1. Methane cycling. Nonequilibrium clumped isotope signals in microbial methane.

    Science 348(6233):428 (2015) PMID 25745067

    Methane is a key component in the global carbon cycle, with a wide range of anthropogenic and natural sources. Although isotopic compositions of methane have traditionally aided source identification, the abundance of its multiply substituted "clumped" isotopologues (for example, (13)CH3D) has r...
  2. Millimeter-wave optical double resonance schemes for rapid assignment of perturbed spectra, with applications to the C̃ (1)B(2) state of SO2.

    Journal of Chemical Physics 142(14):144201 (2015) PMID 25877571

    Millimeter-wave detected, millimeter-wave optical double resonance (mmODR) spectroscopy is a powerful tool for the analysis of dense, complicated regions in the optical spectra of small molecules. The availability of cavity-free microwave and millimeter wave spectrometers with frequency-agile ge...
  3. Decline in oceanic sulfate levels during the early Mesoproterozoic

    Precambrian Research 258:36 (2015)

    • Multiple sulfur isotopes were analyzed for early Mesoproterozoic CAS and pyrite. • Paired CAS and pyrite δ34S suggest low sulfur isotope fractionation (<10‰). ...
  4. Predictive isotope model connects microbes in culture and nature.

    PNAS 111(51):18102 (2014) PMID 25480549

  5. Predictive isotope model connects microbes in culture and nature.

    PNAS 111(51):18102 (2014) PMID 25480549 PMCID PMC4280631

  6. Predictive isotope model connects microbes in culture and nature.

    PNAS 111(51):18102 (2014) PMID 25480549 PMCID PMC4280631

  7. Predictive isotope model connects microbes in culture and nature.

    PNAS 111(51):18102 (2014) PMID 25480549 PMCID PMC4280631

  8. Measurement of a doubly substituted methane isotopologue, ¹³CH₃D, by tunable infrared laser direct absorption spectroscopy.

    Analytical chemistry 86(13):6487 (2014) PMID 24895840

    Methane is an important energy resource and significant long-lived greenhouse gas. Carbon and hydrogen isotope ratios have been used to better constrain the sources of methane but interpretations based on these two parameters alone can often be inconclusive. The precise measurement of a doubly s...
  9. Measurement of a doubly substituted methane isotopologue, ¹³CH₃D, by tunable infrared laser direct absorption spectroscopy.

    Analytical chemistry 86(13):6487 (2014) PMID 24895840

    Methane is an important energy resource and significant long-lived greenhouse gas. Carbon and hydrogen isotope ratios have been used to better constrain the sources of methane but interpretations based on these two parameters alone can often be inconclusive. The precise measurement of a doubly s...
  10. Sulfur isotope evidence for low and fluctuating sulfate levels in the Late Devonian ocean and the potential link with the mass extinction event

    Earth and Planetary Science Letters (2014)

    High amplitude positive carbon isotope excursions in the Late Devonian, the punctata and Kellwasser events, reflect major perturbations in the global carbon cycle that have been attributed to increased continental weathering and subsequent ocean eutrophication. Despite the comparable c...
  11. Sulfur isotope evidence for low and fluctuating sulfate levels in the Late Devonian ocean and the potential link with the mass extinction event

    Earth and Planetary Science Letters 419 (2014)

    High amplitude positive carbon isotope excursions in the Late Devonian, the punctata and Kellwasser events, reflect major perturbations in the global carbon cycle that have been attributed to increased continental weathering and subsequent ocean eutrophication. Despite the comparable c...
  12. Consumption of atmospheric hydrogen during the life cycle of soil-dwelling actinobacteria.

    Environmental Microbiology Reports 6(3):226 (2014) PMID 24983527

    Microbe-mediated soil uptake is the largest and most uncertain variable in the budget of atmospheric hydrogen (H2 ). The diversity and ecophysiological role of soil microorganisms that can consume low atmospheric abundances of H2 with high-affinity [NiFe]-hydrogenases is unknown. We expanded the...
  13. Consumption of atmospheric hydrogen during the life cycle of soil-dwelling actinobacteria.

