Speaker: Dr. David J. Masiello, Professor of Chemistry, Adj Professor of Materials Science & Engineering, Adj Professor of Applied Mathematics
Vice Chair, American Physical Society Division of Chemical Physics, Department of Chemistry, University of Washington

Title: Characterizing Bloch-Wave Excitations in 2D Crystals From Atomic to Nanophotonic Scales Using Conventional and Unconventional Electron and Optical Probes

Abstract: Spectroscopies utilizing free electron beams as probes offer detailed information on the reciprocal-space excitations of 2D materials such as graphene and transition metal dichalcogenide monolayers. Yet, despite the attention paid to such quantum materials, less consideration has been given to the electron-beam characterization of 2D periodic nanostructures such as metasurfaces, photonic crystals, and plasmon arrays, which can exhibit the same lattice and excitation symmetries as their atomic analogues albeit at drastically different energy, length, and momentum scales. Because of their lack of covalent bonding and influence of retarded electromagnetic interactions, important physical distinctions arise that complicate interpretation of established scattering signals and call for the invention of new ones. In this talk, I will discuss the intrinsic Bloch wave excitations in these different crystalline systems and propose a variety of new signals that utilize both conventional and unconventional electron beam and optical probes (and their combination) to characterize 2D crystals at their natural response scales in energy, length, Bloch momentum, pseudo-angular momentum, and polarization.
https://faculty.washington.edu/masiello