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Valkiers S.,IRMM Institute for Reference Materials and Measurements | Mana G.,INRIM - Istituto Nazionale di Ricerca Metrologica | Fujii K.,Japan Advanced Institute of Science and Technology | Becker P.,Physikalisch - Technische Bundesanstalt
Metrologia | Year: 2011

A procedure is described to obtain SI-traceable silicon isotope amount ratios in the BaSiF6 form. On the basis of a gravimetric approach, three synthetic isotope mixtures were made, very similar to natural Si, by blending silicon isotopically enriched with 28Si, 29Si and 30Si. These mixtures served as references to calibrate measurements of (SiF3)+ current ratios. In this way, it was possible to make SI-traceable measurements of silicon isotope amount ratios, without any assumptive correction. The isotopic composition of the natural Si crystal WASO17.2 was remeasured and its molar mass was redetermined. © 2011 BIPM & IOP Publishing Ltd. Source

Mana G.,INRIM - Istituto Nazionale di Ricerca Metrologica | Massa E.,INRIM - Istituto Nazionale di Ricerca Metrologica | Valkiers S.,IRMM Institute for Reference Materials and Measurements | Willenberg G.-D.,Physikalisch - Technische Bundesanstalt
International Journal of Mass Spectrometry | Year: 2010

The uncertainty of the Si molar mass measurement is theoretically investigated by means of a two-isotope model, with particular emphasis to the role of this measurement in the determination of the Avogadro constant. This model allows an explicit calibration formula to be given and propagation of error analysis to be made. It also shows that calibration cannot correct for non-linearity. © 2009 Elsevier B.V. All rights reserved. Source

Andreas B.,Physikalisch - Technische Bundesanstalt | Azuma Y.,NMIJ National Metrology Institute of Japan | Bartl G.,Physikalisch - Technische Bundesanstalt | Becker P.,Physikalisch - Technische Bundesanstalt | And 22 more authors.
Physical Review Letters | Year: 2011

The Avogadro constant links the atomic and the macroscopic properties of matter. Since the molar Planck constant is well known via the measurement of the Rydberg constant, it is also closely related to the Planck constant. In addition, its accurate determination is of paramount importance for a definition of the kilogram in terms of a fundamental constant. We describe a new approach for its determination by counting the atoms in 1 kg single-crystal spheres, which are highly enriched with the Si28 isotope. It enabled isotope dilution mass spectroscopy to determine the molar mass of the silicon crystal with unprecedented accuracy. The value obtained, NA=6.02214078(18) ×1023mol⊃-1, is the most accurate input datum for a new definition of the kilogram. © 2011 American Physical Society. Source

Becker P.,Physikalisch - Technische Bundesanstalt | Bettin H.,Physikalisch - Technische Bundesanstalt | Borys M.,Physikalisch - Technische Bundesanstalt | Busch I.,Physikalisch - Technische Bundesanstalt | And 11 more authors.
CPEM Digest (Conference on Precision Electromagnetic Measurements) | Year: 2010

This paper reports the progress and the achievements of an international research project aimed at determining the Avogadro constant by counting the atoms in enriched 28Si spheres. ©2010 IEEE. Source

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