"Monochromania: A look into the new types of science enabled by ultrahigh energy resolution electron microscopy"
Electron energy-loss spectroscopy (EELS) within the scanning transmission electron microscopy (STEM) has been a widely used technique to understand composition, bonding, and electronic structure with high spatial resolution in a diverse range of materials. Conventionally, the technique is limited to higher energies (i.e. excitations of greater than 2 or 3 eV) due to the spread of energies coming out of the electron gun. However, over the last ten years breakthroughs in monochromation of the electron source has enabled that limit to drop down orders of magnitude, enabling ultrahigh energy resolution STEM-EELS and access all the way down into the mid-infrared spectral regime. Critically, these breakthroughs have come without compromising spatial resolution, enabling new types of experiments to perform and new classes of phenomena to explore. In this talk, I will present a range of the different types of materials systems and infrared phenomena that we have been studying at Oak Ridge National Laboratory using our monochromated STEM. Specifically, we will address applications to nanophotonics, complex oxides, biological specimens, and quantum materials. Furthermore, I will focus on the different experimental geometries that become critical in this spectral regime to isolate and enhance different types of scattering and signals that occur in the infrared.