Mechanisms of non-adiabatic charge-exchange transitions in slow collisions of W ions with He, Ar and Kr atoms

Abstract

The study of slow collisions of heavy particles is a challenging task from both experimental and theoretical points of view. A powerful tool for the theoretical description of these collisions is the adiabatic theory of transitions in slow collisions developed by Solov’ev (1989), which is applied here to study low-energy charge exchange between tungsten ions and inert-gas atoms at 0.01–1 keV/u. It is found that the main mechanism of charge-exchange transitions in collisions of W+ ions with Ar and Kr atoms at energies below 1 keV/u is the rotational coupling associated with internuclear axis rotation in close collisions, while charge exchange between W8+ ions and He atoms is mainly due to the radial Landau–Zener type transitions. For all cases, potential curves as a function of the internuclear distance are calculated together with the charge-exchange cross sections. The cross sections obtained are compared with experimental data, showing good agreement and explaining the mechanisms of the transitions.