POLARIZED REFLECTION SPECTRA OF IODINE-DOPED NEW-TYPE POLYACETYLENE

The polarized reflection spectra of lightly and moderately iodine-doped new-type polyacetylene films have been measured in the range 60 ∼ 36 000 cm-1. The optical conductivity spectra along the polyacetylene chain direction were calculated by the Kramers-Kronig transformation of reflection spectra, in which several elementary transitions are characterized by polarization measurements. In the lightly doped film ((CHIy)x, y ≤ 0.10), only the spectrum of the charged soliton structure is predominant. Above a critical concentration (y ≅ 0.10) the free carrier contribution becomes evident. With a moderate doping level (0.10 ≤ y ≤ 0.18) the number of free carriers is increased. A fairly long lifetime for the free carriers is indicated in the far-IR spectra. The conduction mechanism of the iodine-doped new polyacetylene is suggested, based on the analysis of optical conductivity spectra. © 1990.