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Keywords:

  • NMR;
  • 7Li;
  • gelatin gel;
  • Markov chain Monte Carlo;
  • residual quadrupolar coupling;
  • stretched gel;
  • z-spectrum

ABSTRACT

7Li 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 7Li+ dissolved in 1H2O 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.