Improved Uranium Particle Analysis by SIMS using O3 - Primary Ions.
Evan E Groopman1, Todd L Williamson1, David S Simons2
1Materials Measurement Science Division, National Institute of Standards and Technology, Gaithersburg, MD, 20899, USA.
Journal of Analytical Atomic Spectrometry
|December 29, 2022
Summary
Using ozone (O3-) beams in secondary ion mass spectrometry (SIMS) significantly improves uranium particle analysis. This method enhances ionization yield, reduces mass fractionation, and improves measurement precision compared to traditional oxygen (O-) beams.
Area of Science:
- Geochemistry
- Analytical Chemistry
- Materials Science
Background:
- Secondary Ion Mass Spectrometry (SIMS) is crucial for isotopic analysis of geological materials.
- Conventional SIMS uranium particle analysis often uses negative oxygen (O-) primary ion beams.
- Advancements in ion source technology enable the use of molecular oxygen beams like O2- and O3-.
Purpose of the Study:
- To evaluate the benefits of negative molecular oxygen primary ion beams (O2-, O3-) for uranium particle SIMS analysis.
- To compare the performance of O3- beams against conventional O- beams for uranium isotopic measurements.
- To assess the impact of molecular oxygen beams on ionization yield, mass fractionation, and sensitivity factors.
Main Methods:
- Utilized negative molecular oxygen primary ion beams (O2-, O3-) in SIMS analyses.
- Compared O3- beam performance with traditional O- beams for uranium particle analysis.
- Investigated ionization yield, mass fractionation, and Th/U relative sensitivity factors.
Main Results:
- Ozone (O3-) beams increased ionization yield by approximately two-fold (up to 4.7%) compared to O- beams.
- O3- beams reduced instrumental mass fractionation and matrix/substrate effects.
- Particle measurements using O3- beams showed improved precision and reduced correction factors.
Conclusions:
- Negative molecular oxygen beams, particularly O3-, offer significant advantages for uranium particle SIMS analysis.
- O3- beams enhance measurement precision, detection limits, and reduce analytical uncertainties.
- This advancement improves the reliability of age dating and isotopic analysis of uranium-bearing particles.
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