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Fang YG, Wei L, Francisco JS, Zhu C, Fang WH. Mechanistic Insights into Chloric Acid Production by Hydrolysis of Chlorine Trioxide at an Air-Water Interface. J Am Chem Soc 2024. [PMID: 39013148 DOI: 10.1021/jacs.4c06269] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 07/18/2024]
Abstract
Chlorine oxides play crucial roles in ozone depletion, and the final oxidation steps of chlorine oxide potentially result in the formation of chloric acid (HClO3) or perchloric acid (HClO4). Herein, the solvation and reactive uptake of three stable isomers of chlorine trioxide (Cl2O3), namely, ClOCl(O)O, ClClO3, and ClOOOCl, at the air-water interface were investigated using classical and hybrid quantum mechanics/molecular mechanics (QM/MM) molecular dynamics (MD) coupled with advanced free energy methods. Two distinct mechanisms were revealed for the hydrolysis of ClOCl(O)O and ClClO3: molecular and ionic mechanisms. A comparison of the computed free-energy profiles for the gaseous and air-water interfacial systems indicated that the air-water interface could markedly lower the free-energy barrier for ClO 3 - or HClO3 formation while stabilizing the product state. In particular, the hydrolysis of ClClO3 at the air-water interface was barrierless. In contrast, our calculations showed that the hydrolysis of ClOOOCl was very slow, indicating that ClOOOCl was inert to water at the air-water interface. This study provides theoretical evidence for the hypothesis that HClO3 is a sink for chlorine oxides and for the widespread distributions of HClO3 recently observed in the Arctic region.
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Affiliation(s)
- Ye-Guang Fang
- Key Laboratory of Theoretical and Computational Photochemistry, Ministry of Education, College of Chemistry, Beijing Normal University, Beijing 100875, PR China
- Laboratory of Theoretical and Computational Nanoscience, CAS Key Laboratory of Nanosystem and Hierarchical Fabrication, CAS Centre for Excellence in Nanoscience, National Centre for Nanoscience and Technology, Beijing 100190, PR China
| | - Laiyang Wei
- Key Laboratory of Theoretical and Computational Photochemistry, Ministry of Education, College of Chemistry, Beijing Normal University, Beijing 100875, PR China
| | - Joseph S Francisco
- Department of Chemistry, University of Pennsylvania, Philadelphia, Pennsylvania 19104, United States
| | - Chongqin Zhu
- Key Laboratory of Theoretical and Computational Photochemistry, Ministry of Education, College of Chemistry, Beijing Normal University, Beijing 100875, PR China
| | - Wei-Hai Fang
- Key Laboratory of Theoretical and Computational Photochemistry, Ministry of Education, College of Chemistry, Beijing Normal University, Beijing 100875, PR China
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2
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Evan S, Brioude J, Rosenlof KH, Gao RS, Portmann RW, Zhu Y, Volkamer R, Lee CF, Metzger JM, Lamy K, Walter P, Alvarez SL, Flynn JH, Asher E, Todt M, Davis SM, Thornberry T, Vömel H, Wienhold FG, Stauffer RM, Millán L, Santee ML, Froidevaux L, Read WG. Rapid ozone depletion after humidification of the stratosphere by the Hunga Tonga Eruption. Science 2023; 382:eadg2551. [PMID: 37856589 DOI: 10.1126/science.adg2551] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2022] [Accepted: 09/05/2023] [Indexed: 10/21/2023]
Abstract
The eruption of the Hunga Tonga-Hunga Ha'apai volcano on 15 January 2022 offered a good opportunity to explore the early impacts of tropical volcanic eruptions on stratospheric composition. Balloon-borne observations near Réunion Island revealed the unprecedented amount of water vapor injected by the volcano. The enhanced stratospheric humidity, radiative cooling, and expanded aerosol surface area in the volcanic plume created the ideal conditions for swift ozone depletion of 5% in the tropical stratosphere in just 1 week. The decrease in hydrogen chloride by 0.4 parts per million by volume (ppbv) and the increase in chlorine monoxide by 0.4 ppbv provided compelling evidence for chlorine activation within the volcanic plume. This study enhances our understanding of the effect of this unusual volcanic eruption on stratospheric chemistry and provides insights into possible chemistry changes that may occur in a changing climate.
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Affiliation(s)
- Stephanie Evan
- Laboratoire de l'Atmosphère et des Cyclones (LACy), UMR8105, CNRS, Université de La Réunion, Météo-France, Saint-Denis, France
| | - Jerome Brioude
- Laboratoire de l'Atmosphère et des Cyclones (LACy), UMR8105, CNRS, Université de La Réunion, Météo-France, Saint-Denis, France
| | | | - Ru-Shan Gao
- NOAA Chemical Sciences Laboratory, Boulder, CO, USA
| | | | - Yunqian Zhu
- NOAA Chemical Sciences Laboratory, Boulder, CO, USA
- Cooperative Institute for Research in Environmental Sciences, University of Colorado, Boulder, CO, USA
| | - Rainer Volkamer
- Department of Chemistry and Cooperative Institute for Research in Environmental Sciences, University of Colorado, Boulder, CO, USA
| | - Christopher F Lee
- Department of Chemistry and Cooperative Institute for Research in Environmental Sciences, University of Colorado, Boulder, CO, USA
| | - Jean-Marc Metzger
- Observatoire des Sciences de l'Univers de la Réunion, UAR 3365 (CNRS, Université de la Réunion, Météo-France), Saint-Denis, France
| | - Kevin Lamy
- Laboratoire de l'Atmosphère et des Cyclones (LACy), UMR8105, CNRS, Université de La Réunion, Météo-France, Saint-Denis, France
| | | | | | | | - Elizabeth Asher
- NOAA Chemical Sciences Laboratory, Boulder, CO, USA
- Cooperative Institute for Research in Environmental Sciences, University of Colorado, Boulder, CO, USA
| | - Michael Todt
- Finnish Meteorological Institute, Helsinki, Finland
| | - Sean M Davis
- NOAA Chemical Sciences Laboratory, Boulder, CO, USA
| | | | - Holger Vömel
- National Center for Atmospheric Research, Boulder, CO, USA
| | - Frank G Wienhold
- Swiss Federal Institute of Technology (ETH), Zurich, Switzerland
| | - Ryan M Stauffer
- Atmospheric Chemistry and Dynamics Laboratory, NASA Goddard Space Flight Center, Greenbelt, MD, USA
| | - Luis Millán
- Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA, USA
| | - Michelle L Santee
- Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA, USA
| | - Lucien Froidevaux
- Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA, USA
| | - William G Read
- Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA, USA
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3
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Ulenikov O, Bekhtereva E, Gromova O, Fomchenko A, Morzhikova Y, Sidko S, Sydow C, Bauerecker S. Effective Dipole Moment Model for Axially Symmetric C3v Molecules: Application to the Precise Study of Absolute Line Strengths of the ν6 Fundamental of CH 335Cl. Int J Mol Sci 2023; 24:12122. [PMID: 37569499 PMCID: PMC10418978 DOI: 10.3390/ijms241512122] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2023] [Revised: 07/21/2023] [Accepted: 07/25/2023] [Indexed: 08/13/2023] Open
Abstract
The effective dipole moment model for molecules of axial C3v symmetry is derived on the basis of the symmetry properties of a molecule which, on the one hand, is of the same order of efficiency (but much simpler and clearer in applications) as the analogous models derived on the basis of the irreducible tensorial sets theory, and, on the other hand, mathematically more correct in comparison with concepts like the Herman-Walles function used in the models. As an application of the general results obtained, we discuss high-resolution infrared spectra of CH335Cl, recorded with the Zürich prototype ZP2001 (Bruker IFS125 HR) Fourier transform infrared spectrometer at a resolution of 0.001 cm-1 and analyzed in the region of 880-1190 cm-1 (ν6 bending fundamental centered at ν0 = 1018.070790 cm-1). Absolute strengths of more than 2800 transitions (2081 lines) were obtained from the fit of their shapes both with Voigt and Hartmann-Tran profiles, and parameters of the effective dipole moment of the ν6 band were determined by the computer code SYMTOMLIST (SYMmetric TOp Molecules: LIne STrengths), created on the basis of a derived theoretical model. As the first step of the analysis of the experimental data, assignments of the recorded lines were made. A total of 5124 transitions with Jmax = 68, Kmax = 21 were assigned to the ν6 band. The weighted fit of 2077 upper energy values obtained from the experimentally recorded transitions was made with a Hamiltonian which takes into account different types of ro-vibrational effects in doubly degenerate vibrational states of the C3v-symmetric molecule. As the result, a set of 25 fitted parameters was obtained which reproduces the initial 2077 upper "experimental" ro-vibrational energy values with a root mean square deviation drms=4.7×10-5 cm-1. At the second step of the analysis, the computer code SYMTOMLIST was used for determination of the parameters of the derived effective dipole moment model. Six effective dipole moment parameters were obtained from the weighted fit procedure which reproduces absolute experimental strengths of the 2804 initial experimental transitions with a relative drms=3.4%.
