Timing many-body effects in atomic systems

Light-sources based on the process of High-Harmonic Generations provide now increased repetition rates, as well as photon energies approaching the soft-X-ray region, at the same time the duration of intense x-ray pulses from X-ray Free-Electron Lasers is reaching the sub-femtosecond level.

These developments make possible a shift of the focus of attosecond physics from valence electron dynamics to the tighter bound orbitals in the core of atoms and molecules.

Here the dynamics of electron correlation driven relaxation - charge rearrangement - and its interplay with, in particular, the Auger-Meitner process is of special interest.

We build theoretical and computational tools for the interpretation and quantitative description of experimental observations with attosecond light-sources, in close contact with experimental groups.

We use advanced many-body theory based on the Dirac- as well as the Schrödinger equation, and time-dependent as well as time-independent methods are utilized.

Our aim is to study the plethora of screening and relaxation processes that are initiated when electrons are ionized from deeper energy levels.

Important questions are the duration of different processes, the relative time when secondary electrons appear in the continuum, its dependence on the coherence of the particles, and the reality of time-order in quantum mechanical systems.