Probing Nanoscale Phenomena by In Situ Electron Microscopy
| Date/Time: | Thursday, 26 Feb 2015 from 4:10 pm to 5:00 pm |
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| Location: | Physics 0003 |
| Phone: | 515-294-5441 |
| Channel: | College of Liberal Arts and Sciences |
| Actions: | Download iCal/vCal | Email Reminder |
Abstract: Understanding the physical and chemical processes occurring at nanoscale environments is essential to a variety of scientific disciplines. Advanced transmission electron microscopy (TEM) combined with in situ experimental approach represents a powerful characterization method to provide atomic-scale spatial resolution, quantitative chemical information, real-time visualization, and quantum-mechanics phase change detectability. Here, I will present our recent research accomplishments towards understanding the nanoscale phenomena and device functionalities using complementary in situ electron microscopy, spectroscopy, holography, and tomography at all relevant length scales and dimensions. The talk will start from energy storage devices, where the kinetic pathways of electrochemical reactions in lithium-ion batteries were tracked in real time and three dimensions to unlock the intrinsic limiting mechanism for fast-charging electrode materials. I will also cover the topics in probing the spatially-resolved electromagnetic field within nanoscale electronic and magnetic systems and measuring simultaneous transport properties at realistic operando conditions using in situ Lorentz microscopy combined with quantitative electron holography. These findings are crucial for revealing a full panorama of the underlying mechanisms ranging from atomic level to device scale, while the methodology can be equally valid for diverse scientific areas. An outlook for future electron microscopy development and its implementation for solving grand challenges in mesoscale and multidimensional sciences will also be discussed.
Bio: Dr. Kai He is a postdoctoral research associate at the Center for Functional Nanomaterials in Brookhaven National Laboratory. He received his PhD from Arizona State University in 2010, and then worked as the Ellen Williams Fellow at University of Maryland. His research expertise includes atomic-resolution transmission electron microscopy, spectroscopy, holography, tomography, and their in situ implementations in the nanostructured magnetic, electronic, and energy materials. He has received multiple academic awards from the electron microscopy and magnetism societies, and served as a co-organizer for APS March Meeting.