Localized and long-range diffusion in condensed matter: state of the art of QENS studies and future prospects

Bée, M.

doi:10.1016/s0301-0104(03)00257-x

Cited by 66 publications

(25 citation statements)

References 118 publications

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“…Similar to what was observed for liquid crystals [32,33], this motion can be described by the uniaxial rotational diffusion model [34]. The corresponding EISF, averaged over all the possible orientations of the bond direction with respect to Q, can be written as follows:…”

Section: Resultsmentioning

confidence: 76%

Molecular Dynamics of POPC Phospholipid Bilayers through the Gel to Fluid Phase Transition: An Incoherent Quasi-Elastic Neutron Scattering Study

Wanderlingh¹,

Branca²,

Crupi³

et al. 2017

Journal of Chemistry

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The microscopic dynamics for the gel and liquid-crystalline phase of highly aligned D 2 O-hydrated bilayers of 1-palmitoyl-oleoylsn-glycero-phosphocholine (POPC) were investigated in the temperature range from 248 to 273 K by using incoherent quasielastic neutrons scattering (QENS). We develop a model for describing the molecular motions of the liquid phase occurring in the 0.3 to 350 ps time range. Accordingly, the complex dynamics of hydrogen are described in terms of simple dynamical processes involving different parts of the phospholipid chain. The analysis of the data evidences the existence of three different motions: the fast motion of hydrogen vibrating around the carbon atoms, the intermediate motion of carbon atoms in the acyl chains, and the slower translational motion of the entire phospholipid molecule. The influence of the temperature on these dynamical processes is investigated. In particular, by going from gel to liquid-crystalline phase, we reveal an increase of the segmental motion mainly affecting the terminal part of the acyl chains and a change of the diffusional dynamics from a localized rattling-like motion to a confined diffusion.

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Section: Resultsmentioning

confidence: 76%

Molecular Dynamics of POPC Phospholipid Bilayers through the Gel to Fluid Phase Transition: An Incoherent Quasi-Elastic Neutron Scattering Study

Wanderlingh¹,

Branca²,

Crupi³

et al. 2017

Journal of Chemistry

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“…An energy offset at small || has been reported for confined diffusion, such as diffusion in a sphere or cylinder [29][30][31]. At smaller length scales (large || ), the particles follow a typical Brownian diffusion process.…”

Section: Discussionmentioning

confidence: 92%

Incoherent Neutron Spin-Echo Spectroscopy as an Option to Study Long-Range Lipid Diffusion

et al. 2013

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Diffusion is the fundamental mechanism for lipids and other molecules to move in a membrane. It is an important process to consider in modelling the formation of membrane structures, such as rafts. Lipid diffusion is mainly studied by two different techniques: incoherent neutron scattering and fluorescence microscopy. Both techniques access distinctly different length scales. While neutron scattering measures diffusion over about 3 lipid diameters, microscopic techniques access motions of lipids over micrometer distances. The diffusion constants which are determined by these two methods often differ by about an order of magnitude, with the neutrons usually seeing a faster lipid diffusion. Different theories are used to describe lipid diffusion in the two experiments. In order to close the "gap" between these two techniques, we propose to study lipid diffusion at mesoscopic length scales using a neutron spin-echo (NSE) spectrometer. We have conducted an experiment in highly oriented, solid supported lipid bilayers to prove the feasibility of performing incoherent NSE on biological samples. Lateral lipid diffusion was measured in a fluid phase model membrane system at a length scale of 12Å. Using the high-energy resolution of the NSE technique, we find evidence for two dynamic processes.

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“…For an aqueous solution, I ( Q, t) can be written as (see, e.g., Ref. 13) (2) where R iμ is the vector giving the position of the μth nucleus in the ith molecule, b iμ is the neutron scattering length of this nucleus. N w and N sol denote the number of water and solute molecules, respectively.…”

Section: A the Scattering Function For An Aqueous Solutionmentioning

confidence: 99%

“…4 and 6. Our QENS investigations 7,8 that included a partial account for coherent scattering were on D 2 O solutions of cyclodextrins (CDs) and their methylated derivatives (mCDs). The CDs are macrocycles consisting of 6, 7, or 8 D-glucose units, and are called α-, β-, and γ -CDs, respectively, 9 see Fig.…”

Section: Introductionmentioning

confidence: 99%

“…We were, however, successful in explaining this with a phenomenological model that includes an additional coherent scattering contribution from the hydration shell of mCDs. 7,8 In this model two approximations were made: the coherent scattering due to solute-D 2 O spatial correlations was neglected, and both coherent and incoherent D 2 O scattering in solution were described by the same parameter values as used for the description of the scattering by pure D 2 O.…”

Section: Introductionmentioning

confidence: 99%

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Quasielastic small-angle neutron scattering from heavy water solutions of cyclodextrins

Kusmin

Lechner

2011

The Journal of Chemical Physics

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We present a model for quasielastic neutron scattering (QENS) by an aqueous solution of compact and inflexible molecules. This model accounts for time-dependent spatial pair correlations between the atoms of the same as well as of distinct molecules and includes all coherent and incoherent neutron scattering contributions. The extension of the static theory of the excluded volume effect [A. K. Soper, J. Phys.: Condens. Matter 9, 2399 (1997)] to the time-dependent (dynamic) case allows us to obtain simplified model expressions for QENS spectra in the low Q region in the uniform fluid approximation. The resulting expressions describe the quasielastic small-angle neutron scattering (QESANS) spectra of D 2 O solutions of native and methylated cyclodextrins well, yielding in particular translational and rotational diffusion coefficients of these compounds in aqueous solution. Finally, we discuss the full potential of the QESANS analysis (that is, beyond the uniform fluid approximation), in particular, the information on solute-solvent interactions (e.g., hydration shell properties) that such an analysis can provide, in principle.

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Localized and long-range diffusion in condensed matter: state of the art of QENS studies and future prospects

Cited by 66 publications

References 118 publications

Molecular Dynamics of POPC Phospholipid Bilayers through the Gel to Fluid Phase Transition: An Incoherent Quasi-Elastic Neutron Scattering Study

Molecular Dynamics of POPC Phospholipid Bilayers through the Gel to Fluid Phase Transition: An Incoherent Quasi-Elastic Neutron Scattering Study

Incoherent Neutron Spin-Echo Spectroscopy as an Option to Study Long-Range Lipid Diffusion

Quasielastic small-angle neutron scattering from heavy water solutions of cyclodextrins

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