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Shuman NS, Sweeny BC, Viggiano AA, Plane JMC, Feng W, Lachowicz A, Heaven MC, Ard SG. Kinetics of O 3 with Ca + and Its Higher Oxides CaO n+ ( n = 1-3) and Updates to a Model of Meteoric Calcium in the Mesosphere and Lower Thermosphere. J Phys Chem A 2023; 127:4043-4054. [PMID: 37115955 DOI: 10.1021/acs.jpca.3c01126] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/30/2023]
Abstract
The room-temperature rate constants and product branching fractions of CaOn+ (n = 0-3) + O3 are measured using a selected ion flow tube apparatus. Ca+ + O3 produces CaO+ + O2 with k = 9 ± 4 × 10-10 cm3 s-1, within uncertainty equal to the Langevin capture rate constant. This value is significantly larger than several literature values. Most likely, those values were underestimated due to the reformation of Ca+ from the sequential chemistry of higher calcium oxide cations with O3, as explored here. A rate constant of 8 ± 3 × 10-10 cm3 s-1 is recommended. Both CaO+ and CaO2+ react near the capture rate constant with ozone. The CaO+ reaction yields both CaO2+ + O2 (0.80 ± 0.15 branching) and Ca+ + 2O2. Similarly, the CaO2+ reaction yields both CaO3+ + O2 (0.85 ± 0.15 branching) and CaO+ + 2O2. CaO3+ + O3 yield CaO2+ + 2O2 at 2 ± 1 × 10-11 cm3 s-1, about 2% of the capture rate constant. The results are supported using density functional calculations and statistical modeling. In general, CaOn+ + O3 yield CaOn+1+ + O2, the expected oxidation. Some fraction of CaOn+1+ is produced with sufficient internal energy to further dissociate to CaOn-1+ + O2, yielding the same products as the oxidation of O3 by CaOn+. Mesospheric Ca and Ca+ concentrations are modeled as functions of day, latitude, and altitude using the Whole Atmosphere Community Climate Model (WACCM); incorporating the updated rate constants improves agreement with concentrations derived from lidar measurements.
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Affiliation(s)
- Nicholas S Shuman
- Air Force Research Laboratory, Space Vehicles Directorate, Kirtland Air Force Base, Albuquerque, New Mexico 87117, United States
| | - Brendan C Sweeny
- Boston College Institute for Scientific Research, Boston, Massachusetts 02549, United States
| | - Albert A Viggiano
- Air Force Research Laboratory, Space Vehicles Directorate, Kirtland Air Force Base, Albuquerque, New Mexico 87117, United States
| | - John M C Plane
- School of Chemistry, University of Leeds, Leeds LS2 9JT, U.K
| | - Wuhu Feng
- School of Chemistry, University of Leeds, Leeds LS2 9JT, U.K
- National Centre for Atmospheric Science and School of Earth and Environment, University of Leeds, Leeds LS2 9JT, U.K
| | - Anton Lachowicz
- Air Force Research Laboratory, Space Vehicles Directorate, Kirtland Air Force Base, Albuquerque, New Mexico 87117, United States
| | - Michael C Heaven
- Department of Chemistry, Emory University, Atlanta, Georgia 30322, United States
| | - Shaun G Ard
- Air Force Research Laboratory, Space Vehicles Directorate, Kirtland Air Force Base, Albuquerque, New Mexico 87117, United States
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2
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Sweeny BC, Long BA, Maffucci D, Zuo J, Guo H, Viggiano AA, Ard SG, Shuman NS. Activation of Methane by Zr +: A Deep-Dive into the Potential Surface via Pressure- and Temperature-Dependent Kinetics with Statistical Modeling. J Phys Chem A 2023; 127:1818-1830. [PMID: 36802591 DOI: 10.1021/acs.jpca.2c07584] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/22/2023]
Abstract
The kinetics of Zr+ + CH4 are measured using a selected-ion flow tube apparatus over the temperature range 300-600 K and the pressure range 0.25-0.60 Torr. Measured rate constants are small, never exceeding 5% of the Langevin capture value. Both collisionally stabilized ZrCH4+ and bimolecular ZrCH2+ products are observed. A stochastic statistical modeling of the calculated reaction coordinate is used to fit the experimental results. The modeling indicates that an intersystem crossing from the entrance well, necessary for the bimolecular product to be formed, occurs faster than competing isomerization and dissociation processes. That sets an upper limit on the lifetime of the entrance complex to crossing of 10-11 s. The endothermicity of the bimolecular reaction is derived to be 0.09 ± 0.05 eV, in agreement with a literature value. The observed ZrCH4+ association product is determined to be primarily HZrCH3+ not Zr+(CH4), indicating that bond activation has occurred at thermal energies. The energy of HZrCH3+ relative to separated reactants is determined to be -0.80 ± 0.25 eV. Inspection of the statistical modeling results under best-fit conditions reveals reaction dependences on impact parameter, translation energy, internal energy, and angular momentum. Reaction outcomes are heavily affected by angular momentum conservation. Additionally, product energy distributions are predicted.
