title: Uranium isotopic ratio measurements of U3O8 reference materials by atom probe tomography.
abstract: We report results of measurements of isotopic ratios obtained with atom probe tomography on U3O8 reference materials certified for their isotopic abundances of uranium. The results show good agreement with the certified values. High backgrounds due to tails from adjacent peaks complicate the measurement of the integrated peak areas as well as the fact that only oxides of uranium appear in the spectrum, the most intense of which is doubly charged. In addition, lack of knowledge of other instrumental parameters, such as the dead time, may bias the results. Isotopic ratio measurements can be performed at the nanometer-scale with the expectation of sensible results. The abundance sensitivity and mass resolving power of the mass spectrometer are not sufficient to compete with magnetic-sector instruments but are not far from measurements made by ToF-SIMS of other isotopic systems. The agreement of the major isotope ratios is more than sufficient to distinguish most anthropogenic compositions from natural.
authors.affiliation: Naval Research Lab, 4555 Overlook Ave. SW, Washington, DC, 20375, USA. Electronic address: albert.fahey@nrl.navy.mil.
authors.forename: Albert J
authors.initials: AJ
authors.lastname: Fahey
authors.affiliation: Pacific Northwest National Laboratory, Environmental Molecular Sciences Laboratory, 902 Battelle Blvd, P.O. Box 999, MS J4-70, Richland, WA, 99352, USA.
authors.forename: Daniel E
authors.initials: DE
authors.lastname: Perea
authors.affiliation: Pacific Northwest National Laboratory, Environmental Molecular Sciences Laboratory, 902 Battelle Blvd, P.O. Box 999, MS J4-70, Richland, WA, 99352, USA.
authors.forename: Jonah
authors.initials: J
authors.lastname: Bartrand
authors.affiliation: Pacific Northwest National Laboratory, Environmental Molecular Sciences Laboratory, 902 Battelle Blvd, P.O. Box 999, MS J4-70, Richland, WA, 99352, USA.
authors.forename: Bruce W
authors.initials: BW
authors.lastname: Arey
authors.affiliation: Pacific Northwest National Laboratory, Environmental Molecular Sciences Laboratory, 902 Battelle Blvd, P.O. Box 999, MS J4-70, Richland, WA, 99352, USA.
authors.forename: Suntharampillai
authors.initials: S
authors.lastname: Thevuthasan
mesh_terms: D010087:Oxides / Q000032:analysis*; D011834:Radiation Monitoring / Q000379:methods*; D011848:Radioactive Pollutants / Q000032:analysis*; D015203:Reproducibility of Results; D014054:Tomography; D017974:Uranium Compounds / Q000032:analysis*
chemical_list: D010087:Oxides; D011848:Radioactive Pollutants; D017974:Uranium Compounds; C054287:uranium octoxide
keywords: Atom probe tomography; Isotopic ratios; Uranium