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Rapid, molecule-free, in situ rare earth element abundances by SIMS-SSAMS
Journal of Analytical Atomic Spectrometry ( IF 3.1 ) Pub Date : 2017-09-19 00:00:00 , DOI: 10.1039/c7ja00294g
Evan E. Groopman 1, 2, 3, 4 , Kenneth S. Grabowski 1, 2, 3, 4 , Albert J. Fahey 4, 5, 6, 7 , Levke Kööp 4, 8, 9, 10
Affiliation  

We present a novel method for rapid and high-sensitivity in situ measurements of the rare earth elements (REEs) by combined secondary ion mass spectrometry and single-stage accelerator mass spectrometry (SIMS-SSAMS). Traditional SIMS can be limited in its REE sensitivity by the presence of abundant molecular isobars, whose discrimination is often beyond the range of high mass resolving power, and which require energy filtering and careful calibration to deconvolve. These greatly reduce sensitivity and require a priori assumption of terrestrial isotope ratios for deconvolution, which precludes the analysis of some nuclear forensic materials and presolar stardust grains. With the SSAMS, molecular background is reduced by 5 to 6 orders of magnitude, precluding the need for energy filtering and/or high mass resolution. We demonstrate measurement of Gd isotopes (6 μmol mol−1) in the presence of a molecular background more than 4 orders of magnitude more intense from a single 15 μm spot in a sample of Madagascar hibonite. From the same spot we can resolve 7 nmol mol−1 of Tm from its comparably large background. Traditional SIMS requires the measurement of 47+ masses over 0.5 to 3 hours to perform REE deconvolution, while we collect full REE abundance patterns from several minerals in 10 to 30 minutes per spot. We observe no instrumental mass fractionation (±1%) in either Gd or Dy isotope ratio measurements of NIST610/612 glass. These improvements in sensitivity and measurement rapidity open important new avenues for REE imaging of samples and analyses of particles, nuclear materials, and mineral inclusions.

中文翻译:

SIMS-SSAMS快速,无分子的原位稀土元素丰度

我们提出了一种通过二次离子质谱和单级加速器质谱(SIMS-SSAMS)相结合的稀土元素(REE)快速高灵敏度原位测量的新方法。传统的SIMS可能由于存在大量的分子等压线而限制了其REE敏感性,这些等压线的辨别力通常超出了高质量分辨能力的范围,并且需要进行能量过滤和仔细的校正才能消除卷积。这些大大降低了灵敏度,需要先验假设对反卷积的地球同位素比率是假定的,这排除了对某些核法证材料和太阳前星尘颗粒的分析的需要。使用SSAMS,分子本底降低了5到6个数量级,从而消除了对能量过滤和/或高质量分离的需求。我们证明了在马达加斯加菱铁矿样品中的单个15μm光斑强度超过​​4个数量级的分子背景下,对Gd同位素(6μmolmol -1)的测量。从同一点,我们可以分辨出7 nmol mol -1Tm来自其相对较大的背景。传统的SIMS需要在0.5到3个小时内测量47个以上的质量才能进行REE反褶积,而我们需要在每点10到30分钟内收集几种矿物的完整REE丰度图。在NIST610 / 612玻璃的Gd或Dy同位素比测量中,我们没有观察到仪器质量分数(±1%)。灵敏度和测量速度的这些提高为样品的REE成像以及对颗粒,核材料和矿物包裹体的分析开辟了重要的新途径。
更新日期:2017-11-02
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