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Affiliation(s)
- Brendan C Sweeny
- Boston College Institute for Scientific Research, Boston, Massachusetts 02549, United States
| | - Bryan A Long
- Air Force Research Laboratory, Space Vehicles Directorate, Kirtland Air Force Base, New Mexico 87117, United States
| | - Dominique Maffucci
- Air Force Research Laboratory, Space Vehicles Directorate, Kirtland Air Force Base, New Mexico 87117, United States
| | - Junxiang Zuo
- Department of Chemistry and Chemical Biology, University of New Mexico, Albuquerque, New Mexico 87131, United States
| | - Hua Guo
- Department of Chemistry and Chemical Biology, University of New Mexico, Albuquerque, New Mexico 87131, United States
| | - Albert A Viggiano
- Air Force Research Laboratory, Space Vehicles Directorate, Kirtland Air Force Base, New Mexico 87117, United States
| | - Shaun G Ard
- Air Force Research Laboratory, Space Vehicles Directorate, Kirtland Air Force Base, New Mexico 87117, United States
| | - Nicholas S Shuman
- Air Force Research Laboratory, Space Vehicles Directorate, Kirtland Air Force Base, New Mexico 87117, United States
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Sweeny BC, Long BA, Viggiano AA, Ard SG, Shuman NS. Effect of Intersystem Crossings on the Kinetics of Thermal Ion-Molecule Reactions: Ti + + O 2, CO 2, and N 2O. J Phys Chem A 2022; 126:859-869. [PMID: 35107288 DOI: 10.1021/acs.jpca.1c10196] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
A selected-ion flow tube apparatus has been used to measure rate constants and product branching fractions of 2Ti+ reacting with O2, CO2, and N2O over the range of 200-600 K. Ti+ + O2 proceeds at near the Langevin capture rate constant of 6-7 × 10-10 cm3 s-1 at all temperatures to yield 4TiO+ + O. Reactions initiated on doublet or quartet surfaces are formally spin-allowed; however, the 50% of reactions initiated on sextet surfaces must undergo an intersystem crossing (ISC). Statistical theory is used to calculate the energy and angular momentum dependences of the specific rate constants for the competing isomerization and dissociation channels. This acts as an internal clock on the lifetime to ISC, setting an upper limit on the order of τISC < 1e-11 s. 2Ti+ + CO2 produces 4TiO+ + CO less efficiently, with a rate constant fit as 5.5 ± 1.3 × 10-11 (T/300)-1.1 ± 0.2 cm3 s-1. The reaction is formally spin-prohibited, and statistical modeling shows that ISC, not a submerged transition state, is rate-limiting, occurring with a lifetime on the order of 10-7 s. Ti+ + N2O proceeds at near the capture rate constant. In this case, both Ti+ON2 and Ti+N2O entrance channel complexes are formed and can interconvert over a barrier. The main product is >90% TiO+ + N2, and the remainder is TiN+ + NO. Both channels need to undergo ISC to form ground-state products but TiO+ can be formed in an excited state exothermically. Therefore, kinetic information is obtained only for the TiN+ channel, where ISC occurs with a lifetime on the order of 10-9 s. Statistical modeling indicates that the dipole-preferred Ti+ON2 complex is formed in ∼80% of collisions, and this value is reproduced using a capture model based on the generic ion-dipole + quadrupole long-range potential.
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Affiliation(s)
- Brendan C Sweeny
- Institute for Scientific Research, Boston College, Boston, Massachusetts 02467, United States
| | - Bryan A Long
- NRC Postdoc at Air Force Research Laboratory, Space Vehicles Directorate, Kirtland Air Force Base, New Mexico 87117, United States
| | - Albert A Viggiano
- Air Force Research Laboratory, Space Vehicles Directorate, Kirtland Air Force Base, New Mexico 87117, United States
| | - Shaun G Ard
- Air Force Research Laboratory, Space Vehicles Directorate, Kirtland Air Force Base, New Mexico 87117, United States
| | - Nicholas S Shuman
- Air Force Research Laboratory, Space Vehicles Directorate, Kirtland Air Force Base, New Mexico 87117, United States
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Pazdera TM, Wenz J, Olzmann M. The unimolecular decomposition of dimethoxymethane: channel switching as a function of temperature and pressure. Faraday Discuss 2022; 238:665-681. [DOI: 10.1039/d2fd00039c] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Branching ratios of competing unimolecular reactions often exhibit a complicated temperature and pressure dependence that makes modeling of complex reaction systems in the gas phase difficult. In particular, the competition...
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McDonald DC, Sweeny BC, Viggiano AA, Ard SG, Shuman NS. Cyclotrimerization of Acetylene under Thermal Conditions: Gas-Phase Kinetics of V + and Fe + + C 2H 2. J Phys Chem A 2021; 125:9327-9337. [PMID: 34665622 DOI: 10.1021/acs.jpca.1c06439] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The kinetics of successive reactions of acetylene (C2H2) initiated on either vanadium or iron atomic cations have been investigated under thermal conditions using the variable-ion source and temperature-adjustable selected-ion flow tube apparatus. Consistent with the literature results, the reaction of Fe+ + C2H2 primarily yields Fe+(m/z = (C2H2)3); however, analysis via quantum chemical calculations and statistical modeling shows that the mechanism does not form benzene upon the third acetylene addition. The kinetics are more consistent with successive addition of three acetylene molecules, yielding Fe+(C2H2)3, followed by an addition of a fourth acetylene molecule, initiating cyclotrimerization, yielding either Fe+(C2H2) + neutral benzene or Fe+(Bz) + acetylene, where Bz is a benzene ligand. In contrast, the reaction of V+ + C2H2 yields products via successive associations V+(m/z = (C2H2)n) either with or without a bimolecular step involving loss of one H2 and V+C2(m/z = (C2H2)m), where n and m extend at least up to 11 under conditions of 0.32 Torr at 300 K. Stabilized V+(Bz) is not a significant intermediate in the association mechanism. We propose a plausible mechanism for the generation of neutral benzene in this reaction and compare with the Fe+ results. The reaction steps that produce benzene result in turnover of the single-atom catalyst, and the large hydrocarbons produced that remain associated to the catalyst are proposed to be polycyclic aromatic hydrocarbons.
