| Popis: |
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%(I3), the dc conductivity was about 104 /Ω cm at 300 K, decreasing as temperature is lowered and reaching 2.5×103 /Ω 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 [sgrave]1(Ω) for polarization parallel to the chain direction. This [sgrave]1(Ω) at zero frequency was found to be 1.2×104/Ω cm, which is in good agreement with measured dc conductivity, 104/Ωcm. |
