Date: Tuesday, October 18, 2022
Time: 11:00 am
Location: Chemla Room (67-3111) and Zoom
Talk Title: Understanding strain and deformation in 2D materials via 4D-STEM and cryo-EM
Zoom recording (passcode lb2^j&Y8)
Strain and deformations play a critical role in the mechanical, electrical, and chemical properties of two-dimensional (2D) materials due to their atomic thinness. This presentation will discuss using the state-of-the-art transmission electron microscopy (TEM) techniques to study the strain and deformations in 2D materials. First, the speaker will introduce the study of strain relaxation in epitaxial lateral heterojunctions of 2D transition metal dichalcogenides (TMD) using nano-beam four-dimensional scanning TEM (4D-STEM)1. By developing an unsupervised learning approach, we were able to accelerate and automate the method for more general users2. In addition, the speaker will also present the direct visualization of the floppiness of 2D DNA origami using cryo-EM. The work uncovers flexible arms in 2D cross tiles, as well as clusters and stacks, which may potentially affect the assembly of DNA origami3.
1. Han, Y. et al. Strain Mapping of Two-Dimensional Heterostructures with Subpicometer Precision. Nano Letters 18, 3746–3751 (2018).
2. Shi, C. et al. Uncovering material deformations via machine learning combined with four-dimensional scanning transmission electron microscopy. Npj Comput Mater 8, 114 (2022).
3. Ni, H. et al. Direct visualization of floppy two-dimensional DNA origami using cryogenic electron microscopy. Iscience 25, 104373 (2022).
Dr. Han is an assistant professor of Materials Science and NanoEngineering. She received her B.S. in Physics from Tsinghua University and Ph.D. in Applied Physics from Cornell. Her research focused on electron microscopy and the characterization of nanomaterials. After graduating from Cornell University, she joined the Department of Molecular Biology at Princeton University to expand her knowledge on cryo-EM, as well as develop ways to utilize nanomaterials in biological characterization. Dr. Han started her own lab in the Department of Materials Science and NanoEngineering at Rice University in July 2020. Her group has a focus on developing novel TEM techniques to investigate nanomaterials and nano-bio interfaces.