Abstract

In this experiment, Li₂ is excited from ground electronic state to the first excited state by 1 μJ, 75 s pulses from an amplified CPM laser at about 620 nm. The birefringence created by the pump pulses is measured at a delayed time by using a white-light-continuum probe (10 nm width, center at 770 nm and 800 nm). Unlike similar experiments, we are pumping in the resonance regime (the Rabi period here is 1-10 ps). This experiment is laying the groundwork for the use of shaped ultrafast pulses to develop a birefringence time history by design. We have computed a birefringence and dichroism signal based upon spectroscopy parameters. Most of the features have been confirmed experimentally. Experimentally, a birefringence step is observed after the initial pump pulse; this is due to a population transfer that results from the pumping process. Peaks that appear later are believed to be due to rotational coherences in the ground and first excited states.

© 1992 Optical Society of America