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SYF: Symposium Fest-Flüssig-Grenzflächen

SYF 1: Fest/flüssig - Grenzflächen

SYF 1.4: Hauptvortrag

Donnerstag, 26. März 1998, 17:45–18:15, HS 34

ORDERING PHENOMENA AT THE SOLID-LIQUID INTERFACE AS VIEWED FROM THE LIQUID SIDE — •J.F. van der Veen¹, W.J. Huisman², J.F. Peters¹, and M.J. Zwanenburg¹ — ¹Van der Waals-Zeeman Laboratory, University of Amsterdam — ²FOM Institute for Atomic and Molecular Physics, Amsterdam

When a liquid makes contact with a solid wall, theoretical studies indicate that the atoms or molecules will become layered adjacent to the wall, giving rise to an oscillatory density profile. Such wall-induced oscillations in the atomic density are difficult to detect because they occur at a deeply buried interface over a depth interval of typically less than a nanometer. Synchrotron X-ray scattering has proven to be the technique of choice for the detection of layering in liquids. We show how it is applied to detect layering at the interface between a drop of liquid gallium and a diamond or silicon substrate. In addition, X-ray scattering can be used to pick up in-plane residual order in the liquid induced by the atomic structure of the wall. Wall-induced density oscillations are expected to be more pronounced in ultrathin liquid films compressed between two solid surfaces. In gaps of only a few nanometers, the modified arrangement of the liquid molecules influences properties such as flow, lubrication and capillary osmosis. We discuss the possiblity of using X-ray scattering in wave-guiding geometry for the measurement of ordering effects in confined liquid films.