NMR diffusion measurements

This review focuses on the study of self-diffusion (intra-diffusion) by NMR, although NMR in the form of magnetic resonance imaging (MRI) can provide information on mutual-diffusion as described below. Hereinafter, however, the term 'diffusion' will signify self-diffusion. NMR provides two ways for studying diffusion and these are as follows: (i) measurement of spin relaxation; and (ii) the imposition of magnetic field gradients. Although this review is almost completely concerned with the field gradient approach, for completeness a brief description of the relaxation method for the study of self-diffusion and the use of MRI to study mutual diffusion will be given. The literature pertaining to NMR diffusion measurements is vast and growing exponentially with time. Consequently, the references provided in this chapter are a mixture of seminal accounts together with more recent works, which are both accessible and span the literature. Extensive coverage of the field is given in ref. 2 to 10.