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Title: Experimental and theoretical determinations of hydrogen isotopic equilibrium in the system CH4—H2—H2O from 3 to 200°C

Abstract

The stable isotopic composition of methane (CH4) is commonly used to fingerprint natural gas origins. Over the past 50 years, there have been numerous proposals that both microbial and thermogenic CH4 can form in or later attain hydrogen isotopic equilibrium with water (H2O) and carbon isotopic equilibrium with carbon dioxide (CO2). Evaluation of such proposals requires knowledge of the equilibrium fractionation factors between CH4 and H2O or CO2 at the temperatures where microbial and thermogenic CH4 form in or are found in the environment, which is generally less than 200°C. Experimental determinations of these fractionation factors are only available above 200°C, requiring extrapolation of these results beyond the calibrated range or the use of theoretical calculations at lower temperatures. Here, we provide a calibration of the equilibrium hydrogen isotopic fractionation factor for CH4 and hydrogen gas (H2) (DαCH4(g)–H2(g)) based on experiments using γ-Al2O3 and Ni catalysts from 3 to 200°C. Results were regressed as a 2nd order polynomial of 1000 × lnDαCH4(g)–H2(g) vs. 1/T (K-1) yielding: 1000 × l n D α C H 4 ( g ) - H 2 ( g ) = 3.5317 × 10 7 T 2 + 2.7749 × 10 5 T - 179.48 We combine this calibration with previous experimental determinations of hydrogen isotope equilibrium between H2, H2O(g), and H2O(l) and we provide an interpolatable experimental calibration of 1000 × lnDαCH4(g)–H2O(l) from 3 to 200°C. Our resulting 4th order polynomial is the following equation: 1000 × l n D α C H 4 ( g ) - H 2 O l = - 7.9443 × 10 12 T 4 + 8.7772 × 10 10 T 3 - 3.4973 × 10 8 T 2 + 5.4398 × 10 5 T - 382.05 At 3°C, the value from our calibration differs by 93‰ relative to what would be calculated based on the extrapolation of the only experimental calibration currently available to temperatures below its calibrated range (lowest temperature of 200°C; Horibe and Craig, 1995). We additionally provide new theoretical estimates of hydrogen isotopic equilibrium between CH4(g), H2(g), and H2O(g) and carbon isotopic equilibrium between CH4(g) and CO2(g) using Path Integral Monte Carlo (PIMC) calculations. Our PIMC calculations for hydrogen isotopic equilibrium between CH4 and H2 agree 1:1 with our experiments. Finally, we compile carbon and hydrogen isotopic measurements of CH4, CO2, and H2O from various environmental systems and compare observed differences between carbon and hydrogen isotopes to those expected based on isotopic equilibrium. We find that isotopic compositions of some microbial gases from marine sedimentary, coalbed, and shale environments are consistent with those expected for CH4H2O(l) hydrogen and CH4CO2 carbon isotopic equilibrium. In contrast, microbial terrestrial and pure culture gases are not consistent with both CH4H2O(l) hydrogen and CH4CO2 carbon isotopic equilibrium. Overall, these results are explained qualitatively using previously developed conceptual models that link free energy gradients available to microorganisms to the degree that their enzymes can promote isotope-exchange reactions between CH4, CO2, and H2O.

Authors:
 [1]; ORCiD logo [2];  [3];  [4];  [4];  [2];  [3]
  1. Univ. of California, Berkeley, CA (United States)
  2. California Institute of Technology (CalTech), Pasadena, CA (United States)
  3. Univ. of California, Berkeley, CA (United States); Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)
  4. Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)
Publication Date:
Research Org.:
Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)
Sponsoring Org.:
USDOE Office of Science (SC), Basic Energy Sciences (BES). Chemical Sciences, Geosciences & Biosciences Division; USDOE Office of Science (SC), Basic Energy Sciences (BES)
OSTI Identifier:
1863786
Alternate Identifier(s):
OSTI ID: 1868683
Grant/Contract Number:  
AC02-05CH11231; CHE-1611581
Resource Type:
Accepted Manuscript
Journal Name:
Geochimica et Cosmochimica Acta
Additional Journal Information:
Journal Volume: 314; Journal ID: ISSN 0016-7037
Publisher:
Elsevier; The Geochemical Society; The Meteoritical Society
Country of Publication:
United States
Language:
English
Subject:
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY; 58 GEOSCIENCES; experimental calibration; methane isotopic equlibrium; methane geochemistry; Path Integral Monte Carlo calculations

