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Zhang Y, He B, Sun Y, Huang B, Wang Z, Zhou Y. Theoretical investigations on mechanisms and pathways of CH 2ClO 2/CHCl 2O 2 with ClO reactions in the atmosphere. ENVIRONMENTAL SCIENCE AND POLLUTION RESEARCH INTERNATIONAL 2020; 27:20457-20468. [PMID: 32242320 DOI: 10.1007/s11356-020-08315-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/27/2019] [Accepted: 03/02/2020] [Indexed: 06/11/2023]
Abstract
A global and systematic theoretical research on the singlet and triplet potential energy surfaces (PESs) of the CH2ClO2/CHCl2O2 with ClO reactions are done at the CCSD(T)//B3LYP level and accompanied with RRKM computations to forecast the mechanism and distribution of products. The simulation results revealed that, on the singlet PES, products P1 (CHClO + HO2 + Cl)/P1 (CCl2O + HO2 + Cl) from IM1 (CH2ClOOOCl)/IM1 (CHCl2OOOCl) are forecasted to the primary products of the CH2ClO2/CHCl2O2 + ClO reactions, which are initiated by the oxygen atom of ClO radical addition to the terminal-O atom of CH2ClO2/CHCl2O2 barrierlessly, while other product channels contribute less to the whole reactions owing to higher barriers. Two other isomers, including IM2 (CH2ClOOClO) and IM3 (CH2ClOClO2) for the CH2ClO2 + ClO reaction, and three other isomers, including IM2 (CHCl2OOClO), IM3 (CHCl2OClO2), and IM4 (CHCl2ClO3) for the CHCl2O2 + ClO reaction, could be produced as less significant products. RRKM calculations presented that the initial adducts IM1 (CH2ClOOOCl)/IM1 (CHCl2OOOCl) are the primary products at T < 400 K and T < 600 K, respectively, and products P1 (CHClO + HO2 + Cl)/P1 (CCl2O + HO2 + Cl) are dominant the reactions at T ≥ 400 K and T ≥ 600 K, respectively. The atmospheric lifetime of CH2ClO2 and CHCl2O2 in ClO is around 4.61 and 3.24 h, respectively.
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Affiliation(s)
- Yunju Zhang
- Key Laboratory of Photoinduced Functional Materials, Mianyang Normal University, Mianyang, 621000, People's Republic of China.
| | - Bing He
- College of Chemistry and Life Science, Institute of functional molecules, Chengdu Normal University, Chengdu, 611130, Sichuan, People's Republic of China
| | - Yuxi Sun
- Key Laboratory of Photoinduced Functional Materials, Mianyang Normal University, Mianyang, 621000, People's Republic of China
| | - Baomei Huang
- Key Laboratory of Photoinduced Functional Materials, Mianyang Normal University, Mianyang, 621000, People's Republic of China
| | - Zhiguo Wang
- Key Laboratory of Photoinduced Functional Materials, Mianyang Normal University, Mianyang, 621000, People's Republic of China
| | - Yan Zhou
- Key Laboratory of Photoinduced Functional Materials, Mianyang Normal University, Mianyang, 621000, People's Republic of China
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Horný Ľ, Quack M, Schaefer HF, Willeke M. Chlorine peroxide (Cl2O2) and its isomers: structures, spectroscopy, formation and thermochemistry. Mol Phys 2016. [DOI: 10.1080/00268976.2016.1143984] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
Affiliation(s)
- Ľuboš Horný
- Laboratory of Physical Chemistry, ETH Zürich, CH-8093 Zürich, Switzerland
| | - Martin Quack
- Laboratory of Physical Chemistry, ETH Zürich, CH-8093 Zürich, Switzerland
| | - Henry F. Schaefer
- Center for Computational Chemistry, University of Georgia, Athens, GA, USA
| | - Martin Willeke
- Department of Materials, ETH Zürich, Zürich, Switzerland
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3
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Ferracci V, Rowley DM. The temperature dependence of the bimolecular channels of the ClO + ClO reaction over the range T
= 298-323 K. INT J CHEM KINET 2012. [DOI: 10.1002/kin.20573] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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4
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Zhu R, Lin M. Ab initio chemical kinetics for ClO reactions with HOx, ClOx and NOx (x=1,2): A review. COMPUT THEOR CHEM 2011. [DOI: 10.1016/j.comptc.2010.12.002] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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5
