31. The absolute isotopic abundance ratio and the atomic weight of natural silver

Crouch, Edmund A. C.; Turnbull, A.H.

doi:10.1039/jr9620000161

Cited by 9 publications

(5 citation statements)

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“…Pyrex pipers resulted in an impurity interference at masses 104 to 109. From the relative peak heights at these masses it appears that this impurity was NaKB0•, which had also been observed byCrouch and Turnbull [1962]. The sample filaments of a standard Inghram-Chupka multiple-filament surface ionization assembly were made of 0.002-inch Ta, and the surface ionization filaments, of 0.001-inch Re.…”

supporting

confidence: 54%

Isotopic composition of silver in iron meteorites

Chakraburtty¹,

Stevens²,

Rushing³

et al. 1964

J. Geophys. Res.

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With a view to developing a new dating method based on extinct 6.8 m.y. Pd107, we isolated silver from 18 samples of the iron meteorites Bristol, Canyon Diablo, Grant, Odessa, Piñon, Sandia Mountains, and Toluca. The silver concentration (11 to 197 ppb) was determined on an aliquot by isotope dilution, and also by neutron activation analysis of separate samples. The isotopic composition was measured by surface ionization on the Argonne 100‐inch‐radius mass spectrometer. No enrichment of Ag107 was detected in any of these samples: our δAg107 values for Canyon Diablo and Toluca were 1.2±2.3 and 3.5±3.7 per mil, compared with Murthy's values of 40±4 and 22±4 per mil. The grand average of all our analyses was 0±1.5 per mil. That this discrepancy was not due to contamination is shown by our low blanks (<5 per cent), by the agreement of the neutron activation and isotope dilution results, and by other evidence. Sampling error is also not a likely explanation, since its probability is <1.6 × 10−3 under the most favorable assumptions. Possibly the apparent anomalies found by Murthy are in some way related to the anomalous value he obtained for terrestrial silver (Ag107/Ag109 = 1.064±0.002, compared with 1.082±0.002, the average ratio found by four other investigators).

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supporting

confidence: 54%

Isotopic composition of silver in iron meteorites

Chakraburtty¹,

Stevens²,

Rushing³

et al. 1964

J. Geophys. Res.

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“…By comparing the measured value with a known standard, a fractionation factor is obtained and applied to samples of unknown composition. This approach has been used by Crouch and Turnbull (18) and Shields et al (19) at the National Bureau of Standards (NBS). In this study, no correction factors were applied to the data.…”

Section: Resultsmentioning

confidence: 99%

“…Several investigators have alluded to spuriously high 107 beams during the isotopic analysis of Ag. Some workers (1,3,4,18) have attributed this to ZrO+, but this species was never identified by its spectral signature. The well-known difficulty with which Zr is ionized makes this assignment highly improbable.…”

Section: Discussionmentioning

confidence: 99%

Isotopic determination of silver in picomole quantities by surface ionization mass spectrometry

Kelly¹,

Tera²,

Wasserburg³

1978

Anal. Chem.

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“…Examining diverse silver samples, Crouch and Turnbull (138) obtain the ratio AgI07/Ag109 as 1.0733 ± 0.0043 and the atomic weight of silver as 107.8470 ± 0.0033 (chemical scale), 107.9037 ± 0.0026 (physical scale), and 107.8694 ± 0.0026 (unified scale). White, Sheffield, and Rourke (594) analyze the secondary ions formed by bombarding a copper target with (Cs133)+ ions to obtain an isotopic ratio of Cu63/Cu66 of 2.25 ± 0.02 which agrees with results of previous investigators.…”

Section: Precise Mass Measurement and Isotope Abundancementioning

confidence: 99%