Electric field gradients in ionic crystals III. nuclear quadrupole resonance in thorium tetrachloride

Abstract

Abstract The electric field gradient tensor at the chlorine site in a single crystal of thorium tetrachloride is estimated using the point charge model. This is used to calculate the resonance frequency, assuming the anti-shielding factor, and it is found that the calculated value is very much higher than the observed value. This is rather surprising in view of the highly ionic nature of the sample. These calculations indicate a large asymmetry parameter and the principal axes are found to be nearly the same as the crystalline axes. The effect of dipole polarization of the ions is taken into account in all these calculations, but the nature of the results remains unaffected. Finally, these calculations indicate a very small value for the anti-shielding factor.