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

Sakellariou, Dimitrios; Meriles, Carlos A.; Martin, Rachel W.; Pines, Alexander

doi:10.1016/s0009-2614(03)01149-7

Cited by 8 publications

(13 citation statements)

References 26 publications

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“…Initially this was tested using a model system of water beads and oil. [38] The results presented here suggest that the tissue broadening is spatially correlated as the results from the model system had suggested. This provides motivation to further pursue development of the p-MAT sequence.…”

Section: Introductionsupporting

confidence: 69%

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New Methodology For Use in Rotating Field Nuclear MagneticResonance

Jachmann

2007

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High-resolution NMR spectra of samples with anisotropic broadening are simplified to their isotropic spectra by fast rotation of the sample at the magic angle 54.7 • . This dissertation concerns the development of novel Nuclear Magnetic Resonance(NMR) methodologies which would rotate the magnetic field instead of the sample, i.e. rotating field NMR. It also provides an overview of the NMR concepts, procedures, and experiments needed to understand the methodologies that will be used for rotating field NMR.A simple two-dimensional shimming method based on harmonic corrector rings provides arbitrary multiple order shimming corrections that are necessary for rotating field systems, but can be used in shimming other systems as well. Those results demonstrate, for example, that quadrupolar order shimming improves the linewidth by up to a factor of ten. An additional order of magnitude reduction is in principle achievable by utilizing this shimming method for z-gradient correction and higher order xy gradients.Additionally, initial investigations into a specialized pulse sequence for the rotating field NMR experiment, which allows for spinning at angles other than the magic angle and spinning slower than the anisotropic broadening is discussed. This will be useful for rotating field NMR because there are limits on how fast a field can be spun and difficulties of reaching the magic angle. This pulse sequence is a combination of the previously established projected magic angle spinning (p-MAS) and magic angle turning (MAT) pulse sequences. One of the goals of this project is for rotating field NMR to be used on biological systems. The p-MAS pulse sequence was successfully tested on bovine tissue samples, which suggests that it will be a viable methodology to use in rotating field NMR.A side experiment on steering magnetic particles by MRI gradients was also carried out.Initial investigations indicate some movement, but for total steering control, further experiments are needed.1

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Section: Introductionsupporting

confidence: 69%

“…For p-MAS, depicted in Figure 7.4 [38], a two-dimensional data set was collected. Frequency sign discrimination in both dimensions was achieved with phase cycling.…”

Section: Methodsmentioning

confidence: 99%

New Methodology For Use in Rotating Field Nuclear MagneticResonance

Jachmann

2007

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“…Futhermore, Halbach arrays eliminate the need for a power supply, which can be important in portable "exsitu" and rotating field type sytems. Fulfilling the need for a shimming systems suited for rotating field NMR systems 5,6 would be technically challenging in connecting and controling electro-coil shims as the shimming coils would need to rotate with the field. However permanent magnets supply a perfect solution as they have no leads which would tangle as the bore rotates.…”

Section: Introductionmentioning

confidence: 99%

Multipole shimming of permanent magnets using harmonic corrector rings

Jachmann

Trease

Bouchard

et al. 2007

Review of Scientific Instruments

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Shimming systems are required to provide sufficient field homogeneity for high resolution NMR. In certain specialized applications, such as rotating-field NMR and portable (ex-situ) NMR, permanent magnet-based shimming systems can provide considerable advantages. We present a simple two-dimensional shimming method based on harmonic corrector rings which can provide arbitrary multipole order shimming corrections. Results demonstrate, for example, that quadrupolar order shimming improves the linewidth by up to an order of magnitude. An additional order of magnitude reduction is in princliple achievable by ultilizing this shimming method for z-gradient correction and higher order xy gradients.

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“…This shows that the field one can achieve for such system will always be of the order of 0.5 Tesla having a relatively large inhomogeneity at the center. The power that is needed for the rotation depends dramatically on the angle as shown in [9] and a decrease of 70 % can be easily performed by working between 0 and 20 degrees. Such projected-MAS experiments should be in principle possible using an electromagnetic field rotation, provided that the size of the field and it inhomogeneity are enough in order to see fine interactions (chemical shifts).…”

Section: Discussion About Field Rotationmentioning

confidence: 99%

NMR in rotating magnetic fields: magic-angle field spinning

Sakellariou¹,

Meriles²,

Martin³

et al. 2005

Magnetic Resonance Imaging

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Magic angle sample spinning has been one of the cornerstones in high-resolution solid state NMR. Spinning frequencies nowadays have increased by at least one order of magnitude over the ones used in the first experiments and the technique has gained tremendous popularity. It is currently a routine procedure in solid-state NMR, highresolution liquid-state NMR and solid-state MRI. The technique enhances the spectral resolution by averaging away rank 2 anisotropic spin interactions thereby producing isotropic-like spectra with resolved chemical shifts and scalar couplings. Andrew proposed that it should be possible to induce similar effects in a static sample if the direction of the magnetic field is varied, e.g., magic-angle rotation of the B 0 field (B 0 -MAS) and this has been recently demonstrated using electromagnetic field rotation. Here we discuss on the possibilities to perform field rotation using alternative hardware, together with spectroscopic methods to recover isotropic resolution even in cases where the field is not rotating at the magic angle. Extension to higher magnetic fields would be beneficial in situations where the physical manipulation of the sample is inconvenient or impossible. Such situations occur often in materials or biomedical samples where "exsitu" NMR spectroscopy and imaging analysis is needed.

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

Cited by 8 publications

References 26 publications

New Methodology For Use in Rotating Field Nuclear MagneticResonance

New Methodology For Use in Rotating Field Nuclear MagneticResonance

Multipole shimming of permanent magnets using harmonic corrector rings

NMR in rotating magnetic fields: magic-angle field spinning

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