DC and microwave conductivity of iodine-doped polyacetylene

The microwave and DC conductivities of several samples of trans- and cis-polyacetylene, doped with iodine to sub-metallic levels, were measured in the temperature range 8 to 300K. The DC conductivity shows Mott's T-14/-law at low temperatures where the microwave conductivity is up to two orders of magnitude higher. An energy-dependent hopping model is therefore employed in an analysis of the data. Care is taken to identify correctly the regime in which the T-14/-law may be applied. A qualitative description of the density of states is suggested by an analysis.