Biography: Frances M. Ross is a faculty member at the Department of Materials Science and Engineering at the Massachusetts Institute of Technology in Cambridge, MA, USA. She received her B.A. in Physics and Ph.D. in Materials Science from Cambridge University, UK, and along the way became an enthusiast of electron microscopy. She extended her interests to include in situ microscopy during her postdoc at A.T.&T. Bell Laboratories, then as a Staff Scientist at the National Center for Electron Microscopy, Lawrence Berkeley National Laboratory, and finally as a Research Staff Member at the IBM T. J. Watson Research Center, before joining MIT. Her research is based around the development of in situ electron microscopy techniques to help understand crystal growth, epitaxy, self-assembly and electrochemical and other liquid phase processes.

Talk title: Measuring and controlling atomic-scale transformations via in situ electron microscopy

Abstract: Electron microscopy helps us visualize the details of crystal growth and phase transformations with high spatial and temporal resolution, offering prospects for understanding and controlling the formation of nanostructures with useful properties. Two strategies for driving transformations in the microscope are to expose a sample to a gas-phase reactive environment or to excite it with a precisely placed electron beam. I will show examples of both approaches and discuss how they can be generalised. I will first describe transformations in faceted nanoscale islands. Oxide formation, silicidation and other processes can be studied by forming metal islands on inert graphene membranes then exposing them to oxygen or other gases, all under ultra high vacuum conditions in a customized microscope. We can quantify size effects and fabricate heterostructures by sequential metal deposition to yield information on strain relief and dislocation formation. I will then show phase transformations that are triggered and measured at individual atomic columns of a crystal using high-precision electron beam targeting. The resulting structural changes may offer a route to create defect arrays with electronic properties suited for quantum computing applications. As the sample environment and beam steering in the electron microscope continue to become more accurately controlled, broad prospects lie ahead for designing nanomaterials using electron microscopy.

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