Title: Advancing Atomic-resolution TEM of Electron Beam-sensitive Crystalline Materials from “Impossible” to “Routine”

Speaker: Prof. Han Yu (King Abdullah University of Science and Technology)

Time: 10:00-11:00a.m., Jan. 4th, 2018

Venue: Room 105, Shaw Engineering Building, Wushan Campus 

[Abstract]

High-resolution imaging of electron beam-sensitive crystalline materials is one of the most difficult applications of transmission electron microscopy (TEM). The challenges are manifold, including the acquisition of images with an extremely low beam dose, the timeconstrained search for crystal zone axes, the precise alignment of successive images, and the accurate determination of the defocus value. We reported that using a direct-detection electron-counting (DDEC) camera, it is possible to acquire useful high-resolution TEM images with electron dose as low as a few electrons per square angstrom to ensure that the intact structure was captured before damage occurred.

In this talk, we will present a suite of new methods that we recently developed to address the rest challenges mentioned above. Our methods advance the HRTEM of extremely beamsensitive materials from “occasionally possible” to “routine”. We demonstrate the effectiveness of our methodology by capturing atomic-resolution (~ 1.5 Å) TEM images of several metal organic frameworks (MOFs) that are generally recognized as highly sensitive to electron beams. In the case of MOF UiO-66, individual metal atomic columns, various types of surface termination, and benzene rings in the organic linkers, are clearly identified. We also successfully apply our methods to other electron beam-sensitive materials, and achieve atomicresolution TEM imaging of the organic-inorganic hybrid perovskite CH3NH3PbBr3 for the first time.