Erlangen 2022 – wissenschaftliches Programm
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MO: Fachverband Molekülphysik
MO 4: Electronic II
MO 4.2: Vortrag
Dienstag, 15. März 2022, 10:45–11:00, MO-H5
Detecting Chirality in Mixtures Using Nanosecond Photoelectron Circular Dichroism — •Simon Ranecky1, Baratt Park2,3, Peter Samartzis4, Ioannis Giannakidis4, Dirk Schwarzer2, Arne Senftleben1, Thomas Baumert1, and Tim Schäfer2 — 1Uni Kassel — 2Uni Göttingen — 3Texas Tech Lubbock (USA) — 4IESL-FORTH Iraklio (Greek)
The ionization of randomly oriented chiral molecules with circularly polarized light leads to an asymmetric angular photoelectron distribution. Depending on the handedness of the molecules and the sense of rotation of the incident light, more electrons are scattered forward or backward with respect to the direction of the incident ligh. This effect is called photoelectron circular dichroism (PECD). Its size can reach more than 10% for pure enantiomers and decreases for lower enantiomeric excesses (e.e.). It can be applied to determine the e.e. of chiral substances with a precision below 1% [1].
Tunable narrowband nanosecond lasers in combination with a cold molecular beam achive vibrational resolution in resonance-enhanced multiphoton ionization [2]. As a proof of principle, we made four mixtures of pure enantiomers of fenchone and camphor and selectively ionized either fenchone or camphor by tuning the wavelength to the band origin of their B-band and measured their background suppressed PECD. We were able to discriminate the enantiomers of both substances. This opens the perspective to determine the e.e. in mixtures.
[1] A. Kastner et al., ChemPhysChem, 17, 1119 - 1122, (2016)
[2] A. Kastner et al., Phys. Chem. Chem. Phys., 22, 7404, (2020)