Quantification of the Imperfectness of the Molecular Flow Conditions of the Gas Entering the Mass Spectrometer Ion Source for Ionization: Exemplified for CO2 Isotope Amount Ratio Measurements

A new model to describe the gas flow status inside the gas mass spectrometer (MAT 271) inlet system has been developed and applied to the latest isotope amount ratio measurements.JRC.D.4-Isotope measurement

Steady State Isotopic Transient Kinetic Analysis Study of PEM Fuel Cell Anodes (SPA)

The hydrogen oxidation reaction at Proton Exchange Membrane Fuel Cell anodes is poisoned by part per million levels of carbon monoxide. Pt is the catalyst of choice for the oxidation of pure hydrogen, but it has recently been demonstrated that there is a dynamic equilibrium between CO adsorbed on Pt or Pt/Ru nanoparticles and CO in the gas phase, and that this equilibrium is affected by the competitive adsorption between CO and hydrogen. The purpose of this research is to perform Steady State Isotopic Transient Kinetic Analysis (SSITKA) experiments using the isotopic exchange between 13CO and 12CO to investigate the competitive adsorption of hydrogen and CO on commercial Pt and PtRu catalysts.JRC.D.4-Isotope measurement

Determination by Isotope Ratio Mass Spectrometry of the Absolute Isotope Amount Fractions of Oxygen and Nitrogen in Nitrous Oxide

A measurement procedure for the complete isotope characterisation of atmospheric nitrous oxide sample has been developed and applied to establish a first Reference Material for this gas. The whole work has been based on the peculiar instrumental capabilites of "Avogadro" MAT 271IRMS. Additional hardware and software improvement has been done for this mass spectrometer to apply the proposed method.JRC.D.4-Isotope measurement

Determination of the Avogadro Constant, a Contribution to the New Definition of Mass

An improved attempt of several national metrology institutes to replace the present definition of the kilogram with the mass of a certain number of 12C atoms is described. This requires the determination of the Avogadro constant, NA, via the silicon route with a relative uncertainty better than 2*10-8. Previously, the limiting factor is the measurement of the average molar mass. Consequently, a world-wide collaboration has been set up, to produce, approximately, 5 kg of 28Si single-crystal with an enrichment factor greater than 99.985 % to be used for an improved determination of NA. The first successful tests of all technological steps (enrichment of SiF4, purification and synthesis of silane, deposition of polycrystalline 28Si, single crystal growth) for the production of high-purity 28Si are reported.JRC.D.4-Isotope measurement

The Nature and Role of Primary Certified Isotopic Reference Materials - A Tool to Underpin Isotopic Measurements on a Global Scale

A Chapter that focuses on isotopic reference materials with certified values that are traceable to SI, and explains how they can be produced. An overview is given of cases where such materials have already been realised.JRC.D.4-Isotope measurement

Determination of the Avogadro Constant: A Contribution to the New Definition of Mass

An improved attempt of several national metrology institutes to replace the present definition of the kilogram with the mass of a certain number of 12C atoms is described. This requires the determination of the Avogadro constant, NA, via the silicon route with a relative uncertainty better than 2×10-8. Previously, the limiting factor is the measurement of the average molar mass. Consequently, a world-wide collaboration has been set up, to produce, approximately, 5 kg of 28Si single-crystal with an enrichment factor greater than 99.985% to be used for an improved determination of NA. The first successful tests of all technological steps (enrichment of SiF4, purification and synthesis of silane, deposition of polycrystalline 28Si, single crystal growth) for the production of high-purity 28Si are reported.JRC.D.4-Isotope measurement

Synthetic Isotope Mixtures for the Calibration of Isotope Amount Ratio Measurements of Carbon.

Abstract not availableJRC.D-Institute for Reference Materials and Measurements (Geel

Si Primary Standards for the Calibration of Ion-Current Ratios in the Molar-Mass Measurement of Natural Si Single Crystals

A procedure is described to obtain Si-traceable silicon isotope amount in the BaSiF6 form. On the basis of a gravimetric approach, three synthetic isotope mixtures were made, very similar tot natural Si, by blending silicon isotopically enriched 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 naural Si crystal WASO17.2 was remeasured and its molar mass was redetermined.JRC.DG.D.4-Isotope measurement

Calibration of Isotopic Measurements.

Abstract not availableJRC.D-Institute for Reference Materials and Measurements (Geel

Release of Anthropogenic Xenon to the Atmosphere. A Large Scale Isotope Dilution.

The following calculations and considerations are intended to serve as a contribution to the attempt to detect nuclear fuel reprocessing activities through 'environmental' measurements. As a result of the reprocessing process, the fission products xenon and krypton are released to the atmosphere. They show a different isotopic composition compared to natural atmospheric xenon (krypton). The released fission xenon (krypton) is diluted in air, mixed with natural xenon (krypton) and therefore results in a change of isotopic composition. Consequently, the question arises whether it is possible to detect the small isotopic alterations in atmospheric xenon (krypton) and the detection limit thereof. The calcualtions performed in this context are based on the principles of isotope mixing as in dilution. In order to provide an estimation of the isotopic alterations in atmospheric xenon (krypton) blendingcalculations were carried out using the isotopic compositions of atmospheric xenon (krypton) and calculated compositions of fission gases. Subsequently, the calculated ratios in the blend were compared to the ratios of natural xenon as measured using the highly developed, ultra-accurate measurement facilities on isotopic mass spectrometry at the IRMM.JRC.D-Institute for Reference Materials and Measurements (Geel