Experimental and thoeretical studies of the two-center electron-electron interaction occurring during energetic ion-atom collisions are presented. Experiments were performed using the accelerator facility VICKSI at HMI, Berlin. Electron spectra from Auger and Coster-Kronig transitions following the excitation of a highly charged neon projectile have been studied by zero-degree electron spectroscopy. Various target atoms with atomic numbers ranging from 1-18 were used as exciting partners. We applied both impact parameter treatments and the plane wave Born approximation to describe screening effects and dielectronic two-center processes ("antiscreening"). We found that the 1s-2l excitation of the Ne7+ projectile at 8.5 MeV/u impact energy is mainly due to the screened target nucleus. In contrary, two-center processes are likely to be dominant in the 2s-nl excitation of the 6 MeV/u Ne6+ projectile. The 2s-nl cross sections are roughly proportional to the number of electrons per target atom. This fact suggests that, in disagreement with first order theories, the 2s-nl excitation is significantly governed by the two center electron-electron interaction.
ASJC Scopus subject areas
- Nuclear and High Energy Physics