Variable-angle correlation spectroscopy in solid-state nuclear magnetic resonancea)

Frydman, Lucio; Chingas, G. C.; Lee, Young Kyung; Grandinetti, Philip J.; Eastman, Margaret A.; Barrall, Geoffrey A.; Pines, Alexander

doi:10.1063/1.463860

Cited by 135 publications

(91 citation statements)

References 22 publications

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“…Since it would require stroboscopic acquisition during fast reorientation of the spinning axis, such 1D versions would be particularly well adapted for field spinning experiments. Along the same ideas, Variable Angle Spinning [26] could also offer an interesting alternative. Its limited angle version is currently under development.…”

Section: Discussionmentioning

confidence: 99%

High-resolution NMR of anisotropic samples with spinning away from the magic angle

Sakellariou

Meriles

Martin

et al. 2003

Chemical Physics Letters

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High-resolution NMR of samples in the solid state is typically performed under mechanical sample spinning around an axis that makes an angle, called the magic angle, of 54.7 degrees with the static magnetic field. There are many cases in which geometrical and engineering constraints prevent spinning at this specific angle. Implementations of in-situ and ex-situ magic angle field spinning might be extremely demanding because of the power requirements or an inconvenient sample size or geometry. Here we present a methodology based on switched angle spinning between two angles, none of which is the magic angle, which provides both isotropic and anisotropic information. Using this method, named Projected Magic Angle Spinning, we were able to obtain resolved scaled isotropic chemical shifts in spinning samples where the broadening is mostly inhomogeneous.

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Section: Discussionmentioning

confidence: 99%

High-resolution NMR of anisotropic samples with spinning away from the magic angle

Sakellariou

Meriles

Martin

et al. 2003

Chemical Physics Letters

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“…This expression could be modified to include multiple components with different diffusion properties, which could then be resolved in the experimental data if they have significantly different values of the isotropic diffusivity D iso . Such a separation and correlation of the isotropic and anisotropic features are analogous to the variable-angle spinning 51 and switched-angle spinning 52 techniques in solidstate NMR spectroscopy.…”

Section: Discussionmentioning

confidence: 99%

NMR diffusion-encoding with axial symmetry and variable anisotropy: Distinguishing between prolate and oblate microscopic diffusion tensors with unknown orientation distribution

Eriksson

Lasič

Nilsson

et al. 2015

The Journal of Chemical Physics

173

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We introduce a nuclear magnetic resonance method for quantifying the shape of axially symmetric microscopic diffusion tensors in terms of a new diffusion anisotropy metric, DΔ, which has unique values for oblate, spherical, and prolate tensor shapes. The pulse sequence includes a series of equal-amplitude magnetic field gradient pulse pairs, the directions of which are tailored to give an axially symmetric diffusion-encoding tensor b with variable anisotropy bΔ. Averaging of data acquired for a range of orientations of the symmetry axis of the tensor b renders the method insensitive to the orientation distribution function of the microscopic diffusion tensors. Proof-of-principle experiments are performed on water in polydomain lyotropic liquid crystals with geometries that give rise to microscopic diffusion tensors with oblate, spherical, and prolate shapes. The method could be useful for characterizing the geometry of fluid-filled compartments in porous solids, soft matter, and biological tissues.

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“…Numerous methods have been developed to reintroduce the anisotropic chemical shift interactions in the indirect dimensions under MAS conditions. [15][16][17][18][19][20][21][22][23][24][25][26][27][28][29][30][31][32] For most of these recoupling methods, determination of the CSA parameters requires analysis of the spinning sideband patterns 16, 21, 23, 26-29, 31, 32 or powder patterns, 15, 17-20, 22, 24, 25, 30 and usually periodic radio frequency (rf) field irradiation is applied in synchrony with the MAS sample rotation during the evolution period. In these recoupling techniques, the required rf field strengths are generally so high that, in practice, these sequences are only applicable under low or moderate MAS conditions.…”

Section: Introductionmentioning

confidence: 99%

Recoupling of chemical shift anisotropy by R-symmetry sequences in magic angle spinning NMR spectroscopy

Hou

Byeon

Ahn

et al. 2012

The Journal of Chemical Physics

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C and15 N chemical shift (CS) interaction is a sensitive probe of structure and dynamics in a wide variety of biological and inorganic systems, and in the recent years several magic angle spinning NMR approaches have emerged for residue-specific measurements of chemical shift anisotropy (CSA) tensors in uniformly and sparsely enriched proteins. All of the currently existing methods are applicable to slow and moderate magic angle spinning (MAS) regime, i.e., MAS frequencies below 20 kHz. With the advent of fast and ultrafast MAS probes capable of spinning frequencies of 40-100 kHz, and with the superior resolution and sensitivity attained at such high frequencies, development of CSA recoupling techniques working under such conditions is necessary. In this work, we present a family of R-symmetry based pulse sequences for recoupling of 13 C/ 15 N CSA interactions that work well in both natural abundance and isotopically enriched systems. We demonstrate that efficient recoupling of either first-rank (σ 1 ) or second-rank (σ 2 ) spatial components of CSA interaction is attained with appropriately chosen γ -encoded RN n v symmetry sequences. The advantage of these γ -encoded RN n v -symmetry based CSA (RNCSA) recoupling schemes is that they are suitable for CSA recoupling under a wide range of MAS frequencies, including fast MAS regime. Comprehensive analysis of the recoupling properties of these RN n v symmetry sequences reveals that the σ 1 -CSA recoupling symmetry sequences exhibit large scaling factors; however, the partial homonuclear dipolar Hamiltonian components are symmetry allowed, which makes this family of sequences suitable for CSA measurements in systems with weak homonuclear dipolar interactions. On the other hand, the γ -encoded symmetry sequences for σ 2 -CSA recoupling have smaller scaling factors but they efficiently suppress the homonuclear dipole-dipole interactions. Therefore, the latter family of sequences is applicable for measurements of CSA parameters in systems with strong homonuclear dipolar couplings, such as uniformly-13 C labeled biological solids. We demonstrate RNCSA NMR experiments and numerical simulations establishing the utility of this approach to the measurements of 13

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Variable-angle correlation spectroscopy in solid-state nuclear magnetic resonancea)

Cited by 135 publications

References 22 publications

High-resolution NMR of anisotropic samples with spinning away from the magic angle

High-resolution NMR of anisotropic samples with spinning away from the magic angle

NMR diffusion-encoding with axial symmetry and variable anisotropy: Distinguishing between prolate and oblate microscopic diffusion tensors with unknown orientation distribution

Recoupling of chemical shift anisotropy by R-symmetry sequences in magic angle spinning NMR spectroscopy

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