Rotor-synchronized acquisition of quadrupolar satellite-transition NMR spectra: practical aspects and double-quantum filtration

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 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
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: 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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