A nanosims 50 L investigation into improving the precision and accuracy of the235U/238U ratio determination by using the molecular235U16O and238u16O secondary ions

Nasser Alex Zirakparvar; Cole R. Hexel; Andrew J. Miskowiec; Julie B. Smith; Michael W. Ambrogio; Douglas C. Duckworth; Roger Kapsimalis; Brian W. Ticknor

doi:10.3390/min9050307

A nanosims 50 L investigation into improving the precision and accuracy of the²³⁵U/²³⁸U ratio determination by using the molecular²³⁵U¹⁶O and²³⁸u¹⁶O secondary ions

Nasser Alex Zirakparvar, Cole R. Hexel, Andrew J. Miskowiec, Julie B. Smith, Michael W. Ambrogio, Douglas C. Duckworth, Roger Kapsimalis, Brian W. Ticknor

Research output: Contribution to journal › Article › peer-review

7 Scopus citations

Abstract

A NanoSIMS 50 L was used to study the relationship between the²³⁵U/²³⁸U atomic and²³⁵U¹⁶O/²³⁸U¹⁶O molecular uranium isotope ratios determined from a variety of uranium compounds (UO₂, UO₂F₂, UO₃, UO₂(NO₃)₂·6(H₂O), and UF₄) and silicates (NIST-610 glass and the Plesovice zircon reference materials, both containing µg/g uranium). Because there is typically a greater abundance of²³⁵U¹⁶O⁺ and²³⁸U¹⁶O⁺ molecular secondary ions than²³⁵U⁺ and²³⁸U⁺ atomic ions when uranium-bearing materials are sputtered with an oxygen primary ion beam, the goal was to understand whether use of²³⁵U¹⁶O/²³⁸U¹⁶O has the potential for improved accuracy and precision when compared to the²³⁵U/²³⁸U ratio. The UO₂ and silicate reference materials showed the greatest potential for improved accuracy and precision through use of the²³⁵U¹⁶O/²³⁸U¹⁶O ratio as compared to the²³⁵U/²³⁸U ratio. For the UO₂, which was investigated at a variety of primary beam currents, and the silicate reference materials, which were only investigated using a single primary beam current, this improvement was especially pronounced at low²³⁵U⁺ count rates. In contrast, comparison of the²³⁵U¹⁶O/²³⁸U¹⁶O ratio versus the²³⁵U/²³⁸U ratio from the other uranium compounds clearly indicates that the²³⁵U¹⁶O/²³⁸U¹⁶O ratio results in worse precision and accuracy. This behavior is based on the observation that the atomic (²³⁵U⁺ and²³⁸U⁺) to molecular (²³⁵U¹⁶O⁺ and²³⁸U¹⁶O⁺) secondary ion production rates remain internally consistent within the UO₂ and silicate reference materials, whereas it is highly variable in the other uranium compounds. Efforts to understand the origin of this behavior suggest that irregular sample surface topography, and/or molecular interferences arising from the manner in which the UO₂F₂, UO₃, UO₂(NO₃)₂·6(H₂O), and UF₄ were prepared, may be a major contributing factor to the inconsistent relationship between the observed atomic and molecular secondary ion yields. Overall, the results suggest that for certain bulk compositions, use of the²³⁵U¹⁶O/²³⁸U¹⁶O may be a viable approach to improving the precision and accuracy in situations where a relatively low²³⁵U⁺ count rate is expected.

Original language	English
Article number	307
Journal	Minerals
Volume	9
Issue number	5
DOIs	https://doi.org/10.3390/min9050307
State	Published - May 2019

Funding

Funding: Notice: This manuscript has been authored by UT-Battelle, LLC, under contract DE-AC05-00OR22725 with the US Department of Energy (DOE). The US government retains and the publisher, by accepting the article for publication, acknowledges that the US government retains a nonexclusive, paid-up, irrevocable, worldwide license to publish or reproduce the published form of this manuscript, or allow others to do so, for US government purposes. DOE will provide public access to these results of federally sponsored research in accordance with the DOE Public Access Plan (http://energy.gov/downloads/doe-public-access-plan). SEM analyses were conducted at the ORNL Center for Nanophase Materials Sciences, which is a DOE Office of Science user facility.

