Femtosecond impulsive vibrational spectroscopy in conjugated polymers

We apply the impulsive coherent vibrational spectroscopy technique to the s tudy of the vibrational structure of conjugated polymers and oligomers. Mol ecular 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, poli diacetylene and poly(p-phenylenevinylene), observing modes with frequencies up to 2100 cm(-1) (16 fs period). We directly measure vibrational dephasin g times and gain hints on the potential energy surface anharmonicity. (C) 2 000 Elsevier Science B.V. All rights reserved.