Observation of ultrafast chemical dynamics using femtosecond laser spectroscopy

Many important photochemical reactions occur on timescales from femtosecond to picosecond, requiring the use of ultrafast laser spectroscopy methods to observe the chemical dynamics. This project will use femtosecond laser pulses to initiate and monitor processes of photochemical change, both in isolated gas-phase molecules and in solution, allowing the development of a precise understanding of how the molecular dynamics are modified by a surrounding solvent. The gas-phase experiments will use velocity map imaging and ultrafast Coulomb explosion methods to take snapshots of the evolving structures of photoexcited molecules, thereby tracking the deformations which occur as chemical bonds are broken in energized molecules. The solution phase studies will use transient absorption spectroscopy in the infra-red, visible and ultraviolet regions to observe the changes in electronic state which photoexcited molecules undergo, their interactions with the surrounding solvent, dissipation of excess energy to the solvent bath, and reactions with other solute molecules. The outcomes of these complementary studies will be time constants and rate coefficients for the steps in molecular isomerization, dissociation or relaxation following absorption of ultraviolet radiation.
The experimental studies will make use of two EPSRC-supported experiments in the Bristol laboratory: a Coulomb explosion and velocity map imaging experiment funded by EP/L005913/1 and an ultrafast transient absorption spectroscopy experiment supported by EP/R012695/1.