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Affiliation(s)
- Oleg Ulenikov
- Research School of High-Energy Physics, National Research Tomsk Polytechnic University, 634050 Tomsk, Russia; (E.B.); (O.G.); (A.F.); (Y.M.); (S.S.)
| | - Elena Bekhtereva
- Research School of High-Energy Physics, National Research Tomsk Polytechnic University, 634050 Tomsk, Russia; (E.B.); (O.G.); (A.F.); (Y.M.); (S.S.)
| | - Olga Gromova
- Research School of High-Energy Physics, National Research Tomsk Polytechnic University, 634050 Tomsk, Russia; (E.B.); (O.G.); (A.F.); (Y.M.); (S.S.)
| | - Anna Fomchenko
- Research School of High-Energy Physics, National Research Tomsk Polytechnic University, 634050 Tomsk, Russia; (E.B.); (O.G.); (A.F.); (Y.M.); (S.S.)
| | - Yulia Morzhikova
- Research School of High-Energy Physics, National Research Tomsk Polytechnic University, 634050 Tomsk, Russia; (E.B.); (O.G.); (A.F.); (Y.M.); (S.S.)
| | - Sergei Sidko
- Research School of High-Energy Physics, National Research Tomsk Polytechnic University, 634050 Tomsk, Russia; (E.B.); (O.G.); (A.F.); (Y.M.); (S.S.)
| | - Christian Sydow
- Institut für Physikalische und Theoretische Chemie, Technische Universität Braunschweig, D-38106 Braunschweig, Germany; (C.S.); (S.B.)
| | - Sigurd Bauerecker
- Institut für Physikalische und Theoretische Chemie, Technische Universität Braunschweig, D-38106 Braunschweig, Germany; (C.S.); (S.B.)
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4
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Jiang J, Ji Y, Li X. On-line trace monitoring of volatile halogenated compounds in air by improved thermal desorption-gas chromatography-mass spectrometry. J Chromatogr A 2022; 1682:463507. [PMID: 36155078 DOI: 10.1016/j.chroma.2022.463507] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2022] [Revised: 09/09/2022] [Accepted: 09/14/2022] [Indexed: 11/24/2022]
Abstract
Volatile halogenated compounds (VHCs) are important industrial chemicals and play a crucial role in potential stratospheric ozone-depletion and global warming. Profiling of VHCs is of great significance but replete with challenges due to the species' richness and diversity. In this study, we developed a novel method employing water removal mode combined with thermal desorption-gas chromatography-mass spectrometry (TD-GC-MS) for on-line measurement of VHCs at the ultratrace level. By removing water with Nafion dryer tandem cold trap device, VHCs could achieve better separation and identification, and detection precision of VHCs lower than 10%. The proposed method exhibited limits of detection for VHCs ranging from 0.1 to 6.2 pptv. Benefiting from the improved trapping efficiency due to water removal, we successfully quantified 34 VHCs at the Shangdianzi background station and achieved a comprehensive assessment of VHCs in ambient air.
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Affiliation(s)
- Jiakui Jiang
- Department of Environmental Science & Engineering, Fudan University, Shanghai 200438, PR China
| | - Yongyan Ji
- Department of Environmental Science & Engineering, Fudan University, Shanghai 200438, PR China
| | - Xiang Li
- Department of Environmental Science & Engineering, Fudan University, Shanghai 200438, PR China; Institute of Eco-Chongming (IEC), Shanghai 200062, PR China.
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5
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The influence of iodine on the Antarctic stratospheric ozone hole. Proc Natl Acad Sci U S A 2022; 119:2110864119. [PMID: 35131938 PMCID: PMC8851550 DOI: 10.1073/pnas.2110864119] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 12/14/2021] [Indexed: 11/29/2022] Open
Abstract
The role of chlorine and bromine in Antarctic stratospheric ozone depletion is well known. However, the contribution of iodine to the ozone hole chemistry has not been assessed, mainly due to the negligible amounts of iodine previously reported to enter the stratosphere. New measurements demonstrate that the injection of iodine to the lower stratosphere is higher than previously assumed. Based on these observations, our modeling work shows that iodine chemistry can enhance spring ozone loss at the lower part of the Antarctic ozone hole, and even dominate the halogen-mediated ozone loss during summer. Iodine can also alter, by several days, the timing of the seasonal formation and closure of the ozone hole. The catalytic depletion of Antarctic stratospheric ozone is linked to anthropogenic emissions of chlorine and bromine. Despite its larger ozone-depleting efficiency, the contribution of ocean-emitted iodine to ozone hole chemistry has not been evaluated, due to the negligible iodine levels previously reported to reach the stratosphere. Based on the recently observed range (0.77 ± 0.1 parts per trillion by volume [pptv]) of stratospheric iodine injection, we use the Whole Atmosphere Community Climate Model to assess the role of iodine in the formation and recent past evolution of the Antarctic ozone hole. Our 1980–2015 simulations indicate that iodine can significantly impact the lower part of the Antarctic ozone hole, contributing, on average, 10% of the lower stratospheric ozone loss during spring (up to 4.2% of the total stratospheric column). We find that the inclusion of iodine advances the beginning and delays the closure stages of the ozone hole by 3 d to 5 d, increasing its area and mass deficit by 11% and 20%, respectively. Despite being present in much smaller amounts, and due to faster gas-phase photochemical reactivation, iodine can dominate (∼73%) the halogen-mediated lower stratospheric ozone loss during summer and early fall, when the heterogeneous reactivation of inorganic chlorine and bromine reservoirs is reduced. The stratospheric ozone destruction caused by 0.77 pptv of iodine over Antarctica is equivalent to that of 3.1 (4.6) pptv of biogenic very short-lived bromocarbons during spring (rest of sunlit period). The relative contribution of iodine to future stratospheric ozone loss is likely to increase as anthropogenic chlorine and bromine emissions decline following the Montreal Protocol.
