Optical spectroscopy of the bulk and interfacial hydrated electron from ab initio calculations.

The optical spectrum of the hydrated (aqueous) electron, e(aq)(–), is the primary observable by means of which this species is detected, monitored, and studied. In theoretical calculations, this spectrum has most often been simulated using one-electron models. Here, we present ab initio simulations of that spectrum in both bulk water and, for the first time, at the water/vapor interface, using density functional theory and its time-dependent variant. Our results indicate that this approach provides a reliable description, and quantitative agreement with the experimental spectrum for the bulk species is obtained using a “tuned” long-range corrected functional. The spectrum of the interfacial electron is found to be very similar to the bulk spectrum.