A primary xenon isotopic gas standard with SI traceable values for isotopic composition and molar mass

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• 作者：Valkiers ; S. ; Aregbe ; Y. ; Taylor ; P.D.P. ; De Biè ; vre ; P.
• 关键词：Primary isotopic gas standard ; Isotopic composition ; Xenon ; Isotope amount ratios ; Gas isotope mass spectrometry ; Traceability ; SI ; Avogadro constant
• 刊名：International Journal of Mass Spectrometry and Ion Processes
• 出版年：1998
• 出版时间：January, 1998
• 年：1998
• 卷：173
• 期：1-2
• 页码：55-63
• 全文大小：575 K

文摘

A metrological certification measurement was made on a large batch of xenon separated from the terrestrial atmosphere by Messer Griesheim (Duisburg, Germany). The measurements were performed using the same procedure for measurements of amount ratios as developed for the improvement of the Avogadro constant N_A. During the measurement, the gas effusion from the expansion vessel into the ion source was continuously monitored by measuring experimental values for [m(ⁱ(E)/m(^jE)]^−φ to enable correction for mass discrimination. Synthetic mixtures were made of enriched Xenon isotopes and measured. They did not reveal a significant correction factor for residual unknown errors within the measurement uncertainty of 5 × 10⁻⁴. Thus, an isotopic composition and a molar mass (atomic weight) value M(Xe) = 131.29276 ± 0.00033 g mol⁻¹ for xenon in this batch was established by procedures confirmed by kinetic gas theory at this level. The measured isotope amount ratios were compared to previous measurements on atmospheric xenon. They are in good agreement but now have considerably smaller relative combined uncertainties: n(¹²⁴Xe)/n(¹³²Xe)=0.003 536(12); n(¹²⁶Xe)/n(¹³²Xe) = 0.003 307 7(72); n(¹²⁸Xe)/n(¹³²Xe) = 0.070 989(29); n(¹²⁹Xe)/n(¹³²Xe) = 0.981 12(41); n(¹³⁰Xe)/n(¹³²Xe) = 0.151 290(47); n(¹³¹Xe)/n(¹³²Xe) = 0.789 055(76); n(¹³⁴Xe)/n(¹³²Xe) = 0.387 819(69); n(¹³⁶Xe)/n(¹³²Xe) = 0.329 16(17).