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6
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Antarctic ozone hole modifies iodine geochemistry on the Antarctic Plateau. Nat Commun 2021; 12:5836. [PMID: 34611165 PMCID: PMC8492625 DOI: 10.1038/s41467-021-26109-x] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2021] [Accepted: 09/17/2021] [Indexed: 11/08/2022] Open
Abstract
Polar stratospheric ozone has decreased since the 1970s due to anthropogenic emissions of chlorofluorocarbons and halons, resulting in the formation of an ozone hole over Antarctica. The effects of the ozone hole and the associated increase in incoming UV radiation on terrestrial and marine ecosystems are well established; however, the impact on geochemical cycles of ice photoactive elements, such as iodine, remains mostly unexplored. Here, we present the first iodine record from the inner Antarctic Plateau (Dome C) that covers approximately the last 212 years (1800-2012 CE). Our results show that the iodine concentration in ice remained constant during the pre-ozone hole period (1800-1974 CE) but has declined twofold since the onset of the ozone hole era (~1975 CE), closely tracking the total ozone evolution over Antarctica. Based on ice core observations, laboratory measurements and chemistry-climate model simulations, we propose that the iodine decrease since ~1975 is caused by enhanced iodine re-emission from snowpack due to the ozone hole-driven increase in UV radiation reaching the Antarctic Plateau. These findings suggest the potential for ice core iodine records from the inner Antarctic Plateau to be as an archive for past stratospheric ozone trends.
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7
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Clapp CE, Anderson JG. Modeling the Effect of Potential Nitric Acid Removal During Convective Injection of Water Vapor Over the Central United States on the Chemical Composition of the Lower Stratosphere. JOURNAL OF GEOPHYSICAL RESEARCH. ATMOSPHERES : JGR 2019; 124:9743-9770. [PMID: 31763110 PMCID: PMC6853249 DOI: 10.1029/2018jd029703] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/22/2018] [Revised: 07/30/2019] [Accepted: 08/04/2019] [Indexed: 06/10/2023]
Abstract
Tropopause-penetrating convection is a frequent seasonal feature of the Central United States climate. This convection presents the potential for consistent transport of water vapor into the upper troposphere and lower stratosphere (UTLS) through the lofting of ice, which then sublimates. Water vapor enhancements associated with convective ice lofting have been observed in both in situ and satellite measurements. These water vapor enhancements can increase the probability of sulfate aerosol-catalyzed heterogeneous reactions that convert reservoir chlorine (HCl and ClONO2) to free radical chlorine (Cl and ClO) that leads to catalytic ozone loss. In addition to water vapor transport, lofted ice may also scavenge nitric acid and further impact the chlorine activation chemistry of the UTLS. We present a photochemical model that resolves the vertical chemical structure of the UTLS to explore the effect of water vapor enhancements and potential additional nitric acid removal. The model is used to define the response of stratospheric column ozone to the range of convective water vapor transported and the temperature variability of the lower stratosphere currently observed over the Central United States in conjunction with potential nitric acid removal and to scenarios of elevated sulfate aerosol surface area density representative of possible future volcanic eruptions or solar radiation management. We find that the effect of HNO3 removal is dependent on the magnitude of nitric acid removal and has the greatest potential to increase chlorine activation and ozone loss under UTLS conditions that weakly favor the chlorine activation heterogeneous reactions by reducing NOx sources.
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Affiliation(s)
- C. E. Clapp
- Department of Chemistry and Chemical BiologyHarvard UniversityCambridgeMAUSA
| | - J. G. Anderson
- Department of Chemistry and Chemical BiologyHarvard UniversityCambridgeMAUSA
- Harvard John A. Paulson School of Engineering and Applied SciencesHarvard UniversityCambridgeMAUSA
- Department of Earth and Planetary SciencesHarvard UniversityCambridgeMAUSA
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8
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Gope K, Mason N, Krishnakumar E, Prabhudesai VS. DEA dynamics of chlorine dioxide probed by velocity slice imaging. Phys Chem Chem Phys 2019; 21:14023-14032. [PMID: 30640334 DOI: 10.1039/c8cp06660d] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
We report, for the first time, the detailed dynamics of dissociative electron attachment to the atmospherically important chlorine dioxide (OClO) molecule exploring all the product anion channels. Below 2 eV, the production of vibrationally excited OCl- dominates the DEA process whereas at electron energies greater than 2 eV, three-body dissociation is found to result in O- and Cl- production. We find that the internal energy of OCl- and the kinetic energy of Cl- are large enough for them to be relevant in the ozone-depleting catalytic cycle and more investigations on the reaction of these anions with ozone are necessary to completely understand the role of DEA to OClO in ozone depletion. These results also point to an urgent need for comprehensive theoretical calculations of the DEA process to this atmospherically important molecule.
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Affiliation(s)
- Krishnendu Gope
- Tata Institute of Fundamental Research, Homi Bhabha Road, Colaba, 400005 Mumbai, India.
| | - Nigel Mason
- School of Physical Sciences, University of Kent, Canterbury, CT2 7NH, UK
| | - E Krishnakumar
- Tata Institute of Fundamental Research, Homi Bhabha Road, Colaba, 400005 Mumbai, India.
| | - Vaibhav S Prabhudesai
- Tata Institute of Fundamental Research, Homi Bhabha Road, Colaba, 400005 Mumbai, India.
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9
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10
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Abstract
Abstract
Remarkable progress has occurred over the last 100 years in our understanding of atmospheric chemical composition, stratospheric and tropospheric chemistry, urban air pollution, acid rain, and the formation of airborne particles from gas-phase chemistry. Much of this progress was associated with the developing understanding of the formation and role of ozone and of the oxides of nitrogen, NO and NO2, in the stratosphere and troposphere. The chemistry of the stratosphere, emerging from the pioneering work of Chapman in 1931, was followed by the discovery of catalytic ozone cycles, ozone destruction by chlorofluorocarbons, and the polar ozone holes, work honored by the 1995 Nobel Prize in Chemistry awarded to Crutzen, Rowland, and Molina. Foundations for the modern understanding of tropospheric chemistry were laid in the 1950s and 1960s, stimulated by the eye-stinging smog in Los Angeles. The importance of the hydroxyl (OH) radical and its relationship to the oxides of nitrogen (NO and NO2) emerged. The chemical processes leading to acid rain were elucidated. The atmosphere contains an immense number of gas-phase organic compounds, a result of emissions from plants and animals, natural and anthropogenic combustion processes, emissions from oceans, and from the atmospheric oxidation of organics emitted into the atmosphere. Organic atmospheric particulate matter arises largely as gas-phase organic compounds undergo oxidation to yield low-volatility products that condense into the particle phase. A hundred years ago, quantitative theories of chemical reaction rates were nonexistent. Today, comprehensive computer codes are available for performing detailed calculations of chemical reaction rates and mechanisms for atmospheric reactions. Understanding the future role of atmospheric chemistry in climate change and, in turn, the impact of climate change on atmospheric chemistry, will be critical to developing effective policies to protect the planet.
