Spatial decomposition of molecular ions within 3D atom probe reconstructions

Area of Science:

• Materials Science
• Analytical Chemistry
• Physics

Background:

• Atom probe tomography (APT) is a powerful technique for nanoscale material analysis.
• Accurate reconstruction of atomic positions is crucial for understanding material properties.
• Molecular ions in APT data can complicate accurate elemental and structural analysis.

Purpose of the Study:

• To develop and validate new methods for separating constituent atoms of molecular ions in APT reconstructions.
• To improve the accuracy and interpretability of APT data, especially for complex materials.
• To demonstrate the practical application of these methods on experimental datasets.

Main Methods:

• Development of the Gaussian Separation Method for deconvoluting two-atom molecular ions.
• Development of the Delaunay Separation Method for separating larger, complex molecular ions (>3 atoms).
• Testing and validation using simulated APT data and application to experimental HSLA steel (NbN) and GaAs datasets.

Main Results:

• The Gaussian Separation Method effectively deconvolutes diatomic molecular ions, validated on simulated and HSLA steel data.
• The Delaunay Separation Method successfully separates complex molecular ions, demonstrated on simulated and GaAs data.
• Analysis of first nearest neighbour (1NN) distributions and reconstruction images confirms the algorithms' effectiveness.

Conclusions:

• The presented Gaussian and Delaunay Separation Methods are valid and practical for deconvoluting molecular ions in APT.
• These algorithms significantly enhance the accuracy of atomic-scale reconstructions in materials science.
• The methods offer improved insights into material composition and structure at the atomic level.