Conformational defects in Durham-route polyacetylene

摘要: Abstract Polyacetylene prepared by the Durham precursor route can be obtained either in a poorly-crystalline form thermal conversion of film cast from solution onto substrate, or well-aligned and highly crystalline if free-standing is stretched during transformation reaction. We find that measurements sensitive to length defect-free polyene chain show similar ‘long-chain’ characteristics both stretch-aligned films Shirakawa polyacetylene. These include dispersion resonant-Raman spectra with excitation energy ESR linewidth for neutral spin defects present materials. In contrast, unstretched properties expected chains frequently interrupted defects. consider these are mostly bends twists, conformational do not break bond-alternation symmetry on therefore prevent creation soliton-like defect states chemical doping. The evidence this comes analysis (the very weak), optical absorption doped films. peak at 2.3–2.5 eV, ‘mid-gap’ 1 eV; energies significantly higher than material.