Heidelberg 2015 – wissenschaftliches Programm

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A: Fachverband Atomphysik

A 13: Precision spectroscopy of atoms and ions II (with Q)

A 13.1: Hauptvortrag

Dienstag, 24. März 2015, 11:00–11:30, M/HS1

Observation of wave function collapse and four-electron Auger process in inner-shell photoionization of atomic ions — •Stefan Schippers — IAMP, Justus-Liebig-Universität Gießen, Germany

Inner-shell ionization of atomic ions is an important process in astrophysical and man-made plasmas. The creation of an inner-shell vacancy leads to the formation of multiply excited states which de-excite via many competing channels, some of which are quite exotic. Recently, the study of inner-shell photoionization of ions has become feasible at the PETRA III synchrotron radiation facility at DESY in Hamburg, Germany. There, the Photon-Ion spectrometer at PETRA III (PIPE) [1] was set up at the beam line P04 [2] which provides photons in the 250–3000 eV energy range. First results were obtained on the 3d ionization of multiply charged xenon ions where the formation of resonances via the collapse of nf wave functions was studied as a function of the primary ion charge [3]. Further experiments with singly charged carbon ions gave a compelling evidence of the new experimental capabilities of the PIPE setup. For the first time, multiple ionization by K-shell excitation of an atomic ion could be studied. As one of the de-excitation channels, the long sought-after triple Auger process — mediated by a four-body interaction — could be unambiguously identified [4].

[1] S. Schippers et al., J. Phys. B 47, 115602 (2014).

[2] J. Viefhaus et al., Nucl. Instrum. Methods A 710 (2013) 151.

[3] S. Schippers et al., J. Phys. B (in print).

[4] A. Müller et al., Phys. Rev. Lett. (in print).