Investigation of electroactive ultrathin films by surface plasmon spectroscopy

Abstract

Surface plasmon spectroscopy was combined with electrochemistry and high pressure technique to investigate ultrathin electroactive polymer films. Firstly, the electropolymerization of 2, 2a??-bithiophene was investigated by electrochemical surface plasmon spectroscopy. The anion doping and dedoping were monitored during the electropolymerization. A shift of the minimum angle was observed, which means a continuous deposition of polymer on the electrode. Next, gratings were fabricated by photolithography and imprinting technique. These gratings can be used as surface plasmon coupler successfully. Finally, the behavior of polyaniline / sulfonated polyaniline multilayer film manipulated by Layer-by-Layer technique was investigated by high pressure surface plasmon spectroscopy at elevated pressure. A continuous deposition of polyelectrolytes was observed. The peak current decreased with elevated pressure was due to a compactification of film. The refractive index and thickness change of film and refractive index change of pressure medium lead to a larger shift of the surface plasmon resonance angle.