Regensburg 2019 – scientific programme

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O: Fachverband Oberflächenphysik

O 23: Solid-Liquid Interfaces II: Electrode Surfaces

O 23.3: Talk

Tuesday, April 2, 2019, 11:15–11:30, H5

Influence of the polarization of the electrode on the surface plasmon resonance angle shift during adsorption processes on Au(111) — •Karin Schlag, Detlef Nattland, and Rolf Schuster — Karlsruhe Institute of Technology (KIT), Karlsruhe, Germany

Knowledge about the structure and composition of the double layer is essential for the understanding of electrochemical reactions. We therefore investigated the sulfate adsorption on Au(111) with cyclic voltammetry and in-situ surface plasmon resonance (SPR) spectroscopy. SPR is sensitive to changes of the refractive index at the electrolyte-electrode interface, which is connected to concentration changes of the constituents of the double layer. We observed an increase of the SPR angle during the adsorption process of sulfate on Au(111) by 0.14°.

A multi-layer model based on Abeles' formalism was used to quantify the potential dependent refractive index of the double-layer. We found that the experimentally determined, unexpectedly strong shift of the SPR angle can only partly be explained by the increase of the sulfate concentration at the interface. It is suggested that the polarization of the interface and the subsequent changes of the electron density in the metal surface have to be included in the model.