Funders	Funder number
US Department of Energy
U.S. Department of Energy

Keywords

Isotope ratio mass spectrometry
Matrix effect
NanoSIMS
Secondary ion
Uranium

Access to Document

10.3390/min9050307

Cite this

Zirakparvar, N. A., Hexel, C. R., Miskowiec, A. J., Smith, J. B., Ambrogio, M. W., Duckworth, D. C., Kapsimalis, R., & Ticknor, B. W. (2019). A nanosims 50 L investigation into improving the precision and accuracy of the²³⁵U/²³⁸U ratio determination by using the molecular²³⁵U¹⁶O and²³⁸u¹⁶O secondary ions. Minerals, 9(5), Article 307. https://doi.org/10.3390/min9050307

@article{344f9c3cf17d4ca08b0980d34688a410,

title = "A nanosims 50 L investigation into improving the precision and accuracy of the235U/238U ratio determination by using the molecular235U16O and238u16O secondary ions",

abstract = "A NanoSIMS 50 L was used to study the relationship between the235U/238U atomic and235U16O/238U16O molecular uranium isotope ratios determined from a variety of uranium compounds (UO2, UO2F2, UO3, UO2(NO3)2·6(H2O), and UF4) and silicates (NIST-610 glass and the Plesovice zircon reference materials, both containing µg/g uranium). Because there is typically a greater abundance of235U16O+ and238U16O+ molecular secondary ions than235U+ and238U+ atomic ions when uranium-bearing materials are sputtered with an oxygen primary ion beam, the goal was to understand whether use of235U16O/238U16O has the potential for improved accuracy and precision when compared to the235U/238U ratio. The UO2 and silicate reference materials showed the greatest potential for improved accuracy and precision through use of the235U16O/238U16O ratio as compared to the235U/238U ratio. For the UO2, which was investigated at a variety of primary beam currents, and the silicate reference materials, which were only investigated using a single primary beam current, this improvement was especially pronounced at low235U+ count rates. In contrast, comparison of the235U16O/238U16O ratio versus the235U/238U ratio from the other uranium compounds clearly indicates that the235U16O/238U16O ratio results in worse precision and accuracy. This behavior is based on the observation that the atomic (235U+ and238U+) to molecular (235U16O+ and238U16O+) secondary ion production rates remain internally consistent within the UO2 and silicate reference materials, whereas it is highly variable in the other uranium compounds. Efforts to understand the origin of this behavior suggest that irregular sample surface topography, and/or molecular interferences arising from the manner in which the UO2F2, UO3, UO2(NO3)2·6(H2O), and UF4 were prepared, may be a major contributing factor to the inconsistent relationship between the observed atomic and molecular secondary ion yields. Overall, the results suggest that for certain bulk compositions, use of the235U16O/238U16O may be a viable approach to improving the precision and accuracy in situations where a relatively low235U+ count rate is expected.",

keywords = "Isotope ratio mass spectrometry, Matrix effect, NanoSIMS, Secondary ion, Uranium",

author = "Zirakparvar, {Nasser Alex} and Hexel, {Cole R.} and Miskowiec, {Andrew J.} and Smith, {Julie B.} and Ambrogio, {Michael W.} and Duckworth, {Douglas C.} and Roger Kapsimalis and Ticknor, {Brian W.}",

year = "2019",

month = may,

doi = "10.3390/min9050307",

language = "English",

volume = "9",

journal = "Minerals",

issn = "2075-163X",

publisher = "MDPI",

number = "5",

}

TY - JOUR

T1 - A nanosims 50 L investigation into improving the precision and accuracy of the235U/238U ratio determination by using the molecular235U16O and238u16O secondary ions

AU - Zirakparvar, Nasser Alex

AU - Hexel, Cole R.

AU - Miskowiec, Andrew J.

AU - Smith, Julie B.

AU - Ambrogio, Michael W.

AU - Duckworth, Douglas C.

AU - Kapsimalis, Roger

AU - Ticknor, Brian W.

