Séminaire LCPQ
Salle de séminaire IRSAMC
Ionic aqueous clusters constitute a paradigm for detailed investigations of the ion-water and water-water interactions involved in numerous important biological and chemical processes. In this contribution, we explore and discuss the solvation structure of a variety of ions in clusters and their effect on water structure. In particular, some ions have a higher affinity for the cluster surface rather than the interior as they are unable to affect the water structure significantly. Accordingly, an array of efficient first-principles methods has been developed to simulate quantitatively the solvation structure of ionic aqueous clusters and address this issue. Furthermore, an interesting feature of surface-solvation ionic cluster structures lies in the large dipole moment of the water network and its ability to bind an electron upon photo-excitation. Photo-excited iodide-water clusters, for instance, have attracted considerable interest, since investigation of these clusters may provide new insights into the mechanism of formation of the closely related hydrated electron, one of the simplest yet most mysterious ions of chemistry. Ab initio molecular dynamics simulations of the excited-state dynamics of iodide-water clusters are thus presented ; the use of these simulation results along with experimental photoelectron spectra to understand the precise mechanism of excitation and relaxation is then discussed. The cluster structure and dynamics may be understood in terms of the subtle interplay between water-water and ion-water interactions in the clusters.