Preliminary nuclear magnetic resonance studies of the use of stray magnetic fields to increase the rate of polarization of dipolar nuclei

Abstract

For nuclear magnetic resonance(NMR) studies of slowly relaxing dipolar nuclei, a method is proposed to achieve a reduction in the nuclear polarization times. The method relies on the magnetic field dependence of the spin-lattice relaxation times for dipolar nuclei. For different polarizing fields the magnetization relaxation characteristics differ. By using progressively increasing magnetic fields, but lower than that used for analytical purposes, it is possible to transfer from one relaxation pathway to another in order to achieve the optimum rate of polarization. The principles of the proposed method are shown to be borne out by 13 C studies of diamonds.