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摘要
The "Centro Espanol de Metrologia" is carrying out a project to improve the knowledge of the influence of impurities and isotopic composition on the temperature of the mercury triple point. High-purity mercury from the Almaden mine (stated purity of 99.9998%) was further purified by vacuum distillation. Three mercury fractions, the original mercury from Almaden and two distilled fractions, were characterized in terms of both impurities and isotopic composition and used to measure the mercury triple point. The original mercury sample contained silver at 560 ng.g(-1) as the main impurity while the impurity levels were much lower (silver < 1 ng.g(-1)) in the two distilled fractions. The isotopic composition of the distilled fractions showed delta values, expressed as 1,000 x (Hg-198/202(sample) - Hg-198/202(reference))/Hg-198/202(reference), of 1.37 +/- 0.07 (1 sigma) for the first distilled sample and -1.55 +/- 0.03 (1 sigma) for the second distilled sample with reference to the original Almaden mercury. For the measurement of the mercury triple point, an alcohol stirred bath was used that allowed two cells to be compared nearly simultaneously. It was observed that the presence of the silver impurities in the high-purity mercury modified slightly the mercury triple point while the effect of variations in the isotopic composition can be considered negligible.
- 出版日期2008-2
