Non-canonical mass laws in equilibrium isotopic fractionations: Evidence from the vapor pressure isotope effect of SF6

Eiler, John M.; Cartigny, Pierre; Hofmann, Amy E.; Piasecki, Alison

doi:10.1016/j.gca.2012.12.048

Cited by 22 publications

(12 citation statements)

References 47 publications

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“…experimental study (16) has documented anomalous mass laws associated with low-temperature condensation and evaporation of SF 6 . The authors (16) attributed this effect to a competition between low-frequency vibrational modes associated with weak chemical interactions between SF 6 clusters in the condensed phase and high-frequency modes associated with the stronger S−F bonds in the clusters themselves and in the free gas-phase SF 6 .…”

Section: Resultsmentioning

confidence: 99%

“…The authors (16) attributed this effect to a competition between low-frequency vibrational modes associated with weak chemical interactions between SF 6 clusters in the condensed phase and high-frequency modes associated with the stronger S−F bonds in the clusters themselves and in the free gas-phase SF 6 . They diagramed the principle of this competition between effects that enrich the heavy isotope with a shallow slope (e.g., 0.505) and effects that enrich the light isotope with a steeper slope (e.g., 0.515).…”

Section: Resultsmentioning

confidence: 99%

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Early inner solar system origin for anomalous sulfur isotopes in differentiated protoplanets

Antonelli

Kim

Peters

et al. 2014

Proc. Natl. Acad. Sci. U.S.A.

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Achondrite meteorites have anomalous enrichments in 33 S, relative to chondrites, which have been attributed to photochemistry in the solar nebula. However, the putative photochemical reactions remain elusive, and predicted accompanying 33 S depletions have not previously been found, which could indicate an erroneous assumption regarding the origins of the 33 S anomalies, or of the bulk solar system S-isotope composition. Here, we report wellresolved anomalous 33 S depletions in IIIF iron meteorites (<−0.02 per mil), and 33 S enrichments in other magmatic iron meteorite groups. The 33 S depletions support the idea that differentiated planetesimals inherited sulfur that was photochemically derived from gases in the early inner solar system (<∼2 AU), and that bulk inner solar system S-isotope composition was chondritic (consistent with IAB iron meteorites, Earth, Moon, and Mars). The range of mass-independent sulfur isotope compositions may reflect spatial or temporal changes influenced by photochemical processes. A tentative correlation between S isotopes and Hf-W core segregation ages suggests that the two systems may be influenced by common factors, such as nebular location and volatile content.iron meteorites | sulfur isotopes | protoplanetary disk | solar system | photochemistry O f all of the extraterrestrial materials found on Earth, iron meteorites have always been the most conspicuous. Socalled "magmatic" iron meteorites are likely to be samples from the cores of magmatically differentiated protoplanetary parent bodies (1), whereas "nonmagmatic" iron meteorites are commonly suggested to sample solidified melt pockets that formed via impacts onto nondifferentiated (chondritic) parent bodies (2). Individual members from an iron meteorite group are assumed to derive from a common parent body, based on shared chemical and isotopic characteristics (1-4). Chemical and isotopic differences among the different iron groups provide convincing evidence that different individual parent body planetesimals incorporated genetically distinct precursor materials (1-4).Recent observations that several achondrite meteorite groups possess small, mass-independent 33 S enrichments relative to chondrites (5) have led to the conclusion that sulfur isotopes were heterogeneously distributed among the materials that accreted to form early solar system planetesimals. This observation, coupled with the ancient 182 Hf-182 W ages (within 1-3 My of solar system formation) of magmatic irons (6-8), provides impetus to search for systematic variations in mass-independent sulfur isotope compositions among the iron groups. ResultsWe report high-precision δ 34 S, Δ 33 S, and Δ 36 S data (where Δ 33 S = 1000 × {δ 33 S -[(δ 34 S + 1) 0.515 − 1]} and Δ 36 S = 1000 × {δ 36 S -[(δ 34 S + 1) 1.9 − 1]}) for 61 troilite (FeS) nodules extracted from 58 different iron meteorites selected from eight different groups (IAB, IC, IIAB, IIE, IIIAB, IIIF, IVA, and IVB) (Fig. 1, Fig. S1, and Tables S1 and S2). All groups except for IAB and IIE have been classi...