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11
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Basis Set Effects in the Description of the Cl-O Bond in ClO and XClO/ClOX Isomers (X = H, O, and Cl) Using DFT and CCSD(T) Methods. J CHEM-NY 2019. [DOI: 10.1155/2019/4057848] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The performance of a group of density functional methods of progressive complexity for the description of the ClO bond in a series of chlorine oxides was investigated. The simplest ClO radical species and the two isomeric structures XClO/ClOX for each X = H, Cl, and O were studied using the PW91, TPSS, B3LYP, PBE0, M06, M06-2X, BMK, and B2PLYP functionals. Geometry optimizations and reaction enthalpies and enthalpies of formation for each species were calculated using Pople basis sets and the (aug)-cc-pVnZ Dunning sets, with n = D, T, Q, 5, and 6. For the calculation of enthalpies of formation, atomization and isodesmic reactions were employed. Both the precision of the methods with respect to the increase of the basis sets, as well as their accuracy, were gauged by comparing the results with the more accurate CCSD(T) calculations, performed using the same basis sets as for the DFT methods. The results obtained employing composite chemical methods (G4, CBS-QB3, and W1BD) were also used for the comparisons, as well as the experimental results when they are available. The results obtained show that error compensation is the key for successful description of molecular properties (geometries and energies) by carefully selecting the method and basis sets. In general, expansion of the one-electron basis set to the limit of completeness does not improve results at the DFT level, but just the opposite. The enthalpies of formation calculated at the CCSD(T)/aug-cc-pV6Z for the species considered are generally in agreement with experimental determinations and the most accurate theoretical values. Different sources of error in the calculations are discussed in detail.
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12
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Anderson JG, Clapp CE. Coupling free radical catalysis, climate change, and human health. Phys Chem Chem Phys 2018; 20:10569-10587. [PMID: 29638230 DOI: 10.1039/c7cp08331a] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
We present the chain of mechanisms linking free radical catalytic loss of stratospheric ozone, specifically over the central United States in summer, to increased climate forcing by CO2 and CH4 from fossil fuel use. This case directly engages detailed knowledge, emerging from in situ aircraft observations over the polar regions in winter, defining the temperature and water vapor dependence of the kinetics of heterogeneous catalytic conversion of inorganic chlorine (HCl and ClONO2) to free radical form (ClO). Analysis is placed in the context of irreversible changes to specific subsystems of the climate, most notably coupled feedbacks that link rapid changes in the Arctic with the discovery that convective storms over the central US in summer both suppress temperatures and inject water vapor deep into the stratosphere. This places the lower stratosphere over the US in summer within the same photochemical catalytic domain as the lower stratosphere of the Arctic in winter engaging the risk of amplifying the rate limiting step in the ClO dimer catalytic mechanism by some six orders of magnitude. This transitions the catalytic loss rate of ozone in lower stratosphere over the United States in summer from HOx radical control to ClOx radical control, increasing the overall ozone loss rate by some two orders of magnitude over that of the unperturbed state. Thus we address, through a combination of observations and modeling, the mechanistic foundation defining why stratospheric ozone, vulnerable to increased climate forcing, is one of the most delicate aspects of habitability on the planet.
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Affiliation(s)
- J G Anderson
- Department of Chemistry and Chemical Biology, Harvard University, Cambridge, MA 02138, USA.
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13
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Abbott AS, Schaefer HF. The Structure and Cl–O Dissociation Energy of the ClOO Radical: Finally, the Right Answers for the Right Reason. J Phys Chem A 2018; 122:2604-2610. [DOI: 10.1021/acs.jpca.8b00394] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Adam S. Abbott
- Center for Computational Quantum Chemistry, The University of Georgia, Athens, Georgia 30602, United States
| | - Henry F. Schaefer
- Center for Computational Quantum Chemistry, The University of Georgia, Athens, Georgia 30602, United States
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14
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Linear and Non-Linear Trends for Seasonal NO2 and SO2 Concentrations in the Southern Hemisphere (2004−2016). REMOTE SENSING 2017. [DOI: 10.3390/rs9090891] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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15
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Exploring the potential energy surface of novel [H, S, Se, Br] species: a high level first principle study. J Mol Model 2017; 23:232. [PMID: 28730352 DOI: 10.1007/s00894-017-3410-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2017] [Accepted: 06/28/2017] [Indexed: 10/19/2022]
Abstract
The characterization of the seleno-sulfide-bromo systems and the isomerization process on the [H, S, Se, Br] potential energy surface were investigated using state-of-the-art theoretical methods. The CCSD(T) and the MP2 levels of theory were employed along with the series of correlation consistent basis sets extrapolated to the complete basis set (CBS) limit in the optimization of the geometrical parameters and computation of electronic energies. The relative stability, in kcal mol-1, at the CCSD(T)/CBS follows the trend: HSSeBr (0) > HSeSBr (9.51) > SSeHBr (24.02) > SeSHBr (25.42). This order was observed in the previous study of the [H, S, Se, Cl] species. The structural parameters and vibrational frequencies of the [H, S, Se, Br] species are reported. This research work should be helpful to experimentalists in order to gain insights into these novel heteroatom molecules. Graphical abstract Relative energy profile (in kcal mol-1) using the CCSD(T)/CBS and MP2/CBS (in parentheses) method of the stationary states on the [H, S, Se, Br] PES.
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16
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Stoppa P, Visinoni R, Baldacci A, Larsen RW. High-resolution infrared spectroscopy of CH 2D 79Br: ro-vibrational analysis of the ν 4 and ν 8 fundamental bands. Mol Phys 2017. [DOI: 10.1080/00268976.2017.1303547] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
Affiliation(s)
- P. Stoppa
- Dipartimento di Scienze Molecolari e Nanosistemi, Università Ca’ Foscari Venezia, Mestre (Venezia), Italy
| | - R. Visinoni
- Dipartimento di Scienze Molecolari e Nanosistemi, Università Ca’ Foscari Venezia, Mestre (Venezia), Italy
| | - A. Baldacci
- Dipartimento di Scienze Molecolari e Nanosistemi, Università Ca’ Foscari Venezia, Mestre (Venezia), Italy
| | - R. Wugt Larsen
- Department of Chemistry, Technical University of Denmark, Kongens Lyngby, Denmark
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17
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Hossaini R, Chipperfield MP, Montzka SA, Leeson AA, Dhomse SS, Pyle JA. The increasing threat to stratospheric ozone from dichloromethane. Nat Commun 2017; 8:15962. [PMID: 28654085 PMCID: PMC5490265 DOI: 10.1038/ncomms15962] [Citation(s) in RCA: 64] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2016] [Accepted: 05/16/2017] [Indexed: 11/29/2022] Open
Abstract
It is well established that anthropogenic chlorine-containing chemicals contribute to ozone layer depletion. The successful implementation of the Montreal Protocol has led to reductions in the atmospheric concentration of many ozone-depleting gases, such as chlorofluorocarbons. As a consequence, stratospheric chlorine levels are declining and ozone is projected to return to levels observed pre-1980 later this century. However, recent observations show the atmospheric concentration of dichloromethane—an ozone-depleting gas not controlled by the Montreal Protocol—is increasing rapidly. Using atmospheric model simulations, we show that although currently modest, the impact of dichloromethane on ozone has increased markedly in recent years and if these increases continue into the future, the return of Antarctic ozone to pre-1980 levels could be substantially delayed. Sustained growth in dichloromethane would therefore offset some of the gains achieved by the Montreal Protocol, further delaying recovery of Earth’s ozone layer. Chlorine-containing species deplete stratospheric ozone and while chlorofluorocarbons have been drastically reduced, dichloromethane concentrations have recently increased rapidly. Hossaini et al. show that continued growth at this rate could result in important delays to Antarctic ozone recovery.
