scholarly journals Microanisotropy imaging: quantification of microscopic diffusion anisotropy and orientational order parameter by diffusion MRI with magic-angle spinning of the q-vector

2014 ◽  
Vol 2 ◽  
Author(s):  
Samo Lasič ◽  
Filip Szczepankiewicz ◽  
Stefanie Eriksson ◽  
Markus Nilsson ◽  
Daniel Topgaard
Keyword(s):  
Diffusion Mri ◽  
Order Parameter ◽  
Orientational Order ◽  
Magic Angle Spinning ◽  
Magic Angle ◽  
Orientational Order Parameter ◽  
Diffusion Anisotropy ◽  
Angle Spinning ◽  
Q Vector

scholarly journals Efficient polynomial analysis of MAS spinning sidebands and application to order parameter determination in anisotropic samples

2021 ◽  
Author(s):  
Günter Hempel ◽  
Paul Sotta ◽  
Didier R. Long ◽  
Kay Saalwächter
Keyword(s):  
Solid State Nmr ◽  
Order Parameter ◽  
Magic Angle Spinning ◽  
Parameter Determination ◽  
Magic Angle ◽  
Chemical Shift Tensors ◽  
Fitting Procedure ◽  
The Common ◽  
Angle Spinning

Abstract. Chemical shift tensors in 13C solid-state NMR provide valuable localized information on the chemical bonding environment in organic matter, and deviations from isotropic static-limit powder lineshapes sensitively encode dynamic-averaging or orientation effects. Studies in 13C natural abundance require magic-angle spinning (MAS), where the analysis must thus focus on spinning sidebands. We propose an alternative fitting procedure for spinning sidebands based upon a polynomial expansion that is more efficient 5 than the common numerical solution of the powder average. The approach plays out its advantages in the determination of CST principal values from spinning-sideband intensities and order parameters in non-isotropic samples, which is here illustrated on the example of stretched glassy polycarbonate.

Pulse Shaped Dynamic Nuclear Polarization Under Magic Angle Spinning

2019 ◽  
Author(s):  
ASIF EQUBAL ◽  
Kan Tagami ◽  
Songi Han
Keyword(s):  
Electron Spin ◽  
Lattice Relaxation ◽  
Magic Angle Spinning ◽  
Spin Lattice Relaxation ◽  
Magic Angle ◽  
Total Electron ◽  
Spin Lattice ◽  
Maximum Benefit ◽  
Selective Saturation ◽  
Angle Spinning

In this paper, we report on an entirely novel way of improving the MAS-DNP efficiency by shaped μw pulse train irradiation for fast and broad-banded (FAB) saturation of the electron spin resonance. FAB-DNP achieved with Arbitrary Wave Generated shaped μw pulse trains facilitates effective and selective saturation of a defined fraction of the total electron spins, and provides superior control over the DNP efficiency under MAS. Experimental and quantum-mechanics based numerically simulated results together demonstrate that FAB-DNP significantly outperforms CW-DNP when the EPR-line of PAs is broadened by conformational distribution and exchange coupling. We demonstrate that the maximum benefit of FAB DNP is achieved when the electron spin-lattice relaxation is fast relative to the MAS frequency, i.e. at higher temperatures and/or when employing metals as PAs. Calculations predict that under short T<sub>1e </sub>conditions AWG-DNP can achieve as much as ~4-fold greater enhancement compared to CW-DNP.

High Resolution Magic Angle Spinning NMR in Combinatorial Chemistry

2001 ◽  
Vol 4 (4) ◽  
pp. 333-351 ◽  
Author(s):  
G. Lippens ◽  
R. Warrass ◽  
J. Wieruszeski ◽  
P. Rousselot-Pailley ◽  
G. Chessari
Keyword(s):  
High Resolution ◽  
Combinatorial Chemistry ◽  
Magic Angle Spinning ◽  
Magic Angle ◽  
Angle Spinning

Wideline 2H -NMR Spectroscopy and Imaging of Solids

1994 ◽  
Vol 49 (1-2) ◽  
pp. 19-26 ◽  
Author(s):  
B. Blümich
Keyword(s):  
Nmr Spectroscopy ◽  
Excitation Power ◽  
Magic Angle Spinning ◽  
Magic Angle ◽  
2H Nmr ◽  
Stochastic Excitation ◽  
2H Nmr Spectroscopy ◽  
Spatially Inhomogeneous ◽  
Recent Developments ◽  
Angle Spinning

Abstract Recent developments, focussing on reduction of the rf excitation power by stochastic excitation, on improvements in sensitivity and excitation bandwidth by magic angle spinning, and on combining wideline spectroscopy with spatial resolution for investigations o f spatially inhomogeneous objects are reviewed.

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