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Updated: Jul 19, 2026

An Analog Macroscopic Technique for Studying Molecular Hydrodynamic Processes in Dense Gases and Liquids
Published on: December 4, 2017
Anisotropy of Brownian motion caused only by hydrodynamic interaction with a wall
Peter Holmqvist1, Jan K G Dhont, Peter R Lang
1Forschugszentrum Jülich, Institut für Festkörperforschung, Soft Matter Division, D-52425 Julich, Germany.
Abstract:
The diffusivity of spherical colloidal particles close to a planar hard wall is studied by dynamic light scattering with evanescent illumination. A novel setup allows us to independently vary the scattering vector components parallel Q parallel and normal Q perpendicular to the wall. An expression for the initial decay rate Gamma of the time autocorrelation functions is derived as a function of both Q parallel and Q perpendicular, as well as the penetration depth of the evanescent wave, where hydrodynamic interactions of particles with the wall are included. This makes it possible to study the viscous wall drag effect quantitatively for particles as small as 85 nm in radius.
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