We are interested in the physical chemistry of interfaces of condensed matter adjoining vacuum, gases and electrolytes. Major issues are:
- Thermodynamics and kinetics of electrochemical reactions:
Apparently simple electrochemical reactions like copper deposition or hydrogen adsorption are in fact complicated in the electrolytic environment. For example, the deposition of a hydrated Cu ion onto an electrode involves stripping off the solvation shell, adsorption on the metal surface and ordering of the resulting Cu-adatom gas. Furthermore, all processes may be accompanied by co-adsorption of electrolyte constituents.
We use electrochemical microcalorimetry with unprecedented sensitivity for the study of heat effects, e.g., upon the first stages of copper deposition on Au or of phase transitions of sodium dodecyl sulphate adlayers on Au. This provides information on elementary steps of the reaction and the species involved as well as on thermodynamic properties like reaction enthalpy and entropy. See More
- Ordering processes in electrochemical surface systems.
The variation of the electric potential of an electrode provides a convenient and fast means for inducing structural changes of the surface. Applying scanning tunnelling microscopy we investigate phase transitions and subsequent ordering processes in electrochemical systems like an electrochemically produced Au-adatom gas. In addition, we study the elementary steps of metal deposition reactions by combining electrochemical microcalorimetry and surface plasmon resonance spectroscopy. See More
- Electronic structure of adsorbates in electrochemical environment
We employ the scanning tunnelling microscope for pursuing current-voltage and current-distance spectroscopy of adsorbates in electrochemical environment. In preliminary experiments we studied current-voltage curves of simple adsorbates in humid air and performed break junction experiments under various environmental conditions. See More
- Electrochemical Microstructuring
By the use of ultrashort potential pulses of nanosecond duration in electrochemical environment, we are able to machine metals and semiconductors in three dimensions with precision down to 20 nm. See More
- Ellipsometric investigations of interfacial phase transitions
Ellipsometry measures the change of the polarization state of light during reflection at an interface. This is expressed with two angles, Ψ and Δ, which measure the amplitude ratio and the phase shift of the normal (rs) and the parallel (rp) reflection coefficient. Ψ and Δ are very sensitive to changes of the optical parameters at an interface. As examples we present studies of a complete wetting transition in metallic alloy systems (like Ga-Bi) and the oscillatory instability of a complete wetting layer exposed to a temperature gradient See more