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Kokoouline V, Alijah A, Tyuterev V. Lifetimes and decay mechanisms of isotopically substituted ozone above the dissociation threshold: matching quantum and classical dynamics. Phys Chem Chem Phys 2024; 26:4614-4628. [PMID: 38251711 DOI: 10.1039/d3cp04286c] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2024]
Abstract
Energies and lifetimes of vibrational resonances were computed for 18O-enriched isotopologue 50O3 = {16O16O18O and 16O18O16O} of the ozone molecule using hyperspherical coordinates and the method of complex absorbing potential. Various types of scattering resonances were identified, including roaming OO-O rotational states, the series corresponding to continuation of bound vibrational resonances of highly excited bending or symmetric stretching vibrational modes. Such a series become metastable above the dissociation limit. The coupling between the vibrationally excited O2 fragment and rotational roaming gives rise to Feshbach type resonances in ozone. Different paths for the formation and decay of symmetric 16O18O16O and asymmetric species 16O16O18O were also identified. The symmetry properties of the total rovibronic wave functions of the 18O-enriched isotopologues are discussed in the context of allowed dissociation channels.
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Affiliation(s)
| | - Alexander Alijah
- Groupe de Spectrometrie Moléculaire et Atmospherique, UMR CNRS 7331, University of Reims Champagne-Ardenne, Reims Cedex 2, F-51687, France
| | - Vladimir Tyuterev
- Laboratory of Molecular Quantum Mechanics and Radiative transfer, Tomsk State University, Tomsk, Russia
- Laboratory of Theoretical Spectroscopy, V.E. Zuev Institute of Atmospheric Optics, Russian Academy of Sciences, Tomsk, 634055, Russia
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2
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Zadeh-Haghighi H, Simon C. Magnetic isotope effects: a potential testing ground for quantum biology. Front Physiol 2023; 14:1338479. [PMID: 38148902 PMCID: PMC10750422 DOI: 10.3389/fphys.2023.1338479] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2023] [Accepted: 11/29/2023] [Indexed: 12/28/2023] Open
Abstract
One possible explanation for magnetosensing in biology, such as avian magnetoreception, is based on the spin dynamics of certain chemical reactions that involve radical pairs. Radical pairs have been suggested to also play a role in anesthesia, hyperactivity, neurogenesis, circadian clock rhythm, microtubule assembly, etc. It thus seems critical to probe the credibility of such models. One way to do so is through isotope effects with different nuclear spins. Here we briefly review the papers involving spin-related isotope effects in biology. We suggest studying isotope effects can be an interesting avenue for quantum biology.
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Affiliation(s)
- Hadi Zadeh-Haghighi
- Department of Physics and Astronomy, University of Calgary, Calgary, AB, Canada
- Institute for Quantum Science and Technology, University of Calgary, Calgary, AB, Canada
- Hotchkiss Brain Institute, University of Calgary, Calgary, AB, Canada
| | - Christoph Simon
- Department of Physics and Astronomy, University of Calgary, Calgary, AB, Canada
- Institute for Quantum Science and Technology, University of Calgary, Calgary, AB, Canada
- Hotchkiss Brain Institute, University of Calgary, Calgary, AB, Canada
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Zadeh-Haghighi H, Simon C. Magnetic field effects in biology from the perspective of the radical pair mechanism. J R Soc Interface 2022; 19:20220325. [PMID: 35919980 PMCID: PMC9346374 DOI: 10.1098/rsif.2022.0325] [Citation(s) in RCA: 34] [Impact Index Per Article: 17.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2022] [Accepted: 07/14/2022] [Indexed: 04/07/2023] Open
Abstract
Hundreds of studies have found that weak magnetic fields can significantly influence various biological systems. However, the underlying mechanisms behind these phenomena remain elusive. Remarkably, the magnetic energies implicated in these effects are much smaller than thermal energies. Here, we review these observations, and we suggest an explanation based on the radical pair mechanism, which involves the quantum dynamics of the electron and nuclear spins of transient radical molecules. While the radical pair mechanism has been studied in detail in the context of avian magnetoreception, the studies reviewed here show that magnetosensitivity is widespread throughout biology. We review magnetic field effects on various physiological functions, discussing static, hypomagnetic and oscillating magnetic fields, as well as isotope effects. We then review the radical pair mechanism as a potential unifying model for the described magnetic field effects, and we discuss plausible candidate molecules for the radical pairs. We review recent studies proposing that the radical pair mechanism provides explanations for isotope effects in xenon anaesthesia and lithium treatment of hyperactivity, magnetic field effects on the circadian clock, and hypomagnetic field effects on neurogenesis and microtubule assembly. We conclude by discussing future lines of investigation in this exciting new area of quantum biology.
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Affiliation(s)
- Hadi Zadeh-Haghighi
- Department of Physics and Astronomy, University of Calgary, Calgary, Alberta, Canada T2N 1N4
- Institute for Quantum Science and Technology, University of Calgary, Calgary, Alberta, Canada T2N 1N4
- Hotchkiss Brain Institute, University of Calgary, Calgary, Alberta, Canada T2N 1N4
| | - Christoph Simon
- Department of Physics and Astronomy, University of Calgary, Calgary, Alberta, Canada T2N 1N4
- Institute for Quantum Science and Technology, University of Calgary, Calgary, Alberta, Canada T2N 1N4
- Hotchkiss Brain Institute, University of Calgary, Calgary, Alberta, Canada T2N 1N4
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4
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Gayday I, Babikov D. Efficient Method for an Approximate Treatment of the Coriolis Effect in Calculations of Quantum Dynamics and Spectroscopy, with Application to Scattering Resonances in Ozone. J Phys Chem A 2021; 125:5661-5669. [PMID: 34156247 DOI: 10.1021/acs.jpca.1c03350] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
A numerical approach is developed to capture the effect of rotation-vibration coupling in a practically affordable way. In this approach only a limited number of adjacent rotational components are considered to be coupled, while the couplings to other rotational components are neglected. This partially coupled (PC) approach permits to reduce the size of Hamiltonian matrix significantly, which enables the calculations of ro-vibrational states above dissociation threshold (scattering resonances) for large values of total angular momentum. This method is employed here to reveal the role of the Coriolis effect in the ozone formation reaction at room temperature, dominated by large values of total angular momentum states, on the order of J = 24 and 28. We found that, overall, the effect of ro-vibrational coupling is not minor for large J. Compared to the results of symmetric top rotor approximation, where the ro-vibrational coupling is neglected, we found that the widths of scattering resonances, responsible for the lifetimes of metastable ozone states, remain nearly the same (on average), but the number of these states increases by as much as 20%. We also found that these changes are nearly the same in symmetric and asymmetric ozone isotopomers 16O18O16O and 16O16O18O. Therefore, based on the results of these calculations, the Coriolis coupling does not seem to favor the formation of asymmetric ozone molecules and thus cannot be responsible for symmetry-driven mass-independent fractionation of oxygen isotopes.
