Surface characterization of silicon spheres by combined XRF and XPS analysis for determination of the avogadro constant

Fliegauf, R.; Beckhoff, Burkhard; Beyer, Edyta; Darlatt, Erik; Holfelder, Ina; Hönicke, Philipp; Ulm, G.; Kolbe, Michael

doi:10.1109/cpem.2016.7540797

Cited by 4 publications

(4 citation statements)

References 4 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The necessary calibration for the use of this method may be performed 'externally' (proposed for nat Si sc ) or 'internally', as calibration points at the surface of the sphere (recommended for 28 Si and nat Si qp ). The 'internal calibration' is done with an XPS/XRF-measuring system developed at PTB [50]. Of course, other measuring systems realizing these methods could be used as well.…”

Section: Characterization Of Si Spheresmentioning

confidence: 99%

A quantum of action on a scale? Dissemination of the quantum based kilogram

Knopf¹,

Wiedenhöfer²,

Lehrmann³

et al. 2019

Metrologia

View full text Add to dashboard Cite

In a forecast of the revised international system of units, that will come into force on 20th May 2019, the Physikalisch-Technische Bundesanstalt is developing and establishing a strategic concept, that allows the kilogram to be realized and distributed on the basis of new artefacts and methods. Possible paths of the quantum-based kilogram from its definition based on the Planck constant to the macroscopic world are being elucidated, i.e. the use of silicon spheres of different qualities as well as the use of Kibble-Balances and new developments of table-top weighing instruments. Beside metrological aims the availability of realizations and easy handling procedures are of crucial importance within a future dissemination chain. Advantages and disadvantages of different approaches are being examined and current developments, basically on the silicon route, and their expected measurement uncertainty are outlined. Scientific and strategic developments in the use of silicon spheres in the future mass dissemination chain are accompanied by more than 20 national metrological institutes and designated institutes by testing the existing methods and doing their own investigations.

show abstract

Section: Characterization Of Si Spheresmentioning

confidence: 99%

A quantum of action on a scale? Dissemination of the quantum based kilogram

Knopf¹,

Wiedenhöfer²,

Lehrmann³

et al. 2019

Metrologia

View full text Add to dashboard Cite

show abstract

“…Since then, one option for realizing and disseminating the kilogram is via the X‐ray crystal density (XRCD) method 3–7 . Drawing on the information and technical support of the Physikalisch‐Technische Bundesanstalt (PTB, Germany), 8,9 CMS/ITRI adopted this method 10 Here, the Si atoms inside a 28 Si‐enriched sphere are “counted” and the sphere's core mass is determined by multiplying the number of atoms by the molar mass of 28 Si 11,12 . The core mass is stable due to the shielding of the oxide layer on the surface.…”

Section: Introductionmentioning

confidence: 99%

Quantification via X‐ray fluorescence analysis of oxygen in the surface layer of a Si‐sphere used as a new mass standard

Tsao

Chiu

et al. 2021

X-Ray Spectrometry

Self Cite

View full text Add to dashboard Cite

The distribution of oxygen present in the surface layer of the Si‐sphere used as new mass standard is measured and quantified using the combined X‐ray fluorescence (XRF)/X‐ray photoelectron spectroscopy (XPS) surface analysis system in the Center for Measurement Standards, Industrial Technology Research Institute (CMS/ITRI). A radiometric calibration of the X‐ray source is not possible because the spectral distribution of the X‐ray tube used is complex and not stable over the long term. Hence, the quantification of oxygen on the Si‐sphere is based on a calibration curve that establishes a correlation between the mass deposition of oxygen from the calibration samples qualified by PTB and the ratio of the oxygen fluorescence to silicon RRS (resonant Raman scattering) intensities in the in‐house system. This paper presents the methodology for and the results of an oxygen quantification performed using the combined XRF/XPS surface analysis system. With a relative uncertainty of less than 10%, the average mass deposition of oxygen on the Si‐sphere was 133 ± 12 ng/cm2. The oxygen quantified via XRF is treated as a reference for the quantification of other elements on the surface layer. The quantification of carbon mass deposition in the surface layer in relation to the oxygen mass deposition is also described in this paper. The surface analysis system is part of our contribution to the realization and dissemination of the unit of the kilogram (based on its new definition) via the XRCD method.

show abstract

“…It also enables improving the accuracy of OL measurements, due to the high specific sensitivity for carbon (C). Currently, an integrated XPS/XRF instrument is in preparation for combined measurements on the silicon spheres [62].…”

Section: X-ray Photoelectron Spectroscopy (Xps)mentioning

confidence: 99%

“…The new apparatus of PTB is based on XPS and XRF for direct measurements on the sphere. A sample holder with two rotational axes is implemented within the vacuum chamber to enable full mapping of the surface during measurement [62].…”

Section: Further Developmentsmentioning

confidence: 99%

Realization of the kilogram by the XRCD method

Fujii¹,

et al. 2016

View full text Add to dashboard Cite

When the kilogram is redefined in terms of the fixed numerical value of the Planck constant h, the x-ray-crystal-density (XRCD) method, among others, is used for realizing the redefined kilogram. The XRCD method has been used for the determination of the Avogadro constant N A by counting the number of atoms in a 28 Si-enriched crystal, contributing to a substantial reduction of uncertainty in the values of N A and h to 2 parts in 10 8 . This method can be therefore used reversely for the mass determination of a 1 kg sphere prepared from the crystal. This is realized by SI-traceable measurements of its lattice parameter, isotopic composition, volume, and surface properties. Details of the corresponding measurements are provided, as well as the concept of the XRCD method, isotope enrichment, crystal production, sphere manufacturing, and evaluation of impurities and self-point defects in the crystal, together with mass comparison with respect to the silicon sphere for disseminating mass standards.

show abstract

Surface characterization of silicon spheres by combined XRF and XPS analysis for determination of the avogadro constant

Cited by 4 publications

References 4 publications

A quantum of action on a scale? Dissemination of the quantum based kilogram

A quantum of action on a scale? Dissemination of the quantum based kilogram

Quantification via X‐ray fluorescence analysis of oxygen in the surface layer of a Si‐sphere used as a new mass standard

Realization of the kilogram by the XRCD method

Contact Info

Product

Resources

About