Learning Atom Probe Tomography time-of-flight peaks for mass-to-charge ratio spectrometry

Area of Science:

• Materials Science
• Analytical Chemistry
• Spectroscopy

Background:

• Laser-assisted atom probe tomography (LA-APT) is crucial for materials analysis.
• Reconstructing mass-to-charge ratio (m/z) spectra requires understanding ion time-of-flight (TOF) distributions.
• Existing methods struggle with unknown and variable probability mass functions (pmfs) for different ion species.

Purpose of the Study:

• To develop a method for determining TOF pmfs that vary between ion species.
• To enable accurate reconstruction of m/z spectra in LA-APT.
• To overcome the impracticality of measuring individual pmfs through calibration.

Main Methods:

• A mixture model approach is proposed to analyze TOF spectra.
• Maximum likelihood estimation is used to determine weights for candidate pmfs.
• The method is validated on a TOF spectrum from a silicon sample.

Main Results:

• The developed mixture model successfully determined TOF pmfs.
• Intensity estimates for singly charged silicon isotopes were accurately obtained.
• The method demonstrates effectiveness in a proof-of-principle study.

Conclusions:

• The mixture model provides a practical solution for analyzing complex TOF spectra in LA-APT.
• This approach enhances the accuracy of m/z spectrum reconstruction.
• It offers a pathway to better material characterization using LA-APT.