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Affiliation(s)
- Igor Gayday
- Department of Chemistry, Marquette University, Wehr Chemistry Building, Milwaukee, Wisconsin 53201-1881, United States
| | - Dmitri Babikov
- Department of Chemistry, Marquette University, Wehr Chemistry Building, Milwaukee, Wisconsin 53201-1881, United States
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Chi L, Wang M, Yang C, Liu Y, Ma S, Ma X. Ab initio study on the molecular structure and spectroscopic properties of isomers of SO 3. SPECTROCHIMICA ACTA. PART A, MOLECULAR AND BIOMOLECULAR SPECTROSCOPY 2020; 242:118746. [PMID: 32739518 DOI: 10.1016/j.saa.2020.118746] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/04/2020] [Revised: 07/05/2020] [Accepted: 07/13/2020] [Indexed: 06/11/2023]
Abstract
The exploration for the four possible isomers of sulfur trioxide (SO3) has led to the analysis of spectroscopic constants and anharmonic force fields for cis-OSOO, trans-OSOO, OS(=O) O and SOOO. Quantum chemical calculations are performed with Density Functional Theory (DFT) by employing B3LYP, B3P86 and B3PW91 three different functionals, in combination with Dunning's correlation-consistent cc-pVnZ, aug-cc-pVnZ (n = T, Q) basis sets. The equilibrium geometries, energies, force constants, a series of spectroscopic constants of these four isomers of SO3 are calculated. The relationship between their structures and spectroscopic properties are analyzed in detail. The present results well reproduce the previous corresponding theoretical or experimental values. Therefore, we hope that our predictions on the isomers of SO3 can provide the useful reference to further study their spectroscopic properties.
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Affiliation(s)
- Lihan Chi
- School of Physics and Optoelectronics Engineering, Ludong University, Yantai 264025, China
| | - Meishan Wang
- School of Physics and Optoelectronics Engineering, Ludong University, Yantai 264025, China.
| | - Chuanlu Yang
- School of Physics and Optoelectronics Engineering, Ludong University, Yantai 264025, China
| | - Yanli Liu
- School of Physics and Optoelectronics Engineering, Ludong University, Yantai 264025, China
| | - Shanshan Ma
- School of Physics and Optoelectronics Engineering, Ludong University, Yantai 264025, China
| | - Xiaoguang Ma
- School of Physics and Optoelectronics Engineering, Ludong University, Yantai 264025, China
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Cheema AI, Liu G, Yousaf B, Abbas Q, Zhou H. A comprehensive review of biogeochemical distribution and fractionation of lead isotopes for source tracing in distinct interactive environmental compartments. THE SCIENCE OF THE TOTAL ENVIRONMENT 2020; 719:135658. [PMID: 31874752 DOI: 10.1016/j.scitotenv.2019.135658] [Citation(s) in RCA: 29] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/19/2019] [Revised: 11/13/2019] [Accepted: 11/19/2019] [Indexed: 05/06/2023]
Abstract
Lead (Pb) is a non-essential and extremely noxious metallic-element whose biogeochemical cycle has been influenced predominantly by increasing human activities to a great extent. The introduction and enrichment of this ubiquitous contaminant in the terrestrial-environment has a long history and getting more attention due to its adverse health effects to living organisms even at very low exposure levels. Its lethal-effects can vary widely depending on the atmospheric-depositions, fates and distribution of Pb isotopes (i.e., 204Pb, 206Pb, 207Pb &208Pb) in the terrestrial-environment. Thus, it is essential to understand the depositional behavior and transformation mechanism of Pb and the factors affecting Pb isotopes composition in the terrestrial-compartments. Owing to the persistence nature of Pb-isotopic fractions, regardless of ongoing biogeochemical-processes taking place in soils and in other interlinked terrestrial-compartments of the biosphere makes Pb isotope ratios (Pb-IRs) more recognizable as a powerful and an efficient-tool for tracing the source(s) and helped uncover pertinent migration and transformation processes. This review discusses the ongoing developments in tracing migration pathway and distribution of lead in various terrestrial-compartments and investigates the processes regulating the Pb isotope geochemistry taking into account the source identification of lead, its transformation among miscellaneous terrestrial-compartments and detoxification mechanism in soil-plant system. Additionally, this compendium reveals that Pb-pools in various terrestrial-compartments differ in Pb isotopic fractionations. In order to improve understanding of partition behaviors and biogeochemical pathways of Pb isotope in the terrestrial environment, future works should involve investigation of changes in Pb isotopic compositions during weathering processes and atmospheric-biological sub-cycles.
