Relative nuclidic masses

Everling, F.; Konig, Luca; Mattauch, J.; Wapstra, A.H.

doi:10.1016/0029-5582(60)90423-5

Cited by 208 publications

(71 citation statements)

References 6 publications

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“…The atomic masses are derived by a least-squares adjustment from data consisting predominantly of redundant mass-spectrometric measurements based on the "mass-doublet" technique (in which the masses of isotopes with identical mass number are compared) but also of nuclear-reaction data and spontaneous-fission information. Atomic-mass tables have thus been produced over an extended period of time by A. H. Wapstra and his colleagues [23,[48][49][50][51]. IUPAC-CAWIA accepts these atomic-mass values in composing its Tables of Standard Atomic Weights (TSAW).…”

Section: Atomic Massesmentioning

confidence: 99%

“…At the 36 th General Assembly of IUPAC in 1991, CAWIA endorsed an "absolute" determination of the atomic weight of Si in a single sample of 28.085 382 (23), which, when combined with new determinations of density and interatomic spacing, gave a value of N A = 6.022 1363 × 10 23 mol -1 with an uncertainty of 1.1 × 10 -6 [106]. The new value was in excellent agreement with the 1987 CODATA value of N A (6.022 1367 × 10 23 mol -1 ), which has a relative uncertainty of 0.59 × 10 -6 .…”

Section: Atomic Weights For Fundamental Constantsmentioning

confidence: 99%

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Atomic weights of the elements. Review 2000 (IUPAC Technical Report)

Laeter¹,

Böhlke²,

Bièvre³

et al. 2003

Pure and Applied Chemistry

927

554

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Republication or reproduction of this report or its storage and/or dissemination by electronic means is permitted without the need for formal IUPAC permission on condition that an acknowledgmentAbstract: A consistent set of internationally accepted atomic weights has long been an essential aim of the scientific community because of the relevance of these values to science and technology, as well as to trade and commerce subject to ethical, legal, and international standards. The standard atomic weights of the elements are regularly evaluated, recommended, and published in updated tables by the Commission on Atomic Weights and Isotopic Abundances (CAWIA) of the International Union of Pure and Applied Chemistry (IUPAC). These values are invariably associated with carefully evaluated uncertainties. Atomic weights were originally determined by mass ratio measurements coupled with an understanding of chemical stoichiometry, but are now based almost exclusively on knowledge of the isotopic composition (derived from isotope-abundance ratio measurements) and the atomic masses of the isotopes of the elements. Atomic weights and atomic masses are now scaled to a numerical value of exactly 12 for the mass of the carbon isotope of mass number 12. Technological advances in mass spectrometry and nuclear-reaction energies have enabled atomic masses to be determined with a relative uncertainty of better than 1 × 10 -7 . Isotope abundances for an increasing number of elements can be measured to better than 1 × 10 -3 . The excellent precision of such measurements led to the discovery that many elements, in different specimens, display significant variations in their isotope-abundance ratios, caused by a variety of natural and industrial physicochemical processes. While such variations increasingly place a constraint on the uncertainties with which some standard atomic weights can be stated, they provide numerous opportunities for investigating a range of important phenomena in physical, chemical, cosmological, biological, and industrial processes. This review reflects the current and increasing interest of science in the measured differences between source-specific and even sample-specific atomic weights. These relative comparisons can often be made with a smaller uncertainty than is achieved in the best calibrated "absolute" (= SI-traceable) atomic-weight determinations. Accurate determinations of the atomic weights of certain elements also influence the values of fundamental constants such as the Avogadro, Faraday, and universal gas constants. This review is in two parts: the first summarizes the development of the science of atomic-weight determinations during the 20 th century; the second summarizes the changes and variations that have been recognized in the values and uncertainties of atomic weights, on an element-by-element basis, in the latter part of the 20 th century.J. R. de LAETER et al.

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Section: Atomic Massesmentioning

confidence: 99%

Section: Atomic Weights For Fundamental Constantsmentioning

confidence: 99%

Atomic weights of the elements. Review 2000 (IUPAC Technical Report)

Laeter¹,

Böhlke²,

Bièvre³

et al. 2003

Pure and Applied Chemistry

927

554

View full text Add to dashboard Cite

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“…In the (~, ~) experiments with natural sulphur, ZnS targets were used, whereas the 34S(0~, 7)aSAr measurements were performed with a CdS target enriched to 35 ~o 34S, obtained from A.E.R.E., HarweU, England. The proton yield curve was measured with a COC12 target enriched to 99.5 ~o SsC1.…”

Section: Apparatusmentioning

confidence: 99%

Energy levels of 36Ar and 38Ar from alpha capture in sulphur and proton capture in chlorine

Erné

Leun

1964

Nuclear Physics

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Abstract:The reactions ssS(~, 7,)SeAr and e~S(~, 7)~Ar were investigated in the energy range E~ = 2.2-3.2 MeV. Five resonance states in SeAr (Ex = 8.9-9.5 MeV) and six in eSAr(Ex = 9.6-10.1 MeV) were found. The excitation energies and resonance strengths are reported. The spins and parities of most resonances showing a ground-state transition were determined from angular distribution measurements. The relative strengths of the J~ = 1-resonances in neAr and 8nAr indicate that the isobaric-spin selection rule for electric dipole transitions in self-conjugate nuclei is still effective in this mass region. The slowing-down factor for these transitions amounts to about ten. The seCl(p, 7)nnAr reaction for F~ = 0.4-1.0 MeV, leads to twenty SeAr levels in the excitation range covered in the s~S(u, 7')SeAr experiment. The yield curves of the two reactions are compared. Three s6Ar resonance levels are excited in both the (13, 7') and the (u, 7) reaction.

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“…The uncertainties are the sum of the 95 percent confidence limits on the ratio determination and the estimated maximum possible errors in the analyses of the separated isotopes and the compositions of the calibration samples. Using the nuclidic masses given by Everling et al [16], the results yield an atomic weight of 79.90363 ± 0.00051 on the unified scale (CI2= 12) . These calculations are summarized in table 8 where the error statements include the effect of possible natural variation to the extent noted previously .…”

Section: Resultsmentioning

confidence: 93%

“…Also shown are the calculated combining weight ratios of AgCl/Ag and AgBr jAg. " See referen ce [16]. b See reference [1] .…”

Section: Resultsmentioning

confidence: 99%