Ex situ and in situ SERS analyses of polybithiophene using roughened Ag and Cu electrodes and multilayer SERS-active systems

Electrochemical deposition of polybithiophene (PbT) films on suitably roughened silver and copper electrodes enabled us to record surface-enhanced Raman scattering (SERS) spectra of oxidized and reduced species showing the important changes in the spectral features of the different oxidation states of the polymer film. The comparison between SERS spectra and Raman spectra of PbT electrosynthesized on platinum allowed the identification of vibrational modes which are the most sensitive to the surface enhancement effect. The orientation and the anchorage mode of the polymer rings, during the first stages of electropolymerization, were estimated according to the SERS selection rules. In situ SERS analyses revealed that the spectral changes observed during the doping process are due to a transition from aromatic to quinoid structure and to an increase in structural defects along the polymer chain. Ex situ and in situ SERS studies were also carried out using various multilayer SERS-active systems in which the polymer is either electrodeposited on a thin layer of a SERS-active metal coating an iron electrode or sandwiched between the thin SERS-active layer and the iron support. Copyright (c) 2005 John Wiley & Sons, Ltd.