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 U₃O₈ 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 ²³⁵U and ²³⁸U 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.

中文翻译：

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铀同位素参考物质的原子探针质谱分析。

基于原子探针层析成像（APT）的同位素分析对于需要少量材料和亚微米长度尺度的分析应用（例如同位素地球化学，核安全和材料科学）越来越有吸引力。然而，关于原子探针同位素和元素分析的可靠性，原子探针界存在一个悬而未决的问题。使用我们提出的分析指南，结合经验校准曲线和基于机器学习的自适应峰拟合算法，我们通过原子探针质谱法对U ₃ O ₈演示了准确且可重复的铀同位素分析同位素参考资料。通过使用同位素参考材料，可以将每个测得的同位素丰度值直接与已知的认证参考值进行比较，以实现对准确性的定量说明。相对于已知参考值，每个APT样品中²³⁵ U和²³⁸ U的同位素丰度测量值始终在±1.5％以内。准确性和可重复性正在接近与主要受泊松计数统计（即记录的铀原子数）限制的测量值一致的值。