Citation Formats

Turner, Andrew C., Korol, Roman, Eldridge, Daniel L., Bill, Markus, Conrad, Mark E., Miller, III, Thomas F., and Stolper, Daniel A. Experimental and theoretical determinations of hydrogen isotopic equilibrium in the system CH4—H2—H2O from 3 to 200°C. United States: N. p., 2021. Web. doi:10.1016/j.gca.2021.04.026.
Turner, Andrew C., Korol, Roman, Eldridge, Daniel L., Bill, Markus, Conrad, Mark E., Miller, III, Thomas F., & Stolper, Daniel A. Experimental and theoretical determinations of hydrogen isotopic equilibrium in the system CH4—H2—H2O from 3 to 200°C. United States. https://doi.org/10.1016/j.gca.2021.04.026
Turner, Andrew C., Korol, Roman, Eldridge, Daniel L., Bill, Markus, Conrad, Mark E., Miller, III, Thomas F., and Stolper, Daniel A. Wed . "Experimental and theoretical determinations of hydrogen isotopic equilibrium in the system CH4—H2—H2O from 3 to 200°C". United States. https://doi.org/10.1016/j.gca.2021.04.026. https://www.osti.gov/servlets/purl/1863786.
@article{osti_1863786,
title = {Experimental and theoretical determinations of hydrogen isotopic equilibrium in the system CH4—H2—H2O from 3 to 200°C},
author = {Turner, Andrew C. and Korol, Roman and Eldridge, Daniel L. and Bill, Markus and Conrad, Mark E. and Miller, III, Thomas F. and Stolper, Daniel A.},
abstractNote = {The stable isotopic composition of methane (CH4) is commonly used to fingerprint natural gas origins. Over the past 50 years, there have been numerous proposals that both microbial and thermogenic CH4 can form in or later attain hydrogen isotopic equilibrium with water (H2O) and carbon isotopic equilibrium with carbon dioxide (CO2). Evaluation of such proposals requires knowledge of the equilibrium fractionation factors between CH4 and H2O or CO2 at the temperatures where microbial and thermogenic CH4 form in or are found in the environment, which is generally less than 200°C. Experimental determinations of these fractionation factors are only available above 200°C, requiring extrapolation of these results beyond the calibrated range or the use of theoretical calculations at lower temperatures. Here, we provide a calibration of the equilibrium hydrogen isotopic fractionation factor for CH4 and hydrogen gas (H2) (DαCH4(g)–H2(g)) based on experiments using γ-Al2O3 and Ni catalysts from 3 to 200°C. Results were regressed as a 2nd order polynomial of 1000 × lnDαCH4(g)–H2(g) vs. 1/T (K-1) yielding:1000×lnDαCH4(g)-H2(g)=3.5317×107T2+2.7749×105T-179.48We combine this calibration with previous experimental determinations of hydrogen isotope equilibrium between H2, H2O(g), and H2O(l) and we provide an interpolatable experimental calibration of 1000 × lnDαCH4(g)–H2O(l) from 3 to 200°C. Our resulting 4th order polynomial is the following equation:1000×lnDαCH4(g)-H2Ol=-7.9443×1012T4+8.7772×1010T3-3.4973×108T2+5.4398×105T-382.05At 3°C, the value from our calibration differs by 93‰ relative to what would be calculated based on the extrapolation of the only experimental calibration currently available to temperatures below its calibrated range (lowest temperature of 200°C; Horibe and Craig, 1995). We additionally provide new theoretical estimates of hydrogen isotopic equilibrium between CH4(g), H2(g), and H2O(g) and carbon isotopic equilibrium between CH4(g) and CO2(g) using Path Integral Monte Carlo (PIMC) calculations. Our PIMC calculations for hydrogen isotopic equilibrium between CH4 and H2 agree 1:1 with our experiments. Finally, we compile carbon and hydrogen isotopic measurements of CH4, CO2, and H2O from various environmental systems and compare observed differences between carbon and hydrogen isotopes to those expected based on isotopic equilibrium. We find that isotopic compositions of some microbial gases from marine sedimentary, coalbed, and shale environments are consistent with those expected for CH4H2O(l) hydrogen and CH4CO2 carbon isotopic equilibrium. In contrast, microbial terrestrial and pure culture gases are not consistent with both CH4H2O(l) hydrogen and CH4CO2 carbon isotopic equilibrium. Overall, these results are explained qualitatively using previously developed conceptual models that link free energy gradients available to microorganisms to the degree that their enzymes can promote isotope-exchange reactions between CH4, CO2, and H2O.},
doi = {10.1016/j.gca.2021.04.026},
journal = {Geochimica et Cosmochimica Acta},
number = ,
volume = 314,
place = {United States},
year = {Wed Dec 01 00:00:00 EST 2021},
month = {Wed Dec 01 00:00:00 EST 2021}
}

