Regensburg 2007 – wissenschaftliches Programm

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O: Fachverband Oberflächenphysik

O 44: Poster Session II (Semiconductors; Oxides and Insulators: Adsorption, Clean Surfaces, Epitaxy and Growth; Surface Chemical Reactions and Heterogeneous Catalysis; Surface or Interface Magnetism; Solid-Liquid Interfaces; Organic, Polymeric, Biomolecular Films; Particles and Clusters; Methods: Atomic and Electronic Structure; Time-resolved Spectroscopies)

O 44.71: Poster

Mittwoch, 28. März 2007, 17:00–19:30, Poster C

Electric field effects at the ice/SiO₂ interface — •Heiko Schröder¹, Sebastian Schöder^1,2, Markus Mezger¹, Harald Reichert², Veijo Honkimäki², Jörg Bilgram³, and Helmut Dosch¹ — ¹Max-Planck-Institut für Metallforschung, Heisenbergstr. 3, D-70569 Stuttgart, Germany — ²ESRF, 6 rue Jules Horowitz, F-38000 Grenoble, France — ³ETH Zürich, Schafmattstr. 16, CH-8093 Zürich, Switzerland

Since the water molecule has a dipole moment, electric fields are expected to have a strong influence on the water/ice phase transition [1]. A deeper knowledge of the underlying mechanisms could improve our understanding of atmospheric cloud chemistry. To achieve this, we investigate electric field effects at the ice/SiO₂ interface by employing high energy x-ray reflectivity. In earlier experiments, we have studied pre-melting phenomena of ice extensively [2], leading to both a fully established sample preparation technique and a robust experimental setup at a 3rd generation synchrotron source (ESRF, ID15A). Our ice samples are sandwiched between smooth Si(100) substrates to guarantee the application of homogeneous electric fields across the two interfaces. The setup allows voltages up to 40 kV with switchable direction. We show polarization dependent electric field effects leading to structural changes at the ice/SiO₂ interface. Furthermore, our data suggests an influence of substrate preparation on the pre-melting behaviour of buried ice interfaces.

[1] Choi et al, PRL 95 085701 (2005)

[2] Engemann et al, PRL 92, 200401 (2004)