Berlin 2015 – scientific programme

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BP: Fachverband Biologische Physik

BP 38: Electrolytes at Interfaces - Stern Layer (focus session, joint CPP/BP/O)

BP 38.2: Talk

Wednesday, March 18, 2015, 15:30–15:45, C 130

Direct observation of ionic structure at solid-liquid interfaces: A deep look into the Stern Layer — •Igor Siretanu, Daniel Ebeling, Martin P. Andersson, Cunlu Zhao, Dirk van den Ende, and Frieder Mugele — Physics of Complex Fluids and MESA+ Institute for Nanotechnology, Department of Science and Technology, University of Twente, PO Box 217, 7500 AE Enschede, The Netherlands

The distribution of ions and charge at solid-water interfaces plays an essential role in a wide range of processes in biology, geology and technology. While study of the solid-electrolyte interfaces date back to the early 20th century, a detailed picture of the structure of the electric double layer has remained elusive, largely because of experimental techniques have not allowed direct observation of the behaviour of ions, i.e. with subnanometer resolution. Making use of recent advances in Atomic Force Microscopy with atomic level precision, herein, we reveal the local surface charge and the ordered adsorption of the divalent ions, unlikely monovalent ions, to heterogeneous clay surfaces in contact with aqueous electrolytes. Complemented by density functional theory, the experiments produce a detailed picture of the formation of surface phases by templated adsorption of cations, anions and water, stabilized by hydrogen bonding.