Electron Attachment to (H₂O)₂Arn Clusters

The neutral and negatively charged (H 2 O) 2 Ar n, n = 1−14, clusters are investigated theoretically by use of a polarizable model potential together, in the case of the anionic clusters, with a Drude-model approach to incorporate dispersion interactions between the excess electron and the argon atoms and water molecules. The (H 2 O) 2 Ar 11 and (H 2 O) 2 - Ar 12 clusters are predicted to be “magic numbers”, with their high stability being a result of their global minima adopting icosahedral-like structures. On the basis of these results, a mechanism for formation of the anions is proposed. In addition, the rapid falloff in intensity of the n ≥ 7 anionic clusters in the observed mass spectrum and the absence of observable signal for the n = 10 cluster are accounted for.