Düsseldorf 2007 – wissenschaftliches Programm

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A: Fachverband Atomphysik

A 9: Interaction with strong laser pulses II

A 9.7: Vortrag

Dienstag, 20. März 2007, 15:45–16:00, 5M

Orbital imaging with high harmonics: single- vs. multi-electron approach — •Gerald Jordan and Armin Scrinzi — TU Wien, Institut für Photonik

The imaging of molecular orbitals by electron rescattering is revisited from the multi-particle point of view. The interpretation of the experimental data has so far largely relied on the single-active electron approximation, whereby the imaged object is identified with the HOMO of the molecule. In multi-electron systems, correlation tends to blur the distinction between individual orbitals. We investigate the viability of the single-electron approximation and the significance of the single-electron orbitals (in particular the Dyson orbital).

We use the MCTDHF (multi-configuration time-dependent Hartree-Fock) method to systematically account for correlation effects. Laser ionization of a 3-dimensional model diatomic molecule is simulated with 2 and 4 active electrons. The high harmonic spectra obtained with MCTDHF are compared with two single-electron models based on the Dyson orbital: the strong-field approximation (Lewenstein model), and the solution of the TDSE for an effective 1-electron Hamiltonian with the Dyson orbital built in as the ground state.

The Lewenstein spectra fail to qualitatively reproduce the multi-electron results. Solution of the 1e-TDSE allows to further distinguish between effects related to the SFA and the SAE. The features of the harmonic spectra are associated with the time structure of the rescattering current, which in turn reflects molecular multi-electron ionization dynamics.