Electric-Field Gradients in Liquids by Deuteron Quadrupole Relaxation

Abstract

The deuteron quadrupolar relaxation is studied for some liquids. As the spin—lattice quadrupole relaxation depends on the electric-field gradients (efg) at the nucleus the experimental values of T1 have been used in order to obtain the field gradients at the hydrogen site in the benzene and acetone molecules. For this purpose, the correlation times for the molecular motions responsible for the quadrupolar relaxation have been estimated from proton magnetic relaxation measurements in mixtures of the liquid with its perdeuterated analog. A theoretical evaluation of the efg tensor has also been performed by using MO's in the LCAO approximation with Slater's orthogonalized AO's. The agreement between the theoretical evaluation and the experimental results is more than satisfactory and it seems to confirm a certain validity of the wavefunctions and the method of calculation used. For chloroform a calculated efg tensor has been used to obtain a value for the reorientational correlation time from the deuteron spin—lattice relaxation time. This work shows the possibility of using proton and deuteron relaxation measurements to obtain reliable values for the quadrupole coupling constants in liquids.