Frankfurt 2006 – wissenschaftliches Programm

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A: Atomphysik

A 18: Wechselwirkung mit starken Laserpulsen II: Ionisation

A 18.2: Vortrag

Donnerstag, 16. März 2006, 14:30–14:45, H6

Recoil Ion Momentum Spectra in Non-Sequential Double Ionization: Comparison of Different Theoretical Approaches — •Florian Wilken and Dieter Bauer — Max Planck Institute for Nuclear Physics, P.O. Box 10 39 80, 69029 Heidelberg, Germany

Atomic ionization processes in low-frequency strong fields exhibit an increased double ionization probability due to non-sequential double ionization in certain intensity regions [1]. Calculations for one-dimensional model atoms using different theoretical approaches have been successful in reproducing a “knee structure” [2,3,4] in the double ionization probability. We solve numerically the exact time-dependent Schrödinger equation for a one-dimensional model Helium atom in a short laser pulse for various intensities. Double ionization probabilities and momentum distributions of the recoil ion are obtained in agreement with experiments and previous works [5]. Numerical solutions for different theoretical approaches are calculated. The resulting ionization probabilities and momentum distributions are compared to the exact Schrödinger solution. The underlying process of the enhanced double ionization probabilities can be inferred from the momentum distribution of the recoil ion. A first assessment is made whether these approaches describe the non-sequential double ionization process satisfactorily.

[1] B. Walker et al., Phys. Rev. Lett. 73, 1227 (1994).

[2] J.B. Watson et al., Phys. Rev. Lett. 78, 1884 (1997).

[3] N.E. Dahlen and R. van Leeuwen, Phys. Rev. A 64, 23405 (2001).

[4] M. Lein and S. Kümmel, Phys. Rev. Lett. 94, 143003 (2005).

[5] M. Lein et al., Phys. Rev. Lett. 85, 4707 (2000).