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Zhu RS, Lin MC. Ab initio chemical kinetics for reactions of ClO with Cl 2O 2 isomers. J Chem Phys 2011; 134:054307. [DOI: 10.1063/1.3541353] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
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6
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Ferracci V, Rowley DM. Kinetic and thermochemical studies of the ClO + ClO + M <=> Cl(2)O(2) + M reaction. Phys Chem Chem Phys 2010; 12:11596-608. [PMID: 20676457 DOI: 10.1039/c0cp00308e] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
Recent work by von Hobe et al. [Atmos. Chem. Phys., 2007, 7, 3055] has highlighted significant inconsistencies between laboratory results, theoretical calculations and field observations concerning the ClO dimer ozone destruction cycle. This work investigates the temperature dependence of the equilibrium constant of one of the key reactions in this cycle, ClO + ClO + M <=> Cl(2)O(2) + M (1, -1), by means of laser flash photolysis and time-resolved UV absorption spectroscopy. ClO radicals were generated via laser flash photolysis of Cl(2)/Cl(2)O mixtures in synthetic air. Radicals were monitored via UV absorption spectroscopy: the use of a charge coupled device (CCD) detector allowed time resolution over a broad range of wavelengths giving unequivocal concentrations of radicals. The equilibrium constant K(eq) was determined as the ratio of the rate constants of the forward and reverse over the temperature range T = 256.55-312.65 K. Second Law and Third Law thermodynamic methods were employed to determine the standard enthalpy and entropy changes of , Δ(r)H° and Δ(r)S°, from the measured equilibrium constants. The values obtained from Second Law analysis were Δ(r)H° = - 80.7 ± 2.2 kJ mol(-1) and Δ(r)S° = -168.1 ± 7.8 J K(-1) mol(-1). Third Law analysis gave Δ(r)H° = -74.65 ± 0.4 kJ mol(-1) and Δ(r)S° = -148.0 ± 0.4 J K(-1) mol(-1). These values are in good agreement with previous work by Nickolaisen et al. [J. Phys. Chem., 1994, 98, 155] but greater in (negative) magnitude than current JPL-NASA recommendations [Sander et al., Chemical Kinetics and Photochemical Data for Use in Atmospheric Studies, JPL Publication 06-2, NASA Jet Propulsion Laboratory, Pasadena, 2006 (interim update to this reference, 2009)]. The discrepancy between the Second and Third Law analyses also agrees with Nickolaisen et al., possibly indicating an aspect of the ClO recombination reaction not yet fully elucidated. The atmospheric implications of the results and their impact on the current understanding on polar ozone depletion are briefly discussed.
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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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Lien CY, Lin WY, Chen HY, Huang WT, Jin B, Chen IC, Lin JJ. Photodissociation cross sections of ClOOCl at 248.4 and 266 nm. J Chem Phys 2010; 131:174301. [PMID: 19895006 DOI: 10.1063/1.3257682] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023] Open
Abstract
This study utilized a mass-resolved detection of ClOOCl to determine its photodissociation cross section, which is the product of the absorption cross section and dissociation quantum yield. An effusive molecular beam of ClOOCl was generated and its photodissociation probability was determined through measuring the decrease in the ClOOCl beam intensity upon laser irradiation. By comparing with a reference molecule, the absolute cross sections of ClOOCl were obtained without knowing its absolute concentration. The determined cross section of ClOOCl at 248.4 nm is (8.85+/-0.42)x10(-18) cm(2) at 200 K, significantly larger than previously reported values. The temperature dependence of the cross section was investigated at 248.4 nm in the range of 160-260 K; only a very small and negative temperature effect was observed. Because 248.4 nm is very close to the peak of the UV absorption band of ClOOCl, this work provides a new calibration point for normalizing relative absorption spectra of ClOOCl. In this work, the photodissociation cross section at 266 nm and 200 K was also reported to be (4.13+/-0.21)x10(-18) cm(2).
