Condensed Matter Isotope Effects

Hook, W. Alexander Van

doi:10.1002/chin.200642248

Cited by 4 publications

(9 citation statements)

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“…The direction of isotope fractionation is the result of an interplay between the effect of the restricted rotation and translation in the condensed phase (external mode) and the shift of internal vibrational frequencies upon condensation (internal mode). The former always leads to a normal isotope effect because the molecular motion becomes hindered, whereas the latter is usually associated with an inverse isotope effect because frequencies of internal vibration are lower due to the interaction between molecules in the condensed phase. , The observed trends for TCE indicate that in case of carbon changes in the internal mode dominate, whereas for chlorine changes in the external mode control isotope fractionation.…”

Section: Discussionmentioning

confidence: 99%

“…The former always leads to a normal isotope effect because the molecular motion becomes hindered, whereas the latter is usually associated with an inverse isotope effect because frequencies of internal vibration are lower due to the interaction between molecules in the condensed phase. 27,28 The observed trends for TCE indicate that in case of carbon changes in the internal mode dominate, whereas for chlorine changes in the external mode control isotope fractionation.…”

Section: ■ Discussionmentioning

confidence: 99%

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Chlorine and Carbon Isotopes Fractionation during Volatilization and Diffusive Transport of Trichloroethene in the Unsaturated Zone

Jeannottat

Hunkeler

2012

Environ. Sci. Technol.

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To apply compound-specific isotope methods to the evaluation of the origin and fate of organic contaminants in the unsaturated subsurface, the effect of physicochemical processes on isotope ratios needs to be known. The main objective of this study is to quantify chlorine and carbon isotope fractionation during NAPL-vapor equilibration, air-water partitioning, and diffusion of trichloroethene (TCE) and combinations of these effects during vaporization in porous media. Isotope fractionation is larger during NAPL-vapor equilibration than air-water partitioning. During NAPL-vapor equilibration, carbon, and chlorine isotope ratios evolve in opposite directions although both elements are present in the same bond, with a normal isotope effect for chlorine (ε(Cl) = -0.39 ± 0.03‰) and an inverse effect for carbon (ε(C) = +0.75 ± 0.04‰). During diffusion-controlled vaporization in a sand column, no significant carbon isotope fractionation is observed (ε(C) = +0.10 ± 0.05‰), whereas fairly strong chlorine isotope fractionation occurs (ε(Cl) = -1.39 ± 0.06‰) considering the molecular weight of TCE. In case of carbon, the inverse isotope fractionation associated with NAPL-vapor equilibration and normal diffusion isotope fractionation cancel, whereas for chlorine both processes are accompanied by normal isotope fractionation and hence they cumulate. A source of contamination that aged might thus show a shift toward heavier chlorine isotope ratios.

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Section: Discussionmentioning

confidence: 99%

Section: ■ Discussionmentioning

confidence: 99%

Chlorine and Carbon Isotopes Fractionation during Volatilization and Diffusive Transport of Trichloroethene in the Unsaturated Zone

Jeannottat

Hunkeler

2012

Environ. Sci. Technol.

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“…However, most H and especially N isotopic fractionation factors have been derived from theoretical calculations (Busigny and Bebout, 2013) but are not relevant to mineral-fluid-gas (i.e., hydrothermal) systems. Indeed, these studies are based on statistical mechanics models calculated for the ideal behavior of gases between species with zero intermolecular forces, and therefore fail to account for solubility, molar volume, and vapor pressure induced fractionations produced by intermolecular interactions with functional groups within the condensed phases (e.g., Richet et al, 1977;Chialvo and Horita, 2003;Van Hook, 2006). Because H and N isotopic fractionations are key tools for tracing gas or fluid exchanges via fluxing or degassing in a magmatic system, as well as the transport of other materials through the mantle or crust (e.g., melt-versus fluidinduced metasomatism via percolation or infiltration, serpentinizatio; e.g., Pineau et al, 1998;Hauri, 2002;Manning, 2004;Dalou et al, 2022), it is important to better constrain the effects of P-T, fO 2 , and fluid composition on H and N isotopic fractionations in aqueous fluids, and therefore their speciation in fluids.…”

Section: Introductionmentioning

confidence: 99%

Redox controls on H and N speciation and intermolecular isotopic fractionations in aqueous fluids at high pressure and high temperature: Insights from in-situ experiments

et al. 2022

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Aqueous magmatic fluids are essential to the transport of hydrogen (H), carbon (C), and nitrogen (N) from the mantle to the surface, during which changes in pressure, temperature, and redox conditions affect the chemical speciation and intermolecular isotopic fractionations of H, C, and N. Here, we performed a series of hydrothermal diamond-anvil cell experiments to evaluate the role of pressure, temperature, and redox conditions on the speciation and intermolecular fractionations of H and N during the decompression and cooling of aqueous fluids from 780 MPa to 800°C to 150 MPa and 200°C. We used Raman spectroscopy to investigate the distribution and exchange reactions of H and N isotopologues between water, methane, ammonia, and di-nitrogen molecules under changing physicochemical conditions. Our experiments show that upon decompression, a C- and N-bearing fluid will preferentially degas D-rich methane and 15N-rich N2, depleting the residual aqueous fluid in those isotopes. If this fluid precipitates N-rich (i.e., NH4+-bearing) minerals, the observed N isotopic fractionation is opposite to that during N2 degassing, enriching the aqueous fluid in 15N. Because these fractionations result from changes in H, C, and N speciation in the aqueous fluid, their magnitudes depend on redox conditions as well as pressure and temperature. Our new in-situ experimental results are consistent with the large H and N isotopic fractionations observed between water, methane, and ammonia species in aqueous fluids at high pressures and temperatures, although the magnitude of the fractionations in our experiments cannot be quantified. Nonetheless, our results suggest that statistical thermodynamic models likely underestimate isotopic fractionation effects for isotopic molecules under these conditions, and should account for solubility and isotopic effects of the solvent associated with the solvation of water, methane, and ammonia isotopologues in aqueous fluids.This work has significant implications for interpreting isotopic measurements of natural samples from hydrothermal systems because it offers insights into isotopic fractionations in multicomponent and multiphase systems under hydrothermal temperatures and pressures.

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“…For equilibrium conditions in a closed system (i.e. static conditions), an isotope fractionation is expected due to different vapor pressure properties for isotopically different molecules (and called isotopologues) (Van Hook, 2006;Wolfsberg et al, 2010). In contrast, for non-equilibrium conditions in an open system (i.e.…”

Section: Introductionmentioning

confidence: 99%

Stable carbon and hydrogen isotope fractionation of volatile organic compounds caused by vapor-liquid equilibrium

et al. 2022

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Condensed Matter Isotope Effects

Abstract: ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract, please click on HTML or PDF.

Cited by 4 publications

References 71 publications

Chlorine and Carbon Isotopes Fractionation during Volatilization and Diffusive Transport of Trichloroethene in the Unsaturated Zone

Chlorine and Carbon Isotopes Fractionation during Volatilization and Diffusive Transport of Trichloroethene in the Unsaturated Zone

Redox controls on H and N speciation and intermolecular isotopic fractionations in aqueous fluids at high pressure and high temperature: Insights from in-situ experiments

Stable carbon and hydrogen isotope fractionation of volatile organic compounds caused by vapor-liquid equilibrium

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