Atomic Spatial and Temporal Imaging of Local Structures and Light Elements inside Zeolite Frameworks.

Identifying the atomic structures of porous materials in spatial and temporal dimensions by (scanning) transmission electron microscope ((S)TEM) is significant for their wide applications in catalysis, separation and energy storage. However, the sensitivity of materials to electron beams made it difficult to reduce the electron damage to specimens while maintaining the resolution and signal-to-noise ratio. It is therefore still challenging to capture multiple images of the same area in one crystal to image the temporal changes of lattices. Usings integrated differential phase contrast (iDPC) STEM, atomic-resolution imaging of beam-sensitive zeolite frameworks is achieved with an ultralow dose of 40 e- Å-2 , 2-3 orders of magnitude lower than that of conventional STEM. Based on the iDPC technique, not only the atomic 3D architecture of ZSM-5 crystals but also the changes of frameworks are observed during in situ experiments. Local structures and light-element aromatics in ZSM-5 crystals can also be revealed directly under iDPC-STEM. These results provided not only an efficient tool to image beam-sensitive materials with ultralow beam current but also a new strategy to observe and investigate the hydrocarbon pools in zeolite catalysts at the single-molecule scale.