Dephasing Dynamics of the Vibronic States of Epitaxial Polydiacetylene Films

Abstract

The dynamics of polydiacetylene (pDCH) vibronic states has been measured with photon echoes and pump probe techniques using femtosecond optical pulses. The excitonic dephasing (52 fs) is shown to be dominated by interactions between excitons and the vibration modes of the polymer chain. The importance of the C=C double bonds compared to the C\ensuremath{\equiv}C triple bonds shows up both in the dephasing and early population dynamics. These results sugest that just after excitation the polydiacetylene backbone undertakes a transient structural change with a butatrieniclike distribution of the electronic states.