[MOS] 3/23 - Modern Optics and Spectroscopy Seminar with Tobias Brixner (University of Wurzburg)

[Christine Brooks]

There will be a virtual Modern Optics and Spectroscopy Seminar held next Tuesday, March 23 at 12pm. A Q&A segment will immediately follow the conclusion of the seminar.

Zoom link: https://mit.zoom.us/j/92179512988?pwd=QkNSVDZ3cnBGQWNlaG5idlYvN0x3QT09
Password: 513713
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Tobias Brixner
University of Würzburg (Germany)

How Do Excitons Move in Confined Materials?”

Excitons are the eigenstates arising from electronic couplings between quantum systems. They are responsible for energy transport in photosynthetic light harvesting, the function of photovoltaic devices, optoelectronic properties of two-dimensional materials, and more. In this talk, it will be shown how to apply coherent two-dimensional electronic spectroscopy (2DES) for the analysis of restricted exciton movement. For this purpose, we have developed several new 2DES variants. In particular, we use fluorescence detection to avoid solvent contributions or scattering artefacts and retrieve fourth-order and sixth-order spectra simultaneously [Nat. Commun. 10, 4735 (2019)]. Spatial confinement leads to monolayer films with many potential applications. We have obtained the exciton–phonon coupling strength at room temperature [Nat. Commun. 12, 954 (2021)], a quantity previously unknown for 2D materials that is, however, decisive for their unique properties. Restricting the dimensionality further, we arrive at 1D materials. Using a fifth-order 2DES technique, we determine transport in J-aggregates [Nat. Commun. 9, 2466 (2018)], self-organized tubes [Nat. Commun. 10, 4615 (2019)], and polymers [Chem. Sci. 11, 456 (2020)]. We find that the conventional diffusion equation often assumed to describe energy transport does not hold for such systems in general. Spatial restriction in all three dimensions leads to 0D quantum dots in which we resolve multiexciton correlations [doi.org/10.1021/acsnano.0c09080]. Lastly, we ask if it is possible to reduce the size even more and measure single molecules. First 2DES results from an individual quantum object will be shown.


Christine Brooks
Administrative Assistant
Massachusetts Institute of Technology
Department of Chemistry
77 Massachusetts Ave, 6-333
Cambridge, MA 02139
p: 617.253.7239
e: cbrooks at mit.edu<mailto:cbrooks at mit.edu>

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