Stuttgart 2012 – scientific programme

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A: Fachverband Atomphysik

A 22: Poster: Interaction with strong or short laser pulses

A 22.13: Poster

Tuesday, March 13, 2012, 16:30–19:00, Poster.V

Probing Fano resonances with ultrashort pulses — •Jing Zhao and Manfred Lein — Institut für Theoretische Physik and Centre for Quantum Engineering and Space-Time Research (QUEST), Leibniz Universität Hannover, Appelstraße 2, 30167 Hannover, Germany

Autoionizing states in the helium atom are investigated by numerical solution of the one-dimensional two-electron Schrödinger equation for irradiation of an XUV pulse and an infrared pulse with varying time delay. By analysing the photoelectron spectrum as a function of the time delay, it is shown that the line profile of the Fano resonance is modified by the laser-induced coupling between two doubly excited autoionizing resonances. The strong coupling leads to the population of higher autoionizing states, which cannot be reached by absorbing a single XUV photon from the ground state, and the excited atom can ionize from both states. An asymmetric Autler-Townes doublet due to the strong coupling is also observed in the photoelectron spectrum.