Bonn 2025 – scientific programme
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MO: Fachverband Molekülphysik
MO 19: Interaction with Strong or Short Laser Pulses I (joint session A/MO)
MO 19.5: Talk
Wednesday, March 12, 2025, 15:45–16:00, GrHS Mathe
High-harmonic generation in weakly coupled organic molecular systems — •Falk-Erik Wiechmann1, 2, Samuel Schöpa1, Lina Marie Bielke1, Felipe Morales3, Serguei Patchkovskii3, Maria Richter3, Dieter Bauer1, and Franziska Fennel1, 2 — 1Intitute of physics, University of Rostock, 18059 Rostock, Germany — 2Department of Life, Light and Matter, University of Rostock, 18059 Rostock — 3Max Born Institute (MBI) for Nonlinear Optics and Short Pulse Spectroscopy, 12489 Berlin, Germany
We introduce organic molecular crystals (OMCs) as a novel target class for high-harmonic Generation (HHG), bridging the gap between gas phase and solid state high-harmonic spectroscopy. In OMCs, neighboring molecules experience a weak van-der-Waals coupling, considerably smaller compared to the covalent or ionic bonds in previous solid-state target. However, this finite coupling leads to *solid like* features, e.g. a delocalization of the electronic states over several unit cells. Additionally, the perfect inherent alignment of all molecules makes OMCs an ideal target class for HH spectroscopy of large organic molecules, as it avoids the need for extremely challenging alignment techniques that have so far prevented corresponding measurements in the gas phase. With a fundamental 4000 nm mid-IR beam reaching 0.67 TW/cm2 we demonstrate that HHG from Pentacene crystals is possible without imposing physical damage. We find that the harmonic-generation process is driven by collective intermolecular effects and not by the response of non-interacting aligned molecules.
Keywords: High-harmonic generation; Organic molecular crystals; Pentacene; Intermolecular coupling; Polarization dependence