Results 111 to 120 of about 2,447 (151)

Energy levels in chromium isotopes

Nuclear Physics, 1960
Abstract A magnetic spectrograph with photographic detection is used to study the proton groups emitted from the deuteron interaction with a thin chromium target. Applying deuterons of energy 8.67 MeV, nine well-defined proton groups attributed to the isotope 52 of chromium yiels Q-values of 5.73, 5.16, 4.72, 3.41, 3.04, 2.11, 1.60, 1.50 and 1.09 MeV
F.A. El Bedewi, S. Tadros
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Self-supporting isotopic chromium thin films

Journal of Radioanalytical and Nuclear Chemistry, 2013
Chromium is a shiny, hard and malleable metal, which can be cold rolled in good quality to a thickness below a micrometer. Thinner foils can be obtained by electron-beam gun evaporation or by electroplating. Isotopically enriched material typically has not the quality for cold rolling processes.
Birgit Kindler, Andreas Beusch, Willi Hartmann, Annett Hübner, Bettina Lommel, Jutta Steiner, Vera Yakusheva   +6 more
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Isotope effect in chromium self-diffusion

Physical Review B, 1976
The diffusion of $^{51}\mathrm{Cr}$ in chromium has been measured between 1100 and 1820\ifmmode^\circ\else\textdegree\fi{}C, and the data fit the Arrhenius relation $D=970\mathrm{exp}(\ensuremath{-}\frac{104000}{RT})$ ${\mathrm{cm}}^{2}$${\mathrm{sec}}^{\ensuremath{-}1}$.
J. N. Mundy, C. W. Tse, W. D. McFall
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Chromium isotope heterogeneity in the mantle

Earth and Planetary Science Letters, 2017
Abstract To better constrain the Cr isotopic composition of the silicate Earth and to investigate potential Cr isotopic fractionation during high temperature geological processes, we analyzed the Cr isotopic composition of different types of mantle xenoliths from diverse geologic settings: fertile to refractory off-craton spinel and garnet ...
Xia, Jiuxing, Qin, Liping, Shen, Ji, Carlson, Richard W., Ionov, Dmitri, Mock, Timothy D.   +5 more
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The chromium isotope fractionation factor in seawater

Chemical Geology, 2021
Abstract The chromium (Cr) stable isotope system is an increasingly used redox proxy for studying the oxygenation history of Earth's ocean-atmosphere system, but understanding of Cr isotope fractionation in modern seawater is still nascent. A linear relationship has been found between the isotope composition and the logarithmic concentration of total
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Chromium, chromium isotopes and selected trace elements, western Mojave Desert, USA

Applied Geochemistry, 2008
Abstract Chromium(VI) concentrations in excess of the California Maximum Contaminant Level (MCL) of 50 μg/L occur naturally in alkaline, oxic ground-water in alluvial aquifers in the western Mojave Desert, southern California. The highest concentrations were measured in aquifers eroded from mafic rock, but Cr(VI) as high as 27 μg/L was measured in ...
John A. Izbicki, James W. Ball, Thomas D. Bullen, Stephen J. Sutley   +3 more
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Microbial mass-dependent fractionation of chromium isotopes

Geochimica et Cosmochimica Acta, 2008
Abstract Mass-dependent fractionation of Cr isotopes occurs during dissimilatory Cr(VI) reduction by Shewanella oneidensis strain MR-1. Cells suspended in a simple buffer solution, with various concentrations of lactate or formate added as electron donor, reduced 5 or 10 μM Cr(VI) to Cr(III) over days to weeks.
Eric R. Sikora, Thomas M. Johnson, Thomas D. Bullen   +2 more
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Theoretical estimates of equilibrium chromium-isotope fractionations

Chemical Geology, 2004
Equilibrium chlorine-isotope (^(37)Cl/^(35)Cl) fractionations have been determined by using published vibrational spectra and force-field modeling to calculate reduced partition function ratios for Cl-isotope exchange. Ab initio force fields calculated at the HF/6-31G(d) level are used to estimate unknown vibrational frequencies of ^(37)Cl-bearing ...
Schauble, Edwin, Rossman, George R., Taylor, Hugh P., Jr.   +2 more
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Nickel and chromium isotopes in Allende inclusions

Earth and Planetary Science Letters, 1988
High-precision nickel and chromium isotopic measurements were carried out on nine Allende inclusions. It is found that Ni-62, Ni-64, excesses are present in at least three of the samples. The results suggest that the most likely mechanism for the anomalies is a neutron-rich statistical equilibrium process.
J.L. Birck, G.W. Lugmair
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Contributors to chromium isotope variation of meteorites

Geochimica et Cosmochimica Acta, 2010
We report the results of a comprehensive, high precision survey of the Cr isotopic compositions of primitive chondrites, along with some differentiated meteorites. To ensure complete dissolution of our samples, they were first fused with lithium borate–tetraborate at 1050–1000 °C.
Liping Qin, Conel M.O’D. Alexander, Richard W. Carlson, Mary F. Horan, Tetsuya Yokoyama   +4 more
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