Works referenced in this record:

The nuclear mass dependence of the adiabatic correction to the Born–Oppenheimer approximation
journal, June 1975

  • Bardo, Richard D.; Wolfsberg, Max
  • The Journal of Chemical Physics, Vol. 62, Issue 11
  • DOI: 10.1063/1.430363

The adiabatic correction for nonlinear triatomic molecules: Techniques and calculations
journal, January 1978

  • Bardo, Richard D.; Wolfsberg, Max
  • The Journal of Chemical Physics, Vol. 68, Issue 6
  • DOI: 10.1063/1.436104

Mathematical modeling of stable carbon isotope ratios in natural gases
journal, August 2000


Origin of gaseous hydrocarbons in subsurface environments: Theoretical considerations of carbon isotope distribution
journal, December 1988


An accurate ab initio quartic force field and vibrational frequencies for CH 4 and isotopomers
journal, January 1995

  • Lee, Timothy J.; Martin, Jan M. L.; Taylor, Peter R.
  • The Journal of Chemical Physics, Vol. 102, Issue 1
  • DOI: 10.1063/1.469398

Solubility isotope effects in aqueous solutions of methane
journal, June 2002

  • Bacsik, Z.; Lopes, J. N. Canongia; Gomes, M. F. Costa
  • The Journal of Chemical Physics, Vol. 116, Issue 24
  • DOI: 10.1063/1.1480012

Chemical and isotopic equilibrium between CO2 and CH4 in fumarolic gas discharges: Generation of CH4 in arc magmatic-hydrothermal systems
journal, May 2004

  • Fiebig, Jens; Chiodini, Giovanni; Caliro, Stefano
  • Geochimica et Cosmochimica Acta, Vol. 68, Issue 10
  • DOI: 10.1016/j.gca.2003.10.035

Calculation of Equilibrium Constants for Isotopic Exchange Reactions
journal, May 1947

  • Bigeleisen, Jacob; Mayer, Maria Goeppert
  • The Journal of Chemical Physics, Vol. 15, Issue 5
  • DOI: 10.1063/1.1746492

Accurate Adiabatic Treatment of the Ground State of the Hydrogen Molecule
journal, December 1964

  • Kol/os, W.; Wolniewicz, L.
  • The Journal of Chemical Physics, Vol. 41, Issue 12
  • DOI: 10.1063/1.1725796

The global influence of the hydrogen isotope composition of water on that of bacteriogenic methane from shallow freshwater environments
journal, August 1999


Diverse origins of Arctic and Subarctic methane point source emissions identified with multiply-substituted isotopologues
journal, September 2016


Inter-laboratory calibration of natural gas round robins for δ2H and δ13C using off-line and on-line techniques
journal, June 2012


The geochemistry of the stable carbon isotopes
journal, February 1953


Origin of dolomite in Miocene Monterey Shale and related formations in the Temblor Range, California
journal, August 1979


γ-Alumina: The Essential and Unexpected Role of Water for the Structure, Stability, and Reactivity of “Defect” Sites
journal, August 2012

  • Wischert, Raphael; Laurent, Pierre; Copéret, Christophe
  • Journal of the American Chemical Society, Vol. 134, Issue 35
  • DOI: 10.1021/ja3042383

Efficient molecular dynamics and hybrid Monte Carlo algorithms for path integrals
journal, August 1993

  • Tuckerman, Mark E.; Berne, Bruce J.; Martyna, Glenn J.
  • The Journal of Chemical Physics, Vol. 99, Issue 4
  • DOI: 10.1063/1.465188

The Molpro quantum chemistry package
journal, April 2020

  • Werner, Hans-Joachim; Knowles, Peter J.; Manby, Frederick R.
  • The Journal of Chemical Physics, Vol. 152, Issue 14
  • DOI: 10.1063/5.0005081