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Affiliation(s)
- Chien-Yu Lien
- Institute of Atomic and Molecular Sciences, Academia Sinica, Taipei 10617, Taiwan
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Papanastasiou DK, Papadimitriou VC, Fahey DW, Burkholder JB. UV absorption spectrum of the ClO dimer (Cl2O2) between 200 and 420 nm. J Phys Chem A 2010; 113:13711-26. [PMID: 19954253 DOI: 10.1021/jp9065345] [Citation(s) in RCA: 61] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The UV photolysis of Cl(2)O(2) (dichlorine peroxide) is a key step in the catalytic destruction of polar stratospheric ozone. In this study, the gas-phase UV absorption spectrum of Cl(2)O(2) was measured using diode array spectroscopy and absolute cross sections, sigma, are reported for the wavelength range 200-420 nm. Pulsed laser photolysis of Cl(2)O at 248 nm or Cl(2)/Cl(2)O mixtures at 351 nm at low temperature (200-228 K) and high pressure (approximately 700 Torr, He) was used to produce ClO radicals and subsequently Cl(2)O(2) via the termolecular ClO self-reaction. The Cl(2)O(2) spectrum was obtained from spectra recorded following the completion of the gas-phase ClO radical chemistry. The spectral analysis used observed isosbestic points at 271, 312.9, and 408.5 nm combined with reaction stoichiometry and chlorine mass balance to determine the Cl(2)O(2) spectrum. The Cl(2)O(2) UV absorption spectrum peaks at 244.5 nm with a cross section of 7.6(-0.5)(+0.8) x 10(-18) cm(2) molecule(-1) where the quoted error limits are 2sigma and include estimated systematic errors. The Cl(2)O(2) absorption cross sections obtained for wavelengths in the range 300-420 nm are in good agreement with the Cl(2)O(2) spectrum reported previously by Burkholder et al. (J. Phys. Chem. A 1990, 94, 687) and significantly higher than the values reported by Pope et al. (J. Phys. Chem. A 2007, 111, 4322). A possible explanation for the discrepancy in the Cl(2)O(2) cross section values with the Pope et al. study is discussed. Representative, atmospheric photolysis rate coefficients are calculated and a range of uncertainty estimated based on the determination of sigma(Cl(2)O(2))(lambda) in this work. Although improvements in our fundamental understanding of the photochemistry of Cl(2)O(2) are still desired, this work indicates that major revisions in current atmospheric chemical mechanisms are not required to simulate observed polar ozone depletion.
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Affiliation(s)
- Dimitrios K Papanastasiou
- Earth System Research Laboratory, Chemical Sciences Division, National Oceanic and Atmospheric Administration, 325 Broadway, Boulder, Colorado 80305-3328, USA
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Chen HY, Lien CY, Lin WY, Lee YT, Lin JJ. UV absorption cross sections of ClOOCl are consistent with ozone degradation models. Science 2009; 324:781-4. [PMID: 19423825 DOI: 10.1126/science.1171305] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
Recently, discrepancies in laboratory measurements of chlorine peroxide (ClOOCl) absorption cross sections have cast doubt on the validity of current photochemical models for stratospheric ozone degradation. Whereas previous ClOOCl absorption measurements all suffered from uncertainties due to absorption by impurities, we demonstrate here a method that uses mass-selected detection to circumvent such interference. The cross sections of ClOOCl were determined at two critical wavelengths (351 and 308 nanometers). Our results are sufficient to resolve the controversial issue originating from the ClOOCl laboratory cross sections and suggest that the highest laboratory estimates for atmospheric photolysis rates of ClOOCl, which best explain the field measurements via current chemical models, are reasonable.
