Regensburg 2007 – wissenschaftliches Programm

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CPP: Fachverband Chemische Physik und Polymerphysik

CPP 17: Micro and Nano Fluidics I: Structured Substrates

CPP 17.2: Vortrag

Mittwoch, 28. März 2007, 14:30–14:45, H37

Anisotropic self-diffusion in nanofluidic structures — •Martin Schoen¹, Keith Gubbins², and Henry Bock³ — ¹Stranski-Laboratorium für Physikalische und Theoretische Chemie, Fakultät für Mathematik und Naturwissenschaften, Technische Universität Berlin, Straße des 17. Juni 135, 10623 Berlin, Germany — ²Department of Chemical and Biomolecular Engineering, 911 Partners Way, North Carolina State University, Raleigh, NC 27695-7905, U.S.A. — ³Department of Chemical Engineering, Heriot-Watt University, Edinburgh EH14 4AS, United Kingdom

By means of equilibrium molecular dynamics simulations we investigate self-diffusion in a "simple" fluid confined to nanoscopic slit-pores. The pore walls are decorated with wettable and nonwettable chemical "stripes" that alternate in the x-direction and are assumed infinitely long in the y-direction. We consider the impact of pore width as well as variations of the width of the wettable stripes. Depending on these model parameters and the thermodynamic conditions the confined fluid may exist as one of three morphologically distinct phases: a thin fluid film, a fluid bridge spanning the gap between the stripes, or a nanostructured liquid. By analyzing mean square displacements, velocity autocorrelation functions and in particular their power spectra a detailed picture of mass transport and its relation the dimensions of the chemical patterns on the substrates emerges. In particular, we find that the axial symmetry of the diffusion tensor preserved in the liquidlike phases is disrupted in both the film and the bridge phases.