Anisotropic Kinetics of Optically Excited Charge Carriers in Trans -Polyacetylene

Transient photoconductivity in highly oriented polyacetylene has been investigated. A large anisotropy of μ || /μ ⊥ ≈ 50 has been found for carrier motion parallel and perpendicular to the chains. The relaxation has been followed over 8 orders of magnitude in time, establishing directly the existence of a fast (τ 1/2 ≈ 100 ps) and a slow component (lasting up to seconds). An appreciable anisotropy has been observed with respect to the polarization of the incident light, indicating interchain charge creation as predominant mechanism of the photoexcitation of carriers.