Erlangen 2022 – scientific programme
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MO: Fachverband Molekülphysik
MO 5: Femtosecond Spectroscopy I
MO 5.4: Talk
Tuesday, March 15, 2022, 11:30–11:45, MO-H6
Tracking Multi-Exciton Processes in Squaraine Polymers with High-Order Pump–Probe Spectroscopy — •Julian Lüttig1, Pavel Malý1, Peter A. Rose2, Arthur Turkin3, Christoph Lambert3, Jacob J. Krich2, and Tobias Brixner1 — 1Institut für Physikalische und Theoretische Chemie, Universität Würzburg, Am Hubland, 97074 Würzburg, Germany — 2Department of Physics, University of Ottawa, Ontario K1N 6N5, Canada — 3Institut für Organsiche Chemie, Universität Würzburg, Am Hubland, 97074 Würzburg, Germany
The interpretation of time-resolved spectroscopy generally relies on the isolation of a specific nonlinear order of the sample response. Usually the excitation power is chosen to select the wanted signal and to suppress unwanted higher-order contributions such as annihilation. However, measurements at lower power often exhibit low signal-to-noise ratio. In the opposite case of too high powers, the high-order signals are present and have to be considered in the analysis. We solve this dilemma by separating all high-order signals with a novel, simple, data acquisition sequence. Inspired by multidimensional spectroscopy [1], we isolate the different high-order signals by measuring a pump–probe signal at several specific excitation pulse energies. We demonstrate that with our technique annihilation-free measurements of squaraine polymers at high pulse energies are possible. The technique also allows us to measure pure higher-order signals which contain the information on multi-exciton interaction.
[1] J. Dostál et al., Nat. Commun. 9, 2519 (2018).