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Affiliation(s)
- David C McDonald
- NRC Postdoc at Air Force Research Laboratory, Space Vehicles Directorate, Kirtland Air Force Base, Albuquerque, New Mexico 87117, United States
| | - Brendan C Sweeny
- Institute for Scientific Research, Boston College, Boston, Massachusetts 02467, United States
| | - Albert A Viggiano
- Air Force Research Laboratory, Space Vehicles Directorate, Kirtland Air Force Base, Albuquerque, New Mexico 87117, United States
| | - Shaun G Ard
- Air Force Research Laboratory, Space Vehicles Directorate, Kirtland Air Force Base, Albuquerque, New Mexico 87117, United States
| | - Nicholas S Shuman
- Air Force Research Laboratory, Space Vehicles Directorate, Kirtland Air Force Base, Albuquerque, New Mexico 87117, United States
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6
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Ard SG, Viggiano AA, Shuman NS. Old School Techniques with Modern Capabilities: Kinetics Determination of Dynamical Information Such as Barriers, Multiple Entrance Channel Complexes, Product States, Spin Crossings, and Size Effects in Metallic Ion–Molecule Reactions. J Phys Chem A 2021; 125:3503-3527. [DOI: 10.1021/acs.jpca.0c11395] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Affiliation(s)
- Shaun G. Ard
- Air Force Research Laboratory, Space Vehicles Directorate, Kirtland Air Force Base, Albuquerque, New Mexico 87117, United States
| | - Albert A. Viggiano
- Air Force Research Laboratory, Space Vehicles Directorate, Kirtland Air Force Base, Albuquerque, New Mexico 87117, United States
| | - Nicholas S. Shuman
- Air Force Research Laboratory, Space Vehicles Directorate, Kirtland Air Force Base, Albuquerque, New Mexico 87117, United States
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7
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McDonald II DC, Sweeny BC, Viggiano AA, Shuman NS, Ard SG. Role of Spin in the Catalytic Oxidation of CO by N2O Enabled by Co+: New Insights from Temperature-Dependent Kinetics and Statistical Modeling. J Phys Chem A 2020; 124:7966-7972. [DOI: 10.1021/acs.jpca.0c06960] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
| | - Brendan C. Sweeny
- Institute for Scientific Research, Boston College, Boston, Massachusetts 02467, United States
| | - Albert A. Viggiano
- Space Vehicles Directorate, Air Force Research Laboratory, Kirtland Air Force Base, New Mexico 87117, United States
| | - Nicholas S. Shuman
- Space Vehicles Directorate, Air Force Research Laboratory, Kirtland Air Force Base, New Mexico 87117, United States
| | - Shaun G. Ard
- Space Vehicles Directorate, Air Force Research Laboratory, Kirtland Air Force Base, New Mexico 87117, United States
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8
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Sweeny BC, McDonald DC, Ard SG, Viggiano AA, Shuman NS. Barrierless methane-to-methanol conversion: the unique mechanism of AlO . Phys Chem Chem Phys 2020; 22:14544-14550. [PMID: 32589175 DOI: 10.1039/d0cp02316g] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The kinetics of AlO+ + CH4 are studied from 300-500 K using a selected-ion flow tube. At all temperatures the reaction proceeds near the Langevin-Gioumousis-Stevenson collision rate with two product channels: hydrogen atom abstraction (AlOH+ + CH3, 86 ± 5%) and methanol formation (Al+ + CH3OH, 14 ± 5%). Density functional calculations show the key Al-CH3OH+ intermediate is formed barrierlessly via a mechanism unique to aluminum, avoiding the rate-limiting step common to other MO+. The reaction of Al2O3+ + CH4 follows a similar mechanism to that for AlO+ through to the key intermediate; however, the conversion to methanol occurs only for AlO+ due to favorable energetics attributed to a weaker Al+-CH3OH bond. Importantly, that bond strength may be tuned independent of competing product channels by altering the acidity of the Al with electron-withdrawing or donating groups, indicating a key design criteria to develop a real world Al-atom catalyst.
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Affiliation(s)
- Brendan C Sweeny
- NRC Postdoc at Air Force Research Laboratory, Space Vehicles Directorate, Kirtland Air Force Base, New Mexico 87117, USA
| | - David C McDonald
- NRC Postdoc at Air Force Research Laboratory, Space Vehicles Directorate, Kirtland Air Force Base, New Mexico 87117, USA
| | - Shaun G Ard
- Air Force Research Laboratory, Space Vehicles Directorate, Kirtland Air Force Base, New Mexico 87117, USA.
| | - Albert A Viggiano
- Air Force Research Laboratory, Space Vehicles Directorate, Kirtland Air Force Base, New Mexico 87117, USA.
| | - Nicholas S Shuman
- Air Force Research Laboratory, Space Vehicles Directorate, Kirtland Air Force Base, New Mexico 87117, USA.
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Shuman NS, Ard SG, Sweeny BC, Viggiano AA, Owen CJ, Armentrout PB. Methane Adducts of Gold Dimer Cations: Thermochemistry and Structure from Collision-Induced Dissociation and Association Kinetics. J Phys Chem A 2020; 124:3335-3346. [PMID: 32176490 DOI: 10.1021/acs.jpca.0c01217] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The bond dissociation energies at 0 K (BDE) of Au2+-CH4 and Au2CH4+-CH4 have been determined using two separate experimental methods. Analyses of collision-induced dissociation cross sections for Au2CH4+ + Xe and Au2(CH4)2+ + Xe measured using a guided ion beam tandem mass spectrometer (GIBMS) yield BDEs of 0.71 ± 0.05 and 0.57 ± 0.07 eV, respectively. Statistical modeling of association kinetics of Au2(CH4)0-2+ + CH4 + He measured from 200 to 400 K and at 0.3-0.9 Torr using a selected-ion flow tube (SIFT) apparatus yields slightly higher values of 0.81 ± 0.21 and 0.75 ± 0.25 eV. The SIFT data also place a lower limit on the BDE of Au2C2H8+-CH4 of 0.35 eV, likely an activated isomer, not Au2(CH4)2+-CH4. Particular emphasis is placed on determining the uncertainty in the derivation from association kinetics measurements, including uncertainties in collisional energy transfer, calculated harmonic frequencies, and possible contribution of isomerization of the association complexes. This evaluation indicates that an uncertainty of ±0.2 eV should be expected and that an uncertainty of better than ±0.1 eV is unlikely to be reasonable.
