The Experts below are selected from a list of 429 Experts worldwide ranked by ideXlab platform

Kazuyuki Takeda - One of the best experts on this subject based on the ideXlab platform.

  • modulatory resonance recoupling of Heteronuclear Dipolar Interactions under magic angle spinning
    Chemical Physics Letters, 1996
    Co-Authors: Kazuyuki Takeda
    Abstract:

    Abstract A new solid-state NMR technique for recoupling Heteronuclear Dipolar Interactions under magic angle spinning is proposed. In this method, the recoupling is achieved by interference between two non-commutable time-dependent Hamiltonians in the doubly rotating frame: one is the Heteronuclear Dipolar Interaction modulated by MAS and the other is the rf Interaction whose amplitude is modulated. When the two modulation frequencies are matched to each other, the cross term between the two Interactions becomes time-independent. Since the recoupling condition does not include the intensity of the rf field, this recoupling method is insensitive to inhomogeneity of the rf field. This new recoupling method is demonstrated for 2- 13 C/ 15 N doubly labeled glycine.

Le Pollès Laurent - One of the best experts on this subject based on the ideXlab platform.

  • Rationalization of solid-state NMR multi-pulse decoupling strategies : coupling of spin I = ½ and half-integer quadrupolar nuclei
    'Elsevier BV', 2020
    Co-Authors: Kouvatas Cassandre, Kanwal Nasima, Trébosc Julien, Roiland Claire, Delevoye Laurent, Le Fur Eric, Ashbrook, Sharon E., Le Pollès Laurent
    Abstract:

    This work benefited from a grant from Agence Nationale de la Recherche (ANR MOSAIC 13-BS08-0018-01).In this paper we undertake a study of the decoupling efficiency of the Multiple-Pulse (MP) scheme, and a rationalization of its parameterization and of the choice of instrumental set up. This decoupling scheme is known to remove the broadening of spin-1/2 spectra I, produced by the Heteronuclear scalar Interaction with a half-integer quadrupolar nucleus S, without reintroducing Heteronuclear Dipolar Interaction. The resulting resolution enhancement depends on the set-up of the length of the series of pulses and delays of the MP, and some intrinsic material and instrumental parameters. Firstly through a numerical approach, this study investigates the influence of the main intrinsic material parameters (Heteronuclear Dipolar and J coupling, quadrupolar Interaction, spin nature) and instrumental parameters (spinning rate, pulse field strength) on efficiency and resolution enhancement of the scalar decoupling scheme. A guideline is then proposed to obtain quickly and easily the best resolution enhancement via the rationalization of the instrumental and parameter set up. It is then illustrated and tested through experimental data, probing the efficiency of MP-decoupling set up using this guideline. Various spin systems were tested (31P-51V in VOPO4, 31P-93Nb in NbOPO4, 119Sn-17O in Y2Sn2O7), combined with simulations results.PostprintPostprintPeer reviewe

  • Rationalization of solid-state NMR multi-pulse decoupling strategies: Coupling of spin I = ½ and half-integer quadrupolar nuclei
    'Elsevier BV', 2019
    Co-Authors: Kouvatas Cassandre, Kanwal Nasima, Trébosc Julien, Roiland Claire, Delevoye Laurent, Ashbrook Sharon, Le Fur Eric, Le Pollès Laurent
    Abstract:

    International audienceIn this paper we undertake a study of the decoupling efficiency of the Multiple-Pulse (MP) scheme, and a rationalization of its parameterization and of the choice of instrumental set up. This decoupling scheme is known to remove the broadening of spin-1/2 spectra I, produced by the Heteronuclear scalar Interaction with a half-integer quadrupolar nucleus S, without reintroducing Heteronuclear Dipolar Interaction. The resulting resolution enhancement depends on the set-up of the length of the series of pulses and delays of the MP, and some intrinsic material and instrumental parameters. Firstly through a numerical approach, this study investigates the influence of the main intrinsic material parameters (Heteronuclear Dipolar and J coupling, quadrupolar Interaction, spin nature) and instrumental parameters (spinning rate, pulse field strength) on efficiency and resolution enhancement of the scalar decoupling scheme. A guideline is then proposed to obtain quickly and easily the best resolution enhancement via the rationalization of the instrumental and parameter set up. It is then illustrated and tested through experimental data, probing the efficiency of MP-decoupling set up using this guideline. Various spin systems were tested (P-V in VOPO, P-Nb in NbOPO, Sn-O in YSnO), combined with simulations results

Beat H. Meier - One of the best experts on this subject based on the ideXlab platform.

  • Broadband Polarization Transfer under Magic-Angle Spinning: Application to Total Through-Space-Correlation NMR Spectroscopy
    Journal of Magnetic Resonance, 1997
    Co-Authors: Marc Baldus, Beat H. Meier
    Abstract:

    Abstract A pulse sequence is described that leads to a broadband recoupling of the Dipolar Interaction in magic-angle-spinning solid-state NMR experiments of 13 C spins. The sequence is based on a combination of rotating frame and laboratory frame transfer periods. The recovered Dipolar Interaction is only weakly dependent on spectral parameters but is a faithful measure for the internuclear distances. Furthermore, a pure zero-quantum term is recovered (of the type found in static “spin-diffusion” experiments). This makes the pulse sequence particularly suited for incorporation into two-dimensional total through-space correlation experiments that deliver simultaneous information about all Dipolar couplings in a single 2D experiment. It is found that the necessary decoupling from abundant protons is best performed in two steps: first, the strong homonuclear couplings between the high-γ spins are averaged by Lee–Goldburg irradiation and, second, the Heteronuclear Dipolar Interaction is averaged by the combined application of an RF field to the low-γ spins and magic-angle sample spinning. Phase-inversion and amplitude attenuation in the rotating frame and refocusing pulses in the laboratory frame part of the pulse sequence are introduced to achieve an optimum chemical-shift offset-independence and for the suppression of unwanted double-quantum transitions. The design principles are explained in detail. Finally, the pulse scheme is applied to total-correlation spectroscopy of a uniformly labeled amino acid. The experimental cross-peak intensities are in qualitative agreement with the known crystal structure of the model compound.

