Odedra, S. and Wimperis, S. (2012) Improved background suppression in 1H MAS NMR using composite pulses. Journal of Magnetic Resonance, 221, pp. 41-50. (doi: 10.1016/j.jmr.2012.05.010)
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Abstract
A well known feature of 1H MAS NMR spectroscopy, particularly of solids where the concentration of 1H nuclei is low, is the presence in the spectrum of a significant broad “background” signal arising from 1H nuclei that are outside the MAS rotor and radiofrequency coil, probably located on the surfaces of the static components of the probehead. A popular method of suppressing this unwanted signal is the “depth pulse” method, consisting of a 90° pulse followed by one or two 180° pulses that are phase cycled according to the “Exorcycle” scheme, which removes signal associated with imperfect 180° pulses. Consequently, only spins in the centre of the radiofrequency coil contribute to the 1H MAS spectrum, while those experiencing a low B1 field outside the coil are suppressed. Although very effective at removing background signal from the spectrum, one drawback with this approach is that significant loss of the desired signal from the sample also occurs. Here we investigate the 1H background suppression problem and, in particular, the use of novel antisymmetric passband composite pulses to replace the simple pulses in a depth pulse experiment. We show that it is possible to improve the intensity of the 1H signals of interest while still maintaining effective background suppression. We expect that these results will be relevant to 1H MAS NMR studies of, for example, nominally perdeuterated biological samples or nominally anhydrous inorganic materials.
| Item Type: | Articles |
|---|---|
| Status: | Published |
| Refereed: | Yes |
| Glasgow Author(s) Enlighten ID: | Odedra, Dr Smita and Wimperis, Professor Stephen |
| Authors: | Odedra, S., and Wimperis, S. |
| College/School: | College of Science and Engineering > School of Chemistry |
| Journal Name: | Journal of Magnetic Resonance |
| ISSN: | 1090-7807 |
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