XPS INVESTIGATIONS ON CONDUCTING POLYMERS

X-ray photoelectron spectroscopy, XPS, was used for the characterizati on of electrically conducting polymeric materials. In the spectrum of polypyrrole, PPy, the Nls region exhibits two peaks, at 402.0 and 399. 8 eV, corresponding to -N+- and -N-moieties, respectively. The intensi ty of the N+ peak decreases as the material loses its conductivity, he nce the ratio of the experimentally derived N+/C atomic ratio correlat es exponentially with the measured conductivity. A similar observation also exists between the F-/C atomic ratio both in polypyrrole and pol ythiophene. In the XPS spectrum of the composite material prepared usi ng polyaniline, PAN and polyvinylchloride, PVC, two different kinds of Cl2p spin-orbit doublets are present after irradiation by Co-60 gamma -rays. One of the Cl2p doublets can be assigned to the C-Cl in PVC and the other one is assigned to Cl- ions appearing after radiation. Sinc e no Cl- peak is observed in PVC even after radiation, the presence in the composite must be related to dehydrochlorination of PVC and subse quent capture of the H-Cl by the neighboring PAN moieties. The measure d Auger parameter of the Nals level of NaBr deposited on an oxidized f orm of the conducting polymer is between the values of NaBr deposited on Au (metal) and on Si (semiconductor). However, when NaBr is deposit ed on a reduced form of conducting polymer, the corresponding value ap proaches to that deposited on quartz (insulator).