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Affiliation(s)
- Ayesha Imtiyaz Cheema
- CAS-Key Laboratory of Crust-Mantle Materials and the Environments, School of Earth and Space Sciences, University of Science and Technology of China, Hefei 230026, PR China; State Key Laboratory of Loess and Quaternary Geology, Institute of Earth Environment, The Chinese Academy of Sciences, Xi'an, Shaanxi 710075, PR China.
| | - Guijian Liu
- CAS-Key Laboratory of Crust-Mantle Materials and the Environments, School of Earth and Space Sciences, University of Science and Technology of China, Hefei 230026, PR China; State Key Laboratory of Loess and Quaternary Geology, Institute of Earth Environment, The Chinese Academy of Sciences, Xi'an, Shaanxi 710075, PR China.
| | - Balal Yousaf
- CAS-Key Laboratory of Crust-Mantle Materials and the Environments, School of Earth and Space Sciences, University of Science and Technology of China, Hefei 230026, PR China.
| | - Qumber Abbas
- CAS-Key Laboratory of Crust-Mantle Materials and the Environments, School of Earth and Space Sciences, University of Science and Technology of China, Hefei 230026, PR China.
| | - Huihui Zhou
- CAS-Key Laboratory of Crust-Mantle Materials and the Environments, School of Earth and Space Sciences, University of Science and Technology of China, Hefei 230026, PR China.
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7
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Gayday I, Teplukhin A, Kendrick BK, Babikov D. The role of rotation-vibration coupling in symmetric and asymmetric isotopomers of ozone. J Chem Phys 2020; 152:144104. [PMID: 32295370 DOI: 10.1063/1.5141365] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
A theoretical framework and a computer code (SpectrumSDT) are developed for accurate calculations of coupled rotational-vibrational states in triatomic molecules using hyper-spherical coordinates and taking into account the Coriolis coupling effect. Concise final formulas are derived for the construction of the Hamiltonian matrix using an efficient combination of the variational basis representation and discrete variable representation methods with locally optimized basis sets and grids. First, the new code is tested by comparing its results with those of the APH3D program of Kendrick et al. [Kendrick, Pack, Walker, and Hayes, J. Chem. Phys. 110, 6673 (1999)]. Then, accurate calculations of the rovibrational spectra are carried out for doubly substituted symmetric (18O16O18O) and asymmetric (18O18O16O) ozone isotopomers for the total angular momentum up to J = 5. Together with similar data recently reported for the singly substituted symmetric (16O18O16O) and asymmetric (16O16O18O) ozone isotopomers, these calculations quantify the role of the Coriolis coupling effect in the large mass-independent isotopic enrichment of ozone, observed in both laboratory experiments and the atmosphere of the Earth. It is found that the Coriolis effect in ozone is relatively small, as evidenced by deviations of its rotational constants from the symmetric-top-rotor behavior, magnitudes of parity splittings (Λ-doubling), and ratios of rovibrational partition functions for asymmetric vs symmetric ozone molecules. It is concluded that all of these characteristics are influenced by the isotopic masses as much as they are influenced by the overall symmetry of the molecule. It is therefore unlikely that the Coriolis coupling effect could be responsible for symmetry-driven mass-independent fractionation of oxygen isotopes in ozone.
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Affiliation(s)
- Igor Gayday
- Department of Chemistry, Wehr Chemistry Building, Marquette University, Milwaukee, Wisconsin 53201-1881, USA
| | - Alexander Teplukhin
- Theoretical Division (T-1, MS B221), Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA
| | - Brian K Kendrick
- Theoretical Division (T-1, MS B221), Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA
| | - Dmitri Babikov
- Department of Chemistry, Wehr Chemistry Building, Marquette University, Milwaukee, Wisconsin 53201-1881, USA
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Ayari T, Desouter-Lecomte M, Linguerri R, Garcia GA, Nahon L, Ben Houria A, Ghalila H, Ben Said R, Hochlaf M. State-to-state dissociative photoionization of molecular nitrogen: the full story. ADVANCES IN PHYSICS: X 2020. [DOI: 10.1080/23746149.2020.1831955] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022] Open
Affiliation(s)
- T. Ayari
- COSYS/LISIS, Université Gustave Eiffel, Champs-sur-Marne, France
- Laboratoire De Spectroscopie Atomique, Moléculaire Et Applications – LSAMA, Université De Tunis El Manar, Tunis, Tunisia
| | - M. Desouter-Lecomte
- Institut De Chimie Physique, UMR8000, Université Paris-Saclay, CNRS, Orsay, France
| | - R. Linguerri
- COSYS/LISIS, Université Gustave Eiffel, Champs-sur-Marne, France
| | - G. A. Garcia
- Synchrotron SOLEIL, L’orme Des Merisiers, Saint-Aubin, Gif-sur-Yvette Cedex, France
| | - L. Nahon
- Synchrotron SOLEIL, L’orme Des Merisiers, Saint-Aubin, Gif-sur-Yvette Cedex, France
| | - A. Ben Houria
- Laboratoire De Spectroscopie Atomique, Moléculaire Et Applications – LSAMA, Université De Tunis El Manar, Tunis, Tunisia
| | - H. Ghalila
- Laboratoire De Spectroscopie Atomique, Moléculaire Et Applications – LSAMA, Université De Tunis El Manar, Tunis, Tunisia
| | - R. Ben Said
- Department of Chemistry, College of Science and Arts, Qassim University, Ar Rass, Saudi Arabia
| | - M. Hochlaf
- COSYS/LISIS, Université Gustave Eiffel, Champs-sur-Marne, France
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9
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Armstrong DW, Talebi M, Thakur N, Wahab MF, Mikhonin AV, Muckle MT, Neill JL. A Gas Chromatography‐Molecular Rotational Resonance Spectroscopy Based System of Singular Specificity. Angew Chem Int Ed Engl 2019. [DOI: 10.1002/ange.201910507] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Affiliation(s)
- Daniel W. Armstrong
- Department of Chemistry & Biochemistry University of Texas at Arlington Arlington TX 76019 USA
- AZYP, LLC Arlington TX 76012 USA
| | | | - Nimisha Thakur
- Department of Chemistry & Biochemistry University of Texas at Arlington Arlington TX 76019 USA
| | - M. Farooq Wahab
- Department of Chemistry & Biochemistry University of Texas at Arlington Arlington TX 76019 USA
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Armstrong DW, Talebi M, Thakur N, Wahab MF, Mikhonin AV, Muckle MT, Neill JL. A Gas Chromatography‐Molecular Rotational Resonance Spectroscopy Based System of Singular Specificity. Angew Chem Int Ed Engl 2019; 59:192-196. [DOI: 10.1002/anie.201910507] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2019] [Revised: 10/04/2019] [Indexed: 11/09/2022]
