Bonn 2025 – wissenschaftliches Programm

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MO: Fachverband Molekülphysik

MO 4: Molecular Spectroscopy of Liquid Jets I

MO 4.1: Vortrag

Montag, 10. März 2025, 17:00–17:15, HS XVI

Development and implementation of a flat jet device for mesophase-dependent High Harmonic Generation experiments in thermotropic liquid crystals — •Marta Luisa Murillo-Sánchez, Natalia Copete-Plazas, and Laura Cattaneo — Max-Planck-Institut für Kernphysik, Saupfercheckweg 1, 69117 Heidelberg, Deutschland

High harmonic generation (HHG) spectroscopy aims for the study of ultrafast molecular dynamics, offering insights into electronic and nuclear motion. While early work in gas-phase systems can be fully understood by the three-step model, the focus has shifted to condensed matter, where collective interactions make HHG mechanisms more complex to unravel. To explore these mechanisms, thermotropic liquid crystals (LCs) are promising due to their tunable mesophases*intermediate states between liquid and crystalline phases*achieved via temperature changes. Using a custom flat jet device adapted for the high viscosity and non-Newtonian behavior of LCs, we generated stable, down to 2 μm-thin sheets for substrate-free HHG experiments with a precise temperature control. Preliminary HHG spectra were obtained for isotropic (liquid) and nematic phases of 4-cyano-4'-pentylbiphenyl (5CB) under a mid-infrared driving field (4 *m). Results highlighted the nematic phase*s anisotropic structure and birefringence, underscoring the need for molecular alignment control. These findings pave the way for optimizing HHG in LCs and deepening our understanding of nonlinear optical phenomena in soft condensed matter.

Keywords: flatjet device; high order harmonic generation; condense matter; liquid spectroscopy; light-matter interaction