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Single- and multiple-quantum cross-polarization in NMR of quadrupolar nuclei in static samples

 

作者: SHARONE. ASHBROOK,   STEPHEN WIMPERIS,  

 

期刊: Molecular Physics  (Taylor Available online 2000)
卷期: Volume 98, issue 1  

页码: 1-26

 

ISSN:0026-8976

 

年代: 2000

 

DOI:10.1080/00268970009483265

 

出版商: Taylor & Francis Group

 

数据来源: Taylor

 

摘要:

Cross-polarization from a spinI=1/2 nucleus (e.g.,1H) to a spinS= 3/2 nucleus (e.g.,23Na) or a spinS= 5/2 nucleus (e.g.,27A1 ornO) in static powder samples is investigated. The results of conventional (single-quantum), three-quantum, and five-quantum cross-polarization experiments are presented and discussed. Based on a generalization of an existing theory of cross-polarization to quadrupolar nuclei, computer simulations are used to model the intensity and lineshape variations observed in cross-polarized NMR spectra as a function of the radio-frequency field strengths of the two simultaneous spin-locking pulses. These intensity and lineshape variations can also be understood in terms of the spin S = 3/2 or 5/2 nutation rates determined from experimental quadrupolar nutation spectra. The results of this study are intended as a preliminary step towards understanding single- and multiple-quantum cross-polarization to quadrupolar nuclei under MAS conditions and the application of these techniques to the MQMAS NMR experiment.

 

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