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MO: Molekülphysik
MO 12: Photoionisation I (gemeinsam mit FV Atomphysik)
MO 12.6: Vortrag
Mittwoch, 6. März 2002, 17:45–18:00, HS 15/E10
Triple-electron processes in the decay of core-excited atoms — •Jens Viefhaus1, Slobodan Cvejanović1, Burkhard Langer2, Toralf Lischke1, and Uwe Becker1 — 1Fritz-Haber-Institut der Max-Planck-Gesellschaft, Faradayweg 4-6, 14195 Berlin, Germany — 2Max-Born-Institut für Nichtlineare Optik und Kurzzeitspektroskopie, Max-Born-Straße 2a, 12489 Berlin, Germany
We performed measurements on the Auger decay of core-ionized and core-exited Ar atoms at the Ar 2p3/2→3d resonance to study double and triple ionization processes caused by the Coulomb interaction. Using a multiple time-of-flight analyzer arrangement for electron-electron coincidences, we observe for the first time a double Auger continuum following core electron ionization. Our results show clear evidence for continuously distributed Auger electron intensity over a 150 eV range of kinetic energies. This double Auger decay represents roughly 10 percent of the normal single Auger channels. In case of the resonant Auger decay we also observe a two-electron continuum. The coincidence spectra show however that the intensity is concentrated in the region which must yield to triple-electron emission. The integrated intensity has the same order of magnitude as in the nonresonant case, which is surprising because here three Auger electrons have to be involved in the decay. This unexpected behaviour can be explained due to the existence of excited states of the doubly charged ion just above the triple ionization threshold. Therefore these states can further decay via emission of a low kinetic energy electron which may in turn interfere with the two electron continuum of the resonant double Auger decay.