FEMTOSECOND AND PICOSECOND EXCITON DYNAMICS IN POLY-ALKOXY-THIOPHENE AND POLY-ALKOXY-THIOPHENE-VINYLENE

We report on transient saturated absorption measurements on poly(3-pen toxy-thiophene) and poly(3-pentoxy-thiophene-vinylene) by the femtosec ond Pump and probe technique investigating exciton relaxation dynamics . The photoinduced bleachings can be fitted by a fast biexponential de cay followed in some cases by a power law decay. The initial part of t he decay is consistent with the self-trapped exciton relaxation proces ses. The presence of the power law is strictly related to the appearan ce of a long wavelength tail in the absorption spectra.