NMR MEASUREMENT OF SPIN-3 2 TRANSVERSE RELAXATION IN AN INHOMOGENEOUS-B(1) FIELD/

Biexponential transverse relaxation of spin-3/2 nuclei is routinely me asured using either a spin echo or a multiple-quantum filtration NMR e xperiment. If the flip angle of the refocusing pulse used in these exp eriments deviates from 180-degrees then the measured relaxation appear s to be triexponential, with the relative amplitudes of the three comp onents showing a strong flip angle dependence. This has important impl ications for relaxation measurements where, as a result of inhomogenei ty of the B1 radiofrequency field, there is a distribution of flip ang les across the sample. A new experiment is demonstrated in which the m easured spin-3/2 transverse relaxation also appears to be triexponenti al but where the relative amplitudes of the three components are indep endent of flip angle.