Stopping power of fast, partially stripped molecules and clusters: Vicinage effects in charge states - art. no. 022901

We present a consistent variational approach to the vicinage effect on ion charges in a cluster made of partially stripped ions, based on the Brandt-K itagawa theory for isolated ions, supplemented by dynamically screened inte rionic interactions. Interferences in cluster stopping power are shown to b e strongly influenced by the ion-charge dependence on internuclear separati ons, and may give rise to energy loss enhancement or deenhancement, when co mpared to the case when the ion charges are frozen at the value correspondi ng to isolated ions at the same speed. In addition, the ion charge reductio n is shown to be responsible for softening the interionic interactions resp onsible for Coulomb explosion. Calculations of the vicinage effect on ion c harges are performed for a fast N-2 molecule moving through a carbon target , and the roles of Coulomb explosion and multiple scattering in energy loss are discussed.