Van der Waals-Zeeman Colloquium

Tuesday, 16 Jan 2007, 16:00h

Fluids in confinement - how fluid are they?

Prof. dr. Friso van der Veen
Paul Scherrer Institut, Villigen, and ETH-Zürich

Geometrical confinement can dramatically alter properties of fluids such as viscosity and local density. This has important implications for processes like lubrication, friction, crystallization and transport through narrow pores. Direct information on the fluid's microscopic structure is required for a proper theoretical understanding of its macroscopic properties. Here we present the results of recent synchrotron x-ray scattering experiments on colloidal fluids confined within microcavity arrays. The measurements provide direct evidence for an oscillatory ordering of the fluid as a function of the size of the gap (200-600 nm) between the confining surfaces, as predicted for hard-sphere fluids. Prospects for in-situ structural investigations of molecular fluids confined within ultranarrow gaps (2-10 nm) are discussed. The presentation will start with a brief introduction to the Swiss Light Source at the Paul Scherrer Institut, where the experiments have been performed.