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A: Fachverband Atomphysik

A 23: Poster II

A 23.2: Poster

Donnerstag, 11. März 2010, 16:30–19:00, Lichthof

Controlling Two-Electron Threshold Dynamics in Double Photoionization at FLASH — •Michael Schuricke, Gopi Veeravalli, Renate Hubele, Ganjun Zhu, Johannes Albrecht, Jochen Steinmann, Alexander Dorn, and Joachim Ullrich — Max-Planck-Institut für Kernphysik, Saupfercheckweg 1, 69117 Heidelberg, Germany

Controlling the dynamics and understanding the time evolution of correlated many-electron systems is one of the major challenges in physics. Special interest lies in multiple-ionization close to of threshold, where the total kinetic energy available in the final state approaches zero resulting in a strongly correlated system. Thus, in theoretical descriptions all independent particle or self-consistent field approximations fail.
In this regime we investigated the double photoionization (DPI) and ionization-excitation (IE) of state prepared and aligned lithium, from 2 to 12 eV above the DPI threshold (ℏω = 81, 85, 91 eV). Thereby combining three state-of-the-art techniques, namely magneto-optically trapped lithium, a Reaction Microscope and the free-electron laser at Hamburg (FLASH). The total and differential DPI cross sections reveal a strong dependence on the initial state and particularly on the alignment of the 2p-orbital with respect to the VUV-light polarization, whereas no such effect is observed for IE. Approaching threshold the alignment sensitivity increases, which can be understood by attributing these findings to dynamical electron correlations at vanishing excess energy.