David. A. Muller gives a talk on Atomic-Scale Imaging of Composition and Bonding in Nanostructures and Devices using Electron Microscopy
Atomic-resolution spectroscopic imaging in a new generation of electron microscopes is now capable of unraveling bonding details at buried interfaces and clusters, providing both physical and electronic structure information at the Angstrom-level. The sensitivity and resolution can extend to imaging single dopant atoms or vacancies in their native environments, or solving the structure of two-dimensional crystals and glasses. The thousand-fold increase in electron energy loss spectroscopy (EELS) mapping speeds over conventional microscopes allows us to collect data from millions of spectra, generating statistically meaningful maps of heterogeneous populations – such as the facet-dependent leaching in fuel-cell catalysts nanoparticles. Tilt-series tomography allows us to record three-dimensional images with sub-nanometer resolution. Micro-machined environmental cells allow in-situ imaging of liquids and gases for samples ranging in thickness from nanometers to several microns. Current instruments under construction are expected to push spatial and energy resolution into the sub-Angstrom, milli-eV regime. Further developments are likely to enhance in-situ capabilities and detection schemes.
Tuesday, October 2nd, CNS 333 @ 4:00 p.m. - refreshments provided
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