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Affiliation(s)
- Hsueh-Ying Chen
- Institute of Atomic and Molecular Sciences, Academia Sinica, Taipei 10617, Taiwan
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von Hobe M, Stroh F, Beckers H, Benter T, Willner H. The UV/Vis absorption spectrum of matrix-isolated dichlorine peroxide, ClOOCl. Phys Chem Chem Phys 2009; 11:1571-80. [PMID: 19240934 DOI: 10.1039/b814373k] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
UV/Vis absorption spectra of ClOOCl isolated in neon matrices were measured in the wavelength range 220-400 nm. The purity of the trapped samples was checked by infrared and UV/Vis matrix spectroscopy as well as low-temperature Raman spectroscopy. At wavelengths below 290 nm, the results agree with the UV spectrum recently published by Pope et al. [J. Phys. Chem. A, 2007, 111, 4322-4332]. However, the observed absorption in the long wavelength tail of the spectrum-relevant for polar stratospheric ozone loss-is substantially higher than reported by Pope et al. Our results suggest the existence of a ClOOCl electronic state manifold leading to an absorption band similar to those of the near UV spectrum of Cl(2). The differences to previous studies can be accounted for quantitatively by contributions to the reported absorption spectra caused by impurities. The observed band in the long wavelength tail is supported by several high-level ab initio calculations. However, questions arise concerning absolute values of the ClOOCl cross sections, an issue that needs to be revisited in future studies. With calculated photolysis rates based on our spectrum scaled to previous cross sections at the peak absorption, the known polar catalytic ozone-destruction cycles to a large extent account for the observed ozone depletion in the spring polar stratosphere.
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Affiliation(s)
- Marc von Hobe
- Forschungszentrum Jülich GmbH, Institute for Chemistry and Dynamics of the Geosphere ICG-1: Stratosphere, Jülich, Germany.
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11
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Matus MH, Nguyen MT, Dixon DA, Peterson KA, Francisco JS. ClClO2 Is the Most Stable Isomer of Cl2O2. Accurate Coupled Cluster Energetics and Electronic Spectra of Cl2O2 Isomers. J Phys Chem A 2008; 112:9623-7. [DOI: 10.1021/jp806220r] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Affiliation(s)
- Myrna H. Matus
- Department of Chemistry, The University of Alabama, Shelby Hall, Box 870336, Tuscaloosa, Alabama 35487-0336
| | - Minh T. Nguyen
- Department of Chemistry, The University of Alabama, Shelby Hall, Box 870336, Tuscaloosa, Alabama 35487-0336
| | - David A. Dixon
- Department of Chemistry, The University of Alabama, Shelby Hall, Box 870336, Tuscaloosa, Alabama 35487-0336
| | - Kirk A. Peterson
- Department of Chemistry, Washington State University, Pullman, Washington 99164-4630
| | - Joseph S. Francisco
- Department of Chemistry and Department of Earth & Atmospheric Sciences, Purdue University, West Lafayette, Indiana 47907-2084
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12
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Liu J, Barker JR. On the Chaperon Mechanism: Application to ClO + ClO (+N2) → ClOOCl (+N2). J Phys Chem A 2007; 111:8689-98. [PMID: 17696323 DOI: 10.1021/jp072978p] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The dynamics of the ClO + ClO (+N(2)) radical complex (or chaperon) mechanism is studied by electronic structure methods and quasi-classical trajectory calculations. The geometries and frequencies of the stationary points on the potential energy surface (PES) are optimized at the B3LYP/6-311+G(3df) level of theory, and the energies are refined at the CCSD(T)/6-311+G(3df) (single-point) level of theory. Basis set superposition error (BSSE) corrections are applied to obtain 1.5 kcal mol(-1) for the binding energy of the ClO.N(2) van der Waals (VDW) complex. A model PES is developed and used in quasi-classical trajectory calculations to obtain the capture rate constant and nascent energy distributions of ClOOCl* produced via the chaperon mechanism. A range of VDW binding energies from 1.5 to 9.0 kcal mol(-1) are investigated. The anisotropic PES for the ClO.N(2) complex and a separable anharmonic oscillator approximation are used to estimate the equilibrium constant for formation of the VDW complex. Rate constants, branching ratios to produce ClOOCl, and nascent energy distributions of excited ClOOCl* are discussed with respect to the VDW binding energy and temperature. Interestingly, even for weak VDW binding energies, the N(2) usually carries away enough energy to stabilize the nascent ClOOCl*, although the VDW equilibrium constant is small. For stronger binding energies, the stabilization efficiency is reduced, but the capture rate constant is increased commensurately. The resulting rate constants for forming ClOOCl* from the title reaction are only weakly dependent on the VDW binding energy and temperature. As a result, the relative importance of the chaperon mechanism is mostly dependent on the VDW equilibrium constant. For the calculated ClO.N(2) binding energy of 1.5 kcal mol(-1), the VDW equilibrium constant is small, and the chaperon mechanism is only important at very high pressures.