PY - 2019/5

Y1 - 2019/5

N2 - A NanoSIMS 50 L was used to study the relationship between the235U/238U atomic and235U16O/238U16O molecular uranium isotope ratios determined from a variety of uranium compounds (UO2, UO2F2, UO3, UO2(NO3)2·6(H2O), and UF4) and silicates (NIST-610 glass and the Plesovice zircon reference materials, both containing µg/g uranium). Because there is typically a greater abundance of235U16O+ and238U16O+ molecular secondary ions than235U+ and238U+ atomic ions when uranium-bearing materials are sputtered with an oxygen primary ion beam, the goal was to understand whether use of235U16O/238U16O has the potential for improved accuracy and precision when compared to the235U/238U ratio. The UO2 and silicate reference materials showed the greatest potential for improved accuracy and precision through use of the235U16O/238U16O ratio as compared to the235U/238U ratio. For the UO2, which was investigated at a variety of primary beam currents, and the silicate reference materials, which were only investigated using a single primary beam current, this improvement was especially pronounced at low235U+ count rates. In contrast, comparison of the235U16O/238U16O ratio versus the235U/238U ratio from the other uranium compounds clearly indicates that the235U16O/238U16O ratio results in worse precision and accuracy. This behavior is based on the observation that the atomic (235U+ and238U+) to molecular (235U16O+ and238U16O+) secondary ion production rates remain internally consistent within the UO2 and silicate reference materials, whereas it is highly variable in the other uranium compounds. Efforts to understand the origin of this behavior suggest that irregular sample surface topography, and/or molecular interferences arising from the manner in which the UO2F2, UO3, UO2(NO3)2·6(H2O), and UF4 were prepared, may be a major contributing factor to the inconsistent relationship between the observed atomic and molecular secondary ion yields. Overall, the results suggest that for certain bulk compositions, use of the235U16O/238U16O may be a viable approach to improving the precision and accuracy in situations where a relatively low235U+ count rate is expected.

AB - A NanoSIMS 50 L was used to study the relationship between the235U/238U atomic and235U16O/238U16O molecular uranium isotope ratios determined from a variety of uranium compounds (UO2, UO2F2, UO3, UO2(NO3)2·6(H2O), and UF4) and silicates (NIST-610 glass and the Plesovice zircon reference materials, both containing µg/g uranium). Because there is typically a greater abundance of235U16O+ and238U16O+ molecular secondary ions than235U+ and238U+ atomic ions when uranium-bearing materials are sputtered with an oxygen primary ion beam, the goal was to understand whether use of235U16O/238U16O has the potential for improved accuracy and precision when compared to the235U/238U ratio. The UO2 and silicate reference materials showed the greatest potential for improved accuracy and precision through use of the235U16O/238U16O ratio as compared to the235U/238U ratio. For the UO2, which was investigated at a variety of primary beam currents, and the silicate reference materials, which were only investigated using a single primary beam current, this improvement was especially pronounced at low235U+ count rates. In contrast, comparison of the235U16O/238U16O ratio versus the235U/238U ratio from the other uranium compounds clearly indicates that the235U16O/238U16O ratio results in worse precision and accuracy. This behavior is based on the observation that the atomic (235U+ and238U+) to molecular (235U16O+ and238U16O+) secondary ion production rates remain internally consistent within the UO2 and silicate reference materials, whereas it is highly variable in the other uranium compounds. Efforts to understand the origin of this behavior suggest that irregular sample surface topography, and/or molecular interferences arising from the manner in which the UO2F2, UO3, UO2(NO3)2·6(H2O), and UF4 were prepared, may be a major contributing factor to the inconsistent relationship between the observed atomic and molecular secondary ion yields. Overall, the results suggest that for certain bulk compositions, use of the235U16O/238U16O may be a viable approach to improving the precision and accuracy in situations where a relatively low235U+ count rate is expected.

KW - Isotope ratio mass spectrometry

KW - Matrix effect

KW - NanoSIMS

KW - Secondary ion

KW - Uranium

UR - http://www.scopus.com/inward/record.url?scp=85068432441&partnerID=8YFLogxK

U2 - 10.3390/min9050307

DO - 10.3390/min9050307

M3 - Article

AN - SCOPUS:85068432441

SN - 2075-163X

VL - 9

JO - Minerals

JF - Minerals

IS - 5

M1 - 307

ER -