SAMOP 2021 – wissenschaftliches Programm

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MO: Fachverband Molekülphysik

MO 7: Poster 1

MO 7.5: Poster

Donnerstag, 23. September 2021, 17:30–19:30, P

Chirp and intensity dependence of the circular dichroism in ion yield of 3-methylcyclopentanone measured with femtosecond laser pulses — •Sagnik Das, Jayanta Ghosh, Tom Ring, Sudheendran Vasudevan, Hangyeol Lee, Nicolas Ladda, Simon Ranecky, Tonio Rosen, Arne Senftleben, Thomas Baumert, and Hendrike Braun — Institut für Physik, Universität Kassel, Heinrich-Plett-Strasse 40, 34132 Kassel, Germany

One of the methods to differentiate between the two enantiomers of a chiral molecule is Circular Dichroism (CD). It arises due to the difference in absorption of left and right circularly polarised light. The difference in absorption can also be mapped to the difference in ionisation of the enantiomers and is known as CD in ion yield[1,2]. We use our home-built Time of Flight (ToF) mass spectrometer with our recently established twin peak[3] measurement setup to study the effect of linear chirp (GDD) on the anisotropy. The candidate molecule for this experiment is 3-methylcyclopentanone (3-MCP). In the study we present here, we perform all the experiments at 309 nm, where 3-MCP shows high anisotropy, upto 10%. At this wavelength, a 1+1+1 resonance-enhanced multi-photon ionisation (REMPI) takes place in 3-MCP through the π^* ← n transition. We observe enhancement of anisotropy for chirped pulses, which we compare to band-width limited pulses of equal peak intensity.

[1] U. Boesl and A. Bornschlegl, ChemPhysChem, 7, 2085, 2006

[2] H. G. Breunig et al., ChemPhysChem, 10, 1199, 2009

[3] T. Ring et al., Rev. Sci. Instrum., 92, 033001, 2021