ON THE USE OF PULSED-FIELD GRADIENTS IN A HIGH-FIELD NMR SPECTROMETERTO STUDY RESTRICTED DIFFUSION IN ZEOLITES

A probe system is described which allows the application of magnetic f ield gradient pulses with amplitudes up to 24 T/m for self-diffusion m easurements by means of a PFG NMR spectrometer operating at a proton r esonance frequency of 400 MHz. It is demonstrated that PFG NMR measure ments in the high field of a superconducting magnet necessitate precau tions which are of minor relevance for measurements with iron magnets. Taking advantage of the large gradient intensity and the high sensiti vity in signal detection of the described system, attenuation patterns of the NMR spin echo are observed for the first time that represent t he PFG NMR analogue of the diffraction pattern of a sphere.