NMR experimental procedure for obtaining 3Q and 5QMAS spectra from the same multiplex SPAM acquisition

Probing quadrupolar nuclei by solid-state NMR spectroscopy: recent advances

Solid-state nuclear magnetic resonance (NMR) of quadrupolar nuclei has recently undergone remarkable development of capabilities for obtaining structural and dynamic information at the molecular level. This review summarizes the key achievements attained during the last couple of decades in solid-state NMR of both integer spin and half-integer spin quadrupolar nuclei. We provide a concise description of the first- and second-order quadrupolar interactions, and their effect on the static and magic angle spinning (MAS) spectra. Methods are explained for efficient excitation of single- and multiple-quantum coherences, and acquisition of spectra under low- and high-resolution conditions. Most of all, we present a coherent, comparative description of the high-resolution methods for half-integer quadrupolar nuclei, including double rotation (DOR), dynamic angle spinning (DAS), multiple-quantum magic angle spinning (MQMAS), and satellite transition magic angle spinning (STMAS). Also highlighted are methods for processing and analysis of the spectra. Finally, we review methods for probing the heteronuclear and homonuclear correlations between the quadrupolar nuclei and their quadrupolar or spin-1/2 neighbors.

Determination of NMR cogwheel phase cycle with XML

The selection of correct coherence transfer pathways is an essential component of an NMR pulse sequence. This article describes a new method based on the use of web tools (eXtensible Markup Language and eXtensible Stylesheet Language Transformation) to generate a cogwheel phase cycle for selecting coherence transfer pathways. We illustrate this method with the three-pulse phase-modulated shifted-echo or split-t(1) MQMAS sequences for triple-quantum spin-3/2 systems. After generalization to the different half-integer quadrupole spins, we use the SIMPSON program to confirm our results. Finally, we apply our method to the case of the z-filter 3QMAS sequence for I=3/2 systems.