Determination of the absolute molar mass of silicon in a single crystal for a better Avogadro constant
The molar mass (atomic weight) of silicon, M(Si) [g/mol], in a Si single crystal is an essential parameter for modern determinations of the Avogadro constant, N(A). A long-term project at IRMM Geel aims to reduce the uncertainties on M(Si) in order to reduce the uncertainty of the Avogadro constant N(A) by a factor of 10, and later to reduce the uncertainty contribution of M(Si) still further. The measurement method and the required chemical sample preparation are described, together with the principles governing the preparation of the synthetic Si isotope mixtures. The boundary conditions on the chemical compounds carrying the enriched isotopes are indicated: chemical purity, stoichiometry, weighability. The Cs(2)SiF(6) compound fulfills all these conditions and was therefore used.
Bibliographic Reference: Paper presented: Third International Symposium on Separation Technology, Antwerpen (BE), August 22-27, 1993
Availability: Available from (1) as Paper EN 37513 ORA
Record Number: 199311307 / Last updated on: 1994-11-28
Original language: en
Available languages: en