Title: In-situ TEM and Spectroscopy of Structures and Processes in Graphene Sandwiches and Graphene Liquid Cells
Abstract: Recent developments in microfabrication technology have resulted a surge of interest in in-situ transmission electron microscopy (TEM). This dissertation will focus on in-situ imaging and spectroscopy of liquids and materials suspended in liquids using aberration-corrected scanning transmission electron microscopy. I have developed a novel approach to in-situ microcopy that allows the encapsulation of liquid-containing samples using monolayers of graphene. Transmission electron microscopy and spectroscopy is utilized to characterize several beam sensitive materials and processes in a liquid environment at atomic resolution, obtaining information including structures, elemental distribution, bonding information, even phase change and valence state transition in physical and biochemical activities. Radiolysis modeling is performed to assist liquid cell design, as well as control of electron microscope parameters, allowing liquid chemistry modulation by electronic signal. This also allows implementation of graphene liquid cells as nano-scale chemical reactors which enable the precise control of radical and ionic concentration for reaction kinetics modulation as a function of space and time. These approaches can be combined to solve problems in a liquid phase with unprecedented resolution.
Canhui Wang Defense Poster