Transverse Dephasing Optimized Solid-State NMR Spectroscopy

Paëpe, Gaël De; Giraud, Nicolas; Lesage, Anne; Hodgkinson, Paul; Böckmann, Anja; Emsley, Lyndon

doi:10.1021/ja037213j

Cited by 105 publications

(218 citation statements)

References 15 publications

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“…Even in these cases, the values are estimates due to the systematic errors in modeling the spin-echo decays from both 1 H and 13 C data as single exponentials; e.g., spin-echo decay rates from decoupled 13 C spectra have been shown to vary with the 1 H decoupling method. 34 For comparison, an estimated value of about 0.3 ppm was obtained in Ref. 30 for a more typical organic compound, malonic acid, by extrapolating from data points acquired at very high spin rates and static magnetic field.…”

Section: Inhomogeneous Contributions To 1 H Linewidthsmentioning

confidence: 99%

Origins of linewidth in H1 magic-angle spinning NMR

Zorin

Brown

Hodgkinson

2006

The Journal of Chemical Physics

127

116

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A detailed study of the factors determining the linewidth (and hence resolution) in H1 solid-state magic-angle spinning NMR is described. Although it has been known from the early days of magic-angle spinning (MAS) that resolution of spectra from abundant nuclear spins, such as H1, increases approximately linearly with increasing sample rotation rate, the difficulty of describing the dynamics of extended networks of coupled spins has made it difficult to predict a priori the resolution expected for a given sample. Using recently developed, highly efficient methods of numerical simulation, together with experimental measurements on a variety of test systems, we propose a comprehensive picture of H1 resolution under MAS. The “homogeneous” component of the linewidth is shown to depend primarily on the ratio between an effective local coupling strength and the spin rate, modified by geometrical factors which loosely correspond to the “dimensionality” of the coupling network. The remaining “inhomogeneous” component of the natural linewidth is confirmed to have the same properties as in dilute-spin NMR. Variations in the NMR frequency due to chemical shift effects are shown to have minimal impact on H1 resolution. The implications of these results for solid-state NMR experiments involving H1 and other abundant-spin nuclei are discussed.

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Section: Inhomogeneous Contributions To 1 H Linewidthsmentioning

confidence: 99%

Origins of linewidth in H1 magic-angle spinning NMR

Zorin

Brown

Hodgkinson

2006

The Journal of Chemical Physics

127

116

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“…Another important quantity in the discussion of the performance of heteronuclear decoupling sequences is the refocusable linewidth in spin-echo experiments sometimes called T 2 Ј. 29 In this case, the same contributions to the observed linewidth are present as in the case of the observed linewidth during free evolution. Their impact, however, is different due to the additional refocusing pulse in the spinecho sequence.…”

Section: Introductionmentioning

confidence: 99%

Understanding two-pulse phase-modulated decoupling in solid-state NMR

Scholz

Hodgkinson

Meier

et al. 2009

The Journal of Chemical Physics

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A theoretical description of the two-pulse phase-modulated (TPPM) decoupling sequence in magic-angle spinning NMR is presented using a triple-mode Floquet approach. The description is formulated in the radio-frequency interaction-frame representation and is valid over the entire range of possible parameters leading to the well-known results of continuous-wave (cw) decoupling and XiX decoupling in the limit of a phase change of 0° and 180°, respectively. The treatment results in analytical expressions for the heteronuclear residual coupling terms and the homonuclear spin-diffusion terms. It also allows the characterization of all resonance conditions that can contribute in a constructive or a destructive way to the residual linewidth. Some of the important resonance conditions are described for the first time since they are not accessible in previous treatments. The combination of the contributions from the residual couplings and the resonance conditions to the effective Hamiltonian, as obtained in a Floquet description, is shown to be required to describe the decoupling behavior over the full range of parameters. It is shown that for typical spin system and experimental parameters a C13 linewidth of approximately 12Hz can be obtained for TPPM decoupling in an organic solid or a protein. This is a major contribution to the experimentally observed linewidths of around 20Hz and indicates that decoupling techniques are still one of the limiting factors in the achievable linewidths.

