Solitons or inhomogeneous doping in AsF5-doped polyacetylene—EPR and dc conductivity evidence

摘要: The question of whether several properties As${\mathrm{F}}_{5}$-doped ${(\mathrm{CH})}_{x}$ are due to solitons or doping inhomogeneities is investigated. For dopant concentrations ranging from 0.3 4.0 mol% in cis-${(\mathrm{CH})}_{x}$, the EPR spin susceptibility found be essentially independent temperature 300 K down lowest temperatures measured (100 K) but proportional concentration. In trans-${(\mathrm{CH})}_{x}$ results for two that completely consistent with those cis isomer. From these we propose over this concentration range very inhomogeneous, there being distinct doped and undoped regions metallic. 0.95 16 cis-${(\mathrm{CH})}_{x}$ respective dependences dc conductivity, $\mathrm{exp}(\ensuremath{-}A{T}^{\ensuremath{-}\frac{1}{2}})$ $\mathrm{exp}(\ensuremath{-}{A}^{\ensuremath{'}}{T}^{\ensuremath{-}\frac{1}{4}})$, taken support idea inhomogeneous doping. transition metallic previously interpreted as a semiconductor-to-metal throughout sample, attributed crossing percolation threshold at which form continuum. effect on degree isomerization, important interpreting some experiments critically examined. A variety other experimental evidence, particularly evidence others have advanced soliton-doping mechanism, reviewed shown compatible doping, most cases, while incompatible soliton cases.