Angular Scattering In Slow Multiple-charged Ion, Atom Collisions

The C6++H system is used to illustrate the importance of large-angle scattering in collisions between slow multiply charged ions and atoms. A quantum mechanical description based on a diabatic formalism of the collision system is used to obtain differential cross sections for electron capture in the relative velocity range nu =1*107 to 3*107 cm s-1 (Ecm approximately=48 to 430 eV). The threshold for angular scattering is at E theta approximately=0.2 keV deg which correlates with the curve crossing between initial and final molecular states located at Rx approximately=8a0. The centre-of-mass acceptance angles required to observe fixed fractions of the total electron capture cross sections are presented. Representative examples for the detection of 90% of the total electron capture cross section requires angular acceptances of 78 degrees at 1*107 cm s-1 and 8.5 degrees at 3*107 cm s-1