Measuring Dynamic Structural Changes of Nanoparticles at the Atomic Scale Using Scanning Transmission Electron...

Area of Science:

• Materials Science
• Nanotechnology
• Physics

Background:

• Accurate measurement of atomic-scale dynamics is crucial for understanding nanoparticle behavior.
• Current methods for quantifying atom numbers in scanning transmission electron microscopy (STEM) images have limitations.

Purpose of the Study:

• To introduce a novel method for measuring atomic-scale dynamics of nanoparticles using high-resolution annular dark field STEM images.
• To improve the accuracy of atom quantification in atomic columns over time.

Main Methods:

• Utilized a hidden Markov model (HMM) to analyze annular dark field STEM images.
• The HMM explicitly models structural changes, enabling precise quantification of atoms per column.
• Applied the method to determine surface diffusion probabilities and cross sections.

Main Results:

• The proposed HMM-based method outperforms existing atom-counting procedures.
• Successfully quantified atomic-scale dynamics, including adatom dynamics and surface diffusion.
• Enabled the study of beam effects and in situ experiments.

Conclusions:

• The new method provides a significant advancement in measuring and quantifying time-evolving atomic structures.
• It is essential for understanding nanoparticle evolution driven by surface diffusion and other dynamic processes.
• Opens new avenues for in situ studies of nanomaterials.