The Ultrafast Dynamics of Photodetachment

Photodetachment is a general property of condensed-phase anions exposed to visible or ultraviolet light, but its mechanism has not been fully explored until recently. The combination of femtosecond pump-probe experiments in both bulk liquids and solvated clusters and quantum mechanical descriptions of the relevant excited states has provided new insight into the spectroscopy, energetics, and dynamics of the detachment process. We review detachment phenomena for the prototypical atomic systems, iodide in water and sodide in tetrahydrofuran, and these systems provide the relevant framework for molecular systems. The iodide system has been studied in gas-phase clusters as well as bulk solution. This article also contrasts mechanisms as a function of energy from purely charge-transfer-to-solvent detachment to regimes in which there is direct and indirect participation of the bulk conduction band.