Differential scattering in collisions of K⁺ions with Ar atoms

Abstract

Total differential cross sections for K+-Ar collisions have been measured over a wide range of laboratory scattering angles, 5 degrees <or approximately= theta <or approximately=80 degrees , and at ion energies 100-350 eV. Beyond an angle of about 45 degrees , unexpectedly high cross sections have been found. The cross sections are attributed to Ar+ ions produced in charge exchange reactions between K+ ions and Ar atoms and also through autoionisation of doubly excited Ar** atoms formed in the K+-Ar collisions. Elastic and inelastic differential cross sections have been analysed by a semiclassical treatment assuming three-state potentials The result shows the inelastic collisions with high probability are caused in the region of the closest approach Rc<or approximately=1.2 AA, where the repulsive potential V(Rc)>or approximately=41 eV.