Improved uranium particle analysis by SIMS using O3− primary ions. Issue 10 (14th September 2022)

• Record Type: Journal Article
• Authors: Groopman, Evan E.; Williamson, Todd L.; Simons, David S.
• Is Part Of: Journal of analytical atomic spectrometry. Volume 37:Issue 10(2022)
• Page Start: 2089
• Page End: 2102
• Publication Date: 2022-09-14
• Subjects: Atomic spectra -- Periodicals; Atomic absorption spectroscopy -- Periodicals; 543.0858
• DOI: 10.1039/d2ja00231k
• Languages: English
• ISSNs: 0267-9477

Abstract

Abstract : We have investigated the use of negative molecular oxygen primary ion beams ( i.e., O2 − and O3 − ) to determine the benefits of using such beams for uranium particle SIMS analyses. Abstract : We have investigated the use of negative molecular oxygen primary ion beams ( i.e., O2 − and O3 − ) to determine the benefits of using such beams for uranium particle SIMS analyses. Typically, O − is the most practical negative primary ion species from the conventional duoplasmatron ion source for both age dating and uranium isotopic analysis of particles. Newer RF plasma ion sources make it possible to use O2 − and O3 − due to higher brightness and primary ion fluence, and the increased abundance of molecular species in the plasma relative to the duoplasmatron. We have determined that by using an O3 − beam, the ionization yield can be increased by a factor of approximately two over an O − beam, up to 4.7%, a substantial improvement that positively impacts measurement precision and detection limits. We also investigated the effect of the molecular oxygen beams on uranium isotope mass fractionation and the Th/U relative sensitivity factor for SIMS analyses in comparison to O − beams. We found that O3 − reduced instrumental mass fractionation and matrix/substrate effects relative to the other negative ion beams. Particle measurements using O3 − were improved compared to conventional O − beam analyses due to higher yields, smaller corrections, and reduced substrate effects.