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SYAD: Symposium SAMOP Dissertation-Prize 2016

SYAD 1: SAMOP Dissertation-Prize

SYAD 1.3: Hauptvortrag

Dienstag, 1. März 2016, 12:00–12:30, e415

How to determine the handedness of single molecules — •Martin Pitzer — Institut für Kernphysik, Goethe-Universität Frankfurt — Experimentalphysik IV, Universität Kassel

Chiral molecules, i.e. molecules that occur like our hands in two mirror image structures, play an important role in biological processes. A variety of techniques is routinely performed for the distinction and separation of the two so-called enantiomers. These techniques, however, probe macroscopic sample properties, and the direct determination of the molecules' microscopic configuration has so far only been possible by using anomalous X-ray diffraction of crystallized samples.

We demonstrated that a COLTRIMS (Cold Target Recoil Ion Momentum Spectroscopy) setup in combination with a femtosecond laser allows to unambiguously determine the absolute configuration of individual molecules in the gas phase. Our approach relies on the concept of Coulomb Explosion Imaging: After multiple ionization of the molecule, the positively charged atomic cores repel each other and their momentum vectors retain information on the handedness of the molecule. For racemic samples (i.e. 1:1 mixtures of enantiomers) of the chiral prototype CHBrClF and of several isotopically chiral analogues, a clear distinction of enantiomers could be shown. In a second step, we compared the ionization by femtosecond laser pulses to the interaction of the molecules with synchrotron radiation and additionally investigated the photoelectron properties. These results highlight the challenges and chances on the way to application in chemical analysis and to a deeper understanding of molecular chirality.