In applications to systems with resolved scalar couplings, the 2-dimensional exchange expt. (NOESY: nuclear Overhauser effect spectroscopy) can provide greatly increased information if the flip angles of the 2 pulses that precede and follow the mixing interval tm are reduced (typically b ~ 20 Deg). The anal. of the amplitudes of individual signals within diagonal- and cross-peak multiplets allows one to gain insight into a variety of competing longitudinal relaxation mechanisms, not only for the fast- and slow-motion limits but also, in favorable cases, for crit. correlation times. [on SciFinder (R)]