Towards atom counting from first moment STEM images: Methodology and possibilities

Area of Science:

• Materials Science
• Analytical Chemistry
• Physics

Background:

• Accurate atom counting is crucial for understanding material properties.
• Traditional methods like HAADF STEM have limitations in precision, especially under noisy conditions.

Purpose of the Study:

• To develop and validate a statistical model-based quantification method for atomic resolution first moment STEM images.
• To enable precise atom counting by quantifying the projected potential per atomic column.

Main Methods:

• Utilized uniformly weighted least squares estimator for determining image structure parameters.
• Isolated contributions from individual atomic columns to quantify projected potential.
• Compared atom counting performance with traditional HAADF STEM under noisy conditions.

Main Results:

• Achieved quantification of projected potential per atomic column, enabling atom counting.
• Demonstrated superior precision in atom counts from first moment STEM compared to HAADF STEM.
• Validated the robustness of using bulk crystal simulations as a reference library for diverse sample shapes.

Conclusions:

• The developed method offers a significant advancement in atom counting precision.
• First moment STEM imaging is advantageous for accurate atom enumeration in materials.
• The reference library approach allows for reliable atom counting across various sample geometries.