低能N+-He 碰撞中的态选择单电子俘获研究

he state-selective single-electron capture process in the collision of N⁺ ions with He at an energy of 0.64 keV/u has been experimentally studied by the reaction microscopy with a two-fold coincident method, and the state-selective cross-sections and angular distributions of an electron captured into different quantum states of the projectile ions have been obtained. The experimental results show that: the ground state projectile N⁺(³P) captures a 1 electron from the He target mainly to the 2 shell, and the contribution to the higher shells can also be observed; the metastable N⁺(⁵S) captures a 1 electron from the He target mainly to the 2 shell, with almost no contribution to higher shells. The experimental results are interpreted qualitatively using the potential energy curves of the NHe⁺ quasimolecular ion, but the reaction window predictions of the molecular Coulomb over-barrier model differ significantly from the experiments. During the capture of the target electron into the 2 orbital by the metastable projectile N⁺(⁵S), a clear oscillatory structure appears in the angular differential cross-section, which is likely to result from Demkov-type transitions.