Angular differential studies of electron transfer in collisions of He-like ions with Na(3s): The role of electron saddle crossings

Abstract

We present a systematic experimental and theoretical study of angular differential cross sections of singleelectron transfer in collisions of N5+, O6+, and Ne8+ with ground-state Na(3s) in the collision energy range from 1 to 8 keV/amu. Experiments were performed using recoil-ion momentum spectroscopy in combination with a magneto-optically cooled Na atom target. The results are compared with three-body classical-trajectory Monte Carlo theory. Experimental and theoretical angular differential cross sections for capture into highly excited states show an oscillatory structure which is linked to the number of times the active electron crosses the potential energy saddle, i.e., oscillates between the two nuclear centers during the collision process.