MULTIPLE-QUANTUM FILTERS OF SPIN-3 2 WITH PULSES OF ARBITRARY FLIP ANGLE/

The influence of inhomogeneous RF fields on the double- and triple-qua ntum filtering of spin-3/2 nuclei in the presence of biexponential rel axation is analyzed. In this analysis, spherical tenser operators have been used for density-matrix calculations. In the presence of inhomog eneous RF fields, it is shown that the three pulse triple-quantum filt er (TQF) without a refocusing 2 theta pulse (with Delta omega = 0) is on average about 100% more sensitive than the corresponding double-qua ntum filter (DQF), and in the case of four-pulse DQF and TQF with a re focusing 2 theta pulse (with Delta omega not equal 0), two relaxation coefficients f(11)((1))(tau) and f(33)((1))(tau) also contribute to th e observed DQ and TQ coherences. It is also shown that the three-pulse filters are more sensitive than the corresponding four-pulse filters. In both three- and four-pulse cases, when used with surface coils, th ese filters act as depth pulses and thus yield spatial localization. T he experimental results obtained with homogeneous RF coils are in exce llent agreement with the theoretical results. (C) 1994 Academic Press, Inc.