Heteronuclear dipolar decoupling effects on multiple-quantum and satellite-transition magic-angle spinning NMR spectra
✍ Scribed by S. Ganapathy; L. Delevoye; J. P. Amoureux; P. K. Madhu
- Publisher
- John Wiley and Sons
- Year
- 2008
- Tongue
- English
- Weight
- 226 KB
- Volume
- 46
- Category
- Article
- ISSN
- 0749-1581
- DOI
- 10.1002/mrc.2286
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✦ Synopsis
Abstract
We here report on the influence of heteronuclear dipolar decoupling on the ^27^Al 3QMAS, 5QMAS, and the double‐quantum filter–satellite‐transition magic‐angle spinning (DQF‐STMAS) spectra of a strongly dipolar‐coupled system, gibbsite. The requirements for heteronuclear dipolar decoupling increase with the order of coherence evolving in the indirect dimension of a two‐dimensional (2D) experiment. The isotropic line width of the high‐resolution 2D spectra, in samples like gibbsite, is composed of four parts: the distribution of isotropic shifts (δ~ISO~, δ~QIS~), the homogeneous broadening related to the proton–proton flip‐flop terms, the ^27^Al^27^Al homonulcear dipolar couplings, and the ^1^H^27^Al heteronuclear dipolar couplings. It is shown that, even in the case of gibbsite, where a strong proton–proton bath exists, the main resolution limiting factor in these experiments resides in the ^1^H^27^Al dipolar interaction. Copyright © 2008 John Wiley & Sons, Ltd.