The relaxation process of the excitonic states in polydiacetylene studied by time-and wavenumber-resolved femtosecond coherent anti-Stokes Raman scattering

摘要

We report the relaxation process of photoexcited polydiacetylene in its excitonic states.A coherent polarization involving the ~1B_u excitonic stateis generated and probed using thefs-CARS(Coherent anti-StokesRaman scattering)method by varying the delay time between the pump and Stokes laser pulses.We obtain the relaxation data from an analysis of the wavenumber-resolved anti-Sokes signal.The fast dephasing time in the excitonic states was measured and the geometry relaxation model of the polymer chain is discussed.