A5052919461- Scientific Measurement and Uncertainty Evaluation
- Radioactive Decay and Measurement Techniques
- Nuclear Physics and Applications
- Analytical chemistry methods development
- Isotope Analysis in Ecology
- Mass Spectrometry Techniques and Applications
- Radioactive contamination and transfer
- Chemical Thermodynamics and Molecular Structure
- Pesticide Residue Analysis and Safety
- Extraction and Separation Processes
- Electron and X-Ray Spectroscopy Techniques
- Groundwater and Isotope Geochemistry
- X-ray Spectroscopy and Fluorescence Analysis
- Ion-surface interactions and analysis
- Recycling and Waste Management Techniques
- Geology and Paleoclimatology Research
- Atmospheric and Environmental Gas Dynamics
- Melamine detection and toxicity
- Archaeology and ancient environmental studies
- Water Quality Monitoring and Analysis
- Trace Elements in Health
- Heavy Metals in Plants
- Catalytic Processes in Materials Science
- Geochemistry and Geologic Mapping
- Radioactive element chemistry and processing
Physikalisch-Technische Bundesanstalt
2015-2024
Technische Universität Braunschweig
2014-2020
The Avogadro constant links the atomic and macroscopic properties of matter. Since molar Planck is well known via measurement Rydberg constant, it also closely related to constant. In addition, its accurate determination paramount importance for a definition kilogram in terms fundamental We describe new approach by counting atoms 1 kg single-crystal spheres, which are highly enriched with 28Si isotope. It enabled isotope dilution mass spectroscopy determine silicon crystal unprecedented...
This paper concerns an international research project aimed at determining the Avogadro constant by counting atoms in isotopically enriched silicon crystal. The procedure was based on measurement of molar volume and atom two 1 kg crystal spheres. novelty use isotope dilution mass spectrometry as a new very accurate method for determination silicon. Because unexpected metallic contamination sphere surfaces, relative uncertainty, 3 × 10−8 NA, is larger factor 1.5 than that targeted. measured...
New results are reported from an ongoing international research effort to accurately determine the Avogadro constant by counting atoms in isotopically enriched silicon crystal. The surfaces of two 28Si-enriched spheres were decontaminated and reworked order produce outer surface without metal contamination improved sphericity. measurements then made on these reconditioned using methods apparatuses. When combined with other recently refined parameter measurements, derived new has a value NA =...
When the kilogram is redefined in terms of fixed numerical value Planck constant h, x-ray-crystal-density (XRCD) method, among others, used for realizing kilogram. The XRCD method has been determination Avogadro NA by counting number atoms a 28Si-enriched crystal, contributing to substantial reduction uncertainty values and h 2 parts 108. This can be therefore reversely mass 1 kg sphere prepared from crystal. realized SI-traceable measurements its lattice parameter, isotopic composition,...
A new single crystal from isotopically enriched silicon was used to determine the Avogadro constant NA by x-ray-crystal density method. The crystal, named Si28-23Pr11, has a higher enrichment than former 'AVO28' allowing smaller uncertainty of molar mass determination. Again, two 1 kg spheres were manufactured this crystal. and measured with improved methods. One sphere, Si28kg01a, at NMIJ PTB very consistent results. other Si28kg01b, only yielded nearly same value. mean result for both is =...
The molar mass of a new silicon crystal material highly enriched in 28Si ('Si28', x(28Si) >99.99%) has been measured for the first time using combination modified isotope dilution spectrometry (IDMS) technique and high resolution multicollector-ICP-mass spectrometer. This work is related to redetermination Avogadro constant NA with an intended relative measurement uncertainty urel(NA) ⩽ 2 × 10−8. corresponding experimental investigations International Coordination (IAC) were performed this...
Three different MC-ICPMS instruments were calibrated by means of synthetic isotope mixtures to enable absolute Mg ratios with expanded uncertainties ≤0.15‰.
Main text KRISS and NMIJ jointly coordinated the CCQM-K158 comparison on elements inorganic As in polished rice flour. The study comprised two parts, Part A B. Successful participation formal international comparisons is essential for documenting calibration measurement capability claims (CMCs) by national metrology institutes (NMIs) designated (DIs). specifically supports CMCs within food category, corresponding to sample matrix labeled "High organic content" new CC table broad claims....
Nanosecond scanning laser ablation MC-ICP-MS (213 nm) was applied to the measurement of intensity ratios ultrapure single crystalline silicon (WASO04), which is used in XRCD-method and general...
ICP-MS has played a key role in inorganic chemical metrology for 25 years, from the 1993 CIPM feasibility study which led to establishment of CCQM. Since that time, Inorganic Analysis Working Group CCQM organised 56 international comparisons involving measurements by and, recent comparison, 16 different national institutes submitted their results using technique. Metrological applications currently address an enormous range wide variety instrumentation, calibration strategies and...
A new method applying isotope dilution mass spectrometry to determine the molar of a silicon sample, highly enriched with respect 28Si, has been proposed recently. This paper describes different way calculating by solving an equation linking measurement results ratio between amount-of-substance fractions 28Si and 30Si in sample. The mathematical model final are much more straightforward than those previously reported, though fully equivalent.
Within the scope of re-determining Avogadro constant, content impurities in ultra-pure, mono-isotopically enriched silicon 'Si28' was measured by infrared spectrometry. The calibration factors required for calculation concentrations from maximum absorption coefficients had to be determined this context isotopically material. For purpose a model prepared, which enables conversion Si with natural isotopic abundance. On basis these results, three most decisive material were determined. These...
Improved measurements on silicon crystal samples highly enriched in the 28Si isotope (known as 'Si28' or AVO28 material) have been carried out at PTB to investigate local isotopic variations original crystal. This material was used for determination of Avogadro constant NA and therefore plays an important role upcoming redefinition SI units kilogram mole, using fundamental constants. Subsamples extensively studied over past few years National Research Council (NRC, Canada), Metrology...
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Abstract Following the revision of International System Units (SI), that takes effect on 20 May 2019, unit mole is defined by using a fixed number elementary entities. This numerical value Avogadro constant, which defining constant mole. definition was made possible because determination had reached level relative uncertainty allowed its to be and, at same time, safeguard continuity measurement results before and after definition. The motivation for SI in particular will explained...
The continuous improvement of analytical procedures using multi‐collector technologies in ICP‐mass spectrometry has led to an increased demand for isotope standards with improved homogeneity and reduced measurement uncertainty. For magnesium, this a variety available different quality levels ranging from artefact reference materials certified absolute ratios. This required intercalibration all materials, which we present interlaboratory comparison study. Cambridge1, DSM3, ERM‐AE143,...
Healthcare laboratories are increasingly joining into larger laboratory organizations encompassing several physical laboratories. This caters for important new opportunities re-defining the concept of a ‘laboratory’ to encompass all and measurement methods measuring same measurand population patients. In order make results, comparable bias should be minimized or eliminated uncertainty properly evaluated used particular patient population. The as well diagnostic can from internal external...
Main text The pilot study CCQM-P204 was aimed at evaluating the level of compatibility laboratories' measurement capabilities to value assign isotope ratios in samples pure CO 2 gas, expressed as delta values relative relevant international scale: δ 13 C VPDB and 18 O VPDB-CO2 . Pure gas were prepared by BIPM batches 10 same circulated participants for measurement. Each participant received four with a different nominal value: −1 ‰; −9 −35 −42 ‰. also responsible homogeneity stability...