PNNL

Abstract

A primary means to generate hydrated electrons in laboratory experiments is excitation of a charge-transfer-to-solvent (CTTS) state of a solute such as I-(aq), but this initial step in the genesis of e-(aq) has never been simulated directly. We report the first such simulations, via ab initio molecular dynamics of ground- and excited-state I-(aq) combined with an automated diabatization procedure. What emerges is a two-step picture of the evolution of e-(aq) starting from the CTTS state, I-(aq) + h? I-*(aq) I (aq) + e-(aq). Notably, the equilibrated ground state of e-(aq) evolves from I-*(aq) without any nonadiabatic transitions, simply as a result of solvent reorga- nization that can be diabatized based on the solvent’s electrostatic potential. The methodology used here should be applicable to other photochemical electron transfer processes in solution, an important class of problems directly relevant to photocatalysis and energy transfer.