The Experts below are selected from a list of 324 Experts worldwide ranked by ideXlab platform
Jean-paul Amoureux - One of the best experts on this subject based on the ideXlab platform.
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Measurement of through-space connectivities between spin-1/2 and Quadrupolar Nuclei in solid-state NMR: the TEDOR-MQMAS method.
Magnetic resonance in chemistry : MRC, 2020Co-Authors: Jean-paul Amoureux, Julien Trebosc, Grégory TricotAbstract:We present the transferred echo double-resonance multiple-quantum MAS (TEDOR-MQMAS) method that allows to analyze under high resolution the through-bond connectivities between spin-1/2 and Quadrupolar Nuclei. This method avoids some of the limitations related to the spin-lock of half-integer Quadrupolar Nuclei under MAS. However, the losses observed during the TEDOR transfer are related to the T'(2) constants, and they may thus be more important than those observed during the CP-MAS transfer, which are related to T(1rho) > T'(2).
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Magnetization transfer from protons to Quadrupolar Nuclei in solid-state NMR using PRESTO or dipolar-mediated refocused INEPT methods
Journal of Magnetic Resonance, 2018Co-Authors: Raynald Giovine, Julien Trebosc, Olivier Lafon, Frédérique Pourpoint, Jean-paul AmoureuxAbstract:Abstract In solid-state NMR spectroscopy, the through-space transfer of magnetization from protons to Quadrupolar Nuclei is employed to probe proximities between those isotopes. Furthermore, such transfer, in conjunction with Dynamic Nuclear Polarization (DNP), can enhance the NMR sensitivity of Quadrupolar Nuclei, as it allows the transfer of DNP-enhanced 1H polarization to surrounding Nuclei. We compare here the performances of two approaches to achieve such transfer: PRESTO (Phase-shifted Recoupling Effects a Smooth Transfer of Order), which is currently the method of choice to achieve the magnetization transfer from protons to Quadrupolar Nuclei and which has been shown to supersede Cross-Polarization under Magic-Angle Spinning (MAS) for Quadrupolar Nuclei and D-RINEPT (Dipolar-mediated Refocused Insensitive Nuclei Enhanced by Polarization Transfer) using symmetry-based SR 4 1 2 recoupling, which has already been employed to transfer the magnetization in the reverse way from half-integer Quadrupolar spin to protons. We also test the PRESTO sequence with R 16 7 6 recoupling using 270090180 composite π-pulses as inversion elements. This recoupling scheme, which has previously been proposed to reintroduce 1H Chemical Shift Anisotropy (CSA) at high MAS frequencies with high robustness to rf-field inhomogeneity, has not so far been employed to reintroduce dipolar couplings with protons. These various techniques to transfer magnetization from protons to Quadrupolar Nuclei are analyzed using (i) an average Hamiltonian theory, (ii) numerical simulations of spin dynamics, and (iii) experimental 1H → 27Al and 1H → 17O transfers in as-synthesized AlPO4-14 and 17O-labelled fumed silica, respectively. The experiments and simulations are done at two magnetic fields (9.4 and 18.8 T) and several spinning speeds (15, 18–24 and 60 kHz). This analysis indicates that owing to its γ-encoded character, PRESTO yields the highest transfer efficiency at low magnetic fields and MAS frequencies, whereas owing to its higher robustness to rf-field inhomogeneity and chemical shifts, D-RINEPT is more sensitive at high fields and MAS frequencies, notably for protons exhibiting large offset or CSA, such as those involved in hydrogen bonds.