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Affiliation(s)
- Ryan Hossaini
- Lancaster Environment Centre, Lancaster University, Lancaster LA1 4YQ, UK
| | - Martyn P Chipperfield
- School of Earth and Environment, University of Leeds, Leeds LS2 9JT, UK.,National Centre for Earth Observation, University of Leeds, Leeds LS2 9JT, UK
| | - Stephen A Montzka
- National Oceanic and Atmospheric Administration, Boulder, Colorado 80305, USA
| | - Amber A Leeson
- Lancaster Environment Centre, Lancaster University, Lancaster LA1 4YQ, UK
| | - Sandip S Dhomse
- School of Earth and Environment, University of Leeds, Leeds LS2 9JT, UK.,National Centre for Earth Observation, University of Leeds, Leeds LS2 9JT, UK
| | - John A Pyle
- Department of Chemistry, University of Cambridge, Cambridge CB2 1EW, UK.,National Centre for Atmospheric Science, University of Cambridge, Cambridge CB2 1EW, UK
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18
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Anderson JG, Weisenstein DK, Bowman KP, Homeyer CR, Smith JB, Wilmouth DM, Sayres DS, Klobas JE, Leroy SS, Dykema JA, Wofsy SC. Stratospheric ozone over the United States in summer linked to observations of convection and temperature via chlorine and bromine catalysis. Proc Natl Acad Sci U S A 2017; 114:E4905-E4913. [PMID: 28584119 PMCID: PMC5488921 DOI: 10.1073/pnas.1619318114] [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
We present observations defining (i) the frequency and depth of convective penetration of water into the stratosphere over the United States in summer using the Next-Generation Radar system; (ii) the altitude-dependent distribution of inorganic chlorine established in the same coordinate system as the radar observations; (iii) the high resolution temperature structure in the stratosphere over the United States in summer that resolves spatial and structural variability, including the impact of gravity waves; and (iv) the resulting amplification in the catalytic loss rates of ozone for the dominant halogen, hydrogen, and nitrogen catalytic cycles. The weather radar observations of ∼2,000 storms, on average, each summer that reach the altitude of rapidly increasing available inorganic chlorine, coupled with observed temperatures, portend a risk of initiating rapid heterogeneous catalytic conversion of inorganic chlorine to free radical form on ubiquitous sulfate-water aerosols; this, in turn, engages the element of risk associated with ozone loss in the stratosphere over the central United States in summer based upon the same reaction network that reduces stratospheric ozone over the Arctic. The summertime development of the upper-level anticyclonic flow over the United States, driven by the North American Monsoon, provides a means of retaining convectively injected water, thereby extending the time for catalytic ozone loss over the Great Plains. Trusted decadal forecasts of UV dosage over the United States in summer require understanding the response of this dynamical and photochemical system to increased forcing of the climate by increasing levels of CO2 and CH4.
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Affiliation(s)
- James G Anderson
- Department of Chemistry and Chemical Biology, Harvard University, Cambridge, MA 02138;
- Department of Earth and Planetary Sciences, Harvard University, Cambridge, MA 02138
- Harvard John A. Paulson School of Engineering and Applied Sciences, Harvard University, Cambridge, MA 02138
| | - Debra K Weisenstein
- Harvard John A. Paulson School of Engineering and Applied Sciences, Harvard University, Cambridge, MA 02138
| | - Kenneth P Bowman
- Department of Atmospheric Sciences, Texas A&M University, College Station, TX 77843
| | | | - Jessica B Smith
- Harvard John A. Paulson School of Engineering and Applied Sciences, Harvard University, Cambridge, MA 02138
| | - David M Wilmouth
- Department of Chemistry and Chemical Biology, Harvard University, Cambridge, MA 02138
- Harvard John A. Paulson School of Engineering and Applied Sciences, Harvard University, Cambridge, MA 02138
| | - David S Sayres
- Harvard John A. Paulson School of Engineering and Applied Sciences, Harvard University, Cambridge, MA 02138
| | - J Eric Klobas
- Department of Chemistry and Chemical Biology, Harvard University, Cambridge, MA 02138
| | - Stephen S Leroy
- Harvard John A. Paulson School of Engineering and Applied Sciences, Harvard University, Cambridge, MA 02138
| | - John A Dykema
- Harvard John A. Paulson School of Engineering and Applied Sciences, Harvard University, Cambridge, MA 02138
| | - Steven C Wofsy
- Department of Earth and Planetary Sciences, Harvard University, Cambridge, MA 02138
- Harvard John A. Paulson School of Engineering and Applied Sciences, Harvard University, Cambridge, MA 02138
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19
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Short MA, de Caritat P, McPhail DC. Continental-scale variation in chloride/bromide ratios of wet deposition. THE SCIENCE OF THE TOTAL ENVIRONMENT 2017; 574:1533-1543. [PMID: 27577174 DOI: 10.1016/j.scitotenv.2016.08.161] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/25/2016] [Revised: 08/20/2016] [Accepted: 08/22/2016] [Indexed: 06/06/2023]
Abstract
Chlorine and bromine play crucial roles in atmospheric element cycles and are important environmental tracers in catchment investigations, so understanding their distribution at the Earth's near-surface is imperative for deciphering their behaviour. This study presents the first continental-scale analysis of Cl- and Br- concentrations of wet deposition, based on six and half years of weekly samples collected across North America. A recently developed imputation algorithm was applied to estimate the high proportion of censored Br- values, as well as the other eight analytes, based on the multivariate relationships of nine analytes. The results are consistent with previous studies that have found that the concentrations of these two ions in wet deposition, and the Cl-/Br- ratios of wet deposition decrease with distance inland. Close to the coast, Cl-/Br- ratios of wet deposition are similar to the ratio found in seawater (~288 by mass), rapidly decrease to approximately a third of the seawater ratio at ~200km inland, and then decrease at a much lesser rate to reach mass-ratios of 20 to 10 at ~1500km inland, following a logarithmic regression. The Niagara Falls and the Great Salt Lake are identified as localised sources of atmospheric solutes based on elevated Cl-/Br- ratios of wet deposition at proximal sites. Our observations provide further confidence in the findings presented in previous studies that have shown that Cl-/Br- ratios systematically decrease with increasing distance from the coast, despite the potential confounding impact of other processes, such as weather patterns, chemical behaviour and anthropogenic activity. Our results provide improved estimates of Cl-/Br- ratios of wet deposition source water in the absence of site-specific data.
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Affiliation(s)
- M A Short
- Research School of Earth Sciences, The Australian National University, Canberra, Australian Capital Territory 2601, Australia.
| | - P de Caritat
- Research School of Earth Sciences, The Australian National University, Canberra, Australian Capital Territory 2601, Australia
| | - D C McPhail
- Research School of Earth Sciences, The Australian National University, Canberra, Australian Capital Territory 2601, Australia
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20
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Oman LD, Douglass AR, Salawitch RJ, Canty TP, Ziemke JR, Manyin M. The Effect of Representing Bromine from VSLS on the Simulation and Evolution of Antarctic Ozone. GEOPHYSICAL RESEARCH LETTERS 2016; 43:9869-9876. [PMID: 29551840 PMCID: PMC5854488 DOI: 10.1002/2016gl070471] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
We use the Goddard Earth Observing System Chemistry-Climate Model (GEOSCCM), a contributor to both the 2010 and 2014 WMO Ozone Assessment Reports, to show that inclusion of 5 parts per trillion (ppt) of stratospheric bromine (Bry) from very short-lived substances (VSLS) is responsible for about a decade delay in ozone hole recovery. These results partially explain the significantly later recovery of Antarctic ozone noted in the 2014 report, as bromine from VSLS was not included in the 2010 Assessment. We show multiple lines of evidence that simulations that account for VSLS Bry are in better agreement with both total column BrO and the seasonal evolution of Antarctic ozone reported by the Ozone Monitoring Instrument (OMI) on NASA's Aura satellite. In addition, the near zero ozone levels observed in the deep Antarctic lower stratospheric polar vortex are only reproduced in a simulation that includes this Bry source from VSLS.
