PHOTOEXCITED STATES IN DIRECTLY SYNTHESIZED TRANSPOLYACETYLENE FILMS STUDIED BY PHOTOCURRENT MEASUREMENT

A trans-polyacetylene film was directly synthesized to reduce defects introduced during usual thermal isomerization treatment. A photocurren t excitation spectrum of this film showed very low efficiency around a reflection peak which was accompanied with phonon side bands. This st rongly indicates that the lowest optically allowed state of trans-poly acetylene is a 1(1)B(u) exciton state like other conjugated polymers, such as polydiacetylenes. Misinterpretations of the experimental resul ts under the SSH model, because of the use of a film of low quality, a re pointed out and reinterpretations are made according to the present conclusion.