講座內容：Electron microscopy is a very standard powerful technique for the study of atomic structure of materials. In this talk, I will discuss two recent developments in this field: quantitative high angle annular dark field electron microscopy (HAADF-STEM) and electron vortex beam. We will use the quantitative HAADF-STEM imaging of nanoclusters to show that not only we can determine the three dimensional structure of atoms, but also the effect of atom dynamics, particular those near the surface.

This talk will also introduce 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.