Düsseldorf 2007 – scientific programme

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A: Fachverband Atomphysik

A 9: Interaction with strong laser pulses II

A 9.4: Talk

Tuesday, March 20, 2007, 15:00–15:15, 5M

Coulomb effects in strong-field ionization — •Sergei Popruzhenko — Max-Planck-Institut für Kernphysik, Postfach 10 39 80, 69029 Heidelberg, Germany

Recent high-resolution experiments with atoms subjected to short intense laser pulses have generated new interest to the role of long-range atomic field in the ionization dynamics. Here we present a new method of including Coulomb effects in the description of the strong field ionization. The approach is based on the Kapitza method of separation the classical electron dynamics into fast oscillations and slow-varying motion. The method is applied for description of the Coulomb peculiarities in above-threshold ionization (ATI) spectra. In particular, the cusp and the double-hump structures in the photoelectron momentum distribution in a linearly polarized field, as well as the fourfold symmetry violation of the angular distributions with elliptical laser polarization are reproduced in good agreement with the data. Besides, the method gives an insight into the problem: why do Coulomb effects in ATI spectra remain quite pronounced even in the strong-field limit? Basically, this feature results from the fact that relatively weak but slow-varying Coulomb force induces an accumulating effect which can survive after averaging over many laser periods.