Hannover 2016 – wissenschaftliches Programm

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MS: Fachverband Massenspektrometrie

MS 1: Precision Mass Spectrometry and Fundamental Applications I

MS 1.2: Vortrag

Montag, 29. Februar 2016, 11:30–11:45, f128

High resolution MC-ICP-MS of ultra-trace amounts of silicon isotopes with lowest associated measurement uncertainty — •Axel Pramann — Physikalisch-Technische Bundesanstalt (PTB), 38116 Braunschweig, Germany

The redefinition of the Si-unit of the mass - the kilogram - awaited for 2018 will be performed via the Planck constant and the Avogadro constant.(1) The Avogadro-Project (counting Si atoms in a Si sphere) seems to be the canditate resulting in lowest uncertainties for that purpose. PTB developed several complementary methods for the mass spectrometric determination of the isotopic distribution, the molar mass M of the silicon crystal material used for the preparation of the Avogadro silicon spheres with silicon highly enriched in 28Si.(2) In order to reduce the uncertainties further, new silicon crystal material with extended enrichment in 28Si was produced in a cooperation with external companies and institutes in Russia. This work presents the improved MS techniques and current results performed on new crystal material with x(28Si) = 0.999995 mol/mol accompanied with a comprehensive uncertainty analysis showing a reduction in u(rel,M) by three orders of magnitude in ten years.

(1)Y. Azuma et al., Metrologia, 52, 360 (2015). (2)O. Rienitz, A. Pramann, D. Schiel, Int. J. Mass Spectrom., 289, 47 (2010). (3)A. Pramann, K.-S. Lee, J. Noordmann, O. Rienitz. Metrologia, 52, 800 (2015).