The role of solvent intramolecular modes in excess electron solvation dynamics

The role played by solvent molecular flexibility in the dynamics of the solvation of an initially energetically excited excess electron in water is investigated using nonadiabatic molecular dynamics simulation and a classical flexible water model. It is found that the effect of flexibility on relaxation times is substantial, but the effect on the branching ratio for excess electrons passing through alternative intermediate excited states is small. Examination of the optical absorption spectra of the hydrated electron shows that the effect of solvent flexibility is also small here. An analysis of transient spectra supports the validity of a kinetic analysis based on species with individual well defined signatures. However, the data suggest that a two state analysis of the dynamics neglects a potentially important role for early time delocalized electrons.