Coherent transients in simple molecular liquids studied with a femtosecond laser

摘要

The ultra fast inter- and intra-molecular dynamics of simple molecular liquids are studied with a femtosecond (fs) laser whose pulse duration is varied form >100fs to 16fs. A powerful fs pulse in the laser pulse train pumps the transparent liquid sample, and instantaneously establishes an ensemble-coherence in molecular motion. At the same time a fictitiously weak and variously delayed probe pulse is used to follow the evolution of the coherence. The experiment is unique in two aspects: 1) both the pumping and probing pulses are much shorter than the time of molecular dynamics; and 2) the detected probe pulse has its polarization changed (or de-polarized) by the pumped sample-the optical Kerr effect (OKE) experiment.