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

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