else\textpm\fi{}0.05$. For those ${\mathrm{Na}}^{23}$ nuclei at (0,0,2)-type sites, $\frac{{e}^{2}\mathrm{qQ}}{h}=\ifmmode\pm\else\textpm\fi{}(856\ifmmode\pm\else\textpm\fi{}10)$ kHz with $\ensuremath{\eta}=0$. The values of $\mathrm{eq}$ and $\ensuremath{\eta}$ thus obtained are compared with theoretical calculations. A mathematical analysis of the high-field double resonance process as it applies to rare, quadrupole-interacting nuclei is also presented.