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Affiliation(s)
- Nicholas S Shuman
- Air Force Research Laboratory, Space Vehicles Directorate, Kirtland AFB, Albuquerque, New Mexico 87117, United States
| | - Shaun G Ard
- Air Force Research Laboratory, Space Vehicles Directorate, Kirtland AFB, Albuquerque, New Mexico 87117, United States
| | - Brendan C Sweeny
- NRC Postdoc at Air Force Research Laboratory, Space Vehicles Directorate, Kirtland Air Force Base, Albuquerque, New Mexico 87117, United States
| | - Albert A Viggiano
- Air Force Research Laboratory, Space Vehicles Directorate, Kirtland AFB, Albuquerque, New Mexico 87117, United States
| | - Cameron J Owen
- Department of Chemistry, University of Utah, 315 S. 1400 E., Rm 2020, Salt Lake City, Utah 84112, United States
| | - P B Armentrout
- Department of Chemistry, University of Utah, 315 S. 1400 E., Rm 2020, Salt Lake City, Utah 84112, United States
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10
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Sweeny BC, McDonald DC, Poutsma JL, Poutsma JC, Shuman NS, Ard SG, Viggiano AA. Catalytic Oxidation of CO by N2O Enabled by Al2O2/3+: Temperature Dependent Kinetics and Statistical Modeling. J Phys Chem A 2020; 124:1705-1711. [DOI: 10.1021/acs.jpca.9b10732] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Affiliation(s)
- Brendan C. Sweeny
- Air Force Research Laboratory, Space Vehicles Directorate, Kirtland Air Force Base, New Mexico 87117, United States
| | - David C. McDonald
- Air Force Research Laboratory, Space Vehicles Directorate, Kirtland Air Force Base, New Mexico 87117, United States
| | - Jennifer L. Poutsma
- Department of Chemistry and Biochemistry, Old Dominion University, Norfolk, Virginia 23529, United States
| | - John C. Poutsma
- Department of Chemistry and Biochemistry, The College of William and Mary, Williamsburg, Virginia 23185, United States
| | - Nicholas S. Shuman
- Air Force Research Laboratory, Space Vehicles Directorate, Kirtland Air Force Base, New Mexico 87117, United States
| | - Shaun G. Ard
- Air Force Research Laboratory, Space Vehicles Directorate, Kirtland Air Force Base, New Mexico 87117, United States
| | - Albert A. Viggiano
- Air Force Research Laboratory, Space Vehicles Directorate, Kirtland Air Force Base, New Mexico 87117, United States
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11
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Golka L, Gratzfeld D, Weber I, Olzmann M. Temperature- and pressure-dependent kinetics of the competing C–O bond fission reactions of dimethoxymethane. Phys Chem Chem Phys 2020; 22:5523-5530. [DOI: 10.1039/d0cp00136h] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Under typical shock tube conditions, dimethoxymethane decomposes mainly to give CH3 + OCH2OCH3.
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Affiliation(s)
- Leonie Golka
- Institut für Physikalische Chemie
- Karlsruher Institut für Technologie (KIT)
- 76131 Karlsruhe
- Germany
| | - Dennis Gratzfeld
- Institut für Physikalische Chemie
- Karlsruher Institut für Technologie (KIT)
- 76131 Karlsruhe
- Germany
| | - Isabelle Weber
- Institut für Physikalische Chemie
- Karlsruher Institut für Technologie (KIT)
- 76131 Karlsruhe
- Germany
| | - Matthias Olzmann
- Institut für Physikalische Chemie
- Karlsruher Institut für Technologie (KIT)
- 76131 Karlsruhe
- Germany
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12
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Ard SG, Sweeny BC, McDonald DC, Viggiano AA, Shuman NS. Quantifying the Competition between Intersystem Crossing and Spin-Conserved Pathways in the Thermal Reaction of V+ + N2O. J Phys Chem A 2019; 124:30-38. [DOI: 10.1021/acs.jpca.9b09235] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Shaun G. Ard
- Institute for Scientific Research, Boston College, Boston, Massachusetts 02467, United States
| | - Brendan C. Sweeny
- NRC Postdoc at Air Force Research Laboratory, Space Vehicles Directorate, Kirtland Air Force Base, Albuquerque, New Mexico 87117, United States
| | - David C. McDonald
- NRC Postdoc at Air Force Research Laboratory, Space Vehicles Directorate, Kirtland Air Force Base, Albuquerque, New Mexico 87117, United States
| | - Albert A. Viggiano
- Air Force Research Laboratory, Space Vehicles Directorate, Kirtland AFB, Albuquerque, New Mexico 87117, United States
| | - Nicholas S. Shuman
- Air Force Research Laboratory, Space Vehicles Directorate, Kirtland AFB, Albuquerque, New Mexico 87117, United States
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Sweeny BC, Pan H, Ard SG, Shuman NS, Viggiano AA. On the Role of Hydrogen Atom Transfer (HAT) in Thermal Activation of Methane by MnO+: Entropy vs. Energy. ACTA ACUST UNITED AC 2019. [DOI: 10.1515/zpch-2018-1354] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Abstract
The temperature dependent kinetics and product branching fractions of first-row transition metal oxide cation MnO+ with CH4 and CD4 at temperatures between 200 and 600 K are measured using a selected-ion flow tube apparatus. Likely reaction mechanisms are determined by comparison of temperature dependent kinetics to statistical modeling along calculated reaction coordinates. The data is well-modeled with the reaction proceeding over a rate limiting four-centered transition state leading to an insertion intermediate, similar to reactions of NiO+ and FeO+, and showing characteristics of proton-coupled electron transfer (PCET). However, a more direct pathway traversing a transition state of hydrogen atom transfer (HAT) character to a hydroxyl intermediate is found to possibly be competitive, especially with increasing temperature. While uncertainties in calculated energetics limit quantitative assessment of the role of HAT at thermal energies, it is clear that this mechanism becomes increasingly prevalent in higher energy regimes.
