In-situ spectroscopic investigations of the redox behavior of poly(indole-5-carboxylic-acid) modified electrodes in acidic aqueous solutions

The oxidation of electrochemically grown poly(indole-5-carboxylic-acid) (P5 CO2H) and its spectroscopic properties have been studied by in-situ spectro electrochemical techniques. The purpose of this paper is to characterize th e different modifications on the P5CO2H backbone, induced by the electroche mical oxidation in aqueous acidic solution. We have identified, on the basi s of Raman spectra, the vibrational modes associated with neutral and oxidi zed segments of polymer. It was shown that at least three chemically and op tically different species (perhaps other products too) are produced in diff erent potential regimes upon oxidation of this polymer. The results obtaine d also indicate that the molecular properties of this conducting polymer ar e better revealed by in-situ resonant spectra than by ex-situ infrared and Raman studies. (C) 2001 Elsevier Science B.V. All rights reserved.