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Affiliation(s)
- Jingyao Liu
- Department of Atmospheric, Oceanic, and Space Sciences, University of Michigan, Ann Arbor, Michigan 48109-2143, USA
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Plenge J, Kühl S, Vogel B, Müller R, Stroh F, von Hobe M, Flesch R, Rühl E. Bond strength of chlorine peroxide. J Phys Chem A 2007; 109:6730-4. [PMID: 16834026 DOI: 10.1021/jp044142h] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
The bond strength of chlorine peroxide (ClOOCl) is studied by photoionization mass spectrometry. The experimental results are obtained from the fragmentation threshold yielding ClO+, which is observed at 11.52 +/- 0.025 eV. The O-O bond strength D(o) is derived from this value in comparison to the first ionization energy of ClO, yielding D(o)298 = 72.39 +/- 2.8 kJ mol(-1). The present work provides a new and independent method to examine the equilibrium constant K(eq) for chlorine peroxide formation via dimerization of ClO in the stratosphere. This yields an approximation for the equilibrium constant in the stratospheric temperature regime between 190 and 230 K of the form K(eq) = 1.92 x 10(-27) cm3 molecules(-1) x exp(8430 K/T). This value of K(eq) is lower than current reference data and agrees well with high altitude aircraft measurements within their scattering range. Considering the error limits of the present experimental results and the resulting equilibrium constant, there is agreement with previous works, but the upper limit of current reference values appears to be too high. This result is discussed along with possible atmospheric implications.
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Affiliation(s)
- J Plenge
- Department of Chemistry, University of California at Berkeley, USA
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Abstract
ClOOCl was prepared in situ in a temperature controlled photoreactor (v = 420 L) by photolyzing OClO/N2 mixtures in the wavelength range 300-500 nm at temperatures between 242 and 261 K and total pressures between 2 and 480 mbar. After switching off the lights, excess NO2 was added, and IR and UV spectra were monitored simultaneously as a function of time. By spectral stripping of all other known UV absorbers (in particular, other chlorine oxides and chlorine nitrate), we determined rate constants k-1 of the reaction ClOOCl (+M) --> ClO + ClO (+M) from the first-order decay of the residual UV absorption of ClOOCl at 246 and 255 nm. k-1,0 = [N2] x 7.6 x 10(-9) exp[(-53.6 +/- 6.0) kJ mol(-1)/RT] cm3 molecule(-1) s(-1) (2sigma) was derived for the low-pressure limiting rate constant. Application of Troe's expression for the limiting low-pressure rate constants of unimolecular decomposition reactions leads to E0 = Delta(r)H0(0)(ClOOCl-->ClO+ClO) = 66.4 +/- 3.0 kJ mol(-1). k-1,0 started to fall off from the pressure proportional low pressure behavior at p approximately 30 mbar; however, reliable extrapolation to the high pressure limit was not possible. The decomposition rate constants of ClOOCl were directly measured for the first time, and they are higher, depending on temperature and pressure, by factors between 1.5 and 4.2 as compared to experimental data on k-1 by Nickolaisen et al. [J. Phys. Chem. 1994, 98, 155] which were derived from the approach of ClO to thermal equilibrium with its dimer ClOOCl. Combination of the present dissociation rate constants with recommended temperature and pressure dependent data on the reverse reaction (k1) demonstrate inconsistencies between the dissociation and recombination rate constants. Summarizing laboratory data on k1 and k-1 above 250 K and field measurements on the ClO + ClO <= => ClOOCl equilibrium in the nighttime polar stratosphere close to 200 K, the expression Kc = k1/k-1 = 3.0 x 10(-27) exp(8433 K/T) cm3 molecule(-1) is derived for the temperature range 200-300 K.
