Regensburg 2019 – wissenschaftliches Programm

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DS: Fachverband Dünne Schichten

DS 1: Optical Analysis of Thin Films I (Reflection, Ellipsometry, Raman, IR-DUV Spectroscopy, ...

DS 1.1: Hauptvortrag

Montag, 1. April 2019, 09:30–10:00, H32

Charge and ion exchange at electrochemical interfaces: atomistic insights by means of in-situ ellipsometry — •Christoph Cobet — Johannes Kepler University, Altenbergerstr 69, 4040, Linz, Austria

Recently, solid-liquid interfaces and electrochemical surface reactions received more and more attention. The motivation may arise by applications e.g. to solve energy harvesting problems or to develop novel (bio-)sensing techniques. The functionality, however, depends on the adjacent atomic layers near the interface and the development of respective surface sensitive methods allow nowadays a more detailed study. In general we have to deal with alternating charges and chemical compounds perpendicular to the interfaces. In the presented work we use polarization optical methods in the spectral range of transparency of the electrolytes. It is an advantage and at the same time a challenge that all boundaries in the light pass contribute to a polarization change. We show in comparison to conventional cyclic voltammetry, impedance spectroscopy, and electrochemical STM that spectroscopic ellipsometry and reflection anisotropy spectroscopy (RAS) can nevertheless provide quantitative information. At metal single crystal surface it was e.g. possible to determine the amount of surface adsorbates and the amount of interface charges. Thus, we could determine also the so called potential of zero total charge (PZTC). Furthermore, we got evidences for an increased density of the water film near the interface. Time resolved measurements gave supplementary insights in the dynamics of electrochemical absorption processes.