Affiliation(s)
- Daniel W. Armstrong
- Department of Chemistry & Biochemistry University of Texas at Arlington Arlington TX 76019 USA
- AZYP, LLC Arlington TX 76012 USA
| | | | - Nimisha Thakur
- Department of Chemistry & Biochemistry University of Texas at Arlington Arlington TX 76019 USA
| | - M. Farooq Wahab
- Department of Chemistry & Biochemistry University of Texas at Arlington Arlington TX 76019 USA
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11
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Jiang P, Chi X, Zhu Q, Cheng M, Gao H. Strong and selective isotope effect in the vacuum ultraviolet photodissociation branching ratios of carbon monoxide. Nat Commun 2019; 10:3175. [PMID: 31320624 PMCID: PMC6639306 DOI: 10.1038/s41467-019-11086-z] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2019] [Accepted: 06/21/2019] [Indexed: 11/10/2022] Open
Abstract
Rare isotope (13C, 17O and 18O) substitutions can substantially change absorption line positions, oscillator strengths and photodissociation rates of carbon monoxide (CO) in the vacuum ultraviolet (VUV) region, which has been well accounted for in recent photochemical models for understanding the large isotopic fractionation effects that are apparent in carbon and oxygen in the solar system and molecular clouds. Here, we demonstrate a strong isotope effect associated with the VUV photodissociation of CO by measuring the branching ratios of 12C16O and 13C16O in the Rydberg 4p(2), 5p(0) and 5s(0) complex region. The measurements show that the quantum yields of electronically excited C atoms in the photodissociation of 13C16O are dramatically different from those of 12C16O, revealing strong isotope effect. This isotope effect strongly depends on specific quantum states of CO being excited, which implies that such effect must be considered in the photochemical models on a state by state basis.
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Affiliation(s)
- Pan Jiang
- Beijing National Laboratory for Molecular Sciences (BNLMS), Institute of Chemistry, Chinese Academy of Sciences, Beijing, 100190, China.,University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Xiaoping Chi
- Beijing National Laboratory for Molecular Sciences (BNLMS), Institute of Chemistry, Chinese Academy of Sciences, Beijing, 100190, China.,University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Qihe Zhu
- Beijing National Laboratory for Molecular Sciences (BNLMS), Institute of Chemistry, Chinese Academy of Sciences, Beijing, 100190, China
| | - Min Cheng
- Beijing National Laboratory for Molecular Sciences (BNLMS), Institute of Chemistry, Chinese Academy of Sciences, Beijing, 100190, China.
| | - Hong Gao
- Beijing National Laboratory for Molecular Sciences (BNLMS), Institute of Chemistry, Chinese Academy of Sciences, Beijing, 100190, China.
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13
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Gayday I, Teplukhin A, Babikov D. Computational analysis of vibrational modes in tetra-sulfur using dimensionally reduced potential energy surface. Mol Phys 2019. [DOI: 10.1080/00268976.2019.1574038] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Affiliation(s)
- Igor Gayday
- Department of Chemistry, Wehr Chemistry Building, Marquette University, Milwaukee, WI, USA
| | - Alexander Teplukhin
- Department of Chemistry, Wehr Chemistry Building, Marquette University, Milwaukee, WI, USA
| | - Dmitri Babikov
- Department of Chemistry, Wehr Chemistry Building, Marquette University, Milwaukee, WI, USA
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14
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Kumar P, Poirier B. Isotope shifts and band progressions in SO2 rovibrational energy levels: using quantum theory to extract rotational constants. Mol Phys 2019. [DOI: 10.1080/00268976.2019.1567850] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Affiliation(s)
- Praveen Kumar
- Department of Chemistry and Biochemistry, Texas Tech University, Lubbock, Texas, 79409-1061
| | - Bill Poirier
- Department of Chemistry and Biochemistry, Texas Tech University, Lubbock, Texas, 79409-1061
- Max-Planck-Institut für Physik komplexer Systeme, Dresden, Germany
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15
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Teplukhin A, Babikov D. Several Levels of Theory for Description of Isotope Effects in Ozone: Symmetry Effect and Mass Effect. J Phys Chem A 2018; 122:9177-9190. [PMID: 30380876 DOI: 10.1021/acs.jpca.8b09025] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The essential components of theory for the description of isotope effects in recombination reaction that forms ozone are presented, including the introduction of three reaction pathways for symmetric and asymmetric isotopomers, a brief review of relevant experimental data for singly- and doubly substituted isotopologues, the definitions of ζ-effect and η-effect, and the introduction of isotopic enrichment δ. Two levels of theory are developed to elucidate the role of molecular symmetry, atomic masses, vibrational zero-point energies, and rotational excitations in the recombination process. The issue of symmetry is not trivial, since the important factors, such as 1/2 and 2, appear in seven different places in the formalism. It is demonstrated that if all these effects are taken into account properly, then no anomalous isotope effects emerge. At the next level of theory, a model is considered in which one scattering resonance (sitting right at the top of centrifugal barrier) is introduced per ro-vibrational channel. It is found that this approach is equivalent to statistical treatment with partition functions at the transition state. Accurate calculations using hyper-spherical coordinates show that no isotope effects come from difference in the number of states. In contrast, differences in vibrational and rotational energies lead to significant isotope effects. However, those effects appear to be local, found for the rather extreme values of rotational quantum numbers. They largely cancel when rate coefficients are computed for the thermal distribution of rotational excitations. Although large isotope effects (observed in experiments) are not reproduced here, this level of theory can be used as a foundation for more detailed computational treatment, with accurate information about resonance energies and lifetimes computed and included.