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Affiliation(s)
- R Bröske
- Bergische Universität Wuppertal, Physikalische Chemie/FB C, D-42097 Wuppertal, Germany
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Tripathi OP, Godin-Beekmann S, Lefèvre F, Pazmiño A, Hauchecorne A, Chipperfield M, Feng W, Millard G, Rex M, Streibel M, von der Gathen P. Comparison of polar ozone loss rates simulated by one-dimensional and three-dimensional models with Match observations in recent Antarctic and Arctic winters. ACTA ACUST UNITED AC 2007. [DOI: 10.1029/2006jd008370] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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Pope FD, Hansen JC, Bayes KD, Friedl RR, Sander SP. Ultraviolet Absorption Spectrum of Chlorine Peroxide, ClOOCl. J Phys Chem A 2007; 111:4322-32. [PMID: 17474723 DOI: 10.1021/jp067660w] [Citation(s) in RCA: 75] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
The photolysis of chlorine peroxide (ClOOCl) is understood to be a key step in the destruction of polar stratospheric ozone. This study generated and purified ClOOCl in a novel fashion, which resulted in spectra with low impurity levels and high peak absorbances. The ClOOCl was generated by laser photolysis of Cl2 in the presence of ozone, or by photolysis of ozone in the presence of CF2Cl2. The product ClOOCl was collected, along with small amounts of impurities, in a trap at about -125 degrees C. Gas-phase ultraviolet spectra were recorded using a long path cell and spectrograph/diode array detector as the trap was slowly warmed. The spectrum of ClOOCl could be fit with two Gaussian-like expressions, corresponding to two different electronic transitions, having similar energies but different widths. The energies and band strengths of these two transitions compare favorably with previous ab initio calculations. The cross sections of ClOOCl at wavelengths longer than 300 nm are significantly lower than all previous measurements or estimates. These low cross sections in the photolytically active region of the solar spectrum result in a rate of photolysis of ClOOCl in the stratosphere that is much lower than currently recommended. For conditions representative of the polar vortex (solar zenith angle of 86 degrees, 20 km altitude, and O3 and temperature profiles measured in March 2000) calculated photolysis rates are a factor of 6 lower than the current JPL/NASA recommendation. This large discrepancy calls into question the completeness of present atmospheric models of polar ozone depletion.
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Affiliation(s)
- Francis D Pope
- Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA 91109, USA
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18
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Nassar R, Bernath PF, Boone CD, Clerbaux C, Coheur PF, Dufour G, Froidevaux L, Mahieu E, McConnell JC, McLeod SD, Murtagh DP, Rinsland CP, Semeniuk K, Skelton R, Walker KA, Zander R. A global inventory of stratospheric chlorine in 2004. ACTA ACUST UNITED AC 2006. [DOI: 10.1029/2006jd007073] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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Quack M, Willeke M. Stereomutation Tunneling Switching Dynamics and Parity Violation in Chlorineperoxide Cl−O−O−Cl. J Phys Chem A 2006; 110:3338-48. [PMID: 16509660 DOI: 10.1021/jp055770h] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
In a search for efficient spectroscopic avenues toward experiments on molecular parity violation, we investigate the stereomutation tunneling processes in the axially chiral chlorine isotopomers of Cl2O2 by the quasi-adiabatic channel reaction path Hamiltonian (RPH) approach and the corresponding parity violating potentials by means of quantum chemical calculations including our recently developed Multiconfiguration linear response (MC-LR) approach to electroweak quantum chemistry. The calculated ground-state torsional tunneling splittings for all isotopomers of Cl2O2 are much smaller than the parity violating energy differences Delta(pv)E between the enantiomers of these molecules and therefore parity violation is predicted to dominate the quantum dynamics of stereomutation at low energies. We also compare these with torsional ground-state tunneling splittings and parity violating energy differences of the whole series of axially chiral HXYH(+) isotopomers (with X, Y= Cl(+), O, S, Se, Te). A comparison with our previous results for the homologous molecule Cl2S2 shows that for Cl2O2 a spectroscopic high-resolution analysis should be easier and the energy region of large tunneling splittings should be more easily accessible by IR excitation. We thus propose a scheme using "tunneling switching" with vibrational excitation in order to carry out the measurement of time-dependent parity violation in superposition states of initially well-defined parity. We discuss the advantages and drawbacks of such an experiment that can be carried out entirely in the IR spectral range (for Cl2O2 or related molecules).