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Affiliation(s)
- Brendan C. Sweeny
- NRC postdoc at Air Force Research Laboratory, Space Vehicles Directorate, Kirtland Air Force Base , New Mexico 87117 , USA
| | - Hanqing Pan
- USRA Space Scholar at Air Force Research Laboratory, Space Vehicles Directorate, Kirtland Air Force Base , New Mexico 87117 , USA
| | - Shaun G. Ard
- Institute for Scientific Research, Boston College , Boston, MA 02467 , USA
| | - Nicholas S. Shuman
- Air Force Research Laboratory, Space Vehicles Directorate, Kirtland Air Force Base , New Mexico 87117 , USA
| | - Albert A. Viggiano
- Air Force Research Laboratory, Space Vehicles Directorate, Kirtland Air Force Base , New Mexico 87117 , USA
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14
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Ard SG, Shuman NS, Martinez O, Keyes NR, Viggiano AA, Guo H, Troe J. Temperature and Pressure Dependences of the Reactions of Fe + with Methyl Halides CH 3X (X = Cl, Br, I): Experiments and Kinetic Modeling Results. J Phys Chem A 2017; 121:4058-4068. [PMID: 28488864 DOI: 10.1021/acs.jpca.7b02415] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The pressure and temperature dependences of the reactions of Fe+ with methyl halides CH3X (X = Cl, Br, I) in He were measured in a selected ion flow tube over the ranges 0.4 to 1.2 Torr and 300-600 K. FeX+ was observed for all three halides and FeCH3+ was observed for the CH3I reaction. FeCH3X+ adducts (for all X) were detected in all reactions. The results were interpreted assuming two-state reactivity with spin-inversions between sextet and quartet potentials. Kinetic modeling allowed for a quantitative representation of the experiments and for extrapolation to conditions outside the experimentally accessible range. The modeling required quantum-chemical calculations of molecular parameters and detailed accounting of angular momentum effects. The results show that the FeX+ products come via an insertion mechanism, while the FeCH3+ can be produced from either insertion or SN2 mechanisms, but the latter we conclude is unlikely at thermal energies. A statistical modeling cannot reproduce the competition between the bimolecular pathways in the CH3I reaction, indicating that some more direct process must be important.
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Affiliation(s)
- Shaun G Ard
- Air Force Research Laboratory , Space Vehicle Directorate, Kirtland AFB, Albuquerque, New Mexico 87117, United States
| | - Nicholas S Shuman
- Air Force Research Laboratory , Space Vehicle Directorate, Kirtland AFB, Albuquerque, New Mexico 87117, United States
| | - Oscar Martinez
- Air Force Research Laboratory , Space Vehicle Directorate, Kirtland AFB, Albuquerque, New Mexico 87117, United States
| | - Nicholas R Keyes
- Department of Chemistry and Chemical Biology, University of New Mexico , Albuquerque, New Mexico 87131, United States
| | - Albert A Viggiano
- Air Force Research Laboratory , Space Vehicle Directorate, Kirtland AFB, Albuquerque, New Mexico 87117, United States
| | - Hua Guo
- Department of Chemistry and Chemical Biology, University of New Mexico , Albuquerque, New Mexico 87131, United States
| | - Jürgen Troe
- Institut für Physikalische Chemie, Universität Göttingen , Tammannstrasse 6, D-37077 Göttingen, Germany.,Max-Planck-Institut für Biophysikalische Chemie , D-37077 Göttingen, Germany
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15
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Ard SG, Melko JJ, Ushakov VG, Johnson R, Fournier JA, Shuman NS, Guo H, Troe J, Viggiano AA. Activation of Methane by FeO+: Determining Reaction Pathways through Temperature-Dependent Kinetics and Statistical Modeling. J Phys Chem A 2014; 118:2029-39. [DOI: 10.1021/jp5000705] [Citation(s) in RCA: 43] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Affiliation(s)
- Shaun G. Ard
- Air Force Research
Laboratory, Space Vehicles Directorate, Kirtland Air Force Base, New Mexico 87117-5776, United States
| | - Joshua J. Melko
- Air Force Research
Laboratory, Space Vehicles Directorate, Kirtland Air Force Base, New Mexico 87117-5776, United States
| | - Vladimir G. Ushakov
- Institute
of Problems
of Chemical Physics, Russian Academy of Sciences, 142432 Chernogolovka, Russia
- Max-Planck-Institut für Biophysikalische Chemie, D-37077 Göttingen, Germany
| | - Ryan Johnson
- Department
of Chemistry and Chemical Biology, University of New Mexico, Albuquerque, New Mexico 87131, United States
| | - Joseph A. Fournier
- Sterling Chemistry Laboratory, Yale University, P.O. Box 208107, New Haven, Connecticut 06520, United States
| | - Nicholas S. Shuman
- Air Force Research
Laboratory, Space Vehicles Directorate, Kirtland Air Force Base, New Mexico 87117-5776, United States
| | - Hua Guo
- Department
of Chemistry and Chemical Biology, University of New Mexico, Albuquerque, New Mexico 87131, United States
| | - Jürgen Troe
- Max-Planck-Institut für Biophysikalische Chemie, D-37077 Göttingen, Germany
- Institut für
Physikalische Chemie, Universität Göttingen, Tammannstrasse 6, D-37077 Göttingen, Germany
| | - Albert A. Viggiano
- Air Force Research
Laboratory, Space Vehicles Directorate, Kirtland Air Force Base, New Mexico 87117-5776, United States
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Melko JJ, Ard SG, Fournier JA, Li J, Shuman NS, Guo H, Troe J, Viggiano AA. Iron cation catalyzed reduction of N2O by CO: gas-phase temperature dependent kinetics. Phys Chem Chem Phys 2013; 15:11257-67. [DOI: 10.1039/c3cp50335f] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
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Sztáray B, Bodi A, Baer T. Modeling unimolecular reactions in photoelectron photoion coincidence experiments. JOURNAL OF MASS SPECTROMETRY : JMS 2010; 45:1233-1245. [PMID: 20872904 DOI: 10.1002/jms.1813] [Citation(s) in RCA: 114] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/29/2023]
Abstract
A computer program has been developed to model and analyze the data from photoelectron photoion coincidence (PEPICO) spectroscopy experiments. This code has been used during the past 12 years to extract thermochemical and kinetics information for almost a hundred systems, and the results have been published in over forty papers. It models the dissociative photoionization process in the threshold PEPICO experiment by calculating the thermal energy distribution of the neutral molecule, the energy distribution of the molecular ion as a function of the photon energy, and the resolution of the experiment. Parallel or consecutive dissociation paths of the molecular ion and also of the resulting fragment ions are modeled to reproduce the experimental breakdown curves and time-of-flight distributions. The latter are used to extract the experimental dissociation rates. For slow dissociations, either the quasi-exponential fragment peak shapes or, when the mass resolution is insufficient to model the peak shapes explicitly, the center of mass of the peaks can be used to obtain the rate constants. The internal energy distribution of the fragment ions is calculated from the densities of states using the microcanonical formalism to describe consecutive dissociations. Dissociation rates can be calculated by the RRKM, SSACM or VTST rate theories, and can include tunneling effects, as well. Isomerization of the dissociating ions can also be considered using analytical formulae for the dissociation rates either from the original or the isomer ions. The program can optimize the various input parameters to find a good fit to the experimental data, using the downhill simplex algorithm.