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Affiliation(s)
- Luke D. Oman
- NASA Goddard Space Flight Center, Greenbelt, MD, USA
| | | | | | | | - Jerald R. Ziemke
- NASA Goddard Space Flight Center, Greenbelt, MD, USA
- Morgan State University, Baltimore, MD, USA
| | - Michael Manyin
- NASA Goddard Space Flight Center, Greenbelt, MD, USA
- Science Systems and Applications, Inc., Lanham, MD, USA
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21
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Dykema JA, Keith DW, Anderson JG, Weisenstein D. Stratospheric controlled perturbation experiment: a small-scale experiment to improve understanding of the risks of solar geoengineering. PHILOSOPHICAL TRANSACTIONS. SERIES A, MATHEMATICAL, PHYSICAL, AND ENGINEERING SCIENCES 2014; 372:20140059. [PMID: 25404681 PMCID: PMC4240955 DOI: 10.1098/rsta.2014.0059] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
Although solar radiation management (SRM) through stratospheric aerosol methods has the potential to mitigate impacts of climate change, our current knowledge of stratospheric processes suggests that these methods may entail significant risks. In addition to the risks associated with current knowledge, the possibility of 'unknown unknowns' exists that could significantly alter the risk assessment relative to our current understanding. While laboratory experimentation can improve the current state of knowledge and atmospheric models can assess large-scale climate response, they cannot capture possible unknown chemistry or represent the full range of interactive atmospheric chemical physics. Small-scale, in situ experimentation under well-regulated circumstances can begin to remove some of these uncertainties. This experiment-provisionally titled the stratospheric controlled perturbation experiment-is under development and will only proceed with transparent and predominantly governmental funding and independent risk assessment. We describe the scientific and technical foundation for performing, under external oversight, small-scale experiments to quantify the risks posed by SRM to activation of halogen species and subsequent erosion of stratospheric ozone. The paper's scope includes selection of the measurement platform, relevant aspects of stratospheric meteorology, operational considerations and instrument design and engineering.
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Affiliation(s)
- John A Dykema
- School of Engineering and Applied Sciences, Harvard University, One Brattle Square, Cambridge, MA 02138, USA
| | - David W Keith
- School of Engineering and Applied Sciences, Harvard University, One Brattle Square, Cambridge, MA 02138, USA Harvard Kennedy School and School of Engineering and Applied Science, Pierce Hall, 29 Oxford Street, Cambridge, MA 02138, USA
| | - James G Anderson
- School of Engineering and Applied Sciences, Harvard University, One Brattle Square, Cambridge, MA 02138, USA Department of Chemistry and Chemical Biology, Harvard University, Mallinckrodt Link Building, 12 Oxford Street, Cambridge, MA 02138, USA
| | - Debra Weisenstein
- School of Engineering and Applied Sciences, Harvard University, One Brattle Square, Cambridge, MA 02138, USA
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22
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Teixeira OBM, Mota VC, Garcia de la Vega JM, Varandas AJC. Single-Sheeted Double Many-Body Expansion Potential Energy Surface for Ground-State ClO2. J Phys Chem A 2014; 118:4851-62. [DOI: 10.1021/jp503744x] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- O. B. M. Teixeira
- Departamento
de Química Física Aplicada, Universidad Autónoma de Madrid, 28049 Madrid, Spain
| | - V. C. Mota
- Departamento
de Física, Universidade Federal do Espirito Santo, 29075-910 Vitória, Brazil
| | - J. M. Garcia de la Vega
- Departamento
de Química Física Aplicada, Universidad Autónoma de Madrid, 28049 Madrid, Spain
| | - A. J. C. Varandas
- Departamento
de Física, Universidade Federal do Espirito Santo, 29075-910 Vitória, Brazil
- Centro de Química,
and Departamento de Química, Universidade de Coimbra, 3004-535 Coimbra, Portugal
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23
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Ferracci V, Rowley DM. Kinetic studies of the BrO + ClO cross-reaction over the range T = 246-314 K. Phys Chem Chem Phys 2014; 16:1182-96. [PMID: 24292658 DOI: 10.1039/c3cp53440e] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
The kinetics of the atmospherically important gas phase radical reaction between BrO and ClO have been studied over the temperature range T = 246-314 K by means of laser flash photolysis coupled with UV absorption spectroscopy. Charge-coupled-device (CCD) detection allowed simultaneous monitoring of both free radicals and the OClO product using 'differential' spectroscopy, which minimised interference from underlying UV absorbing species. In this way, the total rate coefficient for BrO + ClO → products (1) was measured, along with that for the OClO producing channel of this process BrO + ClO → OClO + Br (1c). These reaction rate coefficients are described by the Arrhenius expressions: k1/cm(3) molecule(-1) s(-1) = (2.5 ± 2.2) × 10(-12) exp[(630 ± 240)/T] and k(1c)/cm(3) molecule(-1) s(-1) = (4.6 ± 3.0) × 10(-12) exp[(280 ± 180)/T], where errors are 2σ, statistical only. An extensive sensitivity analysis was performed to quantify the potential additional systematic uncertainties in this work arising from uncertainties in secondary chemistry, absorption cross-sections and precursor concentrations. This analysis identified the reactions of initial and secondarily generated bromine atoms (specifically Br + O3 and Br + Cl2O) as particularly important, along with the reversible combination of ClO with OClO forming Cl2O3. Potential uncertainty in this latter process was used to define the lowest temperature of the present study. Results from this work indicate larger absolute values for k1 and k(1c) than those reported in previous studies, but a weaker negative temperature dependence for k(1c) than previously observed, resulting in a branching ratio for with a positive temperature dependence, in disagreement with previous studies. is the principal source of OClO in the polar stratosphere and is commonly used in atmospheric models as an indicator of stratospheric bromine chemistry. Thus these measurements might lead to a reinterpretation of modelled stratospheric OClO, which has also been suggested by previous comparisons of observations with atmospheric model studies.
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Affiliation(s)
- Valerio Ferracci
- Department of Chemistry, University College London, Christopher Ingold Laboratories, 20 Gordon Street, London WC1H 0AJ, UK.
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24
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Grubb MP, Dooley KS, Freeman CD, Peterson KA, North SW. Experimental and theoretical investigation of correlated fine structure branching ratios arising from state-selected predissociation of BrO (A2Π3/2). Phys Chem Chem Phys 2014; 16:607-15. [PMID: 24202006 DOI: 10.1039/c3cp53766h] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
We present results for the v'-dependent predissociation dynamics of the BrO (A(2)Π3/2) state using velocity map ion imaging. Correlated fine structure branching ratios, Br((2)P(J)) + O((3)P(J)), have been measured for v' = 5-16 states. The experimental branching ratios are non-statistical and strongly dependent on the initial vibronic state. The current measurements represent an extensive dataset containing rich information about the predissociation dynamics of this system and should provide a stringent test for modern theory. New high level ab initio excited state potentials are presented and have been optimized using experimental v'-dependent predissociation lifetimes and calculated coupling constants. Comparisons between the experimental branching ratios and the predictions based on diabatic and adiabatic limiting models are presented. We find that the adiabatic model is most consistent with the observed trends in the correlated branching ratios, in contrast to previous studies on the related ClO system.
