Multiple Quantum Magic-Angle Spinning (MQ-MAS)

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.

MQ-MAS Sequences

To determine when the MQ-MAS echo occurs in t2 consult the table below:

k values for MQ-MAS experiment
Spint1 transitionk
3/2 3QMAS7/9
5/2 3QMAS19/12
5QMAS25/12
7/2 3QMAS101/45
5QMAS11/9
7QMAS161/45
9/2 3QMAS91/36
5QMAS95/36
7QMAS7/18
9QMAS31/6

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.

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RAPT-enhanced RIACT MQ-MAS Experiment

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References and Related Resources from our Lab