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“…Many of these methods employ pulse sequences which reintroduce the MAS-averaged through-space homonuclear dipolar interaction, to obtain DQ-SQ correlation spectra which reflect the through-space atomic proximities [3][4][5][6][7][8][9][10]. Alternatively, pulse sequences based on throughbond isotropic J-couplings, like the INADEQUATE [11] and refocused INADEQUATE [12] experiments, have also been applied efficiently to obtain through-bond DQ-SQ correlation spectra for large range of materials [12][13][14][15][16][17][18][19][20][21][22][23].In the case of inorganic glasses, for which the characterization of medium range order remains challenging, the DQ-SQ correlation experiment allows to improve the structural description obtained from NMR spectroscopy by determining the pairwise connectivities between the basic building units of the disordered network. In phosphate glasses, homonuclear through-bond [22,23] and through-space [24-25] DQ-SQ correlation methods have been applied successfully to probe P-O-P connectivities between the various network former PO 4 tetrahedral units (Q n with n bridging oxygen atoms).…”

mentioning

confidence: 99%

“…1a and 1b is mostly affected by dephasing effects, it will directly benefit of the increased efficiency of heteronuclear decoupling sequences which enhance the transverse coherence lifetimes [16,44]. For example, the optimised CM decoupling sequence [45] has been shown to provide coherence lifetimes about a factor 2 longer than unoptimised TPPM [46] or SPINAL-64 [36] sequences, leading to significant increase of the sensitivity of DQ-SQ correlation spectra recorded with the refocused INADEQUATE sequence [16]. As mentioned previously [32], the TQF efficiency could also be improved using composite pulses to compensate the effect of RF field inhomogeneities.…”

mentioning

confidence: 99%

Triple-quantum correlation NMR experiments in solids using J-couplings

Fayon

Roiland

Emsley

et al. 2006

Journal of Magnetic Resonance

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We show that triple-quantum -single-quantum (TQ-SQ) correlation spectra of crystalline and disordered solids can be obtained under MAS using pulse sequences based on through-bond J-couplings. The feasibility of the experiments in coupled spin-½ systems is demonstrated for fully 13 C-labelled L-alanine and Pb 3 P 4 O 13 crystalline compounds, considered as model three-spin and four-spin systems, respectively. In the case of phosphate glasses, we show that the obtained TQ-SQ correlation spectra provide an improved description of the glass forming network connectivities and of the chain length distribution in the disordered network. IntroductionHomonuclear double-quantum correlation spectroscopy has been shown to be a valuable tool in solid-state NMR for determining atomic connectivities and studying the structure and dynamic of ordered or disordered materials [1,2]. In this context, various experiments have been developed to obtain two-dimensional (2D) double-quantum -singlequantum (DQ-SQ) correlation spectra of coupled spin-½ systems under magic angle spinning (MAS) which is required for enhanced spectral resolution and sensitivity. Many of these methods employ pulse sequences which reintroduce the MAS-averaged through-space homonuclear dipolar interaction, to obtain DQ-SQ correlation spectra which reflect the through-space atomic proximities [3][4][5][6][7][8][9][10]. Alternatively, pulse sequences based on throughbond isotropic J-couplings, like the INADEQUATE [11] and refocused INADEQUATE [12] experiments, have also been applied efficiently to obtain through-bond DQ-SQ correlation spectra for large range of materials [12][13][14][15][16][17][18][19][20][21][22][23].In the case of inorganic glasses, for which the characterization of medium range order remains challenging, the DQ-SQ correlation experiment allows to improve the structural description obtained from NMR spectroscopy by determining the pairwise connectivities between the basic building units of the disordered network. In phosphate glasses, homonuclear through-bond [22,23] and through-space [24-25] DQ-SQ correlation methods have been applied successfully to probe P-O-P connectivities between the various network former PO 4 tetrahedral units (Q n with n bridging oxygen atoms). These experiments provide enhanced spectral resolution relative to the conventional MAS spectra allowing the distinction between Q n units bonded to different types of PO 4 to be made and giving evidence of a chain length distribution in the disordered network [22][23][24][25].Nevertheless, information about longer range order, which could be obtained from a three-spin correlation experiment, remains desirable for a better description of the disordered glassy network. Recently, various dipolar recoupling pulse sequences have been proposed to obtain 1 H and 13 C homonuclear through-space triple-quantum -single-quantum (TQ-SQ) correlation spectra in solids [26][27][28][29][30]. A modified INADEQUATE experiment was also proposed to record 13 C through-bond TQ-SQ correlatio...

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Transverse Dephasing Optimized Solid-State NMR Spectroscopy

Cited by 105 publications

References 15 publications

Origins of linewidth in H1 magic-angle spinning NMR

Origins of linewidth in H1 magic-angle spinning NMR

Understanding two-pulse phase-modulated decoupling in solid-state NMR

Triple-quantum correlation NMR experiments in solids using J-couplings

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