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Affiliation(s)
- Alexander Teplukhin
- Department of Chemistry , Marquette University , Milwaukee , Wisconsin 53201-1881 , United States
| | - Dmitri Babikov
- Department of Chemistry , Marquette University , Milwaukee , Wisconsin 53201-1881 , United States
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16
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17
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Pack A, Höweling A, Hezel DC, Stefanak MT, Beck AK, Peters STM, Sengupta S, Herwartz D, Folco L. Tracing the oxygen isotope composition of the upper Earth's atmosphere using cosmic spherules. Nat Commun 2017; 8:15702. [PMID: 28569769 PMCID: PMC5461487 DOI: 10.1038/ncomms15702] [Citation(s) in RCA: 37] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2016] [Accepted: 04/21/2017] [Indexed: 11/30/2022] Open
Abstract
Molten I-type cosmic spherules formed by heating, oxidation and melting of extraterrestrial Fe,Ni metal alloys. The entire oxygen in these spherules sources from the atmosphere. Therefore, I-type cosmic spherules are suitable tracers for the isotopic composition of the upper atmosphere at altitudes between 80 and 115 km. Here we present data on I-type cosmic spherules collected in Antarctica. Their composition is compared with the composition of tropospheric O2. Our data suggest that the Earth's atmospheric O2 is isotopically homogenous up to the thermosphere. This makes fossil I-type micrometeorites ideal proxies for ancient atmospheric CO2 levels.
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Affiliation(s)
- Andreas Pack
- Universität Göttingen, Geowissenschaftliches Zentrum, Goldschmidtstraße 1, 37077 Göttingen, Germany
| | - Andres Höweling
- Universität Göttingen, Geowissenschaftliches Zentrum, Goldschmidtstraße 1, 37077 Göttingen, Germany
- Karlsruher Institut für Technologie, Institut für Angewandte Materialien - Werkstoffprozesstechnik, Hermann-von-Helmholtz-Platz 1, 76344 Eggenstein-Leopoldshafen, Germany
| | - Dominik C. Hezel
- Universität Köln, Institut für Geologie und Mineralogie, Greinstraße 4-6, 50939 Köln, Germany
| | - Maren T. Stefanak
- Universität Göttingen, Geowissenschaftliches Zentrum, Goldschmidtstraße 1, 37077 Göttingen, Germany
| | - Anne-Katrin Beck
- Universität Göttingen, Geowissenschaftliches Zentrum, Goldschmidtstraße 1, 37077 Göttingen, Germany
| | - Stefan T. M. Peters
- Universität Göttingen, Geowissenschaftliches Zentrum, Goldschmidtstraße 1, 37077 Göttingen, Germany
| | - Sukanya Sengupta
- Universität Göttingen, Geowissenschaftliches Zentrum, Goldschmidtstraße 1, 37077 Göttingen, Germany
| | - Daniel Herwartz
- Universität Köln, Institut für Geologie und Mineralogie, Greinstraße 4-6, 50939 Köln, Germany
| | - Luigi Folco
- Universitá di Pisa, Dipartimento di Scienze della Terra, Via Santa Maria 53, 56126 Pisa, Italy
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Recombination reactions as a possible mechanism of mass-independent fractionation of sulfur isotopes in the Archean atmosphere of Earth. Proc Natl Acad Sci U S A 2017; 114:3062-3067. [PMID: 28258172 DOI: 10.1073/pnas.1620977114] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
A hierarchy of isotopically substituted recombination reactions is formulated for production of sulfur allotropes in the anoxic atmosphere of Archean Earth. The corresponding system of kinetics equations is solved analytically to obtain concise expressions for isotopic enrichments, with focus on mass-independent isotope effects due to symmetry, ignoring smaller mass-dependent effects. Proper inclusion of atom-exchange processes is shown to be important. This model predicts significant and equal depletions driven by reaction stoichiometry for all rare isotopes: 33S, 34S, and 36S. Interestingly, the ratio of capital [Formula: see text] values obtained within this model for 33S and 36S is -1.16, very close to the mass-independent fractionation line of the Archean rock record. This model may finally offer a mechanistic explanation for the striking mass-independent fractionation of sulfur isotopes that took place in the Archean atmosphere of Earth.
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Ivanov MV, Babikov D. On stabilization of scattering resonances in recombination reaction that forms ozone. J Chem Phys 2017; 144:154301. [PMID: 27389214 DOI: 10.1063/1.4945779] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Calculations of energy transfer in the recombination reaction that forms ozone are carried out within the framework of the mixed quantum/classical theory and using the dimensionally reduced 2D-model of ozone molecule, with bending motion neglected. Recombination rate coefficients are obtained at room temperature for symmetric and asymmetric isotopomers of singly and doubly substituted isotopologues. The processes of resonance formation, spontaneous decay, collisional dissociation, and stabilization by bath gas (Ar) are all characterized and taken into account within the steady-state approximation for kinetics. The focus is on stabilization step, where the mysterious isotopic η-effect was thought to originate from. Our results indicate no difference in cross sections for stabilization of scatteringresonances in symmetric and asymmetric isotopomers. As practical results, the general and simple analytic models for stabilization and dissociation cross sections are presented, which can be applied to resonances in any ozone molecule, symmetric or asymmetric, singly or doubly substituted. Present calculations show some isotope effect that looks similar to the experimentally observed η-effect, and the origin of this phenomenon is in the rates of formation/decay of scatteringresonances, determined by their widths, that are somewhat larger in asymmetric isotopomers than in their symmetric analogues. However, the approximate two-dimensional model used here is insufficient for consistent and reliable description of all features of the isotopic effect in ozone. Calculations using an accurate 3D model are still needed.
