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Exploring the 3D Nano and Atomic World: Coherent Diffractive Imaging and Atomic Electron Tomography

Jianwei (John) Miao, UCLA

Thursday, September 28, 2017
  3:40–5 p.m.

Location: Chung Hall Room 138
  Parking Information

Category: Colloquium


Crystallography has been fundamental to the development of many fields of science over the past century. It has now matured to a point that as long as good quality crystals are available, their atomic structure can be routinely determined in three dimensions. However, many samples in nature are non-crystalline and their three-dimensional (3D) structures are not accessible by crystallography. Overcoming this hurdle has required the development of new structure determination methods. In this talk, I will present two methods that can go beyond crystallography: coherent diffractive imaging (CDI) and atomic electron tomography (AET). In CDI, the diffraction pattern of a non-crystalline sample or a nanocrystal is first measured and then directly phased to obtain an image. The well-known phase problem is solved by combining the oversampling method with iterative algorithms. In the first part of the talk, I will illustrate several important CDI methods and highlight some important applications in the physical and biological sciences using 3rd generation synchrotron radiation and X-ray free electron lasers. In the second part of the talk, I will present a general tomographic method, termed AET, for 3D structure determination of crystal defects and disordered materials at the individual atomic level. By combining advanced electron microscopes with novel data analysis and tomographic reconstruction algorithms, AET has been used to reveal the 3D atomic structure of crystal defects and chemical order/disorder such as grain boundaries, anti-phase boundaries, stacking faults, dislocations and point defects, and to precisely localize the 3D coordinates of individual atoms in materials without assuming crystallinity. As coherent X-ray sources and powerful electron microscopes are under rapid development in the world, it is anticipated that CDI and AET will find broad applications across different disciplines.

1. J. Miao, T. Ishikawa, I. K. Robinson and M. M. Murnane, “Beyond crystallography: Diffractive imaging using coherent x-ray light sources”, Science 348, 530-535 (2015). 2. J. Miao, P. Ercius and S. J. L. Billinge, "Atomic electron tomography: 3D structures without crystals", Science 353, aaf2157 (2016).  3. Y. Yang, C.-C. Chen, M. C. Scott, C. Ophus, R. Xu, A. Pryor Jr, L. Wu, F. Sun, W. Theis, J. Zhou, M. Eisenbach, P. R. C. Kent, R. F. Sabirianov, H. Zeng, P. Ercius and J. Miao, “Deciphering chemical order/disorder and material properties at the single-atom level”, Nature 542, 75-79 (2017).

Additional Information: Colloquia & Seminars

Open to: General Public
Admission: Free
Sponsor: Physics and Astronomy

Contact Information:
Naveen Reddy