PULSED GRADIENT NMR PROBES FOR SOLID-STATE STUDIES

Recently introduced studies of the spatial characteristics of spin dyn amics in dipolarly coupled solids rely upon NMR probes with strong mag netic field gradients to create spatial magnetization gratings with pe riods of from 1 mu m to 1 nm. The measurements are carried out as scat tering experiments where the spatial displacement of spin coherence is recorded as a phase shift or attenuation of the magnetization grating . Recently we have employed these techniques to make a direct measurem ent of the spin diffusion rate in single crystal CaF2. Here we discuss designs for strong pulsed gradient NMR probes. Three gradient coil se ts were designed and constructed, with coil constants of 0.32, 0.67, a nd 4.15 T/m/A. When driven by a pulsed current source that provides up to 300 A, pulsed gradients of 100, 200, and 600 T/m, respectively, we re generated. These designs are fully described, along with practical issues of cell heating and probe stability. (C) 1998 Academic Press.