Dielectronic processes and electron correlation in energetic ion-atom collisions

Abstract

Concepts of electron correlation in energetic ion-atom collisions are discussed in terms of dielectronic processes which are due to two-electron transitions produced by the electron-electron interaction. These dynamic processes are associated with configuration interaction occurring during the collision in the four-body ion-atom system or after the collision in the atomic three-body system. As in previous work, formal aspects of electron correlation in ion-atom collision are introduced in analogy with the treatment in atomic-structure theory. The full electron-electron interaction is partitioned into a mean potential of the passive electrons postulated within the framework of the independent particle model and the residual mutual interaction between two active electrons. Various cases of the interaction of electrons located initially at different nuclear centers are treated. As an example for a dielectronic process, the Bates-Griffing scattering mechanism is discussed concerning the interactions of two electrons centered at the projectile and the target. Furthermore, interferences between the nucleus-electron and electron-electron interaction are analyzed for the process of double excitation.