Comparison of the Isotopic Composition of Silicon Crystals Highly Enriched in 28Si

Crystals

Axel Pramann¹  Olaf Rienitz¹ 

[1] Physikalisch-Technische Bundesanstalt (PTB), Bundesallee 100, 38116 Braunschweig, Germany;

关键词: silicon single crystals;    molar mass;    isotope ratios;    mass spectrometry;    SI revision;    mole dissemination;   

DOI  :  10.3390/cryst10060500

来源: DOAJ

【 摘 要 】

The isotopic composition and molar mass M of silicon in a new crystal (code: Si28-33Pr11) measured by isotope ratio mass spectrometry using a high-resolution multicollector-inductively coupled plasma mass spectrometer (MC-ICP-MS) is presented using the virtual-element isotope dilution mass spectrometry (VE-IDMS) method. For this new crystal, M = 27.976 950 48 (16) g/mol was determined with u_rel(M) = 5.7 × 10⁻⁹. The “X-ray-crystal-density (XRCD) method”, one of the primary methods for realizing and disseminating the SI units kilogram and mole in the recently revised SI, is based on “counting” silicon atoms in silicon single crystal spheres. One of the key quantities is the isotopic composition—expressed by the molar mass M—of the three stable isotopes ²⁸Si, ²⁹Si, and ³⁰Si in the material highly enriched in ²⁸Si. M was determined with lowest possible uncertainty using latest improvements of the experimental techniques. All uncertainties were estimated according to the “Guide to the expression of uncertainty in measurement, GUM”. The results of the new crystal are discussed and compared with the four previously available crystals, establishing a worldwide limited pool of primary reference spheres of highest metrological quality.

【 授权许可】

Unknown