Fast acquisition of multidimensional NMR spectra of solids and mesophases using alternative sampling methods.
Unique information about the atom-level structure and dynamics of solids and mesophases can be obtained by the use of multidimensional nuclear magnetic resonance (NMR) experiments. Nevertheless, the acquisition of these experiments often requires long acquisition times. We review here alternative sampling methods, which have been proposed to circumvent this issue in the case of solids and mesophases. Compared to the spectra of solutions, those of solids and mesophases present some specificities because they usually display lower signal-to-noise ratios, non-Lorentzian line shapes, lower spectral resolutions and wider spectral widths. We highlight herein the advantages and limitations of these alternative sampling methods. A first route to accelerate the acquisition time of multidimensional NMR spectra consists in the use of sparse sampling schemes, such as truncated, radial or random sampling ones. These sparsely sampled datasets are generally processed by reconstruction methods differing from the Discrete Fourier Transform (DFT). A host of non-DFT methods have been applied for solids and mesophases, including the G-matrix Fourier transform, the linear least-square procedures, the covariance transform, the maximum entropy and the compressed sensing. A second class of alternative sampling consists in departing from the Jeener paradigm for multidimensional NMR experiments. These non-Jeener methods include Hadamard spectroscopy as well as spatial or orientational encoding of the evolution frequencies. The increasing number of high field NMR magnets and the development of techniques to enhance NMR sensitivity will contribute to widen the use of these alternative sampling methods for the study of solids and mesophases in the coming years.
RMN en Milieu Orienté, ICMMO, UMR-CNRS 8182, Université de Paris-Sud, Orsay, F-91405, Cedex Orsay, France.
Philippe
P
Lesot
Centre of New Technologies, University of Warsaw, Banacha 2C, 02097, Warsaw, Poland.
Krzysztof
K
Kazimierczuk
Univ. Lille Nord de France, Unité de Catalyse et de Chimie du Solide (UCCS), CNRS UMR 8181, Univ. Lille, 59652, Villeneuve d'Ascq, France.
Julien
J
Trébosc
Univ. Lille Nord de France, Unité de Catalyse et de Chimie du Solide (UCCS), CNRS UMR 8181, Univ. Lille, 59652, Villeneuve d'Ascq, France.|Physics Department and Shanghai Key Laboratory of Magnetic Resonance, East China Normal University, Shanghai, 200062, China.
Jean-Paul
JP
Amoureux
Univ. Lille Nord de France, Unité de Catalyse et de Chimie du Solide (UCCS), CNRS UMR 8181, Univ. Lille, 59652, Villeneuve d'Ascq, France.
Olivier
O
Lafon
liquid crystal; multidimensional NMR; processing; sampling; solid