Hannover 2013 – wissenschaftliches Programm

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MO: Fachverband Molekülphysik

MO 12: Femtosecond Spectroscopy III

MO 12.6: Vortrag

Dienstag, 19. März 2013, 15:45–16:00, F 102

Photoelectron Circular Dichroism of Chiral Molecules from Multi Photon Ionization with Femtosecond Laser Pulses: Intensity and Ellipticity studies — •Christian Lux, Vanessa Brandenstein, Jens Köhler, Cristian Sarpe, Matthias Wollenhaupt, and Thomas Baumert — Universität Kassel, Institut für Physik und CINSaT, D-34132 Kassel, Germany

Photoelectron Circular Dichroism (PECD) shows asymmetries in the electron emission from chiral enantiomers relative to the light propagation direction and was so far investigated using synchrotron radiation [1]. The magnitude of PECD is several orders larger than typically chirooptical asymmetries. Resonance Enhanced Multi-Photon Ionization (REMPI) in mass spectrometry of chiral molecules using laser pulses results in strong asymmetries in the absorption of circularly polarized light [2,3]. We have demonstrated that PECD on randomly oriented chiral enantiomers is accessible via a 2+1 REMPI using femtosecond laser pulses, containing highly structured asymmetries in the ± 10% regime [4]. In this contribution we present our recent findings on the bicyclic ketones Camphor, Norcamphor and Fenchone. On variation of the laser intensity, we observe dissociative ionization. However, the PECD can be unambiguously attributed to direct ionization of the parent ion. Ellipticity studies show the robustness of the PECD effect.
[1] I. Powis in S. A. Rice (Ed.): Adv. Chem. Phys. 138, 267-329 (2008)
[2] C. Logé, U. Boesl, Chem. Phys. Chem. 12, 1940-1947 (2011)
[3] P. Horsch, G. Urbasch, K.-M. Weitzel, Chirality 24, 684-690 (2012)
[4] C. Lux et al., Angew. Chem. Int. Ed. 51, 5001-5005 (2012)