Interface Physics Group, Prof. Dr. Olaf Magnussen

Institute of Experimental and Applied Physics, Christian-Albrechts-Universität zu Kiel

Video - STM

Interfaces between solid metals and liquid electrolyte solutions play a central role in electrochemical processes, ranging from corrosion to galvanic deposition and electrode reactions in batteries and fuel cells. The motion and interaction of atomic and molecular species at these interfaces is an important fundamental step in many of those reactions and of considerable relevance for understanding their precise mechanisms. Our group has developed a worldwide unique high-speed scanning tunnelling microscope (Video-STM), capable of directly observing these dynamic processes with atomic resolution and millisecond time resolution in electrochemical environment.

Examples can be downloaded from our Atomic Movie Library.

By performing these microscopic investigations at variable electrode potential and temperature and analyzing them with statistical methods we can measure the involved energies and obtain detailed data on the dynamics of these elemental processes in well-suited model systems.
The following topics have been studied by this technique:

Dissolution and electrodeposition processes, focussing on the dynamics of kinks in atomic steps on the metal surface. Understanding these processes is of key importance for modern galvanic plating and etching methods. Examples of studied systems are copper dissolution and deposition, lead-copper alloy formation, and the growth of nanoscale needles in Bismuth deposition. Bi-needle.jpg

Surface dynamics of adsorbates at solid-liquid interfaces, such as quantitative studies of adsorbate surface diffusion and adsorbate-adsorbate interactions. Our experiments, performed primarily for sulphur on a copper surface in hydrochloric acid solution, constitute the first direct experimental measurements of the relevant energies of these processes for adsorbates at solid-liquid interfaces. S-Cu100.jpg

Collective nanoscale surface dynamics, specifically the dynamic behavior of surface reconstructions on gold and copper electrode surfaces. These reconstructions form beautiful nanoscale patterns on the metal surfaces, resulting from a rearrangement of the atoms in the metal surface layer, and have a pronounced influence on growth processes and interface reactions. Our studies show that these structures are surprisingly mobile and reveal complex mechanisms of the reconstruction formation and dissolution. Cu-reg-3D.jpg

Contact: Prof. Olaf Magnussen

Funding: DFG projects MA 1618/5, MA 1618/11, MA 1618/14, MA 1618/15

Selected publications: