TOTAL INTERNAL REFLECTANCE IR SPECTROSCOPY OF POLYPYRROLE ON A SILICON ELECTRODE

A new experimental arrangement is described whereby thin films (about 1 mum thick) of polypyrrole have been electrochemically deposited onto a silicon rod single crystal that forms an element of the cylindrical internal reflectance (CIR) accessory of an FT-IR spectrometer. Polypy rrole was deposited from acetonitrile solutions of pyrrole in the pres ence of lithium perchlorate, tetrabutylammonium perchlorate and tetrab utylammonium tetrafluoroborate. Excellent quality in situ ATR-FT-IR sp ectra have been obtained over a range of potentials, with no solvent i nterference, showing systematic changes in spectra with the progressiv e oxidation and reduction of the polymer film. Both anions and cations are found to be present in both oxidized and reduced polypyrrole.