Open Gas-Cell Transmission Electron Microscopy at 50 pm Resolution

Abstract: Transmission electron microscopy (TEM) has reached ~ 50 picometer resolution in a high vacuum, enabling single-atom sensitive imaging of nanomaterials. Extending this capability to gaseous environments would allow for similar visualizations of nanomaterial dynamics under chemically reactive conditions. Here, we examine a new TEM system that maintains 50 pm resolution at pressures up to 1 mbar, demonstrated using nanocrystalline Au immersed in N2. The system features an open gas-cell with a four-stage differential pumping system, a 5th order aberration corrector for broad-beam TEM, a monochromatized electron beam, an ultra-stable microscope platform, Nelsonian low electron dose-rate illumination, and direct electron detection. Young fringe experiments and exit wave phase imaging confirm the atomic resolution and indicate location-dependent vibrational blur at surface terminations. Thus, this platform advances in situ and operando TEM studies of gas-surface interactions in diverse fields, including catalysis, corrosion, and crystal growth.