SELF-DIFFUSION COEFFICIENTS IN PLASTIC CRYSTALS BY MULTIPLE-PULSE NMRIN LARGE STATIC-FIELD GRADIENTS

Measurements of self-diffusion coefficients in solids with the gradien t spin echo technique have until now been limited due to short spin-sp in relaxation times. Here we make use of multiple-pulse sequences, whi ch average out the nuclear dipole interaction, to expand the measurabl e range for macroscopic self-diffusion coefficients by 2 orders of mag nitude. By combining multiple-pulse NMR, in our case using the MREV-8 sequence, with a high static gradient we measured the self-diffusion c oefficient in a molecular crystal of camphene down to a value of D = 3 x 10(-16) m(2) s(-1) at 219 K in the plastic phase.