Liquid-vapor fractionation of oxygen and hydrogen isotopes of water from the freezing to the critical temperature
journal, August 1994


The Activation of Specific Bonds in Complex Molecules at Catalytic Surfaces. I. The Carbon—Hydrogen Bond in Methane and Methane-d 4
journal, August 1936

  • Morikawa, Kiyoshi; Benedict, W. S.; Taylor, Hugh S.
  • Journal of the American Chemical Society, Vol. 58, Issue 8
  • DOI: 10.1021/ja01299a040

Exchange catalysis during anaerobic methanotrophy revealed by 12CH2D2 and 13CH3D in methane
journal, April 2019


Natural gas seepage in the Gulf of Mexico
journal, June 1976


Hydrogen/Deuterium (H/D) Exchange Catalysis in Alkanes
journal, January 2018


Biogenic methane formation in marine and freshwater environments: CO2 reduction vs. acetate fermentation—Isotope evidence
journal, May 1986


Monodeuterated Methane, an Isotopic Tool To Assess Biological Methane Metabolism Rates
journal, August 2017


Isotopic evidence for quasi-equilibrium chemistry in thermally mature natural gases
journal, February 2020

  • Thiagarajan, Nivedita; Xie, Hao; Ponton, Camilo
  • Proceedings of the National Academy of Sciences, Vol. 117, Issue 8
  • DOI: 10.1073/pnas.1906507117

Clumped-isotope signatures at equilibrium of CH4, NH3, H2O, H2S and SO2
journal, February 2016


Variation of carbon isotope fractionation in hydrogenotrophic methanogenic microbial cultures and environmental samples at different energy status
journal, November 2005


The diagonal Born–Oppenheimer correction beyond the Hartree–Fock approximation
journal, March 2003

  • Valeev, Edward F.; Sherrill, C. David
  • The Journal of Chemical Physics, Vol. 118, Issue 9
  • DOI: 10.1063/1.1540626

Carbon and hydrogen isotope systematics of bacterial formation and oxidation of methane
journal, September 1999


Hydrogen isotope equilibriums in the system hydrogen-water
journal, November 1968


Hydrogen isotope systematics among H 2 –H 2 O–CH 4 during the growth of the hydrogenotrophic methanogen Methanothermobacter thermautotrophicus strain ΔH
journal, October 2014

  • Kawagucci, Shinsuke; Kobayashi, Mariko; Hattori, Shohei
  • Geochimica et Cosmochimica Acta, Vol. 142
  • DOI: 10.1016/j.gca.2014.07.020

Trace methane oxidation studied in several Euryarchaeota under diverse conditions
journal, January 2005

  • Moran, James J.; House, Christopher H.; Freeman, Katherine H.
  • Archaea, Vol. 1, Issue 5
  • DOI: 10.1155/2005/650670

Isotopic fractionation between gaseous and dissolved carbon dioxide
journal, June 1970

  • Vogel, J. C.; Grootes, P. M.; Mook, W. G.
  • Zeitschrift für Physik A Hadrons and nuclei, Vol. 230, Issue 3
  • DOI: 10.1007/BF01394688

Comparison of Experimental vs Theoretical Abundances of 13 CH 3 D and 12 CH 2 D 2 for Isotopically Equilibrated Systems from 1 to 500 °C
journal, October 2019


Cell proliferation at 122 C and isotopically heavy CH4 production by a hyperthermophilic methanogen under high-pressure cultivation
journal, July 2008

  • Takai, K.; Nakamura, K.; Toki, T.
  • Proceedings of the National Academy of Sciences, Vol. 105, Issue 31
  • DOI: 10.1073/pnas.0712334105

Fractionnement en oxygène 18 et en deutérium entre l’eau et sa vapeur
journal, January 1971


Direct path integral estimators for isotope fractionation ratios
journal, December 2014

  • Cheng, Bingqing; Ceriotti, Michele
  • The Journal of Chemical Physics, Vol. 141, Issue 24
  • DOI: 10.1063/1.4904293

Convenient and accurate discretized path integral methods for equilibrium quantum mechanical calculations
journal, August 1981

  • Schweizer, Kenneth S.; Stratt, Richard M.; Chandler, David
  • The Journal of Chemical Physics, Vol. 75, Issue 3
  • DOI: 10.1063/1.442141

