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7 Li + NMR quadrupolar splitting in stretched hydrogels: developments in relaxation time estimation from z ‐spectra
Author(s) -
Puckeridge Max,
Chapman Bogdan E.,
Kuchel Philip W.
Publication year - 2012
Publication title -
magnetic resonance in chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.483
H-Index - 72
eISSN - 1097-458X
pISSN - 0749-1581
DOI - 10.1002/mrc.3841
Subject(s) - chemistry , spectral line , relaxation (psychology) , nmr spectra database , context (archaeology) , markov chain monte carlo , monte carlo method , statistical physics , asymmetry , analytical chemistry (journal) , nuclear magnetic resonance , physics , quantum mechanics , statistics , mathematics , psychology , social psychology , paleontology , biology , chromatography
7 Li NMR z ‐spectra were recorded from the cation constituted in gelatin gels that were held stretched. The system has been studied previously, but we revisited the disparity that was noted between estimates of some of the relaxation times of spin‐states of various ranks and orders made using a global data‐fitting strategy and estimates made from data acquired by using multiple‐quantum‐filter pulse sequences. The global data fitting was performed with a probability approach along with the Markov chain Monte Carlo (MCMC) method applied to z ‐spectra from 7 Li + dissolved in 1 H 2 O using more refined experimental methods than hitherto. We also present a more extensive explanation of the MCMC method as it applies in the present NMR context. We achieved much closer agreement between the estimates of relaxation times made by using the two methods of analysis and attribute the previous discrepancies to spectral drift and z ‐spectrum asymmetry. Copyright © 2012 John Wiley & Sons, Ltd.