Kaoru Iwata

Local structure of conducting polypyrrole bromide

Abstract The local structure and bonding states of bromines in conducting polypyrrole bromide (PPyBr) are investigated by polarized X-ray absorption spectroscopy using synchrotron radiation. The analysis of Br K near-edge spectra of PPyBr indicates that bromines are incorporated as isolated ions and not as polyions. In the near-threshold region, no indication of BrN or BrC bond is found, which indicates the chemical stability of PPy in the oxidized form. The Fourier transform of polarized Br K-EXAFS oscillations provides the radial distribution around bromine ions in PPyBr. The BrN distance of 3.74 A is obtained as the interatomic distance between bromine ion and nitrogen of pyrrole, which is longer than the inter-plane spacing (3.41 A), suggesting that bromines are intercalated within the pyrrole plane.