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October 15, 2003


*Keynote Speaker for 2003 Nano Forum

Dr. Stephen Pennycook
Condensed Matter Sciences Division
Oak Ridge National Laboratory
"Navigating the Nanoworld through Z Contrast STEM"

Abstract. Electron microscopy is entering a new era when resolution will no longer be limited by electron optics, and the fundamental quantum mechanical limit to resolution will become attainable.   The ability to correct the aberrations of electron lenses has doubled the achievable resolution in the last few years.  The scanning transmission electron microscope can now detect single impurity atoms within materials and nanostructures or on their surfaces.  Furthermore, single atoms seen in the image can be identified by spectroscopy, and their local electronic environment can be investigated.  Such data is ideally complemented by first-principles theory which gives insight into atomic configurations, bonding and energetics.  Examples will be presented from several areas of nanoscience, including the mechanism for stabilization of -alumina catalyst supports by doping with La, the activity of gold and semiconductor nanocatalysts, and the metal-catalyzed growth of single-wall carbon nanotubes. Prospects for three-dimensional atomic-resolution tomography in next-generation microscopes will be discussed.

Vanderbilt University