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A: Atomphysik

A 11: Photoionisation I

A 11.7: Vortrag

Dienstag, 23. März 2004, 18:00–18:15, HS 132

Partial cross sections of doubly excited helium below the N=7 ionization threshold — •Yuhai Jiang^1,2, Ralph Püttner¹, Rainer Hentges³, Jens Viefhaus³, Uwe Becker³, Jan-Michael Rost², and Günter Kaindl¹ — ¹Institut für Experimentalphysik, Freie Universität Berlin, Arnimallee 14, 14195 Berlin — ²Max-Planck-Institut für Physik Komplexer Systeme, Nöthnitzer Str. 38, 01187 Dresden — ³Fritz-Haber-Institut, Faradayweg 4-6, 14195 Berlin

Partial photoionization cross sections (PCSs), σ_n, leading to final ionic states of helium, He⁺(n), were measured at BESSY II in the region of doubly excited helium up to the ionization threshold I₇ of He⁺ [1]. The experiments were performed with a time-of-flight (TOF) electron spectrometer and high photon resolution, Δ E≅ 6 meV. The results of these measurements are a most critical assessment of the decay dynamics of double-excitation resonances and agree well with those of recent eigenchannel R-matrix calculations. The mirroring behavior in the PCSs predicted recently by Liu and Starace [2] is only partially observed. By discussing the formulas given by these authors in a more general context, the behavior of the PCSs of helium with respect to mirroring can be understood.

[1] Y. H. Jiang, R. Püttner, R. Hentges, J. Viefhaus, M. Poiguine, U. Becker, J. M. Rost, and G. Kaindl, Phys. Rev. A (submitted).

[2] Ch.-N. Liu and A. Starace, Phys. Rev. A 59, R1731 (1999).