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Chapter 4:Two-dimensional Methods for Half-integer Quadrupolar Nuclei
Modern Methods in Solid-state NMR, 2018Co-Authors: Frédérique Pourpoint, Jean-paul Amoureux, Olivier Lafon, Regis M Gauvin, Laurent DelevoyeAbstract:In the present chapter, we review some of the most robust and commonly used two-dimensional (2D) solid-state NMR experiments for half-integer spin Quadrupolar Nuclei. It covers techniques from high-resolution methods, such as Multiple-Quantum Magic-Angle Spinning (MQMAS) or Satellite Transition Magic-Angle Spinning (STMAS), to recent developments of homo- and hetero-nuclear correlation sequences, for the latter with a focus on the most efficient recoupling schemes. For each sequence, strategies for quick and easy experimental optimisation are detailed. Then, the information that can be deduced from the spectra is illustrated by a few recent and complementary examples dealing with inorganic systems, from ordered to partially or totally disordered structures.
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Indirect covariance NMR spectroscopy of through-bond homo-nuclear correlations for Quadrupolar Nuclei in solids under high-resolution
Solid State Nuclear Magnetic Resonance, 2017Co-Authors: Bingwen Hu, Jean-paul Amoureux, Julien TreboscAbstract:Indirect covariance NMR spectroscopy is demonstrated in solids, and we show that it can be used to obtain through-bond 2D homo-nuclear correlation spectra for Quadrupolar Nuclei under high-resolution. These spectra, generated with indirect covariance from a hetero-nuclear correlation spectrum, are equivalent to those recorded with the through-bond homo-nuclear hetero-nuclear single-quantum correlation (H-HSQC) method very recently proposed. However, the indirect covariance method can save a lot of experiment time, compared to the H-HSQC experiments, which allows introducing a high-resolution Quadrupolar filter, thus providing a much better resolution, even on medium-field spectrometers. The covariance concept can be used to generate many different ‘indirectly-detected' high-resolution homo-nuclear correlation spectra with through-space or through-bond correlations for spin 1/2 or Quadrupolar Nuclei. We also propose a simple method that decreases the noise in all (direct or indirect) covariance methods.
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correlation nmr spectroscopy involving Quadrupolar Nuclei
Solid State Nuclear Magnetic Resonance, 2009Co-Authors: Jean-paul Amoureux, Julien Trebosc, Bingwen Hu, Laurent Delevoye, Olivier Lafon, Qiang WangAbstract:We review the recent developments proposed for integer or half-integer Quadrupolar Nuclei, focussing on the methods to observe them under high-resolution and to analyze their through-space and through-bond connectivities. (C) 2008 Elsevier Inc. All rights reserved.
Julien Trebosc - One of the best experts on this subject based on the ideXlab platform.
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Measurement of through-space connectivities between spin-1/2 and Quadrupolar Nuclei in solid-state NMR: the TEDOR-MQMAS method.
Magnetic resonance in chemistry : MRC, 2020Co-Authors: Jean-paul Amoureux, Julien Trebosc, Grégory TricotAbstract:We present the transferred echo double-resonance multiple-quantum MAS (TEDOR-MQMAS) method that allows to analyze under high resolution the through-bond connectivities between spin-1/2 and Quadrupolar Nuclei. This method avoids some of the limitations related to the spin-lock of half-integer Quadrupolar Nuclei under MAS. However, the losses observed during the TEDOR transfer are related to the T'(2) constants, and they may thus be more important than those observed during the CP-MAS transfer, which are related to T(1rho) > T'(2).
