Fragmentation induced by charge exchange in collisions of charged alkaline clusters with alkali atoms

Abstract

We present a theoretical study of the dissociative charge transfer processes induced by collisions between doubly-charged alkaline clusters and alkaline atoms at slow and intermediate impact energies. Charge-exchange cross sections have been evaluated for the collisions of Li312+ and Na312+ clusters with neutral alkaline atoms (Cs and Na) at impact energies between 500 and 4000 eV. The branching ratios of the evaporation processes have been calculated within the framework of the microcanonical statistical theory of Weisskopf. The key ingredient of this model is the cluster vibrational density of states. An approach based on quantum tight-binding Hamiltonian is introduced, allowing us to evaluate this quantity at a microscopic level, including quantum vibrational effects at low temperatures. Comparison with previously reported results obtained using a macroscopic description of the level density are presented and discussed.