Advances in Femtosecond Optical Techniques: Recent Experimental Investigations in the Field of Reaction Dynamics

Summary

The recent advances in the generation and measurement of ultrashort laser pulses has allowed to push most of the optical methods of investigation such as absorption, polarization and chemiluminescence spectroscopy down to the picosecond (10⁻¹²s) and even femtosecond (10⁻¹⁵s) time scale. These new techniques allow now to monitor the molecular dynamics of polar liquids and provide new results in the field of chemical or biochemical reaction dynamics: ultrafast free-radical reactions, intramolecular and intra-ionic dynamical processes.

The information available from the femtosecond optical techniques will be illustrated by recent results on electron trapping and solvation in aqueous media at room temperature. In pure liquid water, the existence of a precursor of hydrated state have been obtained by femtosecond absorption spectroscopy. These studies provide unique experimental basis for testing recent theoretical results obtained by newly developed techniques (Monte Carlo, molecular dynamics simulations, path integral) and to permit the obtention of a consistent picture of electron trapping and solvation in aqueous solutions.