Hamburg 2009 – wissenschaftliches Programm
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A: Fachverband Atomphysik
A 18: Photoionization I
A 18.2: Fachvortrag
Mittwoch, 4. März 2009, 14:30–15:00, VMP 8 R208
Highly doubly excited states of planar helium: Fluctuations in photoionization cross sections — •Johannes Eiglsperger and Javier Madroñero — Physik Department, TU München, Germany
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 photoionization cross section, are expected to become observable. A clear understanding of these issues requires a precise description of individual resonances and of the atomic continuum, which is achieved in our case, for planar helium, through an appropriate representation of the Schrödinger equation in creation and annihilation operators combined with the complex rotation method [1].
Photoionization cross sections calculated up to the 20th single ionization threshold exhibit fluctuations. These are mainly due to a dominant series of resonances which can be associated with an approximate quantum number F=N−K in accordance with 3D full calculations and experimental observations [2]. As the energy increases the dominant role of a single series as sole contributor is apparently lost as new series start to contribute significantly to the cross sections. This would result in an earlier onset of Ericson fluctuations [3] as in the picture of a single dominant series, where the onset is expected around I34.
[1] J. Madroñero and A. Buchleitner, Phys. Rev A 77, 053402 (2008).
[2] Y. H. Jiang et al., Phys. Rev A 78, 021401 (2008).
[3] J. Eiglsperger and J. Madroñero, in preparation.