Researchers from Nagoya College in Japan employed atomic-resolution secondary electron (SE) imaging to look at the atomic construction of the topmost layer of supplies, uncovering variations from the underlying layers. Their findings have been revealed within the journal Microscopy.
Picture Credit score: Nagoya College
Surfaces are important to many chemical processes, akin to corrosion and catalysis. Chemists and engineers should comprehend the atomic construction of a practical materials’s floor.
“Floor reconstruction” is a phenomenon through which the atoms on the floor are organized in another way than these inside sure supplies. This requires surface-sensitive strategies to look at, significantly on the atomic stage.
Scanning electron microscopy (SEM) has lengthy been a precious device for learning nanoscale constructions. SEM works by accumulating SEs launched from a pattern’s floor when it’s scanned with a centered electron beam. Nonetheless, it’s tough to look at processes like floor reconstruction, as SEs are usually emitted from a small depth under the floor, particularly when solely a single atomic layer is concerned.
To quantify the quantity of data that SE imaging can extract from the floor and subsurface layers, the Nagoya College analysis group used probably the most easy system attainable, a two-layered molybdenum disulfide (MoS2) pattern. They used the method to separate the floor layer from the second layer by stacking two layers of MoS₂.
With a really excessive floor sensitivity, the researchers found that atomic decision SE imaging works properly for detecting floor atomic configurations. Their findings strongly confirmed the strategy’s sensitivity, displaying that the depth of SE photos from the floor layer was roughly thrice larger than these from the second layer.
A single-layer MoS₂ pattern’s atomic-resolution SE photos confirmed lovely honeycomb-like formations product of sulfur and molybdenum atoms. Along with being aesthetically pleasing, SE imaging confirmed overlapping patterns that indicated totally different atomic configurations within the second and floor layers.
Most notably, the SE yield from the floor layer was about thrice larger than from the second layer. This outcome means that the floor layer absorbs or scatters SEs from the second layer. This absorption contributes to the strategy’s depth sensitivity.
Koh Saitoh, Research Lead Writer and Researcher, Institute of Supplies and Techniques Sustainability, Nagoya College
The group goals to make use of atomic-resolution SE imaging to uncover the atomic-level floor construction, together with floor reconstruction and different distinct surface-formed options. Comprehending these processes is essential to regulating the event, manufacturing, and mechanical and electrical traits of nanomaterials.
Journal Reference:
Saitoh, Okay., et al. (2024) Floor sensitivity of atomic decision secondary electron imaging. Microscopy. doi.org/10.1093/jmicro/dfae041.
