Stuttgart 2012 – wissenschaftliches Programm

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A: Fachverband Atomphysik

A 14: Interaction with VUV and X-ray light II

A 14.1: Vortrag

Dienstag, 13. März 2012, 10:30–10:45, V57.05

Atomic photoionization in combined intense XUV free-electron and infrared laser fields — •Mathias Arbeiter and Thomas Fennel — Institute of Physics, University of Rostock

The electron emission process of noble gas atoms exposed simultaneously to ultrashort monochromatic extreme ultraviolet (XUV) and to intense near infrared (NIR) laser pulses can be seen as a two-step process consisting of XUV photoionization and subsequent electron-NIR-field interaction. Experiments at the free electron laser in Hamburg (FLASH) have shown that already at modest intensities of the NIR dressing field, the XUV induced photoionization lines are split into a sequence of peaks due to the emission or absorption of several additional infrared photons [1]. A systematic study reveals that this sequence of sidebands forms a plateau-shaped structure, which broadens with increasing field strength. We present a theoretical study of the electron emission based on the Simpleman's model and a fully quantum mechanical TDSE description in single-active-electron-approximation. We find that the quantum calculation well reproduces the formation of individual sidebands, the AC Stark shifts, and the overall shape of the sideband envelope [1]. Furthermore the intensity-dependent cut-off energies of the sideband plateau are in good agreement with the classical trajectory model. The results are compared to the experimental data.

[1] P. Radcliffe, M. Arbeiter, W. B. Li, S. Düsterer, H. Redlin, P. Hayden, P. Hough, V. Richardson, J. T. Costello, T. Fennel, M. Meyer, submitted 2011