Two Electron Transfer and Stabilization in Slow O 6+ and Rare-Gas Collisions
The stabilization ratios R for double-electron transfer, i.e., the cross section ratios of true double capture to total double-electron transfer, are measured in O6+ +He, Ne and Ar collisions at 6 keV/u. A high R value about 68% is obtained for the He target, while for the Ar target, the R value is only 8%. The high R value for the He target is due to the significant direct population of the (2l, nl') configurations with high n. For the Ar target, the (quasi)symmetric configurations (3l, nl') lead to the much lower R value. Neglecting the core effects, the O6+ ion can be taken as a bare ion C6+ except the occupied 1s shell, and then the measured R values are compared with previous experimental results of C6+ projectile ions at similar impact velocity. It yields good agreement with the Ne and Ar target, while the occupied 1s shell for the O6+ +He system results in a higher R value than that in C6+ +He collisions.