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Magnetization transfer from protons to Quadrupolar Nuclei in solid-state NMR using PRESTO or dipolar-mediated refocused INEPT methods
Journal of Magnetic Resonance, 2018Co-Authors: Raynald Giovine, Julien Trebosc, Olivier Lafon, Frédérique Pourpoint, Jean-paul AmoureuxAbstract:Abstract In solid-state NMR spectroscopy, the through-space transfer of magnetization from protons to Quadrupolar Nuclei is employed to probe proximities between those isotopes. Furthermore, such transfer, in conjunction with Dynamic Nuclear Polarization (DNP), can enhance the NMR sensitivity of Quadrupolar Nuclei, as it allows the transfer of DNP-enhanced 1H polarization to surrounding Nuclei. We compare here the performances of two approaches to achieve such transfer: PRESTO (Phase-shifted Recoupling Effects a Smooth Transfer of Order), which is currently the method of choice to achieve the magnetization transfer from protons to Quadrupolar Nuclei and which has been shown to supersede Cross-Polarization under Magic-Angle Spinning (MAS) for Quadrupolar Nuclei and D-RINEPT (Dipolar-mediated Refocused Insensitive Nuclei Enhanced by Polarization Transfer) using symmetry-based SR 4 1 2 recoupling, which has already been employed to transfer the magnetization in the reverse way from half-integer Quadrupolar spin to protons. We also test the PRESTO sequence with R 16 7 6 recoupling using 270090180 composite π-pulses as inversion elements. This recoupling scheme, which has previously been proposed to reintroduce 1H Chemical Shift Anisotropy (CSA) at high MAS frequencies with high robustness to rf-field inhomogeneity, has not so far been employed to reintroduce dipolar couplings with protons. These various techniques to transfer magnetization from protons to Quadrupolar Nuclei are analyzed using (i) an average Hamiltonian theory, (ii) numerical simulations of spin dynamics, and (iii) experimental 1H → 27Al and 1H → 17O transfers in as-synthesized AlPO4-14 and 17O-labelled fumed silica, respectively. The experiments and simulations are done at two magnetic fields (9.4 and 18.8 T) and several spinning speeds (15, 18–24 and 60 kHz). This analysis indicates that owing to its γ-encoded character, PRESTO yields the highest transfer efficiency at low magnetic fields and MAS frequencies, whereas owing to its higher robustness to rf-field inhomogeneity and chemical shifts, D-RINEPT is more sensitive at high fields and MAS frequencies, notably for protons exhibiting large offset or CSA, such as those involved in hydrogen bonds.
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Indirect covariance NMR spectroscopy of through-bond homo-nuclear correlations for Quadrupolar Nuclei in solids under high-resolution
Solid State Nuclear Magnetic Resonance, 2017Co-Authors: Bingwen Hu, Jean-paul Amoureux, Julien TreboscAbstract:Indirect covariance NMR spectroscopy is demonstrated in solids, and we show that it can be used to obtain through-bond 2D homo-nuclear correlation spectra for Quadrupolar Nuclei under high-resolution. These spectra, generated with indirect covariance from a hetero-nuclear correlation spectrum, are equivalent to those recorded with the through-bond homo-nuclear hetero-nuclear single-quantum correlation (H-HSQC) method very recently proposed. However, the indirect covariance method can save a lot of experiment time, compared to the H-HSQC experiments, which allows introducing a high-resolution Quadrupolar filter, thus providing a much better resolution, even on medium-field spectrometers. The covariance concept can be used to generate many different ‘indirectly-detected' high-resolution homo-nuclear correlation spectra with through-space or through-bond correlations for spin 1/2 or Quadrupolar Nuclei. We also propose a simple method that decreases the noise in all (direct or indirect) covariance methods.
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population transfer hmqc for half integer Quadrupolar Nuclei
Journal of Chemical Physics, 2015Co-Authors: Qiang Wang, Julien Trebosc, Bingwen Hu, Jun Xu, Olivier Lafon, Yixuan Li, Ningdong Feng, Qun ChenAbstract:This work presents a detailed analysis of a recently proposed nuclear magnetic resonance method [Wang et al., Chem. Commun. 49(59), 6653-6655 (2013)] for accelerating heteronuclear coherence transfers involving half-integer spin Quadrupolar Nuclei by manipulating their satellite transitions. This method, called Population Transfer Heteronuclear Multiple Quantum Correlation (PT-HMQC), is investigated in details by combining theoretical analyses, numerical simulations, and experimental investigations. We find that compared to instant inversion or instant saturation, continuous saturation is the most practical strategy to accelerate coherence transfers on half-integer Quadrupolar Nuclei. We further demonstrate that this strategy is efficient to enhance the sensitivity of J-mediated heteronuclear correlation experiments between two half-integer Quadrupolar isotopes (e.g., Al-27-O-17). In this case, the build-up is strongly affected by relaxation for small T-2' and J coupling values, and shortening the mixing time makes a huge signal enhancement. Moreover, this concept of population transfer can also be applied to dipolar-mediated HMQC experiments. Indeed, on the AlPO4-14 sample, one still observes experimentally a 2-fold shortening of the optimum mixing time albeit with no significant signal gain in the P-31-{Al-27} experiments. (C) 2015 AIP Publishing LLC.
