Ashbrook, S. E. and Wimperis, S. (2005) Rotor-synchronized acquisition of quadrupolar satellite-transition NMR spectra: practical aspects and double-quantum filtration. Journal of Magnetic Resonance, 177 (1). pp. 44-55. DOI https://doi.org/10.1016/j.jmr.2005.06.013
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Abstract
The very broad resonances of quadrupolar (spin I > 1/2) nuclei are resolved by magic angle spinning (MAS) into a large number of spinning sidebands, each of which often remains anisotropically broadened. The quadrupolar interaction can be removed to a first-order approximation if the MAS NMR spectrum is acquired in a rotor-synchronized fashion, aliasing the spinning sidebands onto a centreband and thereby increasing the signal-to-noise ratio in the resulting, possibly second-order broadened, spectrum. We discuss the practical aspects of this rotor-synchronization in the direct (t2) time domain, demonstrating that the audiofrequency filters in the receiver section of the spectrometer have a significant impact on the precise timings needed in the experiment. We also introduce a novel double-quantum filtered rotor-synchronized experiment for half-integer spin quadrupolar (spin I = 3/2, 5/2, etc.) nuclei that makes use of central-transition-selective inversion pulses to both excite and reconvert double-quantum coherences and yields a simplified spectrum containing only the ST1 (mI = ± 1/2 ↔ ± 3/2) satellite-transition lineshapes. For spin I = 5/2 nuclei, such as 17O and 27Al, this spectrum may exhibit a significant resolution increase over the conventional central-transition spectrum.
Item Type: | Article |
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Uncontrolled Keywords: | 2005 AREP 2005 P IA49 |
Subjects: | 03 - Mineral Sciences |
Divisions: | 03 - Mineral Sciences |
Journal or Publication Title: | Journal of Magnetic Resonance |
Volume: | 177 |
Page Range: | pp. 44-55 |
Identification Number: | https://doi.org/10.1016/j.jmr.2005.06.013 |
Depositing User: | Sarah Humbert |
Date Deposited: | 06 Sep 2011 14:58 |
Last Modified: | 23 Jul 2013 09:58 |
URI: | http://eprints.esc.cam.ac.uk/id/eprint/1573 |
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