Nuclear Quadrupole Interactions in Alkali-Halide Solid Solutions

Abstract

Nuclear quadrupole interactions in dilute alkali halide solid solutions are studied in detail using the results of the calculations in the preceding paper of the relaxation and electronic polarization of ions around the solute ion. It is shown that the available experimental data on first- and second-order effects on nuclear magnetic resonance spectra in the solid solutions NaCl-Br, NaBr-Cl, and KBr-Na can be explained quite well using calculated values of antishielding factors for the ${\mathrm{Na}}^{+}$ and ${\mathrm{Br}}^{-}$ ions. The electronic polarization of the ions is found to be an important contributor to the field gradients at the nuclei, the results being rather sensitive to the choice of polarizabilities for the ions. Better agreement with experiment is obtained when Sternheimer's calculated values of the polarizabilities are used rather than Tessman, Kahn, and Shockley's empirical values. For a nucleus which is quite distant from the solute ion, the ions nearest to the nucleus are seen to be more effective contributors to the field gradient at the nucleus than the ions near the impurity.