SAMOP 2021 – wissenschaftliches Programm
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MO: Fachverband Molekülphysik
MO 7: Poster 1
MO 7.13: Poster
Donnerstag, 23. September 2021, 17:30–19:30, P
Determination of the Enantiomeric Excess of Chiral Substances in Mixtures via Photoelectron Circular Dichroism — •Simon Ranecky1, Giannis Giannakidis3, Petros Samartzis3, Sudheendran Vasudevan1, Han-gyeol Lee1, Nicolas Ladda1, Tonio Rosen1, Sagnik Das1, Jayanta Ghosh1, Hendrike Braun1, Barratt Park2, Tim Schäfer2, and Thomas Baumert1 — 1Uni Kassel — 2Uni Göttingen — 3IESL-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 light. This effect is called photoelectron circular dichroism (PECD). Its size can reach more than 10% for pure enantiomers and decreases for lower enantiomeric excesses (EE). It can be applied to determine the EE of chiral substances with a precision below 1% [1].
Tunable high resolution nanosecond lasers in combination with a cold molecular beam are a highly selective mean for ionization [2]. Here, we mixed fenchone and camphor with different EE and selectively ionized either fenchone or camphor by tuning the wavelength to the band origin of their B-band (2+1 REMPI-scheme with ca. 400 nm) and measured their background suppressed PECD. We report the results and an analysis of the EE of both substances in the mixture
[1] A. Kastner et al., ChemPhysChem, 17, 1119 - 1122, (2016)
[2] A. Kastner et al., Phys. Chem. Chem. Phys., 22, 7404, (2020)