Suppression of the defect contribution to nuclear spin-lattice relaxation by long rf magnetic pulses for the particular case of 23NaCl

Abstract

The recovery of 23Na nuclear magnetization after inversion was observed in a nominally pure sodium chloride single crystal using a Bruker AVANCE 400 spectrometer at room temperature after application of additional pulses of resonance magnetic field. The relaxation rate did not depend on the additional field intensity in the first stage of recovery for negative magnetization while in the range of positive magnetization the recovery slowed down remarkably with increasing the additional field strength. The findings are treated as a result of cutting off the contribution of point defects and nuclear spin diffusion to spin-lattice relaxation of the sodium nuclei. Keywords: Solid state NMR, Spin-lattice relaxation, Nuclear spin diffusion