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A: Fachverband Atomphysik

A 4: Electron Dynamics in Chiral Systems SYCS 1 (with MO)

A 4.4: Hauptvortrag

Montag, 17. März 2014, 12:00–12:30, Audimax

Mass-selective circular dichroism spectroscopy of chiral molecules — •Ulrich Boesl — Technische Universität München, Garching, Germany

The combination of circular dichroism (CD) and mass spectrometry is a young developing research field which promises to become a new analytical tool for mass selective probing of chirality. Such a chiral sensor opens new applications e.g. for studies of chiral catalysis or for analysis of chiral biomolecules brought into the gas phase by laser desorption techniques.This paper deals with a special type of mass selective circular dichroism called REMPI-CD (resonance enhanced multiphoton ionization circular dichroism). REMPI, on the one-hand side, combines optical spectroscopy (first absorption step) with ionization (second absorption step) and thus with mass spectrometry. It has a two-dimensional selectivity with the parameters UV-wavelength and molecular mass. CD, on the other hand, is a frequently used effect to discriminate between the two enantiomers of chiral substances. REMPI-CD then is the small relative difference of ion current induced by left and right circularly polarized laser light. In this paper, measures are presented to enhance the accuracy for these small differences. In addition, REMPI allows for new special effects such as cumulative CD and molecular-ion-CD which are unknown in conventional CD. Finally a strong enhancement of the CD-effect has been observed for cold molecules in supersonic gas beams.