Berlin 2018 – scientific programme

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O: Fachverband Oberflächenphysik

O 8: Solid-liquid interfaces: Structure, Spectroscopy I

O 8.1: Talk

Monday, March 12, 2018, 10:30–10:45, MA 144

Structural changes of water islands due to kosmotropes vs. chaotropes imaged in real space — •Irene Weber and Karina Morgenstern — Chair of Physical Chemistry I, Ruhr-Universität Bochum, Germany

Solvation effects of ions near the liquid-solid interface are of tremendous importance for the understanding of electrochemical processes, i.e. in electrocatalysis or in corrosion. Although studying these solvation effects has a long tradition, the understanding of the microscopic influence of alkali metal ions onto water structure and dynamics near metal surfaces on the atomic scale is still at its infancy. In our study, crystalline water is used to mimic ordered water close to an electrode and lithium or cesium ions to represent circular cations. Lithium with its high charge density is a kosmotrope and cesium with its low charge density a chaotrope. Already, the adsorption of lithium and cesium ions on the Au(111) surface differs at around 215 K. Both ions change the water structure. The lithium ions change the distribution of water islands on Au(111) as compared to water islands on pristine Au(111) and alter their structure. The cesium ions reduce the height of the islands and change the structure of water islands in a different way. Depending on the water-to-ion-ratio, the subtle balance of interactions between water, ions and the substrate is changed. In this contribution, we will present our variable-temperature Scanning Tunneling Microscopy (STM) studies of these differences induced by lithium and cesium ion co-adsorption on crystalline ice structures on Au(111).