NMR lineshape calculations of the doublet splitting for a distribution of correlation times

Abstract

The NMR lineshape for a distribution of correlation times has been calculated by a random walk model using the local frequency approximation for isotopic reorientation and 3cos 2θ−1 angular dependence. It has been found that the sharp cutoff approximation used earlier is well justified for a width parameter β ⩾ 2 for a distribution of correlation times. There are two distinct maxima in the resulting derivative spectra. In the center of the transition the width of the narrow central line is about 25% of the static splitting nearly independent of β. Within the transition range the apparent activation energy of the narrow line is 21% (β=5) to 42% (β=3) of that of the jump process.