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signal enhancement of j hmqc experiments in solid state nmr involving half integer Quadrupolar Nuclei
Chemical Communications, 2013Co-Authors: Qiang Wang, Julien Trebosc, Bingwen Hu, Jun Xu, Yixuan Li, Ningdong Feng, Qun Chen, Olivier LafonAbstract:We show that for half-integer Quadrupolar Nuclei, the manipulation of the satellite transitions can accelerate and enhance coherence transfer to other isotopes. This novel strategy is demonstrated to improve the sensitivity of 31P-{27Al} J-HMQC experiments for a layered aluminophosphate Mu-4.
Dominique Massiot - One of the best experts on this subject based on the ideXlab platform.
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two dimensional one pulse mas of half integer Quadrupolar Nuclei
Journal of Magnetic Resonance, 2006Co-Authors: Dominique Massiot, Franck Fayon, Stefan Steuernagel, Michael Deschamps, Julian Hiet, Nadia Pellerin, Philip J GrandinettiAbstract:We show that the two-dimensional one pulse (TOP) representation of magic-angle spinning nuclear Magnetic resonance data of half-integer Quadrupolar Nuclei has significant advantages over the conventional one-dimensional spectrum. The TOP spectrum, which correlates NMR frequency to spinning sideband order, provides a rapid determination of the number of sites as well as size of the their Quadrupolar coupling. Additionally, synchronous acquisition spectra of the central and satellite transition resonances can be separated by different projections of the TOP spectrum, with higher resolution spectra often found in the satellite transitions projection. A previously perceived problem of centerband aliasing in TOP can be eliminated with an algorithm that uses larger subspectral widths and the sideband order dimension to distinguish centerbands from sidebands.
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nmr heteronuclear correlation between Quadrupolar Nuclei in solids
Journal of the American Chemical Society, 2005Co-Authors: Dinu Iuga, Laurent Cormier, Claudia Morais, Daniel R. Neuville, Dominique MassiotAbstract:We show for the first time that it is possible to acquire high-resolution heteronuclear NMR correlation experiments in solid state between second-order-broadened half integer Quadrupolar Nuclei (i.e., 27Al and 17O) using the scalar J-coupling. The sensitivity of the experiment is dramatically improved at high fields (gain proportional to the fourth power of the principal field) with a combination of signal enhancement techniques. This turns a challenging experiment into a real tool. We apply this experiment to characterize a calcium aluminate glass in which we prove the presence of tricluster μ3 oxygen sites and describe the signature of their directly bonded aluminum sites. Applications involve a large range of possible pairs of Quadrupolar Nuclei in different materials, such as glasses, porous or mesoporous framework materials, zeolites, hybrid organic−inorganic, and bioinvolved materials.
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Measurement of J Couplings between Spin-½ and Quadrupolar Nuclei by Frequency Selective Solid State NMR
Solid State Nuclear Magnetic Resonance, 2005Co-Authors: Jean-paul Amoureux, Julien Trebosc, Dominique Massiot, Jerzy W. Wiench, Marek PruskiAbstract:We report a REDOR-based scheme for the measurement of heteronuclear J-couplings in solid samples with well defined structure, containing spin-1/2 and Quadrupolar Nuclei, which can be used with selective RF irradiation to target a specific spin pair, and which provides direct information about the number of coupled spins
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Chemical bonding differences evidenced from J-coupling in solid state NMR experiments involving Quadrupolar Nuclei
Journal of Magnetic Resonance, 2003Co-Authors: Dominique Massiot, Franck Fayon, Bruno Alonso, Julien Trebosc, Jean-paul AmoureuxAbstract:Small scalar J-coupling between Quadrupolar Nuclei and spin 1/2 can be measured in inorganic solids using J-Resolved experiments and further used to acquire 2D J-HQMC heteronuclear correlation, giving detailed insight into the chemical bonding scheme.
