Multiple - quantum magic - angle spinning NMR: a new technique for probing quadrupolar nuclei in solids

Multiple - Quantum Magic - Angle Spinning NMR: A New Technique for Probing Quadrupolar Nuclei in Solids

Recentemente descrevemos um nova técnica capaz de obter espectros de RMN de alta resolução de núcleos quadrupolares com spins múltiplos de 1/2 no estado sólido, baseada no uso combinado de rotação no ângulo mágico (MAS) e espectroscopia múltipla quântica (MQ). Esta revisão descreve aspectos da teoria básica que suporta o experimento de RMN MQMAS de alta resolução e também enfatiza aspectos prát...

Multiple-quantum magic-angle spinning and dynamic-angle spinning NMR spectroscopy of quadrupolar nuclei.

Several aspects of the Multiple-Quantum Magic-Angle Spinning (MQMAS) technique (L. Frydman and J.S. Harwood, J. Am. Chem. Soc., 117 (1995) 5367) are compared with Dynamic-Angle Spinning (DAS). Examples of MQMAS spectra are shown for I = 3/2 nuclei with CQ up to 3.6 MHz, and for 27Al (I = 5/2) with CQ up to 10 MHz. The MQMAS linewidth is largely independent of the magnitude of the homonuclear di...

Multiple-Quantum Magic- Angle Spinning NMR: A New Method for the Study of Quadrupolar Nuclei in Solids

Whereas solid state isotropic spectra can be obtained from spin-'/2 nuclei by fast magic-angle spinning (MAS), this methodology fails when applied on half-integer quadrupoles due to the presence of non-negligible secondorder anisotropic effects. Very recently, however, we have shown that the combined use of MAS and bidimensional multiple-quantum (MQ) spectroscopy can refocus these anisotropies;...

Decoupling-induced recoupling in multiple-quantum magic-angle-spinning NMR spectra of quadrupolar nuclei

We report the observation of a new decoupling-induced recoupling phenomenon in multiple-quantum magic-angle-spinŽ . ning MQMAS NMR spectra of half-integer quadrupolar nuclei. The origin of the effect is identical to the second-order Ž . recoupling between dipolar and anisotropic chemical shielding interactions under continuous-wave CW spin decoupling, w Ž . x which is first observed by Ernst et...

Fundamentals of Multiple-Quantum Magic-Angle Spinning NMR on Half-Integer Quadrupolar Nuclei