Two Electron Transfer and Stabilization in Slow O ⁶⁺ and Rare-Gas Collisions

Abstract

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 O 6+ +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 O 6+ ion can be taken as a bare ion C 6+ except the occupied 1s shell, and then the measured 𝑅 values are compared with previous experimental results of C 6+ projectile ions at similar impact velocity. It yields good agreement with the Ne and Ar target, while the occupied 1s shell for the O 6+ +He system results in a higher 𝑅 value than that in C 6+ +He collisions.