SKM 2023 – wissenschaftliches Programm

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DS: Fachverband Dünne Schichten

DS 15: Optical Analysis of Thin Films II

DS 15.1: Hauptvortrag

Donnerstag, 30. März 2023, 11:15–11:45, SCH A 316

In-Situ Optical Investigation of Electrochemically Induced Conformational Changes at Solid Liquid Interfaces: A Source of new Electronic States — •Christoph Cobet — Linz School of Education, Center for Surface- and Nanoanalytics (ZONA), Johannes Kepler University, Altenbergerstr 69, A-4040, Linz, Austria

The electrical potential between an electrolyte and a solid electrode, whether it is a metal, semiconductor, polymer or a bio-membrane, could induce considerable changes in the conformational appearance. In biological systems such conformation changes are well-known e.g. as a control element for the chemistry on one or both sides of a membrane. In periodically ordered thin films or at surfaces, one can observe conformation changes at the atomic length scale which could induce new electronic properties. The interfacial electrical potential is in all cases a very versatile control element. On the one hand, it allows to change the chemical formation potential over a huge range which is otherwise only accessible for example by rather extreme temperature or pressure differences. On the other hand, it offers a very precise control of the thermodynamic equilibrium conditions. With the help of in-situ optical methods like spectroscopic ellipsometry (SE) and reflection anisotropy spectroscopy (RAS), we could study the interplay of the potential induced charge accumulation, the conformational changes and the evolution of (self) localized electronic states. The mechanisms will be discussed by two examples: The electrochemical doping and formation of polarons in polymers and the formation of surface quantum well states at a metal-electrolyte interface.