Two-centre dielectronic transitions in fast highly charged ion–atom collisions

We consider two-centre dielectronic transitions occurring in collisions of fast highly charged hydrogen-like projectiles with neutral atomic targets. In such collisions, in addition to the reaction channel due to the two-centre electron–electron interaction, the reaction channel induced by the two-centre electron–nucleus interactions becomes important. We show that the account of distortions of initial and final states of the target caused by the field of the projectile nucleus (which can also be viewed as imposing the Coulomb boundary conditions on these states) leads to an approach in which both these reaction channels are combined in a natural and relatively simple way. As a result, this approach enables one to extend calculations of different cross sections for two-centre dielectronic transitions from the high-velocity to the intermediate-to-high collision velocity regime.