Frankfurt 2006 – scientific programme
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A: Atomphysik
A 22: Poster II: Photoionisation
A 22.2: Poster
Thursday, March 16, 2006, 16:30–18:30, Labsaal
The search for oscillations in the near-threshold double photoionization cross section of helium — •U Kleiman1,2, T Topçu1, M S Pindzola1, and F Robicheaux1 — 1Auburn University, Department of Physics, Auburn, AL 36849, USA — 2Max-Planck-Institut für Physik komplexer Systeme, D-01187 Dresden, Germany
The double photoionization cross section for helium is calculated
in the near-threshold region by direct solution of the time-dependent
Schrödinger equation. Full close-coupling results for the 1s2 1S
ground state are found to be in excellent agreement with experimental
measurements [1]. The calculations confirm the validity of the Wannier power law from 0.1 eV to about 1.7 eV excess energy and find no oscillations in the
threshold cross section beyond numerical uncertainty. Further time-dependent
calculations are made in a simpler s-wave counterlinear model for both the
1s2 1S ground and 1s2s 1S excited states. Although numerical
uncertainties are significantly reduced in the helium model calculations,
again no oscillations in the threshold cross sections are found beyond the
remaining numerical uncertainty.
H Kossmann, V Schmidt and T Andersen, Phys. Rev. Lett. 60, 1266 (1988).