Berlin 2018 – wissenschaftliches Programm

Bereiche | Tage | Auswahl | Suche | Aktualisierungen | Downloads | Hilfe

O: Fachverband Oberflächenphysik

O 60: Solid-liquid interfaces: Structure, Spectroscopy II

O 60.4: Vortrag

Mittwoch, 14. März 2018, 11:15–11:30, MA 144

Time-resolved Electrochemical Surface Plasmon Resonance (SPR) Studies of the Aggregation of Surfactant Molecules at a Solid- liquid Interface — •Karin Schlag, Christian Kühn, Detlef Nattland, and Rolf Schuster — Karlsruhe Institute of Technology, Karlsruhe, Germany

The potential induced adsorption and phase transitions of dodecyl sulfate molecules on Au(111) have been studied with time-resolved surface plasmon resonance spectroscopy (a full plasmon profile per millisecond). Plasmons are excited at a 50 nm thin gold film working electrode using the Kretschmann configuration for attenuated total reflection. Position and shape of the curve are highly sensitive to the dielectric properties at the interface. Thus, changes of the coverage by fractions of a monolayer or variations of the thickness of an adsorbed layer can be detected. A multilayer model is used to interpret the plasmon profiles in which each layer is characterized by its thickness and its complex refractive index. While cycling through the phase transition from a hemicylindrical to a compact phase of the sodium dodecyl sulfate (SDS) system we obtained a shift to higher resonance angles with increasing potential. On the reverse direction we observe a hysteresis in the shift of the resonance angle. This finding is in line with potential pulse experiments, which imply a nucleation and growth process along this first order phase transition on a timescale of several 100 milliseconds.