A P-SPIN HIGH-PASS FILTER USING RADIOFREQUENCY FIELD GRADIENTS FOR HOMONUCLEAR MAGNETIC-RESONANCE EXPERIMENTS

Traditional multiple-quantum filtering in nuclear magnetic resonance s pectroscopy relies on the acquisition of several transients along with appropriate phase cycling. It is shown that similar results can be ob tained in one transient by using a cluster of two radiofrequency field (B-1) gradient pulses (g(1))(x)(rg(1))(y) where g(1) and rg(1) denote the durations of the B-1 gradient pulses and the subscripts x and y t he transmitter phases. This filter acts on single-quantum antiphase co herences and is of high-pass nature. The choice of r determines the or der of the filter (according to the number of spins belonging to the s ystem considered). This property is demonstrated theoretically and ver ified experimentally by dedicated one-dimensional experiments and COSY -type two-dimensional experiments.