Coherent molecular vibrations are detected in sexithiophene thin films. The excitation source is a newly developed optical parametric amplifier that provides l0-l2 fs pulses in the visible wavelength range. Five modes 'that couple strongly with the lowest electronic transition, at ωl = ll2 cm~-l, ω_2 = 299 cm~-1, ω~3 = 702 cm~-l, ω _4 = l040 cm~-l ω_5 = 1454 cm~-l, are identified. Their assignment is discussed based on the comparison with high-resolution absorption and emission spectra and theoretical predictions.
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