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CPP: Chemische Physik und Polymerphysik

CPP 7: Computational Physics

CPP 7.2: Vortrag

Dienstag, 25. März 2003, 17:15–17:30, ZEU/160

Microscopic structure of fluid interfaces — •Thorsten Hiester, Siegfried Dietrich, and Klaus Mecke — Max-Planck-Institut für Metallforschung, Heisenbergstr. 3, 70569 Stuttgart

Molecular orientations at surfaces play a key role in many of the interesting optical properties of thin films, for instance. Accurate determination of ’molecular tilt’ angles and their distribution is therefore essential for interpreting measurements at interfaces such as X-ray scattering experiments and spectroscopic techniques. Starting from a microscopic density functional theory for inhomogeneous fluids we derive an effective Hamiltonian for interfaces of fluid mixtures which goes beyond the common phenomenological capillary-wave description. Explicit expressions for the surface tension and the bending rigidities of capillary waves as well as for the distribution of local orientations of the interface are given. New results from synchrotron x-ray scattering experiments at liquid-vapor interfaces of organic liquids are compared with our theoretical predictions which allow a quantitative determination of microscopic interaction parameters of the fluid.