Ultrahigh-vacuumin situelectrochemistry with solid polymer electrolyte and x-ray photoelectron spectroscopy studies of polypyrrole

A new in situ combined electrochemistry and x-ray photoelectron spectroscopy (XPS) technique using solid polymer electrolytes has been used to characterize electrically conducting films of polypyrrole perchlorate. The technique allows in situ electrochemical oxidation and reduction (doping and undoping) in ultrahigh vacuum and the simultaneous study of the polymer with XPS as a function of its electrochemical potential. We demonstrate that some anion species interact strongly electrostatically with the nitrogen heteroatoms. We also show conclusively that the electrochemistry of polypyrrole is highly irreversible.