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Groopman EE, Williamson TL, Simons DS. Improved Uranium Particle Analysis by SIMS using O 3 - Primary Ions. JOURNAL OF ANALYTICAL ATOMIC SPECTROMETRY 2022; 37:10.1039/d2ja00231k. [PMID: 36578831 PMCID: PMC9791982 DOI: 10.1039/d2ja00231k] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/17/2023]
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.
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Affiliation(s)
- Evan E. Groopman
- Materials Measurement Science Division, National Institute of Standards and Technology, Gaithersburg, MD, 20899, USA
| | - Todd L. Williamson
- Materials Measurement Science Division, National Institute of Standards and Technology, Gaithersburg, MD, 20899, USA
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Manard BT, Rogers KT, Ticknor BW, Metzger SC, Zirakparvar NA, Roach BD, Bostick DA, Hexel CR. Direct Uranium Isotopic Analysis of Swipe Surfaces by Microextraction-ICP-MS. Anal Chem 2021; 93:11133-11139. [PMID: 34236176 DOI: 10.1021/acs.analchem.1c01569] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The ability to directly measure uranium isotope ratios on environmental swipes has been achieved through a solution-based microextraction process and represents a significant advancement toward the development of a rapid method to analyze international nuclear safeguard samples. Here, a microextraction probe is lowered and sealed onto the swipe surface, and analytes within the sampling site (∼8 mm2) are dissolved and extracted into a flowing solvent of 2% nitric acid (HNO3). The mobilized species are subsequently directed into an inductively coupled plasma-mass spectrometer (ICP-MS) for accurate and precise isotope ratio determination. This work highlights the novelty of the sampling mechanism, particularly with the direct coupling of the microextraction probe to the ICP-MS and measurement of uranium isotope ratios. The preliminary method detection limit for the microextraction-ICP-MS method, utilizing a quadrupole-based MS, was determined to be ∼50 pg of 238U. Additionally, precise and accurate isotope ratio measurements were achieved on uranium reference materials for both the major (235U/238U) and minor (234U/238U and 236U/238U) ratios. While the present work is focused on directly measuring uranium isotopic systems on swipe surfaces for nuclear safeguards and verification applications, the benefits would extend across many applications in which direct solid sampling is sought for elemental and isotopic analysis.
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Affiliation(s)
- Benjamin T Manard
- Oak Ridge National Laboratory, Chemical Sciences Division, 1 Bethel Valley Rd, Oak Ridge, Tennessee 37830, United States
| | - Kayron T Rogers
- Oak Ridge National Laboratory, Chemical Sciences Division, 1 Bethel Valley Rd, Oak Ridge, Tennessee 37830, United States
| | - Brian W Ticknor
- Oak Ridge National Laboratory, Chemical Sciences Division, 1 Bethel Valley Rd, Oak Ridge, Tennessee 37830, United States
| | - Shalina C Metzger
- Oak Ridge National Laboratory, Chemical Sciences Division, 1 Bethel Valley Rd, Oak Ridge, Tennessee 37830, United States
| | - N Alex Zirakparvar
- Oak Ridge National Laboratory, Chemical Sciences Division, 1 Bethel Valley Rd, Oak Ridge, Tennessee 37830, United States
| | - Benjamin D Roach
- Oak Ridge National Laboratory, Chemical Sciences Division, 1 Bethel Valley Rd, Oak Ridge, Tennessee 37830, United States
| | - Debra A Bostick
- Oak Ridge National Laboratory, Chemical Sciences Division, 1 Bethel Valley Rd, Oak Ridge, Tennessee 37830, United States
| | - Cole R Hexel
- Oak Ridge National Laboratory, Chemical Sciences Division, 1 Bethel Valley Rd, Oak Ridge, Tennessee 37830, United States
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Rush LA, Cliff JB, Reilly DD, Duffin AM, Menoni CS. Isotopic Heterogeneity Imaged in a Uranium Fuel Pellet with Extreme Ultraviolet Laser Ablation and Ionization Time-of-Flight Mass Spectrometry. Anal Chem 2021; 93:1016-1024. [PMID: 33314923 DOI: 10.1021/acs.analchem.0c03875] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
We use extreme ultraviolet laser ablation and ionization time-of-flight mass spectrometry (EUV TOF) to map uranium isotopic heterogeneity at the nanoscale (≤100 nm). Using low-enriched uranium fuel pellets that were made by blending two isotopically distinct feedstocks, we show that EUV TOF can map the 235U/238U content in 100 nm-sized pixels. The two-dimensional (2D) isotope maps reveal U ratio variations in sub-microscale to ≥1 μm areas of the pellet that had not been fully exposed by microscale or bulk mass spectrometry analyses. Compared to the ratio distribution measured in a homogeneous U reference material, the ratios in the enriched pellet follow a ∼3× wider distribution. These results indicate U heterogeneity in the fuel pellet from incomplete blending of the different source materials. EUV TOF results agree well with those obtained on the same enriched pellets by nanoscale secondary ionization mass spectrometry (NanoSIMS), which reveals a comparable U isotope ratio distribution at the same spatial scale. EUV TOF's ability to assess and map isotopic heterogeneity at the nanoscale makes it a promising tool in fields such as nuclear forensics, geochemistry, and biology that could benefit from uncovering sub-microscale sources of chemical modifications.
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Affiliation(s)
- Lydia A Rush
- Department of Electrical and Computer Engineering, Colorado State University, Fort Collins, Colorado 80523, United States
| | - John B Cliff
- Pacific Northwest National Laboratory, Richland, Washington 99354, United States
| | - Dallas D Reilly
- Pacific Northwest National Laboratory, Richland, Washington 99354, United States
| | - Andrew M Duffin
- Pacific Northwest National Laboratory, Richland, Washington 99354, United States
| | - Carmen S Menoni
- Department of Electrical and Computer Engineering, Colorado State University, Fort Collins, Colorado 80523, United States
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