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Affiliation(s)
- Mikhail V Ivanov
- Chemistry Department, Wehr Chemistry Building, Marquette University, Milwaukee, Wisconsin 53201-1881, USA
| | - Dmitri Babikov
- Chemistry Department, Wehr Chemistry Building, Marquette University, Milwaukee, Wisconsin 53201-1881, USA
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Chakraborty S, Jackson TL, Rude B, Ahmed M, Thiemens MH. Nitrogen isotopic fractionations in the low temperature (80 K) vacuum ultraviolet photodissociation of N2. J Chem Phys 2016. [DOI: 10.1063/1.4962447] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023] Open
Affiliation(s)
- Subrata Chakraborty
- Department of Chemistry and Biochemistry, University of California, San Diego, 9500 Gilman Drive, La Jolla, California 92093-0356, USA
| | - Teresa L. Jackson
- Department of Chemistry and Biochemistry, University of California, San Diego, 9500 Gilman Drive, La Jolla, California 92093-0356, USA
| | - Bruce Rude
- Lawrence Berkeley National Laboratory, 1 Cyclotron Road, Berkeley, California 94720, USA
| | - Musahid Ahmed
- Lawrence Berkeley National Laboratory, 1 Cyclotron Road, Berkeley, California 94720, USA
| | - M. H. Thiemens
- Department of Chemistry and Biochemistry, University of California, San Diego, 9500 Gilman Drive, La Jolla, California 92093-0356, USA
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Wiederhold JG. Metal stable isotope signatures as tracers in environmental geochemistry. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2015; 49:2606-24. [PMID: 25640608 DOI: 10.1021/es504683e] [Citation(s) in RCA: 172] [Impact Index Per Article: 19.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
The biogeochemical cycling of metals in natural systems is often accompanied by stable isotope fractionation which can now be measured due to recent analytical advances. In consequence, a new research field has emerged over the last two decades, complementing the traditional stable isotope systems (H, C, O, N, S) with many more elements across the periodic table (Li, B, Mg, Si, Cl, Ca, Ti, V, Cr, Fe, Ni, Cu, Zn, Ge, Se, Br, Sr, Mo, Ag, Cd, Sn, Sb, Te, Ba, W, Pt, Hg, Tl, U) which are being explored and potentially applicable as novel geochemical tracers. This review presents the application of metal stable isotopes as source and process tracers in environmental studies, in particular by using mixing and Rayleigh model approaches. The most important concepts of mass-dependent and mass-independent metal stable isotope fractionation are introduced, and the extent of natural isotopic variations for different elements is compared. A particular focus lies on a discussion of processes (redox transformations, complexation, sorption, precipitation, dissolution, evaporation, diffusion, biological cycling) which are able to induce metal stable isotope fractionation in environmental systems. Additionally, the usefulness and limitations of metal stable isotope signatures as tracers in environmental geochemistry are discussed and future perspectives presented.
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Affiliation(s)
- Jan G Wiederhold
- Soil Chemistry Group, Institute of Biogeochemistry and Pollutant Dynamics, ETH Zurich , 8092 Zurich, Switzerland
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23
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Carbonate formation events in ALH 84001 trace the evolution of the Martian atmosphere. Proc Natl Acad Sci U S A 2015; 112:336-41. [PMID: 25535348 DOI: 10.1073/pnas.1315615112] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Carbonate minerals provide critical information for defining atmosphere-hydrosphere interactions. Carbonate minerals in the Martian meteorite ALH 84001 have been dated to ∼ 3.9 Ga, and both C and O-triple isotopes can be used to decipher the planet's climate history. Here we report Δ(17)O, δ(18)O, and δ(13)C data of ALH 84001 of at least two varieties of carbonates, using a stepped acid dissolution technique paired with ion microprobe analyses to specifically target carbonates from distinct formation events and constrain the Martian atmosphere-hydrosphere-geosphere interactions and surficial aqueous alterations. These results indicate the presence of a Ca-rich carbonate phase enriched in (18)O that formed sometime after the primary aqueous event at 3.9 Ga. The phases showed excess (17)O (0.7‰) that captured the atmosphere-regolith chemical reservoir transfer, as well as CO2, O3, and H2O isotopic interactions at the time of formation of each specific carbonate. The carbon isotopes preserved in the Ca-rich carbonate phase indicate that the Noachian atmosphere of Mars was substantially depleted in (13)C compared with the modern atmosphere.
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Massive isotopic effect in vacuum UV photodissociation of N2 and implications for meteorite data. Proc Natl Acad Sci U S A 2014; 111:14704-9. [PMID: 25267643 DOI: 10.1073/pnas.1410440111] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Nitrogen isotopic distributions in the solar system extend across an enormous range, from -400‰, in the solar wind and Jovian atmosphere, to about 5,000‰ in organic matter in carbonaceous chondrites. Distributions such as these require complex processing of nitrogen reservoirs and extraordinary isotope effects. While theoretical models invoke ion-neutral exchange reactions outside the protoplanetary disk and photochemical self-shielding on the disk surface to explain the variations, there are no experiments to substantiate these models. Experimental results of N2 photolysis at vacuum UV wavelengths in the presence of hydrogen are presented here, which show a wide range of enriched δ(15)N values from 648‰ to 13,412‰ in product NH3, depending upon photodissociation wavelength. The measured enrichment range in photodissociation of N2, plausibly explains the range of δ(15)N in extraterrestrial materials. This study suggests the importance of photochemical processing of the nitrogen reservoirs within the solar nebula.