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Affiliation(s)
- Bálint Sztáray
- Department of Chemistry, University of the Pacific, Stockton, CA 95211, USA.
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Olzmann M. On nascent angular-momentum distributions in complex-forming bimolecular reactions. ACTA ACUST UNITED AC 2010. [DOI: 10.1002/bbpc.19971010328] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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Schnöckel H. Structures and Properties of Metalloid Al and Ga Clusters Open Our Eyes to the Diversity and Complexity of Fundamental Chemical and Physical Processes during Formation and Dissolution of Metals. Chem Rev 2010; 110:4125-63. [PMID: 20540559 DOI: 10.1021/cr900375g] [Citation(s) in RCA: 138] [Impact Index Per Article: 9.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Affiliation(s)
- Hansgeorg Schnöckel
- Karlsruhe Institute of Technology (KIT), Institute of Inorganic Chemistry, Engesserstrasse 15, Bldg. 30.45, 76131 Karlsruhe, Germany
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22
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Troe J. C. Spectroscopy of Excited States, Kinetics and Photodissociation. Fine Structure and Hyperfine Structure Effects in Unimolecular and Complex-Forming Bimolecular Reactions. ACTA ACUST UNITED AC 2010. [DOI: 10.1002/bbpc.19950990314] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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23
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Olzmann M, Troe J. Approximate determination of rovibrational densities of states ρ(E,J) and numbers of states W(E,J). ACTA ACUST UNITED AC 2010. [DOI: 10.1002/bbpc.19940981210] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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Olzmann M, Burgert R, Schnöckel H. On the kinetics of the Al13−+Cl2 reaction: Cluster degradation in consecutive steps. J Chem Phys 2009; 131:174304. [DOI: 10.1063/1.3257684] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023] Open
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25
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Abstract
Abstract
The distribution of translational, rotational, and vibrational energies in the fragments (benzylium ions and ethyl radicals) of the dissociation of n-propylbenzene cations has been determined by statistical adiabatic channel model/classical trajectory (SACM/CT) calculations. The reaction was treated by CT calculations of capture processes for transitional modes, starting with specified fragment energies. A short-range valence/long-range ion-induced dipole potential model for the transitional modes was employed. The derived distributions approach the results from phase space theory (PST) at small energies and angular momenta. At larger energies and angular momenta, the shapes of the distribution functions remain similar to those from PST; however, the average translational, rotational, and vibrational energies of the fragments increasingly differ from PST predictions. The present results are consistent with separate SACM/CT calculations on the same potential of specific rate constants k(E,J) and thermally averaged rate constants k
∞(T) of the dissociation/recombination reaction.
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Troe J, Ushakov V, Viggiano AA. Classical Trajectory and Statistical Adiabatic Channel Study of the Dynamics of Capture and Unimolecular Bond Fission. VII. Thermal Capture and Specific Rate Constants k(E,J) for the Dissociation of Molecular Ions. ACTA ACUST UNITED AC 2009. [DOI: 10.1524/zpch.219.5.715.64322] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
Abstract
Specific rate constants, k(E,J), and thermal capture rate constants, k
cap(T), are determined by statistical adiabatic channel model/classical trajectory (SACM/CT) calculations for unimolecular dissociation and the reverse association reactions of representative polyatomic molecular ions. Simple short-range valence/long-range ion-induced dipole model potentials without reverse barriers have been employed, using the reactions C8H10
+ ⇔ C7H7
+ + CH3 and C9H12
+ ⇔ C7H7
+ + C2H5 as illustrative examples. Simplified representations of k(E) and k
cap(T) from rigid activated complex Rice–Ramsperger–Kassel–Marcus (RRKM) theory are compared with the SACM/CT treatment and with experimental results. The Massey parameters of the transitional mode dynamics, for the systems considered, are smaller than unity such that their dynamics is nonadiabatic while the dynamics of the conserved modes is adiabatic. Because of the long-range/short-range switching character of the potential, simple rigid activated complex RRKM theory cannot be used without modifications. The effects of a shifting of the effective bottle-neck of the dynamics with increasing energy towards smaller interfragment distances in the present cases are amplified by a shift into a range of increasing anisotropy of the potential. As a consequence, the thermal capture rate constants markedly decrease with increasing temperature.
