Volume determination of two spheres of the new 28Si crystal of PTB
Volume determination of two spheres of the new 28Si crystal of PTB
复制标题
PTB新型28Si晶体两个球体的体积测定
DOI：
10.1088/1681-7575/aa7153
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发表时间：
2017
期刊：
影响因子：
--
通讯作者：
T. Mai
中科院分区：
文献类型：
--
作者：
A. Nicolaus;G. Bartl;A. Peter;E. Kuhn;T. Mai
在重新测定阿伏伽德罗常数NA的范围内，生产了一种新的同位素富集的硅晶体，并由此制造了两个球体。在确定了晶体性质、晶格参数和摩尔质量以及两个球的质量之后，还测量了球的体积。为此，使用了PTB的球面干涉仪。对干涉测量方法进行了改进，并对影响测量不确定度的主要因素进行了深入研究。因此，总的不确定度可以显着降低，产生了实质性的影响阿伏伽德罗常数的测定。每个球体的平均直径测量了两次，重复性为±2 × 10−10，而“表观”体积的相对不确定度（忽略了表面层光学效应的相对较小影响）降低到7 × 10−9。给出了卷的最终结果及其不确定性的评论。
In the scope of the redetermination of Avogadro’s constant NA, a new isotopically enriched silicon crystal has been produced, from which two spheres were manufactured. After the crystal properties, the lattice parameter and molar mass, as well as the masses of the two spheres have been determined, the volume of the spheres was also measured. For this, the sphere interferometer of PTB was used. The methods of the interferometric measurements have been improved and the major contributions to the uncertainty have been investigated thoroughly. As a result, the total uncertainty could be reduced significantly, yielding a substantial impact on the determination of Avogadro’s constant. The mean diameter of each sphere was measured twice with a repeatability of ±2 × 10−10, and the relative uncertainty of the ‘apparent’ volume, which disregards the comparatively small influence of the optical effects of surface layers, was reduced to 7 × 10−9. The final results of the volumes and comments on their uncertainties are given.