The identification of a solvated electron pair in the gaseous clusters of Na-(H2O)n and Li-(H2O)n

By first principles calculations, we explore the possibility that Na-(H2O)(n) and Li-(H2O)(n) clusters, which have been measured previously by photoelectron experiments, could serve as gas-phasemolecular models for the solvation of two electrons. Such models would capture the electron-electron interaction in a solution environment, which is missed in the well-known anionic water clusters (H2O)(n)(-). Our results show that by n = 10, the two loosely bound s electrons in Li-(H2O)(n) are indeed detached from lithium, and they could exist in either the singlet (spin-paring) or the triplet (spin-coupling) state. In contrast, the two electrons would prefer to stay on the sodium atom in Na-(H2O)(n) and on the surface of the cluster. The formation of a solvated electron pair and the variation in solvation structures make these two cluster series interesting subjects for further experimental investigation. (C) 2011 American Institute of Physics. [doi: 10.1063/1.3622562]