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Affiliation(s)
- Michael P Grubb
- Department of Chemistry, Texas A&M University, P. O. Box 30012, College Station, Texas 77842, USA.
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25
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Tu CP, Cheng HI, Chang BC. Spectroscopic study of the I2 formation from the photolysis of iodomethanes (CHI3, CH2I2, CH3I, and CH2ICl) at different wavelengths. J Phys Chem A 2013; 117:13572-7. [PMID: 23952939 DOI: 10.1021/jp407599x] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Emission spectra following the photolysis of iodomethanes (CHI3, CH2I2, CH3I, and CH2ICl) at 266 nm were recorded in a slow flow cell. In addition to emission from the electronically excited species including CH (A(2)Δ, B(2)Σ(-), and C(2)Σ(+)), C2 (d(3)Πg), and atomic iodine ((4)P(o)), a series of emission bands was observed in the 12,000-19,000 cm(-1) region. The dominant structure of these emission bands was verified as the I2 B(3)Π(+)(0,u)-X(1)Σ(+)g emission at the 532 nm excitation, and the observed I2 was formed from collisions between iodine atoms generated from the C-I bond dissociation in these iodomethanes. The I2 emission spectra following the photolysis of CH2I2 at different wavelengths were acquired, and the threshold energy for the first C-I bond cleavage was determined to be 208 ± 1 kJ mol(-1). We also obtained the emission spectra of pure I2 at several visible excitation wavelengths for comparison with those from the photolysis of iodomethanes, and a least-squares global fit of the observed I2 emission bands yields more accurate anharmonicity parameters for the vibrational structure in the I2 B-X transition.
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Affiliation(s)
- Cian-Ping Tu
- Department of Chemistry, National Central University , 300 Jungda Road, Jhongli 32001, Taiwan
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26
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Austin J, Butchart N. A three-dimensional modeling study of the influence of planetary wave dynamics on polar ozone photochemistry. ACTA ACUST UNITED AC 2012. [DOI: 10.1029/92jd00505] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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27
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Wooldridge PJ, Zhang R, Molina MJ. Phase equilibria of H2SO4, HNO3, and HCl hydrates and the composition of polar stratospheric clouds. ACTA ACUST UNITED AC 2012. [DOI: 10.1029/94jd02745] [Citation(s) in RCA: 60] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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28
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Sanders RW, Solomon S, Smith JP, Perliski L, Miller HL, Mount GH, Keys JG, Schmeltekopf AL. Visible and near-ultraviolet spectroscopy at McMurdo Station, Antarctica: 9. Observations of OClO from April to October 1991. ACTA ACUST UNITED AC 2012. [DOI: 10.1029/93jd00042] [Citation(s) in RCA: 50] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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29
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Rietmeijer FJM. The bromine content of micrometeorites: Arguments for stratospheric contamination. ACTA ACUST UNITED AC 2012. [DOI: 10.1029/93je00118] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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30
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Anderson JG, Wilmouth DM, Smith JB, Sayres DS. UV Dosage Levels in Summer: Increased Risk of Ozone Loss from Convectively Injected Water Vapor. Science 2012; 337:835-9. [DOI: 10.1126/science.1222978] [Citation(s) in RCA: 147] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
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31
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Raghunath P, Lin MC. Ab initio chemical kinetics for the ClOO + NO reaction: Effects of temperature and pressure on product branching formation. J Chem Phys 2012; 137:014315. [DOI: 10.1063/1.4731883] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
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32
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Begović N, Marković Z, Anić S. Kinetics of thermal reaction HOCl ⇄ H(2 S) + OCl(X 2Π i ) in gas phase. RUSSIAN JOURNAL OF PHYSICAL CHEMISTRY A 2011. [DOI: 10.1134/s0036024411130048] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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33
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Pan C, Liang X, Wang R, Tao S, Liang J, Cui Z. A combined ab initio and Franck–Condon simulation study of the photodetachment spectrum of the anion. COMPUT THEOR CHEM 2011. [DOI: 10.1016/j.comptc.2011.08.009] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
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34
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Liu Y, Yvon-Lewis SA, Hu L, Salisbury JE, O'Hern JE. CHBr3, CH2Br2, and CHClBr2in U.S. coastal waters during the Gulf of Mexico and East Coast Carbon cruise. ACTA ACUST UNITED AC 2011. [DOI: 10.1029/2010jc006729] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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35
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Chen JL, Hu WP. Theoretical Prediction on the Thermal Stability of Cyclic Ozone and Strong Oxygen Tunneling. J Am Chem Soc 2011; 133:16045-53. [DOI: 10.1021/ja203428x] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Jien-Lian Chen
- Department of Chemistry and Biochemistry, National Chung Cheng University, Chia-Yi, 621, Taiwan
| | - Wei-Ping Hu
- Department of Chemistry and Biochemistry, National Chung Cheng University, Chia-Yi, 621, Taiwan
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36
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Rhew RC. Sources and sinks of methyl bromide and methyl chloride in the tallgrass prairie: Applying a stable isotope tracer technique over highly variable gross fluxes. ACTA ACUST UNITED AC 2011. [DOI: 10.1029/2011jg001704] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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37
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Papanastasiou DK, Feierabend KJ, Burkholder JB. Cl2O photochemistry: Ultraviolet/vis absorption spectrum temperature dependence and O(3P) quantum yield at 193 and 248 nm. J Chem Phys 2011; 134:204310. [DOI: 10.1063/1.3592662] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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38
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Papanastasiou DK, Burkholder JB. Rate coefficients for the O(3
P) + Cl2
O gas-phase reaction between 230 and 357 K. INT J CHEM KINET 2011. [DOI: 10.1002/kin.20556] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
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39
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Wang H, Wang M, Yang C, Ma M. The SAC/SAC-CI studies of ground and low-lying electronic excited states of OClO, OClO+ and OClO−. COMPUT THEOR CHEM 2011. [DOI: 10.1016/j.comptc.2011.01.021] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
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40
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41
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Huang J, Kang S, Shen C, Cong Z, Liu K, Wang W, Liu L. Concentration and seasonal variation of 10Be in surface aerosols of Lhasa, Tibet. ACTA ACUST UNITED AC 2010. [DOI: 10.1007/s11434-010-3233-1] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
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42
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McLinden CA, Haley CS, Lloyd ND, Hendrick F, Rozanov A, Sinnhuber BM, Goutail F, Degenstein DA, Llewellyn EJ, Sioris CE, Van Roozendael M, Pommereau JP, Lotz W, Burrows JP. Odin/OSIRIS observations of stratospheric BrO: Retrieval methodology, climatology, and inferred Bry. ACTA ACUST UNITED AC 2010. [DOI: 10.1029/2009jd012488] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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43
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Anderson JG, Toohey DW, Brune WH. Free Radicals Within the Antarctic Vortex: The Role of CFCs in Antarctic Ozone Loss. Science 2010; 251:39-46. [PMID: 17778601 DOI: 10.1126/science.251.4989.39] [Citation(s) in RCA: 206] [Impact Index Per Article: 14.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
How strong is the case linking global release of chlorofluorocarbons to episodic disappearance of ozone from the Antarctic stratosphere each austral spring? Three lines of evidence defining a link are (i) observed containment in the vortex of ClO concentrations two orders of magnitude greater than normal levels; (ii) in situ observations obtained during ten high-altitude aircraft flights into the vortex as the ozone hole was forming that show a decrease in ozone concentrations as ClO concentrations increased; and (iii) a comparison between observed ozone loss rates and those predicted with the use of absolute concentrations of ClO and BrO, the rate-limiting radicals in an array of proposed catalytic cycles. Recent advances in our understanding of the kinetics, photochemistry, and structural details of key intermediates in these catalytic cycles as well as an improved absolute calibration for ClO and BrO concentrations at the temperatures and pressures encountered in the lower antarctic stratosphere have been essential for defining the link.
