Quasielastic neutron scattering for the investigation of diffusive motions in solids and liquids

Springer, T.

doi:10.1007/bfb0042411

Cited by 192 publications

(164 citation statements)

References 148 publications

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“…This estimation corresponds to a time correlation function of exp[Àir(t)Q] at t¼0. In the NSE measurements, however, the time evolution of fluctuations or the so-called coherent intermediate scattering function I(Q,t), can be observed and is given by 45 IðQ; tÞ…”

Section: Resultsmentioning

confidence: 99%

Structure and dynamics of poly(vinyl alcohol) gels in mixtures of dimethyl sulfoxide and water

Kanaya

Takahashi

Takeshita

et al. 2011

Polym J

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We reviewed our structure studies on poly(vinyl alcohol) (PVA) gels formed in the mixtures of dimethyl sulfoxide (DMSO) and water using various scattering methods, including wide-, small-and ultra-small-angle neutron scattering and light scattering. These studies revealed the hierarchic structure of PVA gels formed in DMSO/water (60/40 v/v) in a very wide spatial scale from 1 Å to several micrometers. The crosslinking points are crystallites with radii of B70 Å , the distance between the neighboring crystallites is 180-200 Å , and the bicontinuous structure due to liquid-liquid phase separation is in lm scale. We also review our dynamic studies on three kinds of PVA gels at the nanometer scale using neutron spin echo techniques to separate the concentration fluctuations observed by small-angle neutron scattering into the static and dynamics contributions.

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Section: Resultsmentioning

confidence: 99%

Structure and dynamics of poly(vinyl alcohol) gels in mixtures of dimethyl sulfoxide and water

Kanaya

Takahashi

Takeshita

et al. 2011

Polym J

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“…For simple translational diffusion, 5,9 we find from a description based on the Langevin equation that the dynamical pair correlation function is a Gaussian in r with a timedependent width, and the intermediate scattering function will accordingly be an exponentially decaying function. This results in a Lorentzian line shape for the scattering function, given by…”

Section: Continuous Translational Diffusionmentioning

confidence: 99%

“…Other more complicated forms of translational diffusion have also been studied. 9 These include oscillating diffusive motion where the molecule, after a period of translational diffusion, may be trapped for a while, performing an oscillatory motion before resuming a diffusive motion. The q dependence of the HWHM of the scattering function for that kind of motion is the same as the one for translational continuous diffusion.…”

Section: Continuous Translational Diffusionmentioning

confidence: 99%

Comparative study of normal and branched alkane monolayer films adsorbed on a solid surface. II. Dynamics

Enevoldsen

Hansen

Diama

et al. 2007

The Journal of Chemical Physics

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The dynamics of monolayer films of the n-alkane tetracosane ͑n-C 24 H 52 ͒ and the branched alkane squalane ͑C 30 H 62 ͒ adsorbed on graphite have been studied by quasielastic and inelastic neutron scattering and molecular dynamics ͑MD͒ simulations. Both molecules have 24 carbon atoms along their carbon backbone, and squalane has an additional six methyl side groups symmetrically placed along its length. The authors' principal objective has been to determine the influence of the side groups on the dynamics of the squalane monolayer and thereby assess its potential as a nanoscale lubricant. To investigate the dynamics of these monolayers they used both the disk chopper spectrometer ͑DCS͒ and the high flux backscattering spectrometer ͑HFBS͒ at the National Institute of Standards and Technology. These instruments made it possible to study dynamical processes such as molecular diffusive motions and vibrations on very different time scales: 1 -40 ps ͑DCS͒ and 0.1-4 ns ͑HFBS͒. The MD simulations were done on corresponding time scales and were used to interpret the neutron spectra. The authors found that the dynamics of the two monolayers are qualitatively similar on the respective time scales and that there are only small quantitative differences that can be understood in terms of the different masses and moments of inertia of the two molecules. In the course of this study, the authors developed a procedure to separate out the low-frequency vibrational modes in the spectra, thereby facilitating an analysis of the quasielastic scattering. They conclude that there are no major differences in the monolayer dynamics caused by intramolecular branching. It remains to be seen whether this similarity in monolayer dynamics also holds for the lubricating properties of these molecules in confined geometries.

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“…To the extent that long-wavelength density fluctuations are governed by a diffusion approximation, the corresponding incoherent response function has a Lorentzian shape: 24,25 …”

Section: ͑31͒mentioning

confidence: 99%

Molecular diffusion in monolayer and submonolayer nitrogen

Hansen¹,

Bruch²

2001

Phys. Rev. B

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The orientational and translational motions in a monolayer fluid of physisorbed molecular nitrogen are treated using molecular dynamics simulations. Dynamical response functions and several approximations to the coefficient of translational diffusion are determined for adsorption on the basal plane surface of graphite and on a fictitious uncorrugated graphite surface. The rotational diffusion constants in the plastic crystal and in the fluid phase are calculated. The possibility of observing these phenomena with quasielastic scattering experiments is discussed. The wave vector range is determined where the ballistic approximation to the translational molecular self-correlation function is accurate.

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Quasielastic neutron scattering for the investigation of diffusive motions in solids and liquids

Cited by 192 publications

References 148 publications

Structure and dynamics of poly(vinyl alcohol) gels in mixtures of dimethyl sulfoxide and water

Structure and dynamics of poly(vinyl alcohol) gels in mixtures of dimethyl sulfoxide and water

Comparative study of normal and branched alkane monolayer films adsorbed on a solid surface. II. Dynamics

Molecular diffusion in monolayer and submonolayer nitrogen

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