Preprints
https://doi.org/10.5194/mr-2021-39
https://doi.org/10.5194/mr-2021-39

  08 Apr 2021

08 Apr 2021

Review status: this preprint is currently under review for the journal MR.

Efficient polynomial analysis of MAS spinning sidebands and application to order parameter determination in anisotropic samples

Günter Hempel1, Paul Sotta2, Didier R. Long3, and Kay Saalwächter1 Günter Hempel et al.
  • 1Martin-Luther-Universität Halle-Wittenberg, Institut für Physik – NMR, Betty-Heimann-Str. 7, 06120 Halle, Germany
  • 2Ingénierie des Matériaux Polymères, INSA Lyon/CNRS UMR 5223, 17 avenue Jean Capelle, 69621 Villeurbanne cedex, France
  • 3Université Lyon, INSA Lyon/CNRS, UCBL, MATEIS, UMR5510, 69100 Villeurbanne, France

Abstract. Chemical shift tensors in 13C solid-state NMR provide valuable localized information on the chemical bonding environment in organic matter, and deviations from isotropic static-limit powder lineshapes sensitively encode dynamic-averaging or orientation effects. Studies in 13C natural abundance require magic-angle spinning (MAS), where the analysis must thus focus on spinning sidebands. We propose an alternative fitting procedure for spinning sidebands based upon a polynomial expansion that is more efficient 5 than the common numerical solution of the powder average. The approach plays out its advantages in the determination of CST principal values from spinning-sideband intensities and order parameters in non-isotropic samples, which is here illustrated on the example of stretched glassy polycarbonate.

Günter Hempel et al.

Status: open (until 29 May 2021)

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse
  • CC1: 'Comment on mr-2021-39 from the NMR Dept., Institute of Macromolecular Chemistry, Prague', Jiří Czernek, 09 Apr 2021 reply

Günter Hempel et al.

Günter Hempel et al.

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Short summary
We develop an exact analytical description of spinning sideband intensities in magic-angle spinning NMR, e.g. for 13C CSA. This can be used in spectral fitting to obtain tensor parameters, and plays out its advantage in the analysis of orientation effects in non-isotropic samples. We present an improved approach to process data obtained with the simple “syncMAS” experiment, which is powerful but not very popular due to the so far not very transparent and difficult data analysis.