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Abstract
The average worldwide tropospheric mixing ratio of methane has increased by 11% from 1.52 parts per million by volume (ppmv) in January 1978 to 1.684 ppmv in September 1987, for an increment of 0.016 +/- 0.001 ppmv per year. Within the limits of our measurements, the global tropospheric mixing ratio for methane over the past decade is consistent either with a linear growth rate of 0.016 +/- 0.001 ppmv per year or with a slight lessening of the rate of growth over the past 5 years. No indications were found of an effect of the El Niño-Southern Oscillation-El Chichon events of 1982-83 on total global methane, although severe reductions were reported in the Pacific Northwest during that time period. The growth in tropospheric methane may have increased the water concentration in the stratosphere by as much as 28% since the 1940s and 45% over the past two centuries and thus could have increased the mass of precipitable water available for formation of polar stratospheric clouds.
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Abstract
The ozone layer in the upper atmosphere is a natural feature of the earth's environment. It performs several important functions, including shielding the earth from damaging solar ultraviolet radiation. Far from being static, ozone concentrations rise and fall under the forces of photochemical production, catalytic chemical destruction, and fluid dynamical transport. Human activities are projected to deplete substantially stratospheric ozone through anthropogenic increases in the global concentrations of key atmospheric chemicals. Human-induced perturbations may be occurring already.
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Schoeberl MR, Hartmann DL. The dynamics of the stratospheric polar vortex and its relation to springtime ozone depletions. Science 2010; 251:46-52. [PMID: 17778602 DOI: 10.1126/science.251.4989.46] [Citation(s) in RCA: 223] [Impact Index Per Article: 15.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
Dramatic springtime depletions of ozone in polar regions require that polar stratospheric air has a high degree of dynamical isolation and extremely cold temperatures necessary for the formation of polar stratospheric clouds. Both of these conditions are produced within the stratospheric winter polar vortex. Recent aircraft missions have provided new information about the structure of polar vortices during winter and their relation to polar ozone depletions. The aircraft data show that gradients of potential vorticity and the concentration of conservative trace species are large at the transition from mid-latitude to polar air. The presence of such sharp gradients at the boundary of polar air implies that the inward mixing of heat and constituents is strongly inhibited and that the perturbed polar stratospheric chemistry associated with the ozone hole is isolated from the rest of the stratosphere until the vortex breaks up in late spring. The overall size of the polar vortex thus limits the maximum areal coverage of the annual polar ozone depletions. Because it appears that this limit has not been reached for the Antarctic depletions, the possibility of future increases in the size of the Antarctic ozone hole is left open. In the Northern Hemisphere, the smaller vortex and the more restricted region of cold temperatures suggest that this region has a smaller theoretical maximum for column ozone depletion, about 40 percent of the currently observed change in the Antarctic ozone column in spring.
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Supercooled Sulfuric Acid Droplets: Perturbed Stratospheric Chemistry in Early Winter. ACTA ACUST UNITED AC 2010. [DOI: 10.1002/bbpc.19920960319] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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Yang SX, Hou GY, Dai JH, Chang CH, Chang BC. Spectroscopic investigation of the multiphoton photolysis reactions of bromomethanes (CHBr3, CHBr2Cl, CHBrCl2, and CH2Br2) at near-ultraviolet wavelengths. J Phys Chem A 2010; 114:4785-90. [PMID: 20041692 DOI: 10.1021/jp909875k] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Nascent emission and laser-induced dispersed fluorescence spectra of products or intermediates from the multiphoton photolysis reaction of bromomethanes (CHBr(3), CHBr(2)Cl, CHBrCl(2), and CH(2)Br(2)) at 266 nm were recorded in a slow flow cell. Electronically excited species including CH (A(2)Delta, B(2)Sigma(-), and C(2)Sigma(+)), C(2) (d(3)Pi(g)), and atomic Br ((4)D(J) and (4)P(J)) were observed in the nascent emission spectra. Free radicals such CHBr or CHCl were also successfully found using laser-induced dispersed fluorescence spectroscopy. The reactive intermediate, CHBr, was seen only in the photolysis of CHBr(3), whereas CHCl was only discovered when the precursor was CHBr(2)Cl or CHBrCl(2). More experiments including the power dependence and temporal waveform measurements were conducted. The present study reports the first direct measurements of the intermediate products in the multiphoton photodissociation reaction of these bromomethanes at 266 nm. Nascent emission spectra following the photolysis at longer near-ultraviolet wavelengths (280 and 355 nm) were also acquired. On the bassis of these results, the multiphoton photodissociation mechanism of these bromomethanes at 266 nm can be confirmed.
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Affiliation(s)
- Shi-Xing Yang
- Department of Chemistry, National Central University, 300 Jhongda Road, Jhongli 32001, Taiwan
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49
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Du S, Francisco JS, Schenter GK, Garrett BC. Interaction of ClO Radical with Liquid Water. J Am Chem Soc 2009; 131:14778-85. [DOI: 10.1021/ja9033186] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023]
Affiliation(s)
- Shiyu Du
- Department of Chemistry and Department of Earth and Atmospheric Sciences, Purdue University, West Lafayette, Indiana 47907-1393, and Fundamental & Computational Sciences Directorate, Pacific Northwest National Laboratory, Richland, Washington 99352
| | - Joseph S. Francisco
- Department of Chemistry and Department of Earth and Atmospheric Sciences, Purdue University, West Lafayette, Indiana 47907-1393, and Fundamental & Computational Sciences Directorate, Pacific Northwest National Laboratory, Richland, Washington 99352
| | - Gregory K. Schenter
- Department of Chemistry and Department of Earth and Atmospheric Sciences, Purdue University, West Lafayette, Indiana 47907-1393, and Fundamental & Computational Sciences Directorate, Pacific Northwest National Laboratory, Richland, Washington 99352
| | - Bruce C. Garrett
- Department of Chemistry and Department of Earth and Atmospheric Sciences, Purdue University, West Lafayette, Indiana 47907-1393, and Fundamental & Computational Sciences Directorate, Pacific Northwest National Laboratory, Richland, Washington 99352
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50
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Cracknell AP, Varotsos CA. The contribution of remote sensing to the implementation of the Montreal Protocol and the monitoring of its success. INTERNATIONAL JOURNAL OF REMOTE SENSING 2009; 30:3853-3873. [DOI: 10.1080/01431160902821999] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/16/2023]
Affiliation(s)
- Arthur P. Cracknell
- a Division of Electronic Engineering and Physics , University of Dundee , Dundee, DD1 4HN, Scotland, UK
| | - Costas A. Varotsos
- b Department of Applied Physics , University of Athens , Panepistimioupolis Building 5, 15784, Athens, Greece
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