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MO: Fachverband Molekülphysik
MO 21: Ultrafast Dynamics II
MO 21.7: Vortrag
Donnerstag, 14. März 2024, 16:00–16:15, HS 3044
Insights into exciton coupling of RNA-templated merocyanine dimer through higher-order transient absorption spectroscopy — •Ajay Jayachandran1, Julia Dietzsch2, Stefan Müller1, Claudia Höbartner2, 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
The synthesis of oligonucleotide scaffolds to arrange chromophores into molecular aggregates with control over the formation of their molecular excitonic states offers an exciting prospect for achieving programmable photophysics. Our study exploits the Watson-Crick base pairing interactions in a RNA double helix by incorporating a new barbituric acid merocyanine as a nucleobase surrogate via solid-phase synthesis [1]. We observe the formation of a non-fluorescent, short-lived H-aggregate.
In order to study the single- and multi-excitonic manifold of this aggregate and its associated dynamics, we use a technique that we recently developed which employs systemic intensity variation of the pump pulse in pump–probe spectroscopy to separate pure third-order and fifth-order nonlinear signals [2]. We apply this higher-order transient absorption spectroscopy for the first time on oligonucleotide scaffolds and find indications for ultrafast exciton–exciton annihilation in the H-type dimer system [1].
[1] J. Dietzsch et al., Chem. Commun. 59, 7395–7398 (2023).
[2] P. Malý et al., Nature 616, 280–287 (2023).
Keywords: higher-order transient absorption; exciton coupling; exciton dynamics