Fragmentation mechanisms of aqueous clusters charged with ions

Fragmentation processes of mesoscopic aqueous clusters charged with ions of similar sign are studied by computer simulations. In order to examine differences in the fragmentation that depend on the nature of the ions and the charge distribution, the clusters contain positive (Na+ and Ca2+) or negative (Cl-) ions. Insight into the fragmentation mechanism is obtained by theories of activated processes. Critical to this approach is the use of a new reaction coordinate that captures the shape fluctuations of the droplet that are responsible for the reaction. Reversible work profiles for the reaction are constructed along the reaction coordinate, and dynamics is performed. The dynamics validates the use of the reaction coordinate, and shows diffusive barrier crossing. It is found that clusters with even number of charges fragment unevenly in contrast to analytical theories that predict even fission by considering only the energetic factors that determine the stability of charged droplets. (C) 2003 American Institute of Physics.