KINETIC-ANALYSIS OF COMPUTER EXPERIMENTS ON ELECTRON HYDRATION DYNAMICS

Based on a careful analysis of recent nonadiabatic dynamical simulations, a new mechanism is proposed to describe the hydration of electrons in pure water, and the solution of the corresponding set of differential equations is given. According to this mechanism, a thermalization via spontaneous de-excitations across a manifold of delocalized excited states is followed by a branching between a two-step hydration and a direct trapping path leading to the ground state of the hydrated electron. From a kinetic perspective, the most important results of the analysis derive from the temporal evolution of the electronic states in two different sets of simulation trajectories; one in which the electron initially possesses about 2 eV excess energy in the unrelaxed solvent, and another at an initial excess energy higher about 0.5 eV. Estimated characteristic rates for energy loss during thermalization are found to be identical for the two cases. However, branching ratios and characteristic times for the solvation steps show considerable differences, depending on the initial energy of the hot electrons injected into the water.