MSE Grads Talk: Benli Jiang

Speaker: Benli Jiang, Boston University

Title: Real-Time Hard X-Ray Scattering for Probing Surface Structure in Nanometer Scale

Abstract: Given that many reactions are driven by the nature of the exposed surfaces, many techniques have been developed to characterize the surface morphological and structural properties of nanomaterials such as Atomic Force Microscopy (AFM), Scanning Tunneling Microscopy (STM), Grazing-Incidence X-ray Scattering (GIXS) and its small-angle subset Grazing-Incidence Small-Angle X-ray Scattering (GISAXS). While they all have some limitations, GISAXS has several unique advantages like non-destructive, better statistics compared to AFM, in-situ and real-time friendly. In this talk, I will use studying the self-organized surface nanopatterns on Si induced by ion bombardment and studying certain epitaxial growth and deposition processes as an example to show our effort using hard x-ray scattering techniques to probe the surface nano-structure. I will first present our post-facto studies using lab-based GISAXS (Bruker N8 Horizon). Then, I will present our real-time studies by utilizing the high brilliance of National Synchrotron Light Source II (NSLS-II). The real-time GISAXS performed at NSLS-II 4-ID beamline can give us a quantitative kinetic record of certain surface processes, which cannot be easily acquired by other means. To further embrace the high brilliance of a 3rd generation synchrotron like NSLS-II, I will discuss our recent studies utilizing the coherent scattering technique of X-ray Photon Correlation Spectroscopy (XPCS) in cooperation with GISAXS at NSLS-II 11-ID beamline. On top of the average surface evolution studied by “low-coherence” GISAXS, coherent GISAXS and XPCS can monitor the fluctuations around the average, which provide more detailed information about the microscopic evolution of the surface.

Bio: Benli Jiang is a fourth-year Ph.D. candidate in Materials Science and Engineering at BU, working under the supervision of Prof. Karl Ludwig. He has participated >10 synchrotron experiments at NSLS-II both as experimental lead and experimenter. He is also a member of the partner user (PU) team with the NSLS-II Complex Scattering Program. His research focuses on better understanding the mechanism of self-organized ion beam nanopatterning using advanced synchrotron x-ray scattering techniques.