Berlin 2014 – wissenschaftliches Programm

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A: Fachverband Atomphysik

A 11: Electron Dynamics in Chiral Systems SYCS 2 (with MO)

A 11.4: Hauptvortrag

Montag, 17. März 2014, 15:00–15:30, BEBEL HS213

Circular Dichroism in Mass Spectrometry: Laser Pulse Induced Electron Wavepacket Dynamics — •Dominik Kröner — Universität Potsdam, Institut für Chemie, D-14476 Potsdam, Germany

The qualitative and quantitative identification of chiral molecules is of central importance in chemical analysis. In mass spectrometry the distinction of enantiomers is achieved by applying circularly polarized laser pulses. The sample is ionized via multiphoton excitation induced by shaped ultrashort laser pulses of opposite helicity, which interact enantiospecifically with the chiral molecules according to their handedness. The resulting differences in the ion yields allow to determine a circular dichroism in the mass spectrum. The polarization is, however, not the only pulse parameter which influences the circular dichroism in the ion yields, but also e.g. the pulse duration or the wavelength [1].

We study the fundamental processes, which lead to the distinction of chiral molecules in mass spectrometry, by performing laser driven quantum electron dynamics based on ab initio electronic structure calculations, in particular TD-CIS(D). For that purpose, a full treatment of the electric field-electric dipole (and quadrupole) as well as magnetic field-magnetic dipole interactions is required [2]. The influence of different laser pulse parameters on the detected circular dichroism is investigated, in order to explain experimental observations and to allow for predictions of an optimal distinction of enantiomers.

[1] P. Horsch, G. Urbasch, K.-M. Weitzel, D. Kröner, Phys. Chem. Chem. Phys. 13, 2378 (2011).

[2] D. Kröner, J. Phys. Chem. A 115, 14510 (2011).