Applied Physics and Materials Science Special Seminar

Abstract:

The ultimate goal of an atomic-resolution imaging technique is to obtain the three-dimensional (3D) coordinates of each atom in a material. Although aberration-corrected (scanning) transmission electron microscopy (S/TEM) has enabled routine atomic-resolution imaging in two dimensions, there exist several challenges which obstruct scientists from obtaining the true 3D atomic structure of materials. While cryo-TEM and X-ray/electron diffraction workflows have provided invaluable experimental models of the 3D structure of crystal unit cells, viruses, proteins and more, these approaches require averaging over multiple identical structures. Determining the unique coordinates of each atom in a material is crucial for understanding non-crystalline structures such as defects, interfaces and amorphous materials – all of which play important roles in science and technology, and all of which cannot be determined using conventional electron microscopy techniques. In this talk, I will discuss several challenges preventing us from routinely obtaining unique 3D atomic coordinates from electron microscopy experiments, and address how we are overcoming these challenges using STEM ptychography, atomic electron tomography and advanced experimental workflows.

More about the Speaker:

Colum is a STROBE Postdoctoral Fellow in the Coherent Imaging Group (led by Prof. John Miao) at the University of California, Los Angeles. He received his B.Sc. in Physics from Trinity College Dublin in 2016 and obtained his Ph.D. (D.Phil.) in Materials from the University of Oxford in 2020. His Ph.D. research focused on the development and applications of electron ptychography – a highly sensitive electron microscopy technique for imaging light-element and beam-sensitive materials at atomic resolution. During his postdoctoral studies, Colum has been situated at the National Center for Electron Microscopy, LBNL, where he is currently working on three-dimensional imaging of non-crystalline structures using atomic electron tomography. Outside of research, Colum enjoys running, playing Gaelic football and telling jokes.