Freiburg 2024 – wissenschaftliches Programm

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MO: Fachverband Molekülphysik

MO 19: Chirality

MO 19.5: Vortrag

Donnerstag, 14. März 2024, 12:15–12:30, HS 3044

Control of circular dichroism in ion yield of 3-methyl cyclopentanone using femtosecond laser pulses — •Sagnik Das, Jayanta Ghosh, Sudheendran Vasudevan, Hangyeol Lee, Nicolas Ladda, Simon Ranecky, Tonio Rosen, Till Stehling, Fabian Westmeier, Arne Senftleben, Thomas Baumert, and Hendrike Braun — Institut für Physik, Universität Kassel, Heinrich-Plett-Strasse 40, 34132 Kassel, Germany

Circular dichroism in ion yield (CDIY) is the difference in ion yield from left and right circular polarised light interacting with an enantiomer of a chiral molecule. The cyclic ketone 3-methyl cyclopentanone (3-MCP) has long been studied for its large circular dichroism in the π^* ← n transition. We used femtosecond laser pulses tuned in wavelength around one of the vibrational modes in the π^* ← n band to study the effect of pulse parameters like linear chirp and peak intensity on the CDIY. In the 3-photon resonance enhanced multiphoton ionization (1+1+1) of 3-MCP, we observed an enhancement of CDIY for chirped pulses. At the same time, almost no change in CDIY was detected for variation of the peak intensity of bandwidth-limited pulses. Not only the magnitude of the chirp but also its sign influences the CDIY, indicating more than the pulse duration or peak intensity as the underlying cause. It highlights the role of frequency ordering in the observed enhancement of CDIY for chirped pulses. Moreover, the progression of the CDIY with regard to the applied linear chirp sensitively depends on the central wavelength of the laser pulses.

Keywords: chirality; femtosecond; coherent control; circular dichroism; femtosecond spectroscopy