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DY: Dynamik und Statistische Physik
DY 17: Fluids II
DY 17.6: Talk
Monday, March 8, 2004, 17:45–18:00, H3
Microscopic theory for interfaces of binary liquid mixtures — •Thorsten Hiester1,2 and Klaus Mecke1,2 — 1Max-Planck-Institut für Metallforschung, Heisenbergstraße 3, 70569 Stuttgart — 2Institut für Theoretische und Angewandte Physik, Pfaffenwaldring 57, 70569 Stuttgart
Binary liquid interfaces, in particular, their nanoscopic structure is still poorly understood. In addition to capillary waves and density fluctuations there are simultaneously fluctuations of the composition. Beginning with a density functional theory for binary mixtures of inhomogeneous fluids we derive an effective Hamiltonian for interfaces of binary liquid mixtures beyond the well-known capillary-wave model. Explicit expressions for the surface tension, the bending ridigities and especially the coupling constants of compositional capillary waves in terms of two number densities are obtained. Finally, we make predictions for grazing-incidence x-ray scattering experiments.