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Affiliation(s)
- Martin Quack
- Physical Chemistry, ETH Zurich, CH-8093 Zurich, Switzerland.
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Francisco JS, Crowley JN. Theoretical Investigation of Product Channels in the CH3O2 + Br Reaction. J Phys Chem A 2006; 110:3778-84. [PMID: 16526662 DOI: 10.1021/jp056794r] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Abstract
Several reaction pathways on the potential energy surface (PES) for the reaction of CH3O2 radicals with Br atoms are examined using both ab initio and density functional methods. Analysis of the PES suggests the presence of the stable intermediates CH3OOBr and CH3OBrO. CH3OOBr is calculated to be more stable than CH3OBrO by 9.7 kcal mol(-1) with a significant barrier preventing formation of CH3OBrO via isomerization of CH3OOBr. The relative importance of bi- and termolecular product channels resulting from the initially formed CH3OOBr adduct are assessed based on calculated barriers to the formation of CH2OO + HBr, CH3O + BrO, CH3Br + O2, and CH2O + HOBr.
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Affiliation(s)
- Joseph S Francisco
- Department of Chemistry, Purdue University, West Lafayette, Indiana 47907, USA.
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Boakes G, Hindy Mok WH, Rowley DM. Kinetic studies of the ClO + ClO association reaction as a function of temperature and pressure. Phys Chem Chem Phys 2005; 7:4102-13. [PMID: 16474875 DOI: 10.1039/b510308h] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
The kinetics of the association reaction of ClO radicals: ClO + ClO + M --> Cl2O2+ M (1), have been investigated as a function of temperature T between 206.0-298.0 K and pressure p between 25-760 Torr using flash photolysis with time-resolved UV absorption spectroscopy. ClO radicals were generated following the photolysis of Br2/Cl2O mixtures in nitrogen diluent gas. Charge coupled device (CCD) detection of time resolved absorptions was used to monitor ClO radicals over a broad wavelength window covering the ClO (A 2Pi<-- X 2Pi) vibronic absorption bands. The high pass filtered ClO absorption cross sections were calibrated as a function of temperature between T = 206.0-320 K, and exhibit a negative temperature dependence. The ClO association kinetics were found to be more rapid than those reported in previous studies, with limiting low and high pressure rate coefficients, in nitrogen bath gas, k0 = (2.78 +/- 0.82) x 10(-32) x (T/300)(-3.99 +/- 0.94) molecule(-2) cm6 s(-1) and k(infinity) = (3.37 +/- 1.67) x 10(-12) x (T/300)(-1.49 +/- 1.81) molecule(-1) cm3 s(-1), respectively, (obtained with the broadening factor F(c) fixed at 0.6). Errors are 2sigma. The pressure dependent ClO association rate coefficients (falloff curves) exhibited some discrepancies at low pressures, with higher than expected rate coefficients on the basis of extrapolation from high pressures (p > 100 Torr). Reanalysis of data excluding kinetic data recorded below p = 100 Torr gave k0 = (2.79 +/- 0.85) x 10(-32) x (T/300)(-3.78 +/- 0.98) molecule(-2) cm6 s(-1) and k(infinity) = (3.44 +/- 1.83)x 10(-12) x (T/300)(-1.73 +/- 1.91) molecule(-1) cm3 s(-1). Potential sources of the low pressure discrepancies are discussed. The expression for k(0) in air bath gas is k0 = (2.62 +/- 0.80) x 10(-32) x (T/300)(-3.78 +/- 0.98) molecule(-2) cm6 s(-1). These results support upward revision of the ClO association rate coefficient recommended for use in stratospheric models, and the stratospheric implications of the results reported here are briefly discussed.
