Reintroducing Anisotropic Interactions in Magic-Angle-Spinning NMR of Half-Integer Quadrupolar Nuclei: 3D MQMAS

Reintroducing anisotropic interactions in magic-angle-spinning NMR of half-integer quadrupolar nuclei: 3D MQMAS.

Selective reintroduction of anisotropic interactions such as the chemical shift anisotropy (CSA) and homonucler dipolar (HMD) coupling were implemented in a high-resolution NMR spectroscopy for half-integer quadrupolar nuclei. Rotary resonance recoupling (R(3)) combined with the multiple-quantum magic-angle spinning (MQMAS) in a three-dimensional (3D) experiment provides not only site-specific ...

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

Isotropic Spectra of Half-Integer Quadrupolar Spins from Bidimensional Magic-Angle Spinning NMR

Interest in the solid state nuclear magnetic resonance (NMR) spectroscopy of half-integer quadrupolar spins is strongly stimulated by the roles that these isotopes play in a variety of important systems such as minerals, structural ceramics, semiconductors, glasses, and catalysts.' In spite of the partly ionic nature of these materials, quadrupole interactions with surrounding electric field gr...

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...

Comparison of high-resolution solid-state NMR MQMAS and STMAS methods for half-integer quadrupolar nuclei.

Several different amplitude-modulated two-dimensional high-resolution methods, based on MQMAS and STMAS, are compared. They include 3QMAS, 5QMAS, DQ-STMAS, and DQF-STMAS experiments. A new method, called t1-split-STMAS, is also proposed for spin-3/2 nuclei. The comparison is performed in terms of isotropic resolution and spectral-width, efficiency, and sensitivity to magic-angle offset and spin...