Electron exchange dynamics in low-energy ion-atom interactions

Electron transfer and ionization processes in collisions of highly charged ions with atoms play a significant role in all astrophysical and man-made plasma environments. The dynamics of such many-body systems is of fundamental interest as a benchmark for theory.

In this thesis a systematic study of electron transfer and ionization in collisions of highly charged ions (N5+, O6+ and Ne8+) with Na atoms in the low keV/amu collision energy is presented. The experiments have been performed by means of measuring the tiny recoil caused by the interaction of the ion and the atom during the collision, which provides all necessary information on the collision process. The atomic target has been provided by magneto-optically cooling and trapping of Na atoms.

From the cross sections obtained with the Na atom target an interpolation of cross sections of the experimentally elusive but fusion-relevant metastable hydrogen is obtained.

Cross sections as a function of the projectile scattering angle give information on the impact parameter dependence of the processes. Theoretical calculations of electron transfer reveal that the structure observed in the scattering angle distributions is related to different dynamic processes: It is shown that during the collision the active electron can oscillate between the target and projectile nuclear centers, with the number of oscillations depending on the electron's final state in the projectile and the collision energy.

First results on two-electron processes in collisions of O6+ ions with Na atoms have been obtained and different electron transfer mechanisms are identified.