[en] Converting neutron scattering data to real-space time-dependent structures can only be achieved through suitable models, which is particularly challenging for geometrically disordered structures. We address this problem by introducing time-dependent clipped Gaussian field models. General expressions are derived for all space- and time-correlation functions relevant to coherent inelastic neutron scattering for multiphase systems and arbitrary scattering contrasts. Various dynamic models are introduced that enable one to add time-dependence to any given spatial statistics, as captured, e.g., by small-angle scattering. In a first approach, the Gaussian field is decomposed into localized waves that are allowed to fluctuate in time or to move either ballistically or diffusively. In a second approach, a dispersion relation is used to make the spectral components of the field time-dependent. The various models lead to qualitatively different dynamics, which can be discriminated by neutron scattering. The methods of this paper are illustrated with oil/water microemulsion studied by small-angle scattering and neutron spin-echo. All available data—in both film and bulk contrasts, over the entire range of q and τ—are analyzed jointly with a single model. The analysis points to the static large-scale structure of the oil and water domains while the interfaces are subject to thermal fluctuations. The fluctuations have an amplitude of around 60 Å and contribute to 30% of the total interface area.
Disciplines :
Materials science & engineering Physics
Author, co-author :
Gommes, Cédric ; Université de Liège - ULiège > Department of Chemical Engineering > Department of Chemical Engineering
Zorn, Reiner; Forschungszentrum Jülich
Jaksch, Sebastian; Forschungszentrum Jülich
Frielinghaus, Heinrich; Forschungszentrum Jülich
Holderer, Olaf; Forschungszentrum Jülich
Language :
English
Title :
Inelastic neutron scattering analysis with time-dependent Gaussian-field models
Publication date :
2021
Journal title :
Journal of Chemical Physics
ISSN :
0021-9606
eISSN :
1089-7690
Publisher :
American Institute of Physics, United States - New York