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Troe J, Ushakov VG. Anharmonic Rovibrational Numbers and Densities of States for HO2, H2CO, and H2O2. J Phys Chem A 2009; 113:3940-5. [DOI: 10.1021/jp8101964] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- J. Troe
- Institut für Physikalische Chemie, Universität Göttingen, Tammannstrasse 6, D-37077 Göttingen, Germany
| | - V. G. Ushakov
- Institut für Physikalische Chemie, Universität Göttingen, Tammannstrasse 6, D-37077 Göttingen, Germany
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Simplified models for anharmonic numbers and densities of vibrational states. Part III: Resonance states of HO2. Chem Phys 2008. [DOI: 10.1016/j.chemphys.2008.02.054] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
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Troe J, Ushakov V. Simplified models for anharmonic numbers and densities of vibrational states. II. All the bound states of HO2. Chem Phys 2008. [DOI: 10.1016/j.chemphys.2008.02.010] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
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Burgert R, Schnöckel H. Monitoring the dissolution process of metals in the gas phase: reactions of nanoscale Al and Ga metal atom clusters and their relationship to similar metalloid clusters. Chem Commun (Camb) 2008:2075-89. [PMID: 18438480 DOI: 10.1039/b801224e] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
Formation and dissolution of metals are two of the oldest technical chemical processes. On the atomic scale, these processes are based on the formation and cleavage of metal-metal bonds. During the past 15 years we have studied intensively the intermediates during the formation process of metals, i.e. the formation of compounds containing many metal-metal bonds between naked metal atoms in the center and ligand-bearing metal atoms at the surface. We have called the clusters metalloid or, more generally, elementoid clusters. Via a retrosynthetic route, the many different Al and Ga metalloid clusters which have been structurally characterized allow us to understand also the dissolution process; i.e. the cleavage of metal-metal (M-M) bonds. However, this process can be detected much more directly by the reaction of single metal atom clusters in the gas phase under high vacuum conditions. A suitable tool to monitor the dissolution process of a metal cluster in the gas phase is FT-ICR (Fourier transform ion cyclotron resonance) mass spectrometry. Snapshots during these cleavage processes are possible because only every 1-10 s is there a contact between a cluster molecule and an oxidizing molecule (e.g. Cl2). This period is long, i.e. the formation of the primary product (a smaller metal atom cluster) is finished before the next collision happens. We have studied three different types of reaction:(1) Step-by-step fragmentation of a structurally known metalloid cluster allows us to understand the bonding principle of these clusters because in every step only the weakest bond is broken.(2) There are three oxidation reactions of an Al13(-) cluster molecule with Cl2, HCl and O2 central to this review. These three reactions represent three different reaction types, (a) an exothermic reaction (Cl2), (b) an endothermic reaction (HCl), and (c) a kinetically limited reaction based on spin conservation rules (O2).(3) Finally, we present the reaction of a metalloid cluster with Cl2 in order to show that in this cluster only the central naked metal atoms are oxidized, and a smaller metalloid cluster results containing the entire protecting shell as the primary cluster. All the experimental results, supported by quantum chemical calculations, give a rough idea about the complex reaction cascades which occur during the dissolution and formation of metals. Furthermore, these results cast a critical light on many simplifying and generalizing rules in order to understand the bonding and structure of metal clusters. Finally, the experiments and some recent results provided by physical measurements on a crystalline Ga(84) compound build a bridge to nanoscience; i.e. they may be a challenge for chemistry in the next decades, since it has been shown that only with a perfect orientation of nanoscale metal clusters, e.g. in a crystal, can novel, unexpected properties (e.g. superconducting nanoscale materials) be obtained.
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Affiliation(s)
- Ralf Burgert
- Universitat Karlsruhe, Institut fur Anorganische Chemie, Engesserstrasse, Karlsruhe, D-76128, Germany
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Troe J. Recent Advances in Statistical Adiabatic Channel Calculations of State-Specific Dissociation Dynamics. ADVANCES IN CHEMICAL PHYSICS 2007. [DOI: 10.1002/9780470141601.ch34] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
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Badenes MP, Croce AE, Cobos CJ. Falloff Curves for the Recombination Reaction Cl + FC(O)O + M → FC(O)OCl + M. J Phys Chem A 2006; 110:3186-96. [PMID: 16509643 DOI: 10.1021/jp054591x] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
The pressure dependence of the recombination reaction Cl + FC(O)O + M --> FC(O)OCl + M has been investigated at 296 K. FC(O)O radicals and Cl atoms were generated by laser flash photodissociation of FC(O)OO(O)CF at 193 nm in mixtures with Cl2 and He or SF6 over the total pressure range 8-645 Torr. The measured FC(O)O radical and F atom yields in the photolysis are 0.33 +/- 0.06 and 0.67 +/- 0.06. The reaction lies in the falloff range approaching the high-pressure limit. The extrapolations toward the limiting low- and high-pressure ranges were carried out using a reduced falloff curves formalism, which includes a recent implementation for the strong-collision broadening factors. The resulting values for the low-pressure rate coefficients are (2.2 +/- 0.4) x 10(-28)[He], (4.9 +/- 0.9) x 10(-28)[SF6], (1.9 +/- 0.3) x 10(-28)[Cl2] and (5.9 +/- 1.1) x 10(-28)[FC(O)OO(O)CF] cm3 molecule(-1) s(-1). The derived high-pressure rate coefficient is (4.4 +/- 0.8) x 10(-11) cm3 molecule(-1) s(-1). For the reaction Cl + FC(O)OCl --> Cl2 + FC(O)O a rate coefficient of (1.6 +/- 0.3) x 10(-11) cm3 molecule(-1) s(-1) was determined. The high-pressure rate coefficient was theoretically interpreted using SACM/CT calculations on an ab initio electronic potential computed at the G3S level of theory. Standard heat of formation values of -99.9 and -102.5 kcal mol(-1) were computed at the G3//B3LYP/6-311++G(3df,3pd) level of theory for cis-FC(O)OCl and trans-FC(O)OCl, respectively. The computed electronic barrier for the conversion between the trans and cis conformers is 8.9 kcal mol(-1). On the basis of the present results, the above reactions are expected to have a negligible impact on stratospheric ozone levels.
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Affiliation(s)
- María P Badenes
- Instituto de Investigaciones Fisicoquímicas Teóricas y Aplicadas (INIFTA), Departamento de Química, Facultad de Ciencias Exactas, Universidad Nacional de La Plata, CONICET, CICPBA, Casilla de Correo 16, Sucursal 4, (1900) La Plata, Argentina
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Troe J, Ushakov VG. A Simple Method Relating Specific Rate Constants k(E,J) and Thermally Averaged Rate Constants k∞(T) of Unimolecular Bond Fission and the Reverse Barrierless Association Reactions. J Phys Chem A 2006; 110:6732-41. [PMID: 16722690 DOI: 10.1021/jp056269s] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
This work describes a simple method linking specific rate constants k(E,J) of bond fission reactions AB --> A + B with thermally averaged capture rate constants k(cap)(T) of the reverse barrierless combination reactions A + B --> AB (or the corresponding high-pressure dissociation or recombination rate constants k(infinity)(T)). Practical applications are given for ionic and neutral reaction systems. The method, in the first stage, requires a phase-space theoretical treatment with the most realistic minimum energy path potential available, either from reduced dimensionality ab initio or from model calculations of the potential, providing the centrifugal barriers E(0)(J). The effects of the anisotropy of the potential afterward are expressed in terms of specific and thermal rigidity factors f(rigid)(E,J) and f(rigid)(T), respectively. Simple relationships provide a link between f(rigid)(E,J) and f(rigid)(T) where J is an average value of J related to J(max)(E), i.e., the maximum J value compatible with E > or = E0(J), and f(rigid)(E,J) applies to the transitional modes. Methods for constructing f(rigid)(E,J) from f(rigid)(E,J) are also described. The derived relationships are adaptable and can be used on that level of information which is available either from more detailed theoretical calculations or from limited experimental information on specific or thermally averaged rate constants. The examples used for illustration are the systems C6H6+ <==> C6H5+ + H, C8H10+ --> C7H7+ + CH3, n-C9H12+ <==> C7H7+ + C2H5, n-C10H14+ <==> C7H7+ + C3H7, HO2 <==> H + O2, HO2 <==> HO + O, and H2O2 <==> 2HO.
