Hannover 2010 – wissenschaftliches Programm
MS 3.3: Vortrag
Dienstag, 9. März 2010, 14:45–15:00, F 428
Isotope dilution mass spectrometry at the limit: a novel concept
— •Axel Pramann, Olaf Rienitz, and Detlef Schiel — Physikalisch-Technische Bundesanstalt, Bundesallee 100, 38116 Braunschweig
The experimental measurement of the molar mass M of silicon crystals has been performed for the first time applying a modification of the powerful isotope dilution mass spectrometry (IDMS) technique. This method has been successfully applied in combination with a multicollector-ICP-mass spectrometer (MC-ICP-MS).1 The background of this work is linked to an international project for the redetermination of the Avogadro constant with an associated relative measurement uncertainty in the range of 10−8.2 M is measured by isotope ratio measurements. Isotope ratios near unity can be measured after separating the element under investigation (silicon) into a virtual element consisting of all isotopes of the element (29Si and 30Si) except the isotope of highest abundance (28Si). Then, IDMS is applied on this virtual element resulting in the isotopic pattern and thus molar mass of the complete element (all isotopes). The novel IDMS-method is explained and first results of silicon crystal material are presented and discussed on a metrological level with the aid of a comprehensive uncertainty budget.
1O. Rienitz, A. Pramann, D. Schiel, Int. J. Mass Spectrom., 289, 47 (2010).
2P. Becker, Metrologia 40, 366 (2003).