Femtosecond impulsive vibrational spectroscopy in conjugated polymers

We apply the impulsive coherent vibrational spectroscopy technique to the study of the vibrational structure of conjugated polymers and oligomers. Molecular vibrations are directly observed in the time domain using tunable 10 fs light pulses from a recently developed optical parametric amplifier. We present results obtained with the prototypical systems sexithiophene, polidiacetylene and poly(p-phenylenevinylene), observing modes with frequencies up to 2100 cm(-1) (16 fs period). We directly measure vibrational dephasing times and gain hints on the potential energy surface anharmonicity. (C) 2000 Elsevier Science B.V. All rights reserved.