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SYCS: Symposium Multidimensional coherent spectroscopy of functional nanostructures

SYCS 1: Symposium: Multidimensional coherent spectroscopy of functional nanostructures

SYCS 1.4: Hauptvortrag

Dienstag, 28. September 2021, 11:45–12:15, Audimax 1

Revealing couplings with action-based 2D microscopy — •Tobias Brixner — Institut für Physikalische und Theoretische Chemie, Universität Würzburg, Am Hubland, 97074 Würzburg, Germany

Coherent two-dimensional (2D) electronic spectroscopy provides frequency resolution both for the excitation and the probe step. We have developed “action-based” 2D micro-spectroscopy variants using either fluorescence detection (with additional 260 nm spatial resolution) or electron detection (3 nm spatial resolution). In several exemplary applications on nanostructured systems, it will be discussed how various types of quantum-mechanical couplings can be retrieved. First, we investigate a MoSe₂ monolayer and observe long-term quantum beating as a function of population time. We analyze the data with a Franck–Condon model and retrieve quantitatively the exciton–phonon coupling strength at room temperature, a quantity previously unknown for 2D materials. Further, we embed a WSe₂ van-der-Waals heterostructure into a microcavity and observe a rich multi-peak structure in 2D spectra which has not been captured in conventional photoluminescence. Simulations reveal hybridized exciton–photon–phonon states, and time-dependent beating signals indicate further fine structure. Lastly, we apply 2D spectroscopy within photoemission electron microscopy (PEEM) on a nanoslit resonator. We find that multiplasmon quantum excitations are required to understand photoemission, going beyond the commonly employed classical linear response model.