    Environmental Microbiology Reports 6(3):226 (2014) PMID 24983527

    Microbe-mediated soil uptake is the largest and most uncertain variable in the budget of atmospheric hydrogen (H2 ). The diversity and ecophysiological role of soil microorganisms that can consume low atmospheric abundances of H2 with high-affinity [NiFe]-hydrogenases is unknown. We expanded the...
  14. Consumption of atmospheric hydrogen during the life cycle of soil-dwelling actinobacteria.

    Environmental Microbiology Reports 6(3):226 (2014) PMID 24983527

    Microbe-mediated soil uptake is the largest and most uncertain variable in the budget of atmospheric hydrogen (H2 ). The diversity and ecophysiological role of soil microorganisms that can consume low atmospheric abundances of H2 with high-affinity [NiFe]-hydrogenases is unknown. We expanded the...
  15. Development of a spectroscopic technique for continuous online monitoring of oxygen and site-specific nitrogen isotopic composition of atmospheric nitrous oxide.

    Analytical chemistry 86(3):1726 (2014) PMID 24328290

    Nitrous oxide is an important greenhouse gas and ozone-depleting-substance. Its sources are diffuse and poorly characterized, complicating efforts to understand anthropogenic impacts and develop mitigation policies. Online, spectroscopic analysis of N2O isotopic composition can provide continuou...
  16. Development of a spectroscopic technique for continuous online monitoring of oxygen and site-specific nitrogen isotopic composition of atmospheric nitrous oxide.

    Analytical chemistry 86(3):1726 (2014) PMID 24328290

    Nitrous oxide is an important greenhouse gas and ozone-depleting-substance. Its sources are diffuse and poorly characterized, complicating efforts to understand anthropogenic impacts and develop mitigation policies. Online, spectroscopic analysis of N2O isotopic composition can provide continuou...
  17. Multiple sulfur isotope signatures of sulfite and thiosulfate reduction by the model dissimilatory sulfate-reducer, Desulfovibrio alaskensis str. G20.

    Frontiers in Microbiology 5:591 (2014) PMID 25505449

    Dissimilatory sulfate reduction serves as a key metabolic carbon remineralization process in anoxic marine environments. Sulfate reducing microorganisms can impart a wide range in mass-dependent sulfur isotopic fractionation. As such, the presence and relative activity of these organisms is iden...
  18. Multiple sulfur isotope signatures of sulfite and thiosulfate reduction by the model dissimilatory sulfate-reducer, Desulfovibrio alaskensis str. G20.

    Frontiers in Microbiology 5:591 (2014) PMID 25505449 PMCID PMC4243691

    Dissimilatory sulfate reduction serves as a key metabolic carbon remineralization process in anoxic marine environments. Sulfate reducing microorganisms can impart a wide range in mass-dependent sulfur isotopic fractionation. As such, the presence and relative activity of these organisms is iden...
  19. Decline in oceanic sulfate levels during the early Mesoproterozoic

    Precambrian Research (2014)

    • Multiple sulfur isotopes were analyzed for early Mesoproterozoic CAS and pyrite. • Paired CAS and pyrite δ34S suggest low sulfur isotope fractionation (<10‰). ...
  20. Multiple sulfur isotope signatures of sulfite and thiosulfate reduction by the model dissimilatory sulfate-reducer, Desulfovibrio alaskensis str. G20.

    Frontiers in Microbiology 5:591 (2014) PMID 25505449 PMCID PMC4243691

    Dissimilatory sulfate reduction serves as a key metabolic carbon remineralization process in anoxic marine environments. Sulfate reducing microorganisms can impart a wide range in mass-dependent sulfur isotopic fractionation. As such, the presence and relative activity of these organisms is iden...