Electron capture by highly charged projectiles under channeling conditions

The impulse approximation for charge transfer in fast, asymmetric ion-atom collisions is modified according to the presence of the axial potential and the geometric target structure when the projectile is axially channeled in a Si single crystal. Calculations of the impact-parameter-dependent capture probability by 1.6--5.6 MeV/amu O⁸⁺ and S¹⁶⁺ show that electron transfer only takes place at short distances to a string of target atoms, combined with a strong reduction as compared to atomic charge transfer.