Picosecond molecular dynamics in liquids via degenerate four-wave mixing

We report measurements of degenerate four-wave mixing in liquids to study the picosecond orientational dynamics of molecules and the transition of a probe molecule from many-particle to single-particle rotational behavior as a function of dilution. Data for CS2in pure and dilute alkane systems are presented, in which the molecular motion is characterized as diffusion, rather than impulsive, at times ≥ 0.9 ps, the limiting single-particle orientational correlation time in n-pentane at 300 K.