29Si dynamic nuclear polarization of dehydrogenated amorphous silicon

Lock, Herman; Wind, Robert A.; Maciel, Gary E.; Zumbulyadis, Nicholas

doi:10.1016/0038-1098(87)90516-3

Cited by 21 publications

(25 citation statements)

References 16 publications

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“…The crystalline Si NP sample shows a slightly narrower resonance (linewidth ~ 2.2 kHz) shifted by ~ 600 Hz from the amorphous peak. Both linewidths are broader than the ~ 500 Hz linewidth observed for bulk crystalline silicon 55 and 1.8 kHz linewidth observed for bulk amorphous silicon, 58 most probably due to strain.…”

Section: Resultsmentioning

confidence: 57%

Synthesis of LongT₁Silicon Nanoparticles for Hyperpolarized²⁹Si Magnetic Resonance Imaging

et al. 2013

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We describe the synthesis, materials characterization and dynamic nuclear polarization (DNP) of amorphous and crystalline silicon nanoparticles for use as hyperpolarized magnetic resonance imaging (MRI) agents. The particles were synthesized by means of a metathesis reaction between sodium silicide (Na4Si4) and silicon tetrachloride (SiCl4) and were surface functionalized with a variety of passivating ligands. The synthesis scheme results in particles of diameter ~10 nm with long size-adjusted 29Si spin lattice relaxation (T1) times (> 600 s), which are retained after hyperpolarization by low temperature DNP.

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Section: Resultsmentioning

confidence: 57%

Synthesis of LongT₁Silicon Nanoparticles for Hyperpolarized²⁹Si Magnetic Resonance Imaging

et al. 2013

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“…DNP phenomenon at low static magnetic field, B 0 , was initially reported in metals (B 0 = 3 mT) [6] and then semiconductors (B 0 & 0.3 T) [7]. For instance, low-field DNP has been applied for n-type silicon, amorphous silicon or hydrogenated amorphous silicon, using dangling bonds as endogenous polarizing agents [7,9,14]. The combination of DNP at B 0 & 1.4 T with magic-angle spinning (MAS) has allowed its application to carbonaceous materials, such as organic polymers, coals and diamonds [8,10].…”

Section: Introductionmentioning

confidence: 98%

“…Dynamic nuclear polarization (DNP) is a promising method to enhance the NMR signal of materials by one or two orders of magnitude [6][7][8][9][10][11][12][13][14][15][16][17][18][19]. Since its invention, DNP has been applied to materials.…”

Section: Introductionmentioning

confidence: 99%

Solvent-Free High-Field Dynamic Nuclear Polarization of Mesoporous Silica Functionalized with TEMPO

Thankamony

Lafon

et al. 2012

Appl Magn Reson

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We report high-field magic-angle spinning dynamic nuclear polarization (MAS DNP) of mesoporous silica functionalized with nitroxide radicals. These results demonstrate that co-condensation can be employed to incorporate DNP polarizing agents into inorganic materials and that solvent-free DNP is feasible for porous materials. For the investigated material, the direct MAS DNP enhances the 29 Si nuclear magnetic resonance (NMR) spectra, whereas the indirect MAS DNP via protons is inapplicable owing to the inefficiency of 1 H ! 29 Si cross polarization transfer. Furthermore, the 29 Si signals in direct experiments build up in a few seconds at 100 K. This fast polarization buildup improves the NMR sensitivity and will be useful for the investigation of direct DNP below 100 K.

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“…The 15 N isotope has a spin 1/2 and, like 13 C, the chemical shift and chemical shift tensor principal values can be related to molecular structure. The large chemical shift range of the 15 N isotope (∼1100 ppm) provides an enhanced sensitivity to molecular structure variations and intermolecular interactions that exceeds other first row elements.…”

Section: Introductionmentioning

confidence: 99%

“…Hence, only limited amounts of data have been acquired in the solid state on the nitrogen shift and their principal shift values in nitrogen heterocycles. For example, for 1 H, 13 C, and 15 N nuclei the maximum enhancement factors are 660, 2600, and 6500, respectively. Further, a third signal enhancement alternative, dynamic nuclear polarization (DNP), has been known 7-11 for a number of years.…”

Section: Introductionmentioning

confidence: 99%

Enantioselective Synthesis of Six-Membered Palladacycles Having Metal-Bound Stereogenic Carbons: Isolation and Reactivity of Palladacycles Containing Readily Accessible β-Hydrogens

Burke

Overman

2004

J. Am. Chem. Soc.

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Five enantiopure palladacycles containing palladium bonded to a stereogenic carbon and an N-coordinated oxindole were synthesized by the reaction of alkenyl aryl triflates 2 and 9 with Pd(0) bisphosphine complexes. Two palladacyclic complexes, 3beta and 10alpha, were characterized by single-crystal X-ray crystallography. The reactivity of neutral palladacycles 3beta and 10beta was studied in detail. These unusual palladium alkyls, which have three accessible beta-hydrogens, are thermally stable at temperatures as high as 120 degrees C. At higher temperature, or at room temperature in the presence of weak acids, these complexes epimerize at the stereogenic carbon bonded to palladium. The mechanism of the acid-promoted epimerization was studied in detail. During this epimerization, cationic palladium alkyls 13/14 and 33 and cationic palladium hydride alkene complexes 31 and 32 are in rapid equilibrium.

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29Si dynamic nuclear polarization of dehydrogenated amorphous silicon

Cited by 21 publications

References 16 publications

Synthesis of LongT₁Silicon Nanoparticles for Hyperpolarized²⁹Si Magnetic Resonance Imaging

Synthesis of LongT₁Silicon Nanoparticles for Hyperpolarized²⁹Si Magnetic Resonance Imaging

Solvent-Free High-Field Dynamic Nuclear Polarization of Mesoporous Silica Functionalized with TEMPO

Enantioselective Synthesis of Six-Membered Palladacycles Having Metal-Bound Stereogenic Carbons: Isolation and Reactivity of Palladacycles Containing Readily Accessible β-Hydrogens

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29Si dynamic nuclear polarization of dehydrogenated amorphous silicon

Cited by 21 publications

References 16 publications

Synthesis of LongT1Silicon Nanoparticles for Hyperpolarized29Si Magnetic Resonance Imaging

Synthesis of LongT1Silicon Nanoparticles for Hyperpolarized29Si Magnetic Resonance Imaging

Solvent-Free High-Field Dynamic Nuclear Polarization of Mesoporous Silica Functionalized with TEMPO

Enantioselective Synthesis of Six-Membered Palladacycles Having Metal-Bound Stereogenic Carbons: Isolation and Reactivity of Palladacycles Containing Readily Accessible β-Hydrogens

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Synthesis of LongT₁Silicon Nanoparticles for Hyperpolarized²⁹Si Magnetic Resonance Imaging

Synthesis of LongT₁Silicon Nanoparticles for Hyperpolarized²⁹Si Magnetic Resonance Imaging