Electron microscopy is a very powerful technique for studying atomic structure of materials, Prof. Yuan has further extended the functions of Tunneling Electron Microscope (TEM) by developing quantitative high angle annular dark field electron microscopy (HAADF-STEM) and electron vortex beam.  With these new features, it is not only possible to determine the three dimensional structure of atoms, but also the effect of atom dynamics, particularly in the near of surface. 
Prof. Yuan also explained in details of the properties of electron vortex beam, a topologically non-trivial form of electron travelling waves with well-defined orbital angular momentum and demonstrate the rotation of nanoparticles by transferring orbital angular momentum from the vortex electron beam to the nanoparticles. His excellent work and amazing results were very impressive to all the attendees, and excited a heated discussion after the seminar.

Prof. Jun Yuan is the Professor of Nanophysics and Electron Microscopy in University of York, United Kingdom.  He obtained his first degree of BSc in Physics from Imperial College of Science and Technology, University of London in 1983 and PhD in Physics from Cavendish Laboratory, University of Cambridge in 1988.  He has since worked in University of Cambridge, Tsinghua University, Japan Fine Ceramics Center and Now in University of York on various topics related to electron microscopy, the related analytical techniques such as electron energy loss spectroscopy as well as their applications in materials science and nanophysics.  His recent interests are the growth and characterization of low dimensional materials such as monolayer of MoS2 as well as developing new types of electron microscopy based on electron vortex beams.