Regensburg 2004 – scientific programme
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O: Oberflächenphysik
O 46: Grenzfläche fest-flüssig
O 46.2: Talk
Friday, March 12, 2004, 11:30–11:45, H45
X-ray reflectivity of thin liquid films — •Robert Fendt1, Christian Gutt1, Michael Sprung1, Tuana Ghaderi1, Oliver Seeck2, and Metin Tolan1 — 1Experimentelle Physik I, Universität Dortmund, 44221 Dortmund — 2IFF, Forschungszentrum Jülich, 52425 Jülich
Physical properties of confined liquids may differ significantly from those of the corresponding bulk liquids. The confinement of a liquid between a hard wall and the liquid-gas interface on a nanometer thick region is expected to alter the liquid structure drastically.
We investigated the structure of thin liquid heptane and heptanol films (thickness of 2-12 nm) adsorbed on silicon substrates by means of x-ray reflectivity. The aim of the experiment was to study (i) the liquid-solid interface, (ii) the influence of substrate-adsorbate interaction and (iii) the capillary wave spectrum of the films. The experiments were carried out using a newly constructed sample cell which allows to cover a substrate by a liquid film via gas adsorption. Experiments were carried out at the W1 diffractometer at Hasylab, Hamburg and at Dortmund using a laboratory diffractometer.
The results show that the density of thin liquid heptane films is well described by a homogenous electron density and a capillary wave broadened interface to the gas phase. In contrast thin films of the corresponding alcohol heptanol show pronounced oscillations in the electron density profile, indicating a layering of the molecules close to the hard wall.