John Miao

Fellowship 2015

ARCHIVE

Jianwei (John) Miao is Professor of Physics & Astronomy and the California NanoSystems Institute at the University of California, Los Angeles (UCLA). He received his Ph. D. in Physics, a M. S. in computer science, and an Advanced Graduate Certificate in Biomedical Engineering from the State University of New York at Stony Brook in 1999. Immediately after graduation, he became a Staff Scientist at the SLAC National Accelerator Laboratory, Stanford University. In 2004, he moved to UCLA as an Assistant Professor and was promoted to Full Professor in 2009. Miao is a pioneer in the development of novel imaging methods with X-rays and electrons. He performed a seminal experiment on extending X-ray crystallography to allow structural determination of non-crystalline specimens in 1999. This method, known as coherent diffractive imaging (CDI) or lensless imaging, has been broadly implemented using synchrotron radiation, X-ray free electron lasers (XFELs), high harmonic generation, optical lasers, and electrons. It has also become one of the major justifications for the construction of XFELs worldwide. In addition to his seminal contribution to CDI, Miao has also pioneered a general electron tomography method for 3D imaging of local structures at atomic resolution. In 2005, he developed a novel data acquisition and tomographic reconstruction method, known as equally sloped tomography (EST). By combining EST with electron microscopy, Miao and collaborators demonstrated electron tomography at 2.4 Å resolution in 2012, the highest resolution ever achieved in any general 3D imaging method. More recently, he led a team that applied this electron tomography method to observe nearly all the atoms in a platinum nanoparticle, and for the first time imaged the 3D core structure of edge and screw dislocations in materials at atomic resolution.

Dynamical electron tomography at the atomic scale

USIAS Fellows : Ovidiu Ersen and John Miao
Post-doc: Georgian Melinte

The development of applications based on nanomaterials calls for ever-more efficient characterization tools. This project aims at gaining the ability to follow, at the atomic scale, the “in situ” evolution of nanoparticles placed under realistic environments. A strong collaboration between the 3D-TEM group of IPCMS and Coherent Imaging Group at UCLA will be able to reach this goal, combining the Strasbourg expertise in the field of in situ environmental microscopy and electron tomography with UCLA's expertise in the field of tomographic studies at the atomic scale. In order to follow the time evolution of a nanoparticle placed under reactive conditions needs, for instance, to dramatically decrease the recording duration of the images series and to align these images with a atomic precision. This will be achieved through the combined effort of the two groups in Strasbourg and Los Angeles to implement specific recording and reconstruction procedures. We plan to study the evolution of single metallic or core-shell nanoparticles dedicated to potential plasmonic applications as model materials.