Combined 13C–D and D–D clumping in methane: Methods and preliminary results
journal, February 2014


fractionation in the system methane-hydrogen-water
journal, December 1995


Fundamental studies on kinetic isotope effect (KIE) of hydrogen isotope fractionation in natural gas systems
journal, May 2011

  • Ni, Yunyan; Ma, Qisheng; Ellis, Geoffrey S.
  • Geochimica et Cosmochimica Acta, Vol. 75, Issue 10
  • DOI: 10.1016/j.gca.2011.02.016

Studies of the Hydrogen Held by Solids. VII. The Exchange of the Hydroxyl Groups of Alumina and Silica-Alumina Catalysts with Deuterated Methane
journal, September 1965

  • Larson, John G.; Hall, W. Keith
  • The Journal of Physical Chemistry, Vol. 69, Issue 9
  • DOI: 10.1021/j100893a044

Carbon isotope exchange in the system CO2-CH4 at elevated temperatures
journal, June 2001


Carbon and sulfur back flux during anaerobic microbial oxidation of methane and coupled sulfate reduction
journal, December 2011

  • Holler, T.; Wegener, G.; Niemann, H.
  • Proceedings of the National Academy of Sciences, Vol. 108, Issue 52
  • DOI: 10.1073/pnas.1106032108

Equilibrium Fractionation of Non-traditional Isotopes: a Molecular Modeling Perspective
journal, January 2017

  • Blanchard, Marc; Balan, Etienne; Schauble, Edwin A.
  • Reviews in Mineralogy and Geochemistry, Vol. 82, Issue 1
  • DOI: 10.2138/rmg.2017.82.2

Method for calibrating methane clumped isotope measurements via catalytic equilibration of methane isotopologues on γ‐alumina
journal, March 2020

  • Wang, David T.; Sattler, Aaron; Paccagnini, Michele
  • Rapid Communications in Mass Spectrometry, Vol. 34, Issue 10
  • DOI: 10.1002/rcm.8555

The Carbon-Isotope Record of the Sub-Seafloor Biosphere
journal, December 2019


Determination of Henry's law constants for aqueous solutions of tetradeuteriomethane between 285 and 325 K and calculation of the H/D isotope effect
journal, January 2001

  • Costa Gomes, Margarida F.; Grolier, Jean-Pierre
  • Physical Chemistry Chemical Physics, Vol. 3, Issue 6
  • DOI: 10.1039/b008755f

The hydrogen and carbon isotopic composition of methane from natural gases of various origins
journal, May 1980


Molpro: a general-purpose quantum chemistry program package: Molpro
journal, July 2011

  • Werner, Hans-Joachim; Knowles, Peter J.; Knizia, Gerald
  • Wiley Interdisciplinary Reviews: Computational Molecular Science, Vol. 2, Issue 2
  • DOI: 10.1002/wcms.82

The thermodynamic properties of isotopic substances
journal, January 1947


Distinguishing and understanding thermogenic and biogenic sources of methane using multiply substituted isotopologues
journal, July 2015


Carbon isotope equilibration during sulphate-limited anaerobic oxidation of methane
journal, January 2014

  • Yoshinaga, Marcos Y.; Holler, Thomas; Goldhammer, Tobias
  • Nature Geoscience, Vol. 7, Issue 3
  • DOI: 10.1038/ngeo2069

Gaussian basis sets for use in correlated molecular calculations. I. The atoms boron through neon and hydrogen
journal, January 1989

  • Dunning, Thom H.
  • The Journal of Chemical Physics, Vol. 90, Issue 2
  • DOI: 10.1063/1.456153

The theory of equilibrium isotope fractionations for gaseous molecules under super-cold conditions
journal, October 2018


An isotopic-independent highly accurate potential energy surface for CO 2 isotopologues and an initial 12 C 16 O 2 infrared line list
journal, March 2012

  • Schwenke, David W.; Tashkun, Sergey A.; Lee, Timothy J.
  • The Journal of Chemical Physics, Vol. 136, Issue 12
  • DOI: 10.1063/1.3697540

Deuterium fractionation between aqueous salt solutions and water vapor
journal, September 1975

  • Stewart, Michael K.; Friedman, Irving
  • Journal of Geophysical Research, Vol. 80, Issue 27
  • DOI: 10.1029/JC080i027p03812

