Femtosecond dynamics of excited states in sexithiophene thin films Original Research Article

The dynamics of excited states of α-6T sexithiophene has been studied by femtosecond pump-probe experiments. Excited states are produced by two-photon absorption processes. Two different excited states have been observed in the induced absorption spectra. The first one, short lived (700 fs) has been assigned to a singlet exciton, and the second one, long lived and non radiative to the bottom of the singlet exciton band. At short time delays (200 fs) a narrow peak in the induced absorption spectrum has been assigned to a transition to an intermolecular biexciton state.