Picosecond dynamics of photogenerated charged solitons in trans- polyacetylene.

Measurements of the dynamics of the photoinduced .45 eV midgap absorption associated with photogenerated charged solitons in trans-polyacetylene are reported. We have studied the intensity, polarization and temperature dependence of the dynamics of this band with 5 ps resolution. Two types of charged solitons are clearly identified. First, there are directly photogenerated Su-Schrieffer soliton pairs which form following intrachain absorption and geminately recombine on subpicosecond time scales. At later times (>~ 20 ps), there are charged solitons formed by an interchain absorption mechanism where polarons are formed and diffuse to convert residual neutral solitons to charged. We discuss the strengths and weaknesses of our picture of the photoexcitation dynamics in trans-polyacetylene in light of other work.