| Zugriffsnummer | 38243 |
| Dokumenttyp | Konferenzartikel |
| Sprache | Englisch |
| Titel | Quantitative surface analysis on28Si-spheres for the redefinition of the kilogram |
| Autor(in); Institution |
Beyer, Edyta; 1.8, Masse - Darstellung der Einheit, PTB-Braunschweig
Darlatt, Erik; 7.1, Radiometrie mit Synchrotronstrahlung, PTB-Berlin
Fliegauf, Rolf; 7.1, Radiometrie mit Synchrotronstrahlung, PTB-Berlin
Härtig, Frank; 1, Mechanik und Akustik, PTB-Braunschweig
Kolbe, Michael; 7.1, Radiometrie mit Synchrotronstrahlung, PTB-Berlin
Müller, Matthias; 1.8, Masse - Darstellung der Einheit, PTB-Braunschweig
|
| Quelle/Jahr | Proceedings of the 17th International Conference of the European Society for Precision Engineering and Nanotechnology:(2017), 325 - 326 |
| ISBN | 978-0-9957751-0-7 |
| Verlag | Bedford: Euspen |
| Konferenzangaben | euspen's 17th International Conference & Exhibition, Hannover, 29, May - 02, June, 2017, Germany |
| Freie Schlagworte | Measurement techniques ; surface analysis ; Avogadro constant ; mass realization |
| Zusammenfassung | A novel instrumentation for the quantitative surface analysis of silicon spheres was set up and taken into operation at the PTB. The instrumentation combines X-ray fluorescence spectroscopy and X-ray photoelectron spectroscopy techniques in order to enable the characterization and quantification of the oxide layer and unintentional contaminations. The instrumentation is equipped with a ball manipulator, giving the opportunity to measure on each point of a spherical sample surface beside common flat samples. Another feature of the instrumentation is a special load lock system, which allows the transportation of a sphere to a mass comparator under vacuum conditions. The surface characterization is needed to reduce the uncertainties in the determination of the Avogadro and Planck constant. Both values are needed for the new definition of the SI unit kg in terms of fundamental constants and independent from a material artefact. Two monocrystalline, isotopically enriched 28Si-spheres were manufactured for this purpose. Since every silicon surface is covered by a surface layer composed of silicon oxide and a contamination layer, the surface layer mass on the 28Si-spheres has to be determined in order to correct the results of the mass measurement of the spheres. The use of complementary X-ray methods allows minimizing the influence of the surface on the total uncertainty budget of the Avogadro and Planck constants. This is relevant, because a relative standard uncertainty of less than 2·10-8 has to be achieved to make a contribution to the new definition of the kilogram. Corresponding to that, the realization of the redefined kilogram via silicon spheres will also be improved. Measurements on the 28Si-spheres were carried out several times. The surface was characterized regarding the elementary composition including the chemical binding states of the components and the mass of the surface layer. |
