Femtosecond two-dimensional spectroscopy of molecular motion in liquids

Intermolecular motion in CS2 and benzene is investigated by femtosecond nonresonant four- and six-wave mixing. Impulsive stimulated six-wave mixing yields new information on dephasing of coherent nuclear motion, not accessible from four-wave mixing experiments. The results cannot be modeled by two independent harmonic modes accounting for coherent librations and rotational diffusion.