Suppressing magnetization exchange effects in stimulated-echo diffusion experiments
2013 (English)In: Journal of magnetic resonance (San Diego, Calif. 1997: Print), ISSN 1090-7807, E-ISSN 1096-0856, Vol. 234, 35-43 p.Article in journal (Refereed) Published
Exchange of nuclear magnetization between spin pools, either by chemical exchange or by cross-relaxation or both, has a significant influence on the signal attenuation in stimulated-echo-type pulsed field gradient experiments. Hence, in such cases the obtained molecular self-diffusion coefficients can carry a large systematic error. We propose a modified stimulated echo pulse sequence that contains T-2-filters during the z-magnetization store period. We demonstrate, using a common theoretical description for chemical exchange and cross-relaxation, that these filters suppress the effects of exchange on the diffusional decay in that frequent case where one of the participating spin pools is immobile and exhibits a short T-2. We demonstrate the performance of this experiment in an agarose/water gel. We posit that this new experiment has advantages over other approaches hitherto used, such as that consisting of measuring separately the magnetization exchange rate, if suitable by Goldman-Shen type experiments, and then correcting for exchange effects within the framework of a two-site exchange model. We also propose experiments based on selective decoupling and applicable in systems with no large T-2 difference between the different spin pools. (C) 2013 The Authors. Published by Elsevier Inc. All rights reserved.
Place, publisher, year, edition, pages
2013. Vol. 234, 35-43 p.
Agarose, Water, Chemical exchange, Cross-relaxation, Diffusion measurements, Pulsed-field-gradient stimulated-echo NMR, PGSTE NMR, T-2 filter
Engineering and Technology
IdentifiersURN: urn:nbn:se:kth:diva-127741DOI: 10.1016/j.jmr.2013.06.001ISI: 000323085800005ScopusID: 2-s2.0-84880182663OAI: oai:DiVA.org:kth-127741DiVA: diva2:646149
FunderKnut and Alice Wallenberg FoundationSwedish Research Council
QC 201406162013-09-062013-09-052014-06-16Bibliographically approved