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Simultaneous measurement of δ2H, δ17O, and δ18O in H2O using a commercial cavity ringdown spectrometer. Anal Chim Acta 2013; 804:176-9. [DOI: 10.1016/j.aca.2013.10.012] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2013] [Revised: 10/03/2013] [Accepted: 10/05/2013] [Indexed: 11/22/2022]
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Thiemens MH. Introduction to chemistry and applications in nature of mass independent isotope effects special feature. Proc Natl Acad Sci U S A 2013; 110:17631-7. [PMID: 24167299 PMCID: PMC3816458 DOI: 10.1073/pnas.1312926110] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Stable isotope ratio variations are regulated by physical and chemical laws. These rules depend on a relation with mass differences between isotopes. New classes of isotope variation effects that deviate from mass dependent laws, termed mass independent isotope effects, were discovered in 1983 and have a wide range of applications in basic chemistry and nature. In this special edition, new applications of these effects to physical chemistry, solar system origin models, terrestrial atmospheric and biogenic evolution, polar paleo climatology, snowball earth geology, and present day atmospheric sciences are presented.
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Affiliation(s)
- Mark H. Thiemens
- Department of Chemistry and Biochemistry, University of California at San Diego, La Jolla, CA 92093-0356
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Chakraborty S, Yanchulova P, Thiemens MH. Mass-independent oxygen isotopic partitioning during gas-phase SiO2 formation. Science 2013; 342:463-6. [PMID: 24159043 DOI: 10.1126/science.1242237] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
Meteorites contain a wide range of oxygen isotopic compositions that are interpreted as heterogeneity in solar nebula. The anomalous oxygen isotopic compositions of refractory mineral phases may reflect a chemical fractionation process in the nebula, but there are no experiments to demonstrate this isotope effect during particle formation through gas-phase reactions. We report experimental results of gas-to-particle conversion during oxidation of silicon monoxide that define a mass-independent line (slope one) in oxygen three-isotope space of (18)O/(16)O versus (17)O/(16)O. This mass-independent chemical reaction is a potentially initiating step in nebular meteorite formation, which would be capable of producing silicate reservoirs with anomalous oxygen isotopic compositions.
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Affiliation(s)
- Subrata Chakraborty
- Department of Chemistry and Biochemistry, University of California, San Diego, La Jolla, CA 92093-0356, USA
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Vibronic origin of sulfur mass-independent isotope effect in photoexcitation of SO2 and the implications to the early earth's atmosphere. Proc Natl Acad Sci U S A 2013; 110:17697-702. [PMID: 23836655 DOI: 10.1073/pnas.1306979110] [Citation(s) in RCA: 79] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Signatures of mass-independent isotope fractionation (MIF) are found in the oxygen ((16)O,(17)O,(18)O) and sulfur ((32)S, (33)S, (34)S, (36)S) isotope systems and serve as important tracers of past and present atmospheric processes. These unique isotope signatures signify the breakdown of the traditional theory of isotope fractionation, but the physical chemistry of these isotope effects remains poorly understood. We report the production of large sulfur isotope MIF, with Δ(33)S up to 78‰ and Δ(36)S up to 110‰, from the broadband excitation of SO2 in the 250-350-nm absorption region. Acetylene is used to selectively trap the triplet-state SO2 ( (3)B1), which results from intersystem crossing from the excited singlet ( (1)A2/ (1)B1) states. The observed MIF signature differs considerably from that predicted by isotopologue-specific absorption cross-sections of SO2 and is insensitive to the wavelength region of excitation (above or below 300 nm), suggesting that the MIF originates not from the initial excitation of SO2 to the singlet states but from an isotope selective spin-orbit interaction between the singlet ( (1)A2/ (1)B1) and triplet ( (3)B1) manifolds. Calculations based on high-level potential energy surfaces of the multiple excited states show a considerable lifetime anomaly for (33)SO2 and (36)SO2 for the low vibrational levels of the (1)A2 state. These results demonstrate that the isotope selectivity of accidental near-resonance interactions between states is of critical importance in understanding the origin of MIF in photochemical systems.
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Production, preservation, and biological processing of mass-independent sulfur isotope fractionation in the Archean surface environment. Proc Natl Acad Sci U S A 2013; 110:17644-9. [PMID: 23572589 DOI: 10.1073/pnas.1213148110] [Citation(s) in RCA: 64] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Mass-independent fractionation of sulfur isotopes (S MIF) in Archean and Paleoproterozoic rocks provides strong evidence for an anoxic atmosphere before ~2,400 Ma. However, the origin of this isotopic anomaly remains unclear, as does the identity of the molecules that carried it from the atmosphere to Earth's surface. Irrespective of the origin of S MIF, processes in the biogeochemical sulfur cycle modify the primary signal and strongly influence the S MIF preserved and observed in the geological record. Here, a detailed model of the marine sulfur cycle is used to propagate and distribute atmospherically derived S MIF from its delivery to the ocean to its preservation in the sediment. Bulk pyrite in most sediments carries weak S MIF because of microbial reduction of most sulfur compounds to form isotopically homogeneous sulfide. Locally, differential incorporation of sulfur compounds into pyrite leads to preservation of S MIF, which is predicted to be most highly variable in nonmarine and shallow-water settings. The Archean ocean is efficient in diluting primary atmospheric S MIF in the marine pools of sulfate and elemental sulfur with inputs from SO2 and H2S, respectively. Preservation of S MIF with the observed range of magnitudes requires the S MIF production mechanism to be moderately fractionating ( 20-40‰). Constraints from the marine sulfur cycle allow that either elemental sulfur or organosulfur compounds (or both) carried S MIF to the surface, with opposite sign to S MIF in SO2 and H2SO4. Optimal progress requires observations from nonmarine and shallow-water environments and experimental constraints on the reaction of photoexcited SO2 with atmospheric hydrocarbons.
