The metallic state of doped polyacetylene and polypyrrole

Summary form only given. A low frequency Drude model was used to analyze the large negative dielectric constants at microwave frequency (/sp epsi//sub mw/ > -5x10/sup 4/) for the center portion of I/sub 2/ doped stretched Tsukamoto polyacetylene (T-(CH)/sub x/) and unoriented polypyrrole (PPY) containing PF/sup -//sub6/. The relatively small plasma frequencies (w/sub p/ /spl sim/- 0.025 eV and 0.011 eV, respectively) and anomalously long scattering times (/spl tau/ /spl sim/- 3.3x10/sup -11/ s and 1.6x10/sup -11/ s, respectively) of these materials indicates the importance of phonon back scattering of the most delocalized conduction electrons as expected for the open Fermi surface of an highly anisotropic metal. Our conclusions for w/sub p/ of doped polyacetylene agree with w/sub p/ obtained from the earlier optical measurements./sup 1/ These results are contrasted with the more localized behavior of the neck and end portions of stretched T-(CH)/sub x/ and of PPY doped with TsO/sup -/. Aging effects for stretched T-(CH)/sub x/ is also reported, together with confirmation/sup 2/ of high Pauli susceptibility for the most metallic heavily doped polyacetylene. * Supported in part by NEDO (New Energy and Industrial Technology Development Org). We gratefully acknowledge discussions with V. N. Prigodin.