Kouvatas Cassandre - One of the best experts on this subject based on the ideXlab platform.

  • Rationalization of solid-state NMR multi-pulse decoupling strategies : coupling of spin I = ½ and half-integer quadrupolar nuclei
    'Elsevier BV', 2020
    Co-Authors: Kouvatas Cassandre, Kanwal Nasima, Trébosc Julien, Roiland Claire, Delevoye Laurent, Le Fur Eric, Ashbrook, Sharon E., Le Pollès Laurent
    Abstract:

    This work benefited from a grant from Agence Nationale de la Recherche (ANR MOSAIC 13-BS08-0018-01).In this paper we undertake a study of the decoupling efficiency of the Multiple-Pulse (MP) scheme, and a rationalization of its parameterization and of the choice of instrumental set up. This decoupling scheme is known to remove the broadening of spin-1/2 spectra I, produced by the Heteronuclear scalar Interaction with a half-integer quadrupolar nucleus S, without reintroducing Heteronuclear Dipolar Interaction. The resulting resolution enhancement depends on the set-up of the length of the series of pulses and delays of the MP, and some intrinsic material and instrumental parameters. Firstly through a numerical approach, this study investigates the influence of the main intrinsic material parameters (Heteronuclear Dipolar and J coupling, quadrupolar Interaction, spin nature) and instrumental parameters (spinning rate, pulse field strength) on efficiency and resolution enhancement of the scalar decoupling scheme. A guideline is then proposed to obtain quickly and easily the best resolution enhancement via the rationalization of the instrumental and parameter set up. It is then illustrated and tested through experimental data, probing the efficiency of MP-decoupling set up using this guideline. Various spin systems were tested (31P-51V in VOPO4, 31P-93Nb in NbOPO4, 119Sn-17O in Y2Sn2O7), combined with simulations results.PostprintPostprintPeer reviewe

  • Rationalization of solid-state NMR multi-pulse decoupling strategies: Coupling of spin I = ½ and half-integer quadrupolar nuclei
    'Elsevier BV', 2019
    Co-Authors: Kouvatas Cassandre, Kanwal Nasima, Trébosc Julien, Roiland Claire, Delevoye Laurent, Ashbrook Sharon, Le Fur Eric, Le Pollès Laurent
    Abstract:

    International audienceIn this paper we undertake a study of the decoupling efficiency of the Multiple-Pulse (MP) scheme, and a rationalization of its parameterization and of the choice of instrumental set up. This decoupling scheme is known to remove the broadening of spin-1/2 spectra I, produced by the Heteronuclear scalar Interaction with a half-integer quadrupolar nucleus S, without reintroducing Heteronuclear Dipolar Interaction. The resulting resolution enhancement depends on the set-up of the length of the series of pulses and delays of the MP, and some intrinsic material and instrumental parameters. Firstly through a numerical approach, this study investigates the influence of the main intrinsic material parameters (Heteronuclear Dipolar and J coupling, quadrupolar Interaction, spin nature) and instrumental parameters (spinning rate, pulse field strength) on efficiency and resolution enhancement of the scalar decoupling scheme. A guideline is then proposed to obtain quickly and easily the best resolution enhancement via the rationalization of the instrumental and parameter set up. It is then illustrated and tested through experimental data, probing the efficiency of MP-decoupling set up using this guideline. Various spin systems were tested (P-V in VOPO, P-Nb in NbOPO, Sn-O in YSnO), combined with simulations results

Marc Baldus - One of the best experts on this subject based on the ideXlab platform.

  • Broadband Polarization Transfer under Magic-Angle Spinning: Application to Total Through-Space-Correlation NMR Spectroscopy
    Journal of Magnetic Resonance, 1997
    Co-Authors: Marc Baldus, Beat H. Meier
    Abstract:

    Abstract A pulse sequence is described that leads to a broadband recoupling of the Dipolar Interaction in magic-angle-spinning solid-state NMR experiments of 13 C spins. The sequence is based on a combination of rotating frame and laboratory frame transfer periods. The recovered Dipolar Interaction is only weakly dependent on spectral parameters but is a faithful measure for the internuclear distances. Furthermore, a pure zero-quantum term is recovered (of the type found in static “spin-diffusion” experiments). This makes the pulse sequence particularly suited for incorporation into two-dimensional total through-space correlation experiments that deliver simultaneous information about all Dipolar couplings in a single 2D experiment. It is found that the necessary decoupling from abundant protons is best performed in two steps: first, the strong homonuclear couplings between the high-γ spins are averaged by Lee–Goldburg irradiation and, second, the Heteronuclear Dipolar Interaction is averaged by the combined application of an RF field to the low-γ spins and magic-angle sample spinning. Phase-inversion and amplitude attenuation in the rotating frame and refocusing pulses in the laboratory frame part of the pulse sequence are introduced to achieve an optimum chemical-shift offset-independence and for the suppression of unwanted double-quantum transitions. The design principles are explained in detail. Finally, the pulse scheme is applied to total-correlation spectroscopy of a uniformly labeled amino acid. The experimental cross-peak intensities are in qualitative agreement with the known crystal structure of the model compound.