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Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Early inner solar system origin for anomalous sulfur isotopes in differentiated protoplanets

Antonelli

Kim

Peters

et al. 2014

Proc. Natl. Acad. Sci. U.S.A.

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“…• θ values for CO 2 (g)-water, quartz-water, and calcite-water oxygen isotope exchange reactions at temperatures from 0 • C to 100 • C (Cao & Liu 2011) • θ = 0.529 ± 0.001 for water liquid-vapor equilibrium at temperatures from 11.4 • C to 41.5 • C • R, ratio of liquid-vapor isotope fractionation factors (Chialvo & Horita 2009) • λ 33/34 = 0.551 ± 0.010 for SF 6 ice-vapor equilibrium at 155 K (Eiler et al 2013) • Equilibrium β (Young et al 2002) • θ = 0.522X for CO 2 -water equilibrium (Barkan & Luz 2012 • β = 0.5240 ± 0.0011 at 685 • C for CO 2 (g)-CeO 2 oxygen exchange (Hofmann & Pack 2010) • θ KIE [triple oxygen isotope exponent for kinetic isotope effect (KIE)]:…”

Section: Triple Isotope Systemmentioning

confidence: 99%

Triple Oxygen Isotopes: Fundamental Relationships and Applications

Bao

Cao

Hayles

2016

Annu. Rev. Earth Planet. Sci.

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The element oxygen has three stable isotopes: 16 O, 17 O, and 18 O. For a defined process, a change in 18 O/ 16 O scales with the corresponding change in 17 O/ 16 O, or the fractionation factors 18 α and 17 α have a relationship of θ = ln 17 α/ln 18 α, in which the triple oxygen isotope exponent θ is relatively fixed but does vary with reaction path, temperature, and species involved. When the small variation is of interest, the distinction of three concepts-θ, S (a slope through data points in δ 17 O-δ 18 O space), and C (an arbitrary referencing number for the degree of 17 O deviation)-becomes important. Triple oxygen isotope variations can be measured by modern instruments and thus offer an additional line of information on the underlying reaction processes and conditions. Analytical methods and Earth science applications have recently been developed for air oxygen, carbon dioxide,

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“…Assume also that the two diatomic molecules contain the same two elements, but their isotopic composition can be different. Examples might include 12…”

Section: Analysis Of a Model Intermolecular Potentialmentioning

confidence: 99%

“…For example, vapor-liquid and vapor-solid equilibrium systems have been found in which inverse fractionation occurs, that is, the vapor phase is the one enriched in heavier stable isotopes. [5][6][7][8][9][10][11][12][13][14] Also, extraction of metals such as cadmium, barium, zinc, and strontium using crown ethers shows a nuclear mass effect where fractionation patterns depend on whether the nuclear mass number is even or odd. [15][16][17][18][19] Chemical reactions do not always follow the classical theory either.…”

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confidence: 99%

An isotopic mass effect on the intermolecular potential

Herman

Currier

Clegg

2015

Chemical Physics Letters

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The impact of isotopic variation on the electronic energy and intermolecular potentials is often suppressed when calculating isotopologue thermodynamics. Intramolecular potential energy surfaces for distinct isotopologues are in fact equivalent under the Born-Oppenheimer approximation, which is sometimes used to imply that the intermolecular interactions are independent of isotopic mass. In this communication, the intermolecular dipole-dipole interaction between hetero-nuclear diatomic molecules is considered. It is shown that the intermolecular potential contains mass-dependent terms even though each nucleus moves on a Born-Oppenheimer surface. The analysis suggests that mass dependent variations in intermolecular potentials should be included in comprehensive descriptions of isotopologue thermodynamics.

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Non-canonical mass laws in equilibrium isotopic fractionations: Evidence from the vapor pressure isotope effect of SF6

Cited by 22 publications

References 47 publications

Early inner solar system origin for anomalous sulfur isotopes in differentiated protoplanets

Early inner solar system origin for anomalous sulfur isotopes in differentiated protoplanets

Triple Oxygen Isotopes: Fundamental Relationships and Applications

An isotopic mass effect on the intermolecular potential

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