Atom-by-Atom Characterization of Nanomaterials with Atomic Electron Tomography: Nano Seminar Series

Seminar | March 10 | 2-3 p.m. | 390 Hearst Memorial Mining Building

 Prof. Mary Scott, UC Berkeley, Materials Science & Engineering

 Berkeley Nanosciences and Nanoengineering Institute

Measuring 3D atomic coordinates in materials has been a driving force behind many scientific and technological advances. Techniques such as X-ray crystallography are powerful tools to measure average atomic positions, but cannot identify individual, atomic scale defects which can strongly influence a material’s behavior, particularly in the case of nanomaterials.

A single image from a high resolution electron microscope can measure crystal lattices, defects, and strain, but only in two dimensions. Extending atomic resolution electron microscopy to three dimensions via tilt axis tomography enables one to determine the 3D atomic structure of a material without averaging or using a priori information. This method has been used to isolate crystal-line grains in 3D, to visualize the atomic arrangement of atoms in defects, and to localize individual atoms of a sample with 20 pm precision. From the measured atomic coordinates, 3D dislocation and strain fields can be determined and related to the surface conditions of the sample. In samples with more than one atomic species, chemical ordering can be mapped in 3D with single atom sensitivity.

In this way, atomic electron tomography characterizes nanomaterials in unprecedented detail to connect local atomic structure to functionality.

Prof. Scott did her PhD in physics at UCLA and joined UCB this year, as asst prof in MSE and staff scientist at the Molecular Foundry.