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A: Fachverband Atomphysik

A 13: Atomic Systems in External Fields II

A 13.1: Invited Talk

Tuesday, March 3, 2009, 16:30–17:00, VMP 6 HS-B

The total break-up of two-electron atoms: from highly doubly excited states to double ionization of helium — •Javier Madroñero^1,2, Johannes Eiglsperger¹, and Bernard Piraux² — ¹Physik Department, TU München, Germany — ²PAMO, UC Louvain, Belgium

The complete breakup of an atomic system involving three or more particles is a very complex process, mostly due to the long range nature of the Coulomb interactions between the electrons. Close to the break-up-threshold of two-electron atoms the spectrum is strongly influenced by the underlying classical mixed regular-chaotic dynamics and typical signatures of quantum chaos, e.g., Ericson fluctuations or scaling laws for the fluctuations of the spectrum, are expected to become observable. Under the action of an electromagnetic field, electronic correlations are brought about by the kinematics of the double ionization, i.e., in two-photon processes, or they might manifiest directly in two-electron nondispersive wave packets which are expected to be observed under near-resonant periodic driving of highly doubly excited states localized in stable regions of the classical system.

In this contribution we give a brief review of our most important recent achievments in the understanding of these issues, namely fluctuations in the photoionization cross sections of planar helium up to the 20th ionization threshold, the formation of two-electron nondispersive wave packets by near-resonant driving of highly doubly excited states and the electron dynamics in double ionization of helium by two XUV photons.