Chinese Journal of Magnetic Resonance ›› 2015, Vol. 32 ›› Issue (2): 363-372.doi: 10.11938/cjmr20150218

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Sensitivity Enhancement of Multiple Quantum and Satellite Transition Magic Angle Spinning Spectra by Optimizing the Initial State

CHENG Ren-hao,WU Zhen,HUANG Po-chi,KE Chi-cheng,DING Shang-wu*   

  1. Department of Chemistry and Center for Nanoscience and Nanotechnology, Sun Yat-sen University of Taiwan, Kaohsiung 80424, China
  • Received:2015-03-23 Revised:2015-05-12 Online:2015-06-05 Published:2015-06-05
  • About author:CHENG Ren-hao(1987-), born in Taichung Taiwan, PhD. student, with research interest in applying solid state NMR spectroscopy and micro-imaging to study polymer materials. *Corresponding author: DING Shang-wu, Tel: +886-7-5253917, E-mail: ding@mail.nsysu.edu.tw.
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Abstract:

A method to significantly enhance the sensitivity of the widely used multiple quantum magic angle spinning (MQMAS), satellite transition magic angle spinning (STMAS) and their variants is proposed. By introducing a preparatory period prior to the normal multiple quantum excitation or satellite transition pulse, the initial state can be optimized so that the recycle delay time can be substantially reduced. The performance of this method, for both MQMAS and
STMAS in two different magnetic fields, has been demonstrated with a number of representative nuclear species (23Na, 11B and 87Rb). This method can be implemented, without any additional hardware or software accessories, on all conventional solid-state NMR spectrometers with operating magnetic field as low as 4.7 T and sample spinning speed as slow as 6 kHz. Moreover, it is a very flexible method so that it can be customized, i.e., for individual compounds, the experimental parameters can be optimized for each compound following a step-by-step procedure specified in this work although a full theoretical exposition will be provided separately.

Key words: solid-state NMR, quadrupolar nuclei, MQMAS, STMAS, pulse optimization

CLC Number: