GRADIENT-BASED SELECTIVE EXCITATION SCHEMES IN NMR

The behaviour of several recently proposed frequency-selective NMR exc itation methods was monitored using brucine as a test sample. For each method the results were compared in terms of selectivity, sensitivity , phase properties and J-coupling refocussing. Methods using pulsed fi eld gradients gave better overall results than shaped pulses alone. A slight modification of the WATERGATE method, incorporating the exclusi ve use of Gaussian pulses and the insertion of a final refocussing del ay, gave the most satisfactory results.