Atomic Physics Workshop

Stephan Fritzsche, Universität Kassel

Alignment and polarization effects in relativistic ion-atom collisions

During the last decade, relativistic collisions of highly- charged ions with different target materials have been studied intensively at the GSI storage ring and elsewhere. In such collisions, one of the major processes is due to the capture of a free or quasi-free electron into a bound state of the ion, accompanied by the simultaneous emission of one or several photons. Apart from the capture into the K-shell of bare ions, much of the recent interest was focused on the alignment of excited states, the angular distribution and polarization of the subsequently emitted radiation, or even the recombination of high-Z, few-electron ions.

In this contribution, I shall review the recent work on the (correlated) capture and decay processes of high-Z ions. Using the density matrix approach, I discuss (i) the angular distribution and polarization of the recombination and subsequent photons, (ii) the differential alignment of the (excited) levels as well as (iii) 'interferences' due to higher multipoles. Although most examples will concern the capture into bare, high-Z ions, it is shown also how the theory can be applied to the radiative recombination of few-electron ions.