Photomodulation spectroscopy of soluble polyacetylene

Abstract Photoexcitation of soluble polyacetylene has been investigated by both steady-state and transient picosecond photomodulation spectroscopies. The steady-state photoinduced absorption spectrum shows the usual band at 0.5 eV assigned to charged solitons, while the neutral soliton absorption band is concealed under the strong photoinduced electroabsorption. The picosecond spectrum confirms the anomaly in the high-energy photoinduced absorption band, which appears to be much weaker, broader and more strongly temperature dependent than in regular Shirakawa polyacetylene films. This is correlated with the particular sample morphology and the defect-mediated stabilization mechanism of the neutral photoexcitations.