RELAXATION OF AN AX(2) NUCLEAR-SPIN SYSTEM - AMPLITUDE-MODULATED PULSES FOR EXCITATION OF LONGITUDINAL MULTISPIN ORDERED STATES

The P-31 and H-1 nuclear magnetic resonance (NMR) longitudinal relaxat ion behavior of the hypophosphite ion (H2PO2)(theta) is investigated i n D2O solution at various temperatures and two magnetic field strength s. Among a number of different well known methods of preparing the mag netization, a new simple procedure is described. This technique allows the excitation of exclusive longitudinal two- or three-spin order by taking advantage of amplitude modulated pulses. By using the semiclass ical Redfield approach and transformation into a normal mode basis, th e experimental data are interpreted in terms of an axially symmetric p hosphorus chemical shift anisotropy (CSA) tenser and anisotropic rotat ional diffusion.