Regensburg 2025 – wissenschaftliches Programm

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O: Fachverband Oberflächenphysik

O 7: Focus Session Ultrafast Electron Microscopy at the Space-Time Limit I

O 7.4: Hauptvortrag

Montag, 17. März 2025, 11:15–11:45, H11

Nanoimaging the electronic, plasmonic, and phononic structure and dynamics of 2D materials — •Sarah King — University of Chicago, Chicago, IL, United States

Heterogeneity plays a critical role in chemistry and physics, from the role of defect states in the carrier dynamics of semiconductors to interfaces and surfaces in catalysis. However, our ability to visualize nano-scale domains and properties in materials and their effect on material dynamics has been hampered by the simple challenge of our inability to meet the necessary nanometer and femtosecond timescales. I will discuss recent efforts by my group to determine the interplay of heterogeneity and morphology on the intrinsic optoelectronic and thermoelectric properties of materials. Using polarization-dependent photoemission electron microscopy (PD-PEEM) we have imaged the spatially dependent optical selection rules of black phosphorus, distinguishing edge-specific modes, and antiferroelectric domains of β'-In2Se3, with spatial resolution as good as 25 nm. Through ultrafast transmission electron microscopy, we've been able to determine how the bond anisotropy and structural morphology of few-layer black phosphorus impacts phonon dynamics. Ultimately my group seeks to identify ways to modify the impact of structural heterogeneity in materials and rationally design energy efficient interfaces on the nanoscale.

Keywords: nanoscale imaging; antiferroelectricity; thermoelectrics; photoemission electron microscopy