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Affiliation(s)
- J Troe
- Institut for Physical Chemistry, University of Göttingen, Tammannstrasse 6, D-37077 Göttingen, Germany.
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Troe J, Ushakov VG, Viggiano AA. On the Model Dependence of Kinetic Shifts in Unimolecular Reactions: The Dissociation of the Cations of Benzene and n-Butylbenzene. J Phys Chem A 2005; 110:1491-9. [PMID: 16435809 DOI: 10.1021/jp0529568] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Abstract
Statistical adiabatic channel model/classical trajectory (SACM/CT) calculations have been performed for transitional mode dynamics in the simple bond fission reactions of C(6)H(6)(+) --> C(6)H(5)(+) + H and n-C(6)H(5)C(4)H(9)(+) --> C(7)H(7)(+) + n-C(3)H(7). Reduced-dimensionality model potentials have been designed that take advantage of ab initio results as far as available. Average anisotropy amplitudes of the potentials were fitted by comparison of calculated specific rate constants k(E,J) with measured values. The kinetic shifts of the calculated k(E) curves and the corresponding bond energies E(0)(J=0), derived as 3.90 +/- 0.05 eV for C(6)H(6)(+) and 1.78 +/- 0.05 eV for n-C(6)H(5)C(4)H(9)(+), were in good agreement with literature values from thermochemical studies. Kinetic shifts from fixed tight activated complex Rice-Ramsperger-Kassel-Marcus (RRKM) theory, which also reproduces the measured k(E), were larger than the present SACM/CT results as well as earlier results from variational transition state theory (for C(6)H(6)(+)). The approach using RRKM theory was found to underestimate E(0)(J=0) by about 0.2-0.3 eV. A simplified SACM/CT-based method is also proposed which circumvents the trajectory calculations and allows derivation of E(0)(J=0) on the basis of measured k(E) and which provides similar accuracy as the full SACM/CT treatment.
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Affiliation(s)
- J Troe
- Institute for Physical Chemistry, University of Göttingen, Tammannstrasse 6, D-37077 Göttingen, Germany.
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Troe J. Toward a Quantitative Analysis of Association Reactions in the Atmosphere. Chem Rev 2003; 103:4565-76. [PMID: 14664623 DOI: 10.1021/cr020514b] [Citation(s) in RCA: 51] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Affiliation(s)
- Jürgen Troe
- Institut für Physikalische Chemie, Universität Göttingen, Tammannstrasse 6, D-37077 Göttingen, Germany
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Maergoiz AI, Nikitin EE, Troe J, Ushakov VG. Classical trajectory and statistical adiabatic channel study of the dynamics of capture and unimolecular bond fission. VI. Properties of transitional modes and specific rate constants k(E,J). J Chem Phys 2002. [DOI: 10.1063/1.1496463] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023] Open
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37
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Hamon S, Speck T, Mitchell JBA, Rowe BR, Troe J. Experimental and theoretical study of the ion–molecule association reaction NH4++NH3(+M)→N2H7+(+M). J Chem Phys 2002. [DOI: 10.1063/1.1491409] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
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38
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Lovejoy ER, Curtius J. Cluster Ion Thermal Decomposition (II): Master Equation Modeling in the Low-Pressure Limit and Fall-Off Regions. Bond Energies for HSO4-(H2SO4)x(HNO3)y. J Phys Chem A 2001. [DOI: 10.1021/jp012496s] [Citation(s) in RCA: 50] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
| | - Joachim Curtius
- NOAA Aeronomy Laboratory, 325 Broadway, Boulder, Colorado 80305
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39
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Troe J. Analysis of the temperature and pressure dependence of the reaction HO + NO2 + M ? HONO2 + M. INT J CHEM KINET 2001. [DOI: 10.1002/kin.10019] [Citation(s) in RCA: 34] [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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Baklanov AV, Aldener M, Lindgren B, Sassenberg U. Time-resolved k(E*) measurements for dissociation of allyl iodide vibrationally excited via C–H overtones (v=6). J Chem Phys 2000. [DOI: 10.1063/1.481239] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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41
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Lipson JB, Beiderhase TW, Molina LT, Molina MJ, Olzmann M. Production of HCl in the OH + ClO Reaction: Laboratory Measurements and Statistical Rate Theory Calculations. J Phys Chem A 1999. [DOI: 10.1021/jp9847787] [Citation(s) in RCA: 22] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Jennifer B. Lipson
- Departments of Earth, Atmospheric, and Planetary Sciences and Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139
| | - Thomas W. Beiderhase
- Departments of Earth, Atmospheric, and Planetary Sciences and Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139
| | - Luisa T. Molina
- Departments of Earth, Atmospheric, and Planetary Sciences and Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139
| | - Mario J. Molina
- Departments of Earth, Atmospheric, and Planetary Sciences and Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139
| | - Matthias Olzmann
- Institut für Physikalische Chemie, Universität Halle-Wittenberg, D-06099 Halle, Germany
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Forst W. Approximations for angular momentum-conserved polyatomic vibrational-rotational sum and density of states under a central potential. Chem Phys Lett 1996. [DOI: 10.1016/s0009-2614(96)01126-8] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
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Schott R, Schlütter J, Olzmann M, Kleinermanns K. CH3 state distributions form the reactions of O(1D) with saturated and chlorinated hydrocarbons. J Chem Phys 1995. [DOI: 10.1063/1.468828] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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44
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Troe J. Simplified models for anharmonic numbers and densities of vibrational states. I. Application to NO2 and H3+. Chem Phys 1995. [DOI: 10.1016/0301-0104(94)00358-h] [Citation(s) in RCA: 80] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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