Deuterium NMR in Solids

Batchelder, Lynne S.

doi:10.1002/9780470034590.emrstm0111

Cited by 5 publications

(6 citation statements)

References 19 publications

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“…Solid-state nuclear magnetic resonance (NMR) assisted in identifying dynamic and frozen water within the hydrogels. Analysis of the line shape of the 2 H NMR spectra (samples prepared in D 2 O) was particularly useful in assessing the behavior of water in these samples . All these findings are consistent with our observation of the increased ionic conductivity of the hydrogel at low temperatures.…”

Section: Introductionsupporting

confidence: 87%

“…Since we normalized I ( q ) by the sample thickness, the relative values of f p are meaningful, assuming that (Δ p ) 2 does not vary from sample to sample. The form factor of a primary particle P ( q ) is modeled as that for polydisperse spheres with fractal internal structure . The fractal power-law exponent D f ∼ 2 ( vide supra ) indicates that the internal structure of the primary particle is Gaussian-chain-like .…”

Section: Resultsmentioning

confidence: 99%

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Low-Temperature Ionic Conductivity Enhanced by Disrupted Ice Formation in Polyampholyte Hydrogels

Charaya

Bernard

et al. 2018

Macromolecules

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The phase behavior of water in hydrogels has a broad impact on many health and energy applications. Our previous study showed that polyampholyte hydrogel has the potential to be used as an aqueous gel electrolyte in electrochemical storage devices at −30 °C due to enhanced low-temperature conductivity. In this study, we detail the impact polymer structure has on this enhanced conductivity, explaining this finding with a model charge-balanced polyampholyte, poly(4-vinylbenzenesulfonate-co-[3-(methacryloylamino)propyl]trimethylammonium chloride), a hydrogel whose polymer and water structures are probed by variable-temperature SAXS, WAXS, and solid-state NMR spectroscopy. SAXS results at room temperature indicate a networked globule structure in the charge-balanced polyampholyte hydrogels. The globular radius of gyration is ∼2.5 nm, whereas the globular size and its clustering structure are dependent on synthesis parameters. Variable-temperature SAXS data reveal a temperature-dependent structure evolution of the polyampholyte hydrogel. An interconnected globular network structure of polymer-rich phase at low temperature, observed by electron microscopy, is suggested to preserve ion-conducting channels of nonfrozen water molecules at low temperatures. This hypothesis is further supported by solid-state NMR spectroscopy. Together these findings provide macromolecular-and molecular-level insight that may be used to design gel electrolytes for enhanced low-temperature performance.

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Section: Introductionsupporting

confidence: 87%

Section: Resultsmentioning

confidence: 99%

Low-Temperature Ionic Conductivity Enhanced by Disrupted Ice Formation in Polyampholyte Hydrogels

Charaya

Bernard

et al. 2018

Macromolecules

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“…Even if short N···O distances (<3.10 Å) have been found in the crystal structure of compound 1 , the 2 H SSNMR data (Figure d) uncover that the strength of the N–H···O hydrogen bond is not sufficient to avoid the rapid reorientation of ND 4 + , which effectively averages the quadrupolar coupling interaction between 2 H and surrounding electric field gradient and results in a narrow and featureless 2 H NMR peak. The reorientation of ND 4 + only slows (with a greater 2 H NMR peak width), and not stops even at 193 K. , More energy is thus exhausted during the breakage and reformation of hydrogen bonds, reducing the radiative recombination efficiency. The extensive exploration of this type of material, with exceptional compositional variability on both metal halides and organic–inorganic hybrid cations, can yield new materials with improved PL performances such as higher PLQY and CRI values, optimized CCT value and CIE coordinates, etc., exhibiting great potential in applications as white-light illumination sources.…”

Section: Resultsmentioning

confidence: 99%

Identification of Singlet Self-Trapped Excitons in a New Family of White-Light-Emitting Zero-Dimensional Compounds

Qin

et al. 2020

J. Phys. Chem. C

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As illumination is a fundamental human need, the exploration of illumination sources possessing high efficiency and broadband white-light emission is highly desirable. Zero-dimensional (0D) metal halide compounds are promising candidates, and some lead-free antimony-containing compounds exhibit bimodal white-light emissions. However, their origins are still unclear. To solve this issue, we designed and prepared a new family of 0D metal halide compounds consisting of [M(18-crown-6)] + (M = NH 4 , Rb) and SbX 5 2− (X = Cl, Br) units. We found that the emission profiles of 0D compounds are distinct to and well separated from that of 18-crown-6 ether, excluding the intraligand charge transfer mechanism proposed in several reports. Femtosecond transient absorption data and the compositional dependence of photophysical properties imply that bimodal white-light emission is induced by both singlet state and triplet state of the self-trapped excitons ( 1 STE and 3 STE) coupled to metal halides. These 0D compounds are also very efficient emitters, with a white-light photoluminescence quantum yield as high as 54%.

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“…In atomic physics, finite moments with rank λ = 1 are called orientation, while finite moments with rank λ = 2 are called alignment (Auzinsh et al (2014)). Although the term orientation is not generally used for this purpose in the magnetic resonance community, the term alignment is used to imply rank-2 multipole order, particularly in the context of solid-state NMR as applied to quadrupolar nuclei (Batchelder (2007)). For isolated spins-I, the terms spin alignment and quadrupolar order may be regarded as synonymous.…”

Section: Discussionmentioning

confidence: 99%

Hyperpolarization and the Physical Boundary of Liouville Space

Levitt¹,

Bengs²

2021

Preprint

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Abstract. The quantum state of a spin ensemble is described by a density operator, which corresponds to a point in the Liouville space of orthogonal spin operators. Valid density operators are confined to a particular region of Liouville space, which we call the physical region, and which is bounded by multidimensional figures called simplexes. Each vertex of a simplex corresponds to a pure-state density operator. We provide examples for spins I = 1 / 2, I = 1, I = 3 / 2, and for coupled pairs of spins-1/2. We use the von Neumann entropy as a criterion for hyperpolarization. It is shown that the inhomogeneous master equation for spin dynamics leads to non-physical results in some cases, a problem that may be avoided by using the Lindbladian master equation.

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Deuterium NMR in Solids

Cited by 5 publications

References 19 publications

Low-Temperature Ionic Conductivity Enhanced by Disrupted Ice Formation in Polyampholyte Hydrogels

Low-Temperature Ionic Conductivity Enhanced by Disrupted Ice Formation in Polyampholyte Hydrogels

Identification of Singlet Self-Trapped Excitons in a New Family of White-Light-Emitting Zero-Dimensional Compounds

Hyperpolarization and the Physical Boundary of Liouville Space

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