Hannover 2020 – scientific programme
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MO: Fachverband Molekülphysik
MO 8: MO Poster 2
MO 8.3: Poster
Tuesday, March 10, 2020, 17:00–19:00, Empore Lichthof
Accessing chiral dynamics via broadband time-resolved circular dichroism spectroscopy — •Lea Ress1, Heiko Hildenbrand1, Hope Bretscher2, Akshay Rao2, and Tobias Brixner1 — 1Institut für Physikalische und Theoretische Chemie, Universität Würzburg, Am Hubland, 97074 Würzburg — 2Department of Physics, Cavendish Laboratory, University of Cambridge, 19 JJ Thompson Avenue, Cambridge, United Kingdom
Time-resolved circular dichroism (TRCD) spectroscopy enables the investigation of the ultrafast dynamics of photoinduced chirality changes on a sub-picosecond timescale. We use a pump-probe approach by exciting the sample with a linearly or circularly polarized pump pulse and detecting the difference in absorption of left- and right-circularly polarized probe pulses on a shot-to-shot basis. For this, we developed a setup that is capable of mirroring the polarization state of an ultrashort broadband laser pulse [1].
Here we demonstrate TRCD spectroscopy of monolayer MoS2 as a proof-of-principle experiment, validating the setup with respect to literature results [2]. In addition to spectroscopy of surfaces, we also investigate the change in chirality of a perylene bisimide folda-dimer in solution [3]. Furthermore, we analyze the arrangement of chiral surfactants around the achiral dye Congo red and the ultrafast change in chirality after excitation.
[1] A. Steinbacher, et al., Opt. Express 25, 21735 (2017)
[2] S. Dal Conte, et al., Phys. Rev. B 92, 235425 (2015)
[3] C. Kaufmann, et al., J. Am. Chem. Soc. 140, 31, 9986 (2018)