Heidelberg 2015 – scientific programme

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MO: Fachverband Molekülphysik

MO 18: Biomolecules

MO 18.5: Talk

Thursday, March 26, 2015, 12:15–12:30, PH/SR106

Enantiomer Identification of Mixtures of Chiral Molecules with Broadband Microwave Spectroscopy — •David Schmitz¹, V. Alvin Shubert¹, David Patterson², John M. Doyle², and Melanie Schnell¹ — ¹Max Planck Institute for the Structure and Dynamics of Matter at the Center for Free-Electron Laser Science, Hamburg, Germany — ²Department of Physics, Harvard University, Cambridge, MA, USA

Most molecules of biochemical relevance are chiral. Even though the physical properties of two enantiomers are nearly identical, they might exhibit completely different biological effects, e.g. one may be beneficial to health while the opposite is toxic. In nature and as products of chemical syntheses, chiral molecules often exist in mixtures with other chiral molecules. The analysis of these complex mixtures to identify the molecular components, determine which enantiomers are present, and to measure the enantiomeric excesses (ee) is still one of the challenging tasks of analytical chemistry.

We present here a new method of differentiating enantiomeric pairs of chiral molecules in the gas phase. It is based on broadband rotational spectroscopy and is a three-wave mixing process that involves a closed cycle of three rotational transitions. The phase of the acquired signal bares the signature of the enantiomer, as it depends upon the product of the three transition dipole moments. Furthermore, this technique allows for determining of the ee, which is proportional to the signal amplitude. Our technique can be applied to mixtures of chiral molecules, even when the molecules are very similar.