The influence of photoinduced structural distortions on interband absorption in polyacetylene

Abstract

Picosecond pump and probe experiments were carried out on fully oriented transpolyacetylene. Exciting the sample at 527 nm, photoinduced bleaching and absorption were observed at 527 nm and 1054 nm, respectively. The measurements give an upper limit of 2 ps for the relaxation time of the photogenerated 0.5 eV hot carriers to the band edges. The evaluation of the measured optical processes strongly suggests the conclusion that photoinduced structural distortions of the polyacetylene chain result in observable transient decrease of the interband absorption. This may be ascribed to the reduction of the density of electronic states and to that of the interband transition matrix element of the momentum operator. © 1988 Springer-Verlag.