Evaluating atomic counts in metal nanoclusters via scanning transmission electron microscopy

Area of Science:

• Materials Science
• Nanotechnology
• Surface Science

Background:

• Metal nanoclusters (NCs) possess unique properties dependent on atomic composition.
• Precise control over NCs is crucial for applications in photonics, catalysis, and spintronics.

Purpose of the Study:

• To visualize and characterize platinum (Pt) nanoclusters (NCs) using HAADF-STEM.
• To establish a correlation between NC size and atomic composition.
• To demonstrate HAADF-STEM as a method for estimating atom counts in NCs.

Main Methods:

• Platinum NCs with 19-70 atoms were deposited onto TEM grids.
• High-angle annular dark-field scanning transmission electron microscopy (HAADF-STEM) was used for imaging.
• STEM image analysis determined NC diameters and structures.

Main Results:

• HAADF-STEM enabled direct visualization of Pt NC deposition states, densities, and structures.
• A clear correlation was observed between the number of atoms in Pt NCs and their STEM-observed diameters.
• STEM-derived diameter distributions were comparable to mass spectrometry data.

Conclusions:

• HAADF-STEM provides a reliable method for estimating the number of constituent atoms in metal NCs.
• This technique offers valuable insights for size-dependent structural analysis of NCs.
• The findings support the exploration of functionalized metal NCs with tailored properties.