Heidelberg 2015 – wissenschaftliches Programm

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A: Fachverband Atomphysik

A 20: Interaction with strong or short laser pulses II

A 20.1: Hauptvortrag

Mittwoch, 25. März 2015, 11:00–11:30, C/HSW

Strong-field ionization of molecules in circularly polarized fields — Ingo Petersen, Jost Henkel, and •Manfred Lein — Institut für Theoretische Physik, Leibniz Universität Hannover, 30167 Hannover

The electron momentum distribution from strong-field ionization of molecules contains rich information about the molecular electronic structure. Circularly polarized light is particularly advantageous because (i) it delivers a 360 degree scan of the molecule, (ii) the absence of recollisions makes the ionization process easier to interpret, and (iii) enantiomers of chiral molecules can be distinguished by exploiting photoelectron circular dichroism. Our calculations for diatomic and polyatomic molecules show that the width of the momentum distribution in the direction perpendicular to the polarization plane is a robust observable that is useful for imaging of aligned molecules. In particular, a strong variation of the width as a function of emission angle indicates contributions of multiple orbitals to the total ionization. For chiral molecules, we implement an extension of the strong-field approximation where the plane-wave continuum states are replaced by the Born approximation. The calculated distributions from a gas of randomly oriented molecules (using the examples camphor and fenchone) exhibit a forward-backward asymmetry as expected due to the dichroism effect, but they are not in quantitative agreement with recent experiments.