Low temperature volatile production at the Lost City Hydrothermal Field, evidence from a hydrogen stable isotope geothermometer
journal, May 2006


Equilibrium clumped-isotope effects in doubly substituted isotopologues of ethane
journal, January 2017

  • Webb, Michael A.; Wang, Yimin; Braams, Bastiaan J.
  • Geochimica et Cosmochimica Acta, Vol. 197
  • DOI: 10.1016/j.gca.2016.10.001

Position-Specific and Clumped Stable Isotope Studies: Comparison of the Urey and Path-Integral Approaches for Carbon Dioxide, Nitrous Oxide, Methane, and Propane
journal, January 2014

  • Webb, Michael A.; Miller, Thomas F.
  • The Journal of Physical Chemistry A, Vol. 118, Issue 2
  • DOI: 10.1021/jp411134v

Carbon isotope fractionation during bacterial methanogenesis by CO2 reduction
journal, December 1996


Das Gleichgewicht H 2 + H D O ⇌ H D + H 2 O und die weiteren Austauschgleichgewichte im System H 2 , D 2 und H 2 O
journal, May 1949


The X1 Σ + g state vibration‐rotational energies of the H 2 , HD, and D 2 molecules
journal, May 1983

  • Wolniewicz, L.
  • The Journal of Chemical Physics, Vol. 78, Issue 10
  • DOI: 10.1063/1.444580

Reverse Methanogenesis: Testing the Hypothesis with Environmental Genomics
journal, September 2004


Clumped isotopologue fractionation by microbial cultures performing the anaerobic oxidation of methane
journal, January 2021


Abiotic Methane on Earth: Abiotic Methane on Earth
journal, April 2013

  • Etiope, Giuseppe; Sherwood Lollar, Barbara
  • Reviews of Geophysics, Vol. 51, Issue 2
  • DOI: 10.1002/rog.20011

Theoretical estimates of equilibrium carbon and hydrogen isotope effects in microbial methane production and anaerobic oxidation of methane
journal, February 2021


Thermal reactions of acetic acid: 13C/12C partitioning between CO2 and CH4
journal, January 1998


Sources of error in electronic structure calculations on small chemical systems
journal, February 2006

  • Feller, David; Peterson, Kirk A.; Crawford, T. Daniel
  • The Journal of Chemical Physics, Vol. 124, Issue 5
  • DOI: 10.1063/1.2137323

Methane sources and sinks in continental sedimentary systems: New insights from paired clumped isotopologues 13CH3D and 12CH2D2
journal, January 2019


A Review of Hydrogen, Carbon, Nitrogen, Oxygen, Sulphur, and Chlorine Stable Isotope Fractionation Among Gaseous Molecules
journal, May 1977


Formation temperatures of thermogenic and biogenic methane
journal, June 2014


A theoretical calculation of the equilibrium constant for the isotopic exchange reaction between water and hydrogen deuteride
journal, May 1976

  • Bardo, Richard D.; Wolfsberg, Max
  • The Journal of Physical Chemistry, Vol. 80, Issue 10
  • DOI: 10.1021/j100551a009

The deuterium isotope separation factor between hydrogen and liquid water
journal, May 1976

  • Rolston, J. H.; Den Hartog, J.; Butler, J. P.
  • The Journal of Physical Chemistry, Vol. 80, Issue 10
  • DOI: 10.1021/j100551a008

Isotopic and quantitative analysis of the major carbon fractions in natural water samples
journal, January 1976

  • Games, Larry M.; Hayes, J. M.
  • Analytical Chemistry, Vol. 48, Issue 1
  • DOI: 10.1021/ac60365a055

Thermodynamics of hydrogen-isotope-exchange reactions. 3. An experimental test of the Born-Oppenheimer approximation
journal, March 1988

  • Postma, James M.; Silvester, Leonard F.; Rock, Peter A.
  • The Journal of Physical Chemistry, Vol. 92, Issue 5
  • DOI: 10.1021/j100316a058

Nonequilibrium clumped isotope signals in microbial methane
journal, March 2015


Der thermodynamische Kohlenstoffisotopieeffekt im System CH 4 –H 2 O
journal, January 1976

  • Harting, P.; Schütze, H.; Christoph, G.
  • Isotopenpraxis Isotopes in Environmental and Health Studies, Vol. 12, Issue 6
  • DOI: 10.1080/10256017608543923