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seeking higher resolution and sensitivity for nmr of Quadrupolar Nuclei at ultrahigh magnetic fields
Journal of the American Chemical Society, 2002Co-Authors: Peter L Gorkov, Timothy A Cross, And Ago Samoson, Dominique MassiotAbstract:We report the acquisition of solid-state NMR spectra of Quadrupolar Nuclei obtained at very high magnetic fields (25 and 40 T), thus improving spectral sensitivity and resolution. For an example compound, the MAS spectrum obtained at 40 T is nearly free from the second-order Quadrupolar broadening and can be interpreted quantitatively in a very simple manner.
Marek Pruski - One of the best experts on this subject based on the ideXlab platform.
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presto polarization transfer to Quadrupolar Nuclei implications for dynamic nuclear polarization
Physical Chemistry Chemical Physics, 2015Co-Authors: Frédéric A. Perras, Marek Pruski, Takeshi KobayashiAbstract:We show both experimentally and numerically on a series of model systems that in experiments involving transfer of magnetization from 1H to the Quadrupolar Nuclei under magic-angle-spinning (MAS), the PRESTO technique consistently outperforms traditionally used cross polarization (CP), affording more quantitative intensities, improved lineshapes, better overall sensitivity, and straightforward optimization. This advantage derives from the fact that PRESTO circumvents the convoluted and uncooperative spin dynamics during the CP transfer under MAS, by replacing the spin-locking of Quadrupolar Nuclei with a single central transition selective 90° pulse and using a symmetry-based recoupling sequence in the 1H channel. This is of particular importance in the context of dynamic nuclear polarization (DNP) NMR of Quadrupolar Nuclei, where the efficient transfer of enhanced 1H polarization is desired to obtain the highest sensitivity.
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Probing Quadrupolar Nuclei by solid-state NMR spectroscopy: Recent advances
Topics in Current Chemistry, 2012Co-Authors: Christian Fernandez, Marek PruskiAbstract: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.
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hmqc and refocused inept experiments involving half integer Quadrupolar Nuclei in solids
Journal of Magnetic Resonance, 2007Co-Authors: Jean-paul Amoureux, Julien Trebosc, Jerzy W. Wiench, Marek PruskiAbstract:Abstract Hetero-nuclear coherence transfers in HMQC and refocused-INEPT experiments involving half-integer Quadrupolar Nuclei in solids are analyzed. 1D and 2D schemes are considered under MAS for the general case of multi-spin systems SI n ( n ⩽ 4), where S is an observed nucleus. These results are also discussed in the context of high-resolution schemes featuring MQMAS or STMAS. The theoretical predictions are verified experimentally in a series of 1D and 2D experiments performed at 9.4 and 18.8 T.
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Measurement of J Couplings between Spin-½ and Quadrupolar Nuclei by Frequency Selective Solid State NMR
Solid State Nuclear Magnetic Resonance, 2005Co-Authors: Jean-paul Amoureux, Julien Trebosc, Dominique Massiot, Jerzy W. Wiench, Marek PruskiAbstract:We report a REDOR-based scheme for the measurement of heteronuclear J-couplings in solid samples with well defined structure, containing spin-1/2 and Quadrupolar Nuclei, which can be used with selective RF irradiation to target a specific spin pair, and which provides direct information about the number of coupled spins
Philip J Grandinetti - One of the best experts on this subject based on the ideXlab platform.
