Hydrogen detachment of the hexahydrated hydroiodic acid upon attaching an excess electron

Abstract

A hydroiodic acid molecule is dissociated by more than four water molecules. Here, the effect of an excess electron on the hexahydated hydroiodic acid where the dissociated structure [H3O+(H2O)(5)I-] is much more stable than the undissociated one [(H2O)(6)HI], is investigated. Upon binding an excess electron (e(-)), the cluster releases a hydrogen radical and forms the stable hexahydrated iodide [(H2O)(6)I-] when the initial kinetic energy is above similar to 200 K, due to the small transition barrier (similar to 0.5 eV). The system with the hydrogen radical released, [(H2O)(6)I- + H center dot], is much more stable than the systems with an excess electron, [(H3O)(+){e(-)(H2O)5}I-] or [e(-)(H2O)(2)(H3O)(+)(H2O)(3)I-].