HIGH MAGNETIC-FIELD GRADIENT PGSE NMR IN THE PRESENCE OF A LARGE POLARIZING FIELD

A description is given of pulsed gradient spin echo (PGSE) NMR experim ents in which large pulsed magnetic field gradients may be required. T he design contraints are discussed and, in particular, the problem of the use of large pulsed magnetic field gradients in conjunction with l arge polarizing fields is considered. Issues addressed concern probe m echanical assembly, current supply requirements, and pulse shape desig n. We describe a quadrupolar coil with a gradient amplitude of 1.65 T m(-1) A(-1) which has been used successfully up to a maximum gradient of around 40 T m(-1). A diffusion coefficent of 7.5 x 10(-16) m(2) s(- 1) has been measured using this system, the lowest yet achieved by PGS E NMR methods. (C) 1998 Academic Press.