Bonn 2025 – scientific programme
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MO: Fachverband Molekülphysik
MO 22: Ultrafast Dynamics III
MO 22.6: Talk
Thursday, March 13, 2025, 12:15–12:30, HS XVI
Investigation of Multi-Exciton Interactions in a Chiral Squaraine Homopolymer Employing Higher-Order Pump–Probe Spectroscopy and Fluorescence-Detected Two-Dimensional Spectroscopy — •Karina Heilmeier1, Stefan Mueller1, Emely Freytag2, Peter A. Rose3, Jacob J. Krich3,4, Christoph Lambert2, and Tobias Brixner1 — 1Institut für Physikalische und Theoretische Chemie, Universität Würzburg, Am Hubland, 97074 Würzburg, Germany — 2Institut für Organische Chemie, Universität Würzburg, Am Hubland, 97074 Würzburg, Germany — 3Department of Physics, University of Ottawa, Ottawa, Ontario, Canada — 4Nexus for Quantum Technologies, University of Ottawa, Ottawa, Ontario, Canada
Third-order spectroscopy such as transient absorption (TA) is often used to investigate the dynamics of single-exciton states. The measurement of higher orders provides information on the interactions of an increasing number of excitons and their dynamics. We recently showed how nonlinear orders can be separated using intensity cycling [1]. Here, we study multi-exciton interaction in a related but structurally different chemical system, a chiral squaraine homopolymer. We use intensity-dependent TA to separate odd orders of nonlinear response. In addition, we employ fluorescence-detected two-dimensional spectroscopy. In that case, we extract the even orders by phase cycling and compare the two approaches.
[1] P. Malý, J. Lüttig, P. A. Rose, A. Turkin, C. Lambert, J. J. Krich, T. Brixner, Nature 616, 280 (2023).
Keywords: Higher-Order Pump--Probe Spectroscopy; Two-Dimensional Fluorescence-Detected Spectroscopy; Multi-Exciton Interaction; Squaraine Polymer