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【26th.May】Advancing atomic-resolution TEM of electron beam-sensitive crystalline materials from “impossible” to “routine”

2018-05-24


题目:Advancing atomic-resolution TEM of electron beam-sensitive crystalline materials from “impossible” to “routine”
演讲人:Prof. Yu Han,King Abdullah University of Science and Technology
时间:2018年5月26日(周六),15:00-17:00
地点:化学A楼528演讲厅
邀请人:崔勇教授

Abstract
High-resolution imaging of electron beam-sensitive crystalline materials is one of the most difficult applications of transmission electron microscopy (TEM). The challenges are manifold, including the acquisition of images with an extremely low beam dose, the time-constrained search for crystal zone axes, the precise alignment of successive images, and the accurate determination of the defocus value.  
We reported that using a direct-detection electron-counting (DDEC) camera, it is possible to acquire useful high-resolution TEM images with electron dose as low as a few electrons per square angstrom to ensure that the intact structure was captured before damage occurred [1]. 


In this talk, we will present a suite of new methods that we recently developed to address the rest challenges mentioned above. Our methods advance the HRTEM of extremely beam-sensitive materials from “occasionally possible” to “routine”. We demonstrate the effectiveness of our methodology by capturing atomic-resolution (~ 1.5 Å) TEM images of several metal organic frameworks (MOFs) that are generally recognized as highly sensitive to electron beams. In the case of MOF UiO-66, individual metal atomic columns, various types of surface termination, and benzene rings in the organic linkers, are clearly identified. We also successfully apply our methods to other electron beam-sensitive materials, and achieve atomic-resolution TEM imaging of the organic-inorganic hybrid perovskite CH3NH3PbBr3 for the first time [2]. 


More recently, we applied this new technology to prove the successful encapsulation of single molecule magnets in MOF NU-1000 [3], and to investigate the evolution and transformation of various defects in MOF UiO-66 [4].  
References  
[1] Y. Zhu, M. Pan, Y. Han et al., Nature Materials, 2017, 16, 532-536  
[2] D. Zhang, Y. Han et al., Science, 2018, 359, 675-679 
[3] M. Wriedt, Y. Han et al., submitted  
[4] L, Liu, D. Zhang, Y. Zhu, Y. Han et al., to be submitted
Biography
Dr Han is a materials chemist and his research is focused on nanoporous and nanostructured materials, including ordered mesoporous materials, hierarchically structured zeolites, porous organic polymers, porous carbons, and metallic plasmonic nanocrystals. His ability to precisely control the structure and morphology of these materials promoted his great success in developing novel applications for them in gas adsorption/separation, heterogeneous catalysis, and nanophotonics. Dr. Han also has expertise in electron microscopy and electron tomography, using which he has successfully solved or identified some complex nanostructures. 


Dr. Han has published > 180 research articles in prestigious journals including Science, Nature, Nature Materials, Nature Chemistry, Nature Nanotechnology, Nature Communications, JACS, and these papers have been cited over 12000 times with h-index of 54. His achievements have garnered international recognition. 


In 2004, he was named as a TR100 Young Innovator by the Massachusetts Institute of Technology’s magazine of innovation, Technology Review. In 2006, he was awarded the Young Scientist Award by the Singapore National Academy of Science. In 2016, he got the Cheung Kong Scholar award, the highest academic award issued to an individual in higher education by the Ministry of Education of the People's Republic of China.  


2017-Professor, King Abdullah University of Science and Technology  
2011-2017 Associate Professor, King Abdullah University of Science and Technology  
2009-2011 Assistant Professor, King Abdullah University of Science and Technology  
2-6/2009 Visiting Professor, Imperial College London, the United Kingdom  
2007-2008 Senior Research Scientist, Institute of Bioengineering and Nanotechnology, Singapore  
2004-2007 Research Scientist, Institute of Bioengineering and Nanotechnology, Singapore  
2003-2004 Post-doctoral, Institute of Bioengineering and Nanotechnology, Singapore  
2003 PhD in Chemistry, Jilin University





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