Depth sectioning combined with atom-counting in HAADF STEM to retrieve the 3D atomic structure.

Area of Science:

• Materials Science
• Nanotechnology
• Microscopy

Background:

• Aberration correction in scanning transmission electron microscopy (STEM) enhances lateral and depth resolution.
• Depth sectioning enables 3D visualization of individual impurity atoms.

Purpose of the Study:

• Investigate 3D reconstruction of nanosized particles by combining depth sectioning and atom-counting.
• Precisely measure the depth location of atomic columns for nanoparticle morphology analysis.

Main Methods:

• Utilized depth sectioning in STEM, recording images at varying defocus values.
• Employed precise atom-counting techniques.
• Validated methods with simulations and experimental data of gold nanorods.

Main Results:

• Demonstrated that while individual atom depth location is not precise, atomic columns' depth can be accurately measured.
• Successfully reconstructed the 3D morphology of a gold nanorod.

Conclusions:

• The combination of depth sectioning and atom-counting offers new possibilities for 3D nanoparticle reconstruction.
• Precise measurement of atomic column depth is key to determining nanoparticle morphology in 3D.