Molecular Crystals and Liquid Crystals Science and Technology. Section A. Molecular Crystals and Liquid Crystals, Vol.280, 169-174, 1996
Spectroscopic Investigation of Highly Oriented Polyacetylene
The doping induced infrared spectra in highly oriented Naarmann-Theophilou type polyacetylene, NT-[CH](x), have been measured. All samples were doped with iodine chemically doping with various dopant levels. In 550% stretched NT-(CH)x, doped at level 6%(I-3-), the dc conductivity was about 10(4)/Omega cm at 300 K, decreasing as temperature is lowered and reaching 2.5x10(3)/Omega cm at 84K. In contrast, the far-infrared oscillator strength in the 500 cm(-1) region, where the "pinning" mode is usually seen, increased and shifted to lower frequencies with decreasing temperature. This effect was observed for polarization parallel and perpendicular to the stretching direction. All stretched samples displayed highly anisotropic behavior with substantially greater optical conductivity sigma(1)(omega) for polarization parallel to the chain direction. This sigma(1)(omega) at zero frequency was found to be 1.2x10(4)/Omega cm, which is in good agreement with measured de conductivity, 10(4)/Omega cm.