Carbon and hydrogen isotopic reversals in deep basin gas: Evidence for limits to the stability of hydrocarbons
journal, December 2010


Experimental determination of equilibrium CH4–CO2–CO carbon isotope fractionation factors (300–1200 °C)
journal, January 2019


Carbon and hydrogen isotope fractionation by moderately thermophilic methanogens 1 1Associate editor: N. E. Ostrom
journal, April 2004

  • Valentine, David L.; Chidthaisong, Amnat; Rice, Andrew
  • Geochimica et Cosmochimica Acta, Vol. 68, Issue 7
  • DOI: 10.1016/j.gca.2003.10.012

Gaussian basis sets for use in correlated molecular calculations. V. Core‐valence basis sets for boron through neon
journal, September 1995

  • Woon, David E.; Dunning, Thom H.
  • The Journal of Chemical Physics, Vol. 103, Issue 11
  • DOI: 10.1063/1.470645

Large carbon isotope variability during methanogenesis under alkaline conditions
journal, September 2018

  • Miller, Hannah M.; Chaudhry, Nabil; Conrad, Mark E.
  • Geochimica et Cosmochimica Acta, Vol. 237
  • DOI: 10.1016/j.gca.2018.06.007

An interlaboratory study to test instrument performance of hydrogen dual-inlet isotope-ratio mass spectrometers
journal, June 2001

  • Brand, W. A.; Coplen, T. B.
  • Fresenius' Journal of Analytical Chemistry, Vol. 370, Issue 4
  • DOI: 10.1007/s002160100814

The relative abundances of resolved l2CH2D2 and 13CH3D and mechanisms controlling isotopic bond ordering in abiotic and biotic methane gases
journal, April 2017


The utility of methane clumped isotopes to constrain the origins of methane in natural gas accumulations
journal, December 2017

  • Stolper, Daniel A.; Lawson, Michael; Formolo, Michael J.
  • Geological Society, London, Special Publications, Vol. 468, Issue 1
  • DOI: 10.1144/SP468.3

Accurate correlation consistent basis sets for molecular core–valence correlation effects: The second row atoms Al–Ar, and the first row atoms B–Ne revisited
journal, December 2002

  • Peterson, Kirk A.; Dunning, Thom H.
  • The Journal of Chemical Physics, Vol. 117, Issue 23
  • DOI: 10.1063/1.1520138

Analytic calculation of the diagonal Born-Oppenheimer correction within configuration-interaction and coupled-cluster theory
journal, October 2006

  • Gauss, Jürgen; Tajti, Attila; Kállay, Mihály
  • The Journal of Chemical Physics, Vol. 125, Issue 14
  • DOI: 10.1063/1.2356465

The stable isotope geochemistry of Australian coals
journal, December 1981


Methane clumped isotopes: Progress and potential for a new isotopic tracer
journal, November 2017


A kinetic model for isotopologue signatures of methane generated by biotic and abiotic CO2 methanation
journal, March 2019


Isotopic Partition Function Ratios Involving H 2 , H 2 O, H 2 S, H 2 Se, and NH 3
journal, February 1973

  • Bron, J.; Chang, Chen Fee; Wolfsberg, M.
  • Zeitschrift für Naturforschung A, Vol. 28, Issue 2
  • DOI: 10.1515/zna-1973-0203

Deviations from Born-Oppenheimer mass scaling in spectroscopy and ultracold molecular physics
journal, December 2016


The determination of an accurate isotope dependent potential energy surface for water from extensive ab initio calculations and experimental data
journal, March 1997

  • Partridge, Harry; Schwenke, David W.
  • The Journal of Chemical Physics, Vol. 106, Issue 11
  • DOI: 10.1063/1.473987

Clumped isotopologue constraints on the origin of methane at seafloor hot springs
journal, February 2018

  • Wang, David T.; Reeves, Eoghan P.; McDermott, Jill M.
  • Geochimica et Cosmochimica Acta, Vol. 223
  • DOI: 10.1016/j.gca.2017.11.030

Corrections to the Born‐Oppenheimer approximation and electronic effects on isotopic exchange equilibria
journal, August 1973

  • Kleinman, Lawrence I.; Wolfsberg, Max
  • The Journal of Chemical Physics, Vol. 59, Issue 4
  • DOI: 10.1063/1.1680290