scholarly journals Direct observation of hyperpolarization breaking through the spin diffusion barrier

2021 ◽  
Vol 7 (18) ◽  
pp. eabf5735
Author(s):  
Quentin Stern ◽  
Samuel François Cousin ◽  
Frédéric Mentink-Vigier ◽  
Arthur César Pinon ◽  
Stuart James Elliott ◽  
...  
Keyword(s):  
Diffusion Barrier ◽  
Nuclear Polarization ◽  
Spin Diffusion ◽  
Magic Angle Spinning ◽  
Resonance Spectroscopy ◽  
Magic Angle ◽  
Paramagnetic Centers ◽  
Static Mode ◽  
Angle Spinning ◽  
Marked Dependence

Dynamic nuclear polarization (DNP) is a widely used tool for overcoming the low intrinsic sensitivity of nuclear magnetic resonance spectroscopy and imaging. Its practical applicability is typically bounded, however, by the so-called “spin diffusion barrier,” which relates to the poor efficiency of polarization transfer from highly polarized nuclei close to paramagnetic centers to bulk nuclei. A quantitative assessment of this barrier has been hindered so far by the lack of general methods for studying nuclear polarization flow in the vicinity of paramagnetic centers. Here, we fill this gap and introduce a general set of experiments based on microwave gating that are readily implemented. We demonstrate the versatility of our approach in experiments conducted between 1.2 and 4.2 K in static mode and at 100 K under magic angle spinning (MAS)—conditions typical for dissolution DNP and MAS-DNP—and directly observe the marked dependence of polarization flow on temperature.

Electron-driven spin diffusion supports crossing the diffusion barrier in MAS DNP

2018 ◽  
Vol 20 (16) ◽  
pp. 11418-11429 ◽  
Author(s):  
Johannes J. Wittmann ◽  
Michael Eckardt ◽  
Wolfgang Harneit ◽  
Björn Corzilius
Keyword(s):  
Dynamic Nuclear Polarization ◽  
Diffusion Barrier ◽  
Nuclear Polarization ◽  
Spin Diffusion ◽  
Hyperfine Interactions ◽  
Magic Angle Spinning ◽  
Magic Angle ◽  
Diffusion Rates ◽  
Angle Spinning

Hyperfine interactions can quench homonuclear spin-diffusion in the direct vicinity of a polarizing agent in dynamic nuclear polarization (DNP). However, under magic-angle spinning (MAS), the same interactions may also enhance the spin-diffusion rates through an electron-driven spin diffusion (EDSD) mechanism introduced here.

scholarly journals Preparation of Li3PS4–Li3PO4 Solid Electrolytes by Liquid-Phase Shaking for All-Solid-State Batteries

2021 ◽  
Vol 2 (1) ◽  
pp. 39-48
Author(s):  
Nguyen H. H. Phuc ◽  
Takaki Maeda ◽  
Tokoharu Yamamoto ◽  
Hiroyuki Muto ◽  
Atsunori Matsuda
Keyword(s):  
Solid Solution ◽  
Solid State ◽  
Liquid Phase ◽  
Room Temperature ◽  
Reaction Medium ◽  
Magic Angle Spinning ◽  
Resonance Spectroscopy ◽  
Synthesis Methods ◽  
Magic Angle ◽  
Angle Spinning

A solid solution of a 100Li3PS4·xLi3PO4 solid electrolyte was easily prepared by liquid-phase synthesis. Instead of the conventional solid-state synthesis methods, ethyl propionate was used as the reaction medium. The initial stage of the reaction among Li2S, P2S5 and Li3PO4 was proved by ultraviolet-visible spectroscopy. The powder X-ray diffraction (XRD) results showed that the solid solution was formed up to x = 6. At x = 20, XRD peaks of Li3PO4 were detected in the prepared sample after heat treatment at 170 °C. However, the samples obtained at room temperature showed no evidence of Li3PO4 remaining for x = 20. Solid phosphorus-31 magic angle spinning nuclear magnetic resonance spectroscopy results proved the formation of a POS33− unit in the sample with x = 6. Improvements of ionic conductivity at room temperature and activation energy were obtained with the formation of the solid solution. The sample with x = 6 exhibited a better stability against Li metal than that with x = 0. The all-solid-state half-cell employing the sample with x = 6 at the positive electrode exhibited a better charge–discharge capacity than that employing the sample with x = 0.

scholarly journals 15N photochemically induced dynamic nuclear polarization magic-angle spinning NMR analysis of the electron donor of photosystem II

2007 ◽  
Vol 104 (31) ◽  
pp. 12767-12771 ◽  
Author(s):  
A. Diller ◽  
E. Roy ◽  
P. Gast ◽  
H. J. van Gorkom ◽  
H. J. M. de Groot ◽  
...  
Keyword(s):  
Photosystem Ii ◽  
Electron Donor ◽  
Dynamic Nuclear Polarization ◽  
Nuclear Polarization ◽  
Magic Angle Spinning ◽  
Magic Angle ◽  
Nmr Analysis ◽  
Angle Spinning

scholarly journals Instrumentation for cryogenic magic angle spinning dynamic nuclear polarization using 90 L of liquid nitrogen per day

2017 ◽  
Vol 283 ◽  
pp. 71-78 ◽  
Author(s):  
Brice J. Albert ◽  
Seong Ho Pahng ◽  
Nicholas Alaniva ◽  
Erika L. Sesti ◽  
Peter W. Rand ◽  
...  
Keyword(s):  
Liquid Nitrogen ◽  
Dynamic Nuclear Polarization ◽  
Nuclear Polarization ◽  
Magic Angle Spinning ◽  
Magic Angle ◽  
Angle Spinning

Leucite-pollucite structure-type variability and the structure of a synthetic end-member calcium wairakite (CaAl2Si4O12·2H2O)

1998 ◽  
Vol 62 (2) ◽  
pp. 165-178 ◽  
Author(s):  
C. M. B. Henderson ◽  
A. M. T. Bell ◽  
S. C. Kohn ◽  
C. S. Page
Keyword(s):  
Rietveld Analysis ◽  
Structure Type ◽  
Magic Angle Spinning ◽  
Resonance Spectroscopy ◽  
Magic Angle ◽  
Synthetic Sample ◽  
Cation Site ◽  
Wide Range ◽  
Angle Spinning ◽  
Cation Sites

AbstractThe structure of a synthetic end-member wairakite (CaAl2Si4O12·2H2O) has been determined using Rietveld analysis of high-resolution, synchrotron X-ray powder diffraction data, and 29Si and 27Al magic angle spinning nuclear magnetic resonance spectroscopy. The framework in the synthetic sample is more disordered than that in natural wairakite. Ca is distributed over the cavity cation sites M2, M12A, M12B in the approximate proportions 0.8:0.1:0.1, respectively, with M11 being vacant. 29Si MAS NMR data are consistent with about 80% of the Si occupying tetrahedral T11 and T12 sites linked to two Al atoms [Q4(2Al) silicons]. Tetrahedral and cavity cation site disorder are coupled so that Al mainly occupies T2 sites, with Ca in M12A and M12B being balanced by Al in T12A and T12B; T11A and T11B sites appear to only contain Si, in agreement with the M11 site being vacant. The crystal chemistries of the wide range of stoichiometries which crystallize with the leucite/pollucite structure-type are also reviewed, with particular attention being paid to the tetrahedral ordering configurations present in these phases, and the implications to crystallographic phase transitions.

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