Exploring the accuracy of isotopic analyses in atom probe mass spectrometry

Meisenkothen, Frederick; Samarov, Daniel V.; Kalish, Irina; Steel, Eric B.

doi:10.1016/j.ultramic.2020.113018

Cited by 26 publications

(48 citation statements)

References 52 publications

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“…Our method also offers several advantages over the full width at half-maximum based method proposed by Fahey et al 13 For example, our use of single-hit data significantly reduces deadtime-related effects and multihit detection artifacts. 37 Also, our adaptive peak fitting algorithm permits full decomposition of partially overlapping peaks and proper attribution of hydride peaks to the parent isotopes for more accurate measurements.…”

Section: Results and Discussionmentioning

confidence: 99%

“…A custom machine-learning-based adaptive peak fitting script was used to provide a mathematically defensible and repeatable method to fit the individual peaks comprising a family of peaks, i.e., the isotopic variants of a given ion species (e.g., 234 UO 2 2+ , 235 UO 2 2+ , 236 UO 2 2+ , 238 UO 2 2+ ). 37 The script was designed to read the *.csv file, subset the spectrum to isolate a single family of peaks, fit each peak within the family, perform peak decompositions, and calculate the isotopic abundances. The script was written in the R programming language using RStudio.…”

Section: Methodsmentioning

confidence: 99%

“…Isotopic analyses based on the CRW-corrected TOF spectrum are generally more accurate than analyses performed with the *.ePOS data. 37 Hence, we restrict our isotopic analyses to the CRW-corrected TOF spectrum exported from the IVAS. The application of our approach is thus currently limited to single-phase samples or easily parsed data sets, since the 3-D reconstructed data (*.ePOS data) cannot be used to perform the highest accuracy analyses.…”

Section: Methodsmentioning

confidence: 99%

“…Therefore, the peak form (including the tail and leading edge) can vary significantly between different ion species in the TOF spectrum (or mass spectrum). 37 This variation in peak form presents a challenge when performing accurate quantitative analyses, since it implies peak shape must be taken into account to obtain the most accurate analysis results, yet no single model peak form can be used to fit all peaks across the full range of the spectrum. Fortunately, the individual peaks comprising a family of peaks, i.e., isotopic variants of a given ion species, have nominally the same peak form.…”

Section: Methodsmentioning

confidence: 99%

“…For the interested reader, a detailed outline of the earlier script is provided in our prior work. 37 The peak positions were defined by the analyst, and the cost function to be minimized was the sum of squared residuals. A constant local background approximation was used under each family of peaks, as determined by averaging the ion counts in tens to hundreds of bins immediately to the left of the peak family.…”

Section: Methodsmentioning

confidence: 99%

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Atom Probe Mass Spectrometry of Uranium Isotopic Reference Materials

et al. 2020

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Atom probe tomography (APT)-based isotopic analyses are becoming increasingly attractive for analysis applications requiring small volumes of material and sub-micrometer length scales, such as isotope geochemistry, nuclear safety, and materials science. However, there is an open question within the atom probe community as to the reliability of atom probe isotopic and elemental analyses. Using our proposed analysis guidelines, in conjunction with an empirical calibration curve and a machine learning-based adaptive peak fitting algorithm, we demonstrate accurate and repeatable uranium isotopic analyses, via atom probe mass spectrometry, on U 3 O 8 isotopic reference materials. By using isotopic reference materials, each measured isotopic abundance value could be directly compared to a known certified reference value to permit a quantitative statement of accuracy. The isotopic abundance measurements for 235 U and 238 U in each individual APT sample were consistently within ±1.5% relative to the known reference values. The accuracy and repeatability are approaching values consistent with measurements limited primarily by Poisson counting statistics, i.e., the number of uranium atoms recorded.

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Section: Results and Discussionmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

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Atom Probe Mass Spectrometry of Uranium Isotopic Reference Materials

et al. 2020

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Atom Probe Tomography: a Local Probe for Chemical Bonds in Solids

Cojocaru‐Mirédin,

Yu,

Köttgen

et al. 2024

Advanced Materials

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Atom probe tomography is frequently employed to characterize the elemental distribution in solids with atomic resolution. Here the potential of this technique to locally probe chemical bonds is reviewed and discussed. Two processes characterize the bond rupture in laser‐assisted field emission, the probability of molecular ions (PMI), i.e., the probability that molecular ions are evaporated instead of single (atomic) ions, and the probability of multiple events (PME), i.e., the correlated field‐evaporation of more than a single fragment upon laser‐ or voltage pulse excitation. Here it is demonstrated that one can clearly distinguish solids with metallic, covalent, and metavalent bonds based on their bond rupture, i.e., their PME and PMI values. These findings open new avenues in understanding and designing advanced materials, since they allow a quantification of bonds in solids on a nanometer scale, as will be shown for several examples. These possibilities would even justify calling the present approach bonding probe tomography (BPT).

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