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Communication Spectral editing in solid-state MAS NMR of Quadrupolar Nuclei using selective satellite inversion
2020Co-Authors: Subramanian Prasad, Michael Deschamps, Philip J GrandinettiAbstract:A sensitivity enhancement method based on selective adiabatic inversion of a satellite transition has been employed in a (p/2)CT‐! p" ST1 ‐(p/2)CT spectral editing sequence to both enhance and resolve multisite NMR spectra of Quadrupolar Nuclei. In addition to a total enhancement of 2.5 times for spin 3/2 Nuclei, enhancements up to 2.0 times is reported for the edited sites in a mixture of rubidium salts. Published by Elsevier Inc.
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spectral editing in solid state mas nmr of Quadrupolar Nuclei using selective satellite inversion
Journal of Magnetic Resonance, 2007Co-Authors: Subramanian Prasad, Michael Deschamps, Philip J GrandinettiAbstract:A sensitivity enhancement method based on selective adiabatic inversion of a satellite transition has been employed in a (π/2)CT–(π)ST1–(π/2)CT spectral editing sequence to both enhance and resolve multisite NMR spectra of Quadrupolar Nuclei. In addition to a total enhancement of 2.5 times for spin 3/2 Nuclei, enhancements up to 2.0 times is reported for the edited sites in a mixture of rubidium salts.
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two dimensional one pulse mas of half integer Quadrupolar Nuclei
Journal of Magnetic Resonance, 2006Co-Authors: Dominique Massiot, Franck Fayon, Stefan Steuernagel, Michael Deschamps, Julian Hiet, Nadia Pellerin, Philip J GrandinettiAbstract:We show that the two-dimensional one pulse (TOP) representation of magic-angle spinning nuclear Magnetic resonance data of half-integer Quadrupolar Nuclei has significant advantages over the conventional one-dimensional spectrum. The TOP spectrum, which correlates NMR frequency to spinning sideband order, provides a rapid determination of the number of sites as well as size of the their Quadrupolar coupling. Additionally, synchronous acquisition spectra of the central and satellite transition resonances can be separated by different projections of the TOP spectrum, with higher resolution spectra often found in the satellite transitions projection. A previously perceived problem of centerband aliasing in TOP can be eliminated with an algorithm that uses larger subspectral widths and the sideband order dimension to distinguish centerbands from sidebands.
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two dimensional magic angle spinning isotropic reconstruction sequences for Quadrupolar Nuclei
Solid State Nuclear Magnetic Resonance, 1996Co-Authors: Dominique Massiot, J Virlet, Bruno Touzo, Dominique Trumeau, J P Coutures, P Florian, Philip J GrandinettiAbstract:Abstract Two-dimensional magic-angle spinning (triple quantum, single quantum) correlation pulse sequences and phase cycles based on the technique of Frydman and Harwood for the reconstruction of the isotropic spectrum of half-integer spin Quadrupolar Nuclei broadened to second-order are described. These sequences provide pure absorption mode two-dimensional lineshapes and increased sensitivity. Experimental examples on spin I = 3/2 (87Rb in RbNO3) and I = 5/2 (27Al in NaSi3AlO8) are presented. The isotropic chemical shift and Quadrupolar coupling parameters could be obtained from a simple analysis of the triple quantum filtered single quantum magic-angle spinning cross-sections.
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Cross-polarization dynamic-angle spinning nuclear magnetic resonance of Quadrupolar Nuclei
Molecular Physics, 1994Co-Authors: Jay H. Baltisberger, Philip J Grandinetti, Sheryl L. Gann, Alexander PinesAbstract:The use of variable-angle spinning (VAS) with cross-polarization (CP) for Quadrupolar Nuclei has been evaluated both experimentally and theoretically. It is known that under normal spinning speeds the best VAS angle for performing CP is 0° (parallel to the magnetic field). We show that, with the use of dynamic-angle spinning (DAS) probes, CP may be done at 0° and detection in a one-dimensional VAS experiment may be performed at any angle in a zero-polarized VAS (ZPVAS) experiment. Finally, the combination of CP with k = 5 DAS (where the sample is spun first at 0° followed by 63·43°) provides both the highest resolution and the greatest sensitivity under normal conditions.