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Tales of volcanoes and El-Nino southern oscillations with the oxygen isotope anomaly of sulfate aerosol. Proc Natl Acad Sci U S A 2013; 110:17662-7. [PMID: 23447567 DOI: 10.1073/pnas.1213149110] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The ability of sulfate aerosols to reflect solar radiation and simultaneously act as cloud condensation nuclei renders them central players in the global climate system. The oxidation of S(IV) compounds and their transport as stable S(VI) in the Earth's system are intricately linked to planetary scale processes, and precise characterization of the overall process requires a detailed understanding of the linkage between climate dynamics and the chemistry leading to the product sulfate. This paper reports a high-resolution, 22-y (1980-2002) record of the oxygen-triple isotopic composition of sulfate (SO4) aerosols retrieved from a snow pit at the South Pole. Observed variation in the O-isotopic anomaly of SO4 aerosol is linked to the ozone variation in the tropical upper troposphere/lower stratosphere via the Ozone El-Niño Southern Oscillations (ENSO) Index (OEI). Higher (17)O values (3.3‰, 4.5‰, and 4.2‰) were observed during the three largest ENSO events of the past 2 decades. Volcanic events inject significant quantities of SO4 aerosol into the stratosphere, which are known to affect ENSO strength by modulating stratospheric ozone levels (OEI = 6 and (17)O = 3.3‰, OEI = 11 and (17)O = 4.5‰) and normal oxidative pathways. Our high-resolution data indicated that (17)O of sulfate aerosols can record extreme phases of naturally occurring climate cycles, such as ENSOs, which couple variations in the ozone levels in the atmosphere and the hydrosphere via temperature driven changes in relative humidity levels. A longer term, higher resolution oxygen-triple isotope analysis of sulfate aerosols from ice cores, encompassing more ENSO periods, is required to reconstruct paleo-ENSO events and paleotropical ozone variations.
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On molecular origin of mass-independent fractionation of oxygen isotopes in the ozone forming recombination reaction. Proc Natl Acad Sci U S A 2013; 110:17708-13. [PMID: 23431175 DOI: 10.1073/pnas.1215464110] [Citation(s) in RCA: 56] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Theoretical treatment of ozone forming reaction is developed within the framework of mixed quantum/classical dynamics. Formation and stabilization steps of the energy transfer mechanism are both studied, which allows simultaneous capture of the delta zero-point energy effect and η-effect and identification of the molecular level origin of mass-independent isotope fractionation. The central role belongs to scattering resonances; dependence of their lifetimes on rotational excitation, asymmetry; and connection of their vibrational wave functions to two different reaction channels. Calculations, performed within the dimensionally reduced model of ozone, are in semiquantitative agreement with experiment.
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Sulfur isotopic fractionation in vacuum UV photodissociation of hydrogen sulfide and its potential relevance to meteorite analysis. Proc Natl Acad Sci U S A 2013; 110:17650-5. [PMID: 23431159 DOI: 10.1073/pnas.1213150110] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Select meteoritic classes possess mass-independent sulfur isotopic compositions in sulfide and organic phases. Photochemistry in the solar nebula has been attributed as a source of these anomalies. Hydrogen sulfide (H2S) is the most abundant gas-phase species in the solar nebula, and hence, photodissociation of H2S by solar vacuum UV (VUV) photons (especially by Lyman-α radiation) is a relevant process. Because of experimental difficulties associated with accessing VUV radiation, there is a paucity of data and a lack of theoretical basis to test the hypothesis of a photochemical origin of mass-independent sulfur. Here, we present multiisotopic measurements of elemental sulfur produced during the VUV photolysis of H2S. Mass-independent sulfur isotopic compositions are observed. The observed isotopic fractionation patterns are wavelength-dependent. VUV photodissociation of H2S takes place through several predissociative channels, and the measured mass-independent fractionation is most likely a manifestation of these processes. Meteorite sulfur data are discussed in light of the present experiments, and suggestions are made to guide future experiments and models.
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Affiliation(s)
- Anatoly L. Buchachenko
- Institute
of Chemical Physics, Russian Academy of Sciences, 119991 Moscow, Russian Federation and Department of Chemistry, Moscow State University, 119992, Moscow, Russian Federation
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Chakraborty S, Davis RD, Ahmed M, Jackson TL, Thiemens MH. Oxygen isotope fractionation in the vacuum ultraviolet photodissociation of carbon monoxide: wavelength, pressure, and temperature dependency. J Chem Phys 2012; 137:024309. [PMID: 22803538 DOI: 10.1063/1.4730911] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023] Open
Abstract
Several absorption bands exist in the vacuum ultraviolet (VUV) region of carbon monoxide (CO). Emission spectra indicate that these bands are all predissociative. Experimental results of CO photodissociation by vacuum ultraviolet photons (90 to 108 nm; ∼13 to 11 eV) from the Advanced Light Source synchrotron by measurement of the oxygen isotopic composition of the products are presented here. A large (few hundred per mil) range of oxygen isotopic compositions are observed in the CO photodissociation product and are wavelength dependent. Slope values (δ('17)O/δ('18)O) ranging from 0.72 to 1.36 were observed in the oxygen three-isotope space (δ('18)O vs. δ('17)O), which anti-correlated with increasing synchrotron photon energy, and indicates a dependency on the upper electronic state specific dissociation dynamics (e.g., perturbation and coupling associated with a particular state). An unprecedented magnitude in isotope fractionation was observed for photodissociation at 105 and 107 nm and is found to be associated with accidental predissociation of the vibrational states (ν = 0 and 1) for the upper electronic state E(1)Π. A significant temperature dependency in oxygen isotopic fractionation was observed, indicating a rotational level dependency in the predissociation process.
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Affiliation(s)
- Subrata Chakraborty
- Department of Chemistry and Biochemistry, University of California, San Diego, La Jolla, California 92093-0356, USA.
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