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

doi:10.11938/cjmr20150218

Abstract

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:

O482.53

CHENG Ren-hao, WU Zhen, HUANG Po-chi, KE Chi-cheng, DING Shang-wu. Sensitivity Enhancement of Multiple Quantum and Satellite Transition Magic Angle Spinning Spectra by Optimizing the Initial State[J]. Chinese Journal of Magnetic Resonance, 2015, 32(2): 363-372.

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