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Affiliation(s)
- Gavin Boakes
- Department of Chemistry, University College London, Christopher Ingold Laboratories, 20 Gordon Street, London, WC1H 0AJ, UK
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McKeachie JR, Appel MF, Kirchner U, Schindler RN, Benter T. Observation of a Heterogeneous Source of OClO from the Reaction of ClO Radicals on Ice. J Phys Chem B 2004. [DOI: 10.1021/jp049314p] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- J. R. McKeachie
- Department of Chemistry, 516 Rowland Hall, University of California, Irvine, California 92697-2025
| | - M. F. Appel
- Department of Biology, Chemistry and Environmental Science, Christopher Newport University, 1 University Place, Newport News, Virginia 23606
| | - U. Kirchner
- Ford Forschungszentrum Aachen GmbH, Süsterfeldstrasse 200, D-52072 Aachen, Germany
| | - R. N. Schindler
- Christian-Albrechts Universität zu Kiel, Institut für Physikalische Chemie, Ludewig-Meyn-Strasse 8, 24098 Kiel, Germany
| | - Th. Benter
- Bergische Universität Wuppertal, FB CMathematik und Naturwissenschaften, Gauss Strasse 20, 42097 Wuppertal, Germany
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24
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Stimpfle RM, Wilmouth DM, Salawitch RJ, Anderson JG. First measurements of ClOOCl in the stratosphere: The coupling of ClOOCl and ClO in the Arctic polar vortex. ACTA ACUST UNITED AC 2004. [DOI: 10.1029/2003jd003811] [Citation(s) in RCA: 73] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Affiliation(s)
- R. M. Stimpfle
- Department of Chemistry and Chemical Biology; Harvard University; Cambridge Massachusetts USA
| | - D. M. Wilmouth
- Department of Chemistry and Chemical Biology; Harvard University; Cambridge Massachusetts USA
| | - R. J. Salawitch
- Jet Propulsion Laboratory; California Institute of Technology; Pasadena California USA
| | - J. G. Anderson
- Department of Chemistry and Chemical Biology; Harvard University; Cambridge Massachusetts USA
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25
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Abstract
Low-lying singlet and triplet electronic excited states of ClOOCl are presented. Calculations of the excitation energies and oscillator strengths are reported using excited state coupled cluster response methods, as well as the complete active space self-consistent field method with the full Breit-Pauli spin-orbit operator. These calculations predict that for ClOOCl there should be a weakly absorbing triplet state lying below the lowest absorbing singlet excited state. This state is predicted to have an absorption maximum at about 385 +/- 25 nm. This lowest triplet state is calculated to be dissociative and leads to ClOO+Cl.
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Affiliation(s)
- Kirk A Peterson
- Department of Chemistry, Washington State University, Pullman, Washington 99164-4630, USA
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26
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Bedjanian Y, Poulet G. Kinetics of Halogen Oxide Radicals in the Stratosphere. Chem Rev 2003; 103:4639-56. [PMID: 14664627 DOI: 10.1021/cr0205210] [Citation(s) in RCA: 56] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Affiliation(s)
- Yuri Bedjanian
- Laboratoire de Combustion et Systèmes Réactifs, CNRS, 45071 Orléans Cedex 2, France.
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27
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Barker JR, Golden DM. Master Equation Analysis of Pressure-Dependent Atmospheric Reactions. Chem Rev 2003; 103:4577-92. [PMID: 14664624 DOI: 10.1021/cr020655d] [Citation(s) in RCA: 87] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- John R Barker
- Department of Atmospheric, Oceanic and Space Sciences and Department of Chemistry, University of Michigan, Ann Arbor, MI 48109-2143, USA.
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28
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Golden DM. Reaction ClO + ClO ? products: Modeling and parameterization for use in atmospheric models. INT J CHEM KINET 2003. [DOI: 10.1002/kin.10120] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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29
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Zhu RS, Lin MC. Ab initiostudies of ClOx reactions. IV. Kinetics and mechanism for the self-reaction of ClO radicals. J Chem Phys 2003. [DOI: 10.1063/1.1540623] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023] Open
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30
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Tuck AF. Law of mass action in the Arctic lower stratospheric polar vortex January–March 2000: ClO scaling and the calculation of ozone loss rates in a turbulent fractal medium. ACTA ACUST UNITED AC 2003. [DOI: 10.1029/2002jd002832] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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