Quantitative Electron Microscopy for
Nanoscale Materials Characterization and Super-Resolution
Jian-Min (Jim) Zuo*
Department of Materials Science and Engineering and F. Seitz Materials Research Laboratory
University of Illinois, Urbana-Champaign
Nanometer-sized cluster or island formation and its interface with substrate have a large effect on late stage thin film growth. Characterizing these nano-structures is a major challenge in surface science and nano-science and technology in general. Prominent to nano-clusters and islands are surfaces and interfaces, e.g. small metal clusters exhibit special polyhedral structures with low surface energies. Interfaces in supported nano-structures, or those in a matrix, often occur between different lattices. In bulk, techniques are well developed in each area, such as X-ray and neutron diffraction for bulk crystal, scanning probes for surfaces and electron microscopy for defect and interfaces. Applications of each of these techniques for nanostructures require a significant improvement in the existing experimental capabilities and interpretation.
This talk reports our progress in characterizing nanostructures by quantitative electron microscopy and achievement of super-resolution by diffractive imaging. In the first half of the talk, I will show three examples of nanostructure characterization: 1) structure determination of individual single wall and double wall carbon nanotubes, 2) formation of charge stripes and holographic measurement of phase field in manganese oxides and 3) the structure and interface of supported nano-clusters. In the second half, I will introduce a technique for single molecular diffraction and imaging. By using a combination of recording diffraction patterns from individual nanostructures and solving the phase problem using ab. initio phase retrieval, we have succeeded in imaging carbon nanotubes with a diffraction-limited resolution. Because this technique does not rely on post-specimen image formation lens, it has the potential to achieve super-resolution for imaging individual macromolecules.
*In collaboration with J. Tao, Boquan Li and M. Gao