Single and Multiple Excitation Processes in Heavy Ion-Atom Collisions at Intermediate Velocity
Résumé
The knowledge of the processes involved in swift heavy ion-atom collisions can be considered as the first step in the understanding of ion-matter interactions. This picture corresponds to a given description of the projectile stopping power. In this respect, the intermediate velocity regime (vp ≡ ve , where vp is the projectile velocity and ve the mean orbital velocity of the active electron) is of particular interest : the ion stopping power is nearly maximum and for applied purposes, the understanding of mechanisms accounting for radiation damage in materials is important. However, in this velocity range, experimental determination of monoelectronic process cross sections is not so simple since the excitation, ionization and capture channels are of the same order of magnitude and may influence each other strongly. On the other hand, the role of target electrons as active partners, via capture channel coupling and direct target electron-projectile electron interaction, is not well known. So far, these effects are not taken into account even by the most sophisticated theories. Furthermore, multiple processes, involving more than one electron of the projectile and of the target as well, are actually under study and ask for much debated questions.