Density fluctuations of hard-sphere fluids in narrow confinement

Nygård, Kim; Sarman, Sten; Hyltegren, Kristin; Chodankar, Shirish; Perret, Edith; Buitenhuis, Johan; Veen, J. Friso van der; Kjellander, Roland

doi:10.1103/PhysRevX.6.011014

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Journal article

Density fluctuations of hard-sphere fluids in narrow confinement

Nygård, Kim Department of Chemistry and Molecular Biology, University of Gothenburg, Sweden
Sarman, Sten Department of Materials and Environmental Chemistry, Stockholm University, Sweden
Hyltegren, Kristin Department of Chemistry and Molecular Biology, University of Gothenburg, Sweden - Division of Theoretical Chemistry, Lund University, Sweden
Chodankar, Shirish Paul Scherrer Institut, Villigen PSI, Switzerland - National Synchrotron Light Source II, Brookhaven National Laboratory, Upton, USA
Perret, Edith Paul Scherrer Institut, Villigen PSI, Switzerland - University of Fribourg, Department of Physics and Fribourg Centre for Nanomaterials, Switzerland.
Buitenhuis, Johan Forschungszentrum Jülich, Germany
Veen, J. Friso van der Paul Scherrer Institut, Villigen PSI, Switzerland - ETH Zürich, Switzerland
Kjellander, Roland Department of Chemistry and Molecular Biology, University of Gothenburg, Sweden

16.02.2016

Published in:

Physical Review X. - 2016, vol. 6, no. 1, p. 11014

English Spatial confinement induces microscopic ordering of fluids, which in turn alters many of their dynamic and thermodynamic properties. However, the isothermal compressibility has hitherto been largely overlooked in the literature, despite its obvious connection to the underlying microscopic structure and density fluctuations in confined geometries. Here, we address this issue by probing density profiles and structure factors of hard- sphere fluids in various narrow slits, using x-ray scattering from colloid-filled nanofluidic containers and integral-equation-based statistical mechanics at the level of pair distributions for inhomogeneous fluids. Most importantly, we demonstrate that density fluctuations and isothermal compressibilities in confined fluids can be obtained experimentally from the long-wavelength limit of the structure factor, providing a formally exact and experimentally accessible connection between microscopic structure and macroscopic, thermodynamic properties. Our approach will thus, for example, allow direct experimental verification of theoretically predicted enhanced density fluctuations in liquids near solvophobic interfaces.

Faculty

Faculté des sciences et de médecine

Department

Département de Physique

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