The determination of isotope ratios of individual uranium particles in environmental swipe samples is very important for nuclear safeguards. A new technique to measure isotope ratios for individual uranium particle was developed in this work, which was a combination of particle transfer by scanning electron microscope (SEM) and isotope ratios analysis by thermal ionization mass spectrometry (TIMS). The technique was verified by measuring isotope ratios in individual micrometer-size uranium particles of known isotopic abundance. The particles were identified by SEM combined with energy dispersive X-ray spectrometer (EDX) and transferred by micromanipulator, which could improve the efficiency of sample preparation and simplify the procedure. The experimental condition was optimized by using a new kind of thermal ion emitter to enhance the ionization efficiency of uranium. Several individual uranium particles from certified reference materials were successfully measured by SEM-TIMS. The results show that the measured isotope ratios were in good agreement with the reference values. The relative errors of 13 particles were within 2.7% for ²³⁴U/²³⁸U, 1.1% for ²³⁵U/²³⁸U and 4.5% for ²³⁶U/²³⁸U isotope ratios, respectively, and the relative standard deviation (RSD) were within 1.6% for ²³⁴U/²³⁸U, 0.5% for ²³⁵U/²³⁸U and 3.3% for ²³⁶U/²³⁸U, respectively. It is expected that this method will become a promising alternative technique for determining uranium isotope ratios in particle analysis. The particles used in this study had sizes between 1.3 and 4.7 μm.

环境擦拭样品中单个铀粒子的同位素比率的测定对于核保障非常重要。在这项工作中开发了一种测量单个铀粒子同位素比率的新技术，该技术将扫描电子显微镜 (SEM) 的粒子转移和热电离质谱 (TIMS) 的同位素比率分析相结合。该技术通过测量已知同位素丰度的单个微米级铀颗粒中的同位素比率得到验证。通过SEM结合能量色散X射线光谱仪（EDX）对颗粒进行鉴定并通过显微操作器转移，这可以提高样品制备的效率并简化步骤。采用新型热离子发射器优化实验条件，提高铀的电离效率。通过 SEM-TIMS 成功测量了来自经认证参考材料的几个单独的铀颗粒。结果表明，测得的同位素比值与参考值吻合良好。13个粒子的相对误差在2.7%以内²³⁴ U / ²³⁸ U，1.1％²³⁵ U / ²³⁸ U和4.5％²³⁶ U / ²³⁸ ü分别同位素比率，相对标准偏差（RSD）为1.6％，为内²³⁴ U / ²³⁸ U，0.5％²³⁵ U/ ²³⁸ U 和²³⁶ U/ ²³⁸ U 分别为 3.3% 。预计该方法将成为确定粒子分析中铀同位素比率的一种有前途的替代技术。本研究中使用的颗粒大小在 1.3 到 4.7 微米之间。