Solvation dynamics of the hydrated electron depends on its initial degree of electron delocalization

We investigate the time scale for hydrated electron solvation as a function of the initial configuration of the electron/water system. The experiments employ various 2-pulse and 3-pulse femtosecond pulse sequences that allow for controllable preparation of the various optically excited and precursor states of the equilibrated hydrated electron. We observe that the conduction band electron, which is produced by detrapping of the hydrated electron, has the slowest time scale for electron solvation with an average solvation time constant of 400 fs. In contrast, the solvation dynamics are significantly faster for electrons that are produced in presolvated environments. These latter examples include the excited p-state of the hydrated electron and the precursor states involved in UV femtosecond multiphoton ionization of water.