Multiple Quantum Magic-Angle Spinning (MQ-MAS) is a solid-state NMR method for obtaining a high resolution spectrum of half-integer spin quadrupolar nuclei. It was invented by Professor Lucio Frydman and coworkers. It is performed as a two-dimensional NMR experiment, and correlates a high resolution (isotropic) spectrum to the anisotropic central transition MAS spectrum. Below are the two most basic MQ-MAS sequences.
To determine when the MQ-MAS echo occurs in t2 consult the table below:
| Spin | t1 transition | k |
|---|---|---|
| 3/2 | 3QMAS | 7/9 |
| 5/2 | 3QMAS | 19/12 |
| 5QMAS | 25/12 | |
| 7/2 | 3QMAS | 101/45 |
| 5QMAS | 11/9 | |
| 7QMAS | 161/45 | |
| 9/2 | 3QMAS | 91/36 |
| 5QMAS | 95/36 | |
| 7QMAS | 7/18 | |
| 9QMAS | 31/6 |
For additional implementation details (phase cycling and data processing), please see the references below, particularly, Massiot et al. Solid-State NMR, 6, 73 (1996).
FASTER (FAst Spinning gives Transfer Enhancement at Rotary resonance) MQ-MAS exploits rotary resonance conditions for exciting multiple quantum coherences of quadrupolar nuclei under fast sample rotation.
RAPT-enhanced RIACT MQ-MAS Experiment
References and Related Resources from our Lab
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027 - Solid-State NMR, 6, 73 (1996),
Two-dimensional Magic-Angle Spinning Isotropic Reconstruction Sequences for Quadrupolar Nuclei
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D. Massiot, B. Touzo, D. Trumeau, J. P. Coutures, J. Virlet, P. Florian and P. J. Grandinetti - Our Shifted Echo MQ-MAS Sequence for Bruker
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038 - J. Chem. Phys. , 114, 4618-4624 (2001)
Multiple Quantum Magic-Angle Spinning using Rotary Resonance Excitation,
T. Vosegaard, P. Florian, D. Massiot, and P. J. Grandinetti -
041 - Chem.Phys.Lett., 352, 252-261 (2002)
Rotary Resonance in Multiple-Quantum Magic-Angle Spinning
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Z. Gan and P. J. Grandinetti -
039 - J. Magn. Reson., 150, 1-80 (2001),
Enhanced Sensitivity in RIACT/MQ-MAS NMR Experiments Using RAPT
H.-T. Kwak, S. Prasad, Z. Yao, P. J. Grandinetti, J. R. Sachleben, and L. Emsley - RAPT-RIACT Bruker Sequence