High-Field High-Speed MAS Resolution Enhancement in 1H NMR Spectroscopy of Solids

Samoson, Ago; Tuherm, Tiit; Gan, Zhehong

doi:10.1006/snmr.2001.0037

Cited by 165 publications

(153 citation statements)

References 13 publications

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“…30 Our own measurements tend to support this proposition. Table III shows estimates of the inhomogeneous linewidths for two samples where the difference between the spin-echo and natural linewidth is large enough to enable reasonable estimates of the inhomogeneous linewidth to be made.…”

Section: Inhomogeneous Contributions To 1 H Linewidthsmentioning

confidence: 57%

“…This can lead to occasional examples where the spin-echo linewidth appears to be larger than the full natural linewidth. The inhomogeneous linewidth can also be estimated by extrapolating plots of natural linewidth versus 1 / r to infinite spin rate, 30 but this approach has its own limitations as such plots are not necessary linear ͓Fig. 9͑a͔͒.…”

Section: Inhomogeneous Contributions To 1 H Linewidthsmentioning

confidence: 99%

“…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%

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Origins of linewidth in H1 magic-angle spinning NMR

Zorin

Brown

Hodgkinson

2006

The Journal of Chemical Physics

128

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: 57%

Section: Inhomogeneous Contributions To 1 H Linewidthsmentioning

confidence: 99%

See 1 more Smart Citation

Origins of linewidth in H1 magic-angle spinning NMR

Zorin

Brown

Hodgkinson

2006

The Journal of Chemical Physics

128

116

View full text Add to dashboard Cite

show abstract

“…The contribution of the rank four component of the susceptibility is averaged out by MAS as shown in Ref. [3].…”

Section: Methodsmentioning

confidence: 99%

“…The time dependent spatial part of the anisotropic interactions averages over a rotor period and the time independent component is canceled by the choice of the angle. Currently, MAS is applied routinely in most high-resolution solid-state NMR experiments, and spinning frequencies continue to increase dramatically with increasing B 0 [3].…”

Section: Introductionmentioning

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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First Experimental Observation on Different Ionic States of thetert-Butoxy [(CH3)3CO.] Radical

et al. 2001

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A continuous tert-butoxy (CH3)+CO* radical beam is produced in situ by respective pyrolysis of both (CH3)3CONO at 115(+/-0.5) degrees C and (CH3)3COOC(CH3)3 at 87(+/- 0.5) degrees C. By combining the HeI photoelectron (PE) spectrum with the improved density function theory (DFT) calculations, we have concluded that the (CH3)3CO* radical has C3V symmetry and X2E ground state. The study does not only provide the ionization energies of different ionic states of the (CH3)3CO* radical for the first time, but also the first example in which there have been similar vibrational structures in different ionic states caused by removal of the electron on an orbital. It is also pointed out that (CH3)3CONO is a good source for obtaining the (CH3)3CO* radical beam, and that NO is a stable regent for the active radical. The results will promote the studies in electron spin resonance (ESR) research on the mechanisms of both the initiation of the formation of a new radical and the radical-chain polymerization in which the (CH3)3CO* radical participates.

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High-Field High-Speed MAS Resolution Enhancement in 1H NMR Spectroscopy of Solids

Cited by 165 publications

References 13 publications

Origins of linewidth in H1 magic-angle spinning NMR

Origins of linewidth in H1 magic-angle spinning NMR

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

First Experimental Observation on Different Ionic States of thetert-Butoxy [(CH3)3CO.] Radical

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