MQ-PGSTE: a new multi-quantum STE-based PGSE NMR sequence.

A new multi-quantum stimulated echo based pulsed gradient spin-echo sequence, MQ-PGSTE, has been developed for measuring translational diffusion. The new sequence provides a higher signal-to-noise ratio than the (Hahn spin-echo based) MAXY-D sequence at long diffusion times, and thus potentially affords better diffusion measurements on macromolecule samples. Based on multi-quantum coherence encoding, the MQ-PGSTE sequence needs considerably lower gradient strengths for diffusion characterization compared to standard single quantum pulsed gradient spin-echo sequences. By using the new sequence, the diffusion coefficient of l-[3-(13)C]-alanine was found to be 8.1+/-0.1 x 10(-10)m(2)s(-1), which is in line with the value obtained by the use of the standard stimulated echo based pulsed gradient spin-echo sequence.