ONE-DIMENSIONAL NOE EXPERIMENTS USING PULSED-FIELD GRADIENTS

Previously, it has been shown that the use of pulsed held gradients in one-dimensional NOE experiments results in spectra of much higher qua lity than it has previously been possible to record, Such high-quality spectra make it possible to measure, with complete confidence, very s mall NOE enhancements and also make it straight-forward to measure NOE buildup curves. In this paper, the spin dynamics behind these NOE exp eriments with gradients are analyzed in detail; the effects of strong coupling and molecular diffusion are also examined. It is also shown h ow the basic experiments can be improved upon, in particular how unwan ted antiphase contributions (SPT effects) can be eliminated entirely. Experimental illustrations of the various methods and improvements are given and practical recommendations made as to how the experiments ar e best performed. (C) 1997 Academic Press.