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Regensburg 2007 – scientific programme

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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

Wednesday, March 28, 2007, 17:00–19:30, Poster C

Electric field effects at the ice/SiO2 interface — •Heiko Schröder1, Sebastian Schöder1,2, Markus Mezger1, Harald Reichert2, Veijo Honkimäki2, Jörg Bilgram3, and Helmut Dosch11Max-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)

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