报告题目： Advancing atomic-resolution TEM of electron beam-sensitive crystalline materials from “impossible” to “routine”
韩宇，现为沙特阿卜杜拉国王科技大学教授。研究领域包括纳米孔材料的合成及应用、多相催化、气体分离、电子显微镜弱光成像技术等，主要研究专长包括复杂结构孔材料、低维和分级异质结构金属材料的设计合成和显微结构表征，以及在非均相催化中的应用；超低剂量电子显微技术的发展以及在电子束敏感材料结构研究中的应用。迄今为止，韩宇教授总共发表学术论文180余篇，其中包括权威期刊如Nature，Science，Nat Nanotechnol，Nat Chem，Nat Mater，Nat Commun，JACS，Angewante Chemie，Advanced Materials等，总引用次数约12000，H-index为54。韩宇教授2004年被麻省理工学院《科技评论》杂志评选为百名青年发明家，2006年获新加坡青年科学家奖；2008年获Thomson Reuters Research Fronts Award(汤姆逊研究前沿奖)； 2016年被评为中国教育部长江学者讲座教授。
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 Catalysis, Nature Communications, JACS, and these papers have been cited over 12,000 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.
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 . 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 [2-3].
 Y. Zhu, M. Pan, Y. Han et al., Nature Materials, 2017, 16, 532-536
 D. Zhang, Y. Han et al., Science, 2018, 359, 675-679
K. Shen et al. Science, 2018, 359, 206-210