This research focuses on the fundamental challenge in the study of nanostructured materials: how to determine their interfacial structure and their thermodynamic properties. A combined synthesis, characterization and modeling effort is proposed to address this challenge. Surface and interfacial properties will be measured and computed for supported nanoparticles and correlated with structure. Results are expected to have a direct impact on materials that are critical to substantial parts of technology, major components of the chemical industry, and exciting new developments in medical diagnostics. The research will be integrated with outreach efforts, including high school visits and undergraduate education. Results from this research project will be incorporated in the web-based educational materials for teaching students about structure and diffraction, infrastructure for which is already in place (see http://emaps.mrl.uiuc.edu/ or google webemaps). This particular website is now listed as one of the best web resources for learning electron diffraction.
A combined experimental and theoretical study is proposed for the determination of surface and interface energies and correlation with atomic structure. Epitaxial Au nanocrystals supported on oxides will be synthesized using techniques developed in the PI's group. Aberration corrected scanning transmission electron microscopy (STEM) and transmission electron microscopy (TEM) will be used to characterize the equilibrium shapes of Au nanocrystals and as well as their interfacial structure. The structural data will be used to compute interface and step energies from first principles, which will be compared with experimental measurements based on the equilibrium shapes of supported nanocrystals. The experimental part takes the advantage of recent developments in electron microscopy, which promise imaging of oxygen atoms at the interface as well as 3D imaging of interfacial structure by depth sectioning. For theory, an energy density method will be used to compute energy distribution at surfaces and interfaces. The program builds upon the progress that has been made on Au nanocrystals supported on flat rutile (110) surfaces, and extends the study to vicinal surfaces to enable a measurement of step energies.
