The importance of Coulomb focusing on electron capture to the continuum investigated by impact-parameter-dependent electron emission probabilities

The probabilities for cusp and delta -electron production were measured as a function of the impact parameter and of the outgoing projectile charge state for collisions of 0.5 MeV u-1 H+, He+, He2+ on Ne and He targets. The experimental results for H+ projectiles are presented here and compared with both quantum mechanical and classical calculations. The results give strong evidence that in collisions between fast light ions and atoms a post-collision Coulomb focusing effect of the outgoing projectile ionic charge on the ionized electrons is of great importance for capture to the continuum.