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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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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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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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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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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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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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Sweeny BC, Pan H, Kassem A, Sawyer JC, Ard SG, Shuman NS, Viggiano AA, Brickel S, Unke OT, Upadhyay M, Meuwly M. Thermal activation of methane by MgO+: temperature dependent kinetics, reactive molecular dynamics simulations and statistical modeling. Phys Chem Chem Phys 2020; 22:8913-8923. [DOI: 10.1039/d0cp00668h] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
The kinetics methane activation (MgO+ + CH4) was studied experimentally and computationally by running and analyzing reactive atomistic simulations.
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Affiliation(s)
- Brendan C. Sweeny
- NRC Postdoc at Air Force Research Laboratory
- Space Vehicles Directorate
- Kirtland Air Force Base
- USA
| | - Hanqing Pan
- USRA Space Scholar at Air Force Research Laboratory
- Space Vehicles Directorate
- Kirtland Air Force Base
- USA
| | - Asmaa Kassem
- USRA Space Scholar at Air Force Research Laboratory
- Space Vehicles Directorate
- Kirtland Air Force Base
- USA
| | - Jordan C. Sawyer
- NRC Postdoc at Air Force Research Laboratory
- Space Vehicles Directorate
- Kirtland Air Force Base
- USA
| | - Shaun G. Ard
- Air Force Research Laboratory
- Space Vehicles Directorate
- Kirtland Air Force Base
- USA
| | - Nicholas S. Shuman
- Air Force Research Laboratory
- Space Vehicles Directorate
- Kirtland Air Force Base
- USA
| | - Albert A. Viggiano
- Air Force Research Laboratory
- Space Vehicles Directorate
- Kirtland Air Force Base
- USA
| | | | - Oliver T. Unke
- Department of Chemistry
- University of Basel
- CH-4056 Basel
- Switzerland
| | - Meenu Upadhyay
- Department of Chemistry
- University of Basel
- CH-4056 Basel
- Switzerland
| | - Markus Meuwly
- Department of Chemistry
- University of Basel
- CH-4056 Basel
- Switzerland
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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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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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Busch A, González-García N, Lendvay G, Olzmann M. Thermal Decomposition of NCN: Shock-Tube Study, Quantum Chemical Calculations, and Master-Equation Modeling. J Phys Chem A 2015; 119:7838-46. [PMID: 25853321 DOI: 10.1021/acs.jpca.5b01347] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The thermal decomposition of cyanonitrene, NCN, was studied behind reflected shock waves in the temperature range 1790-2960 K at pressures near 1 and 4 bar. Highly diluted mixtures of NCN3 in argon were shock-heated to produce NCN, and concentration-time profiles of C atoms as reaction product were monitored with atomic resonance absorption spectroscopy at 156.1 nm. Calibration was performed with methane pyrolysis experiments. Rate coefficients for the reaction (3)NCN + M → (3)C + N2 + M (R1) were determined from the initial slopes of the C atom concentration-time profiles. Reaction R1 was found to be in the low-pressure regime at the conditions of the experiments. The temperature dependence of the bimolecular rate coefficient can be expressed with the following Arrhenius equation: k1(bim) = (4.2 ± 2.1) × 10(14) exp[-242.3 kJ mol(-1)/(RT)] cm(3) mol(-1) s(-1). The rate coefficients were analyzed by using a master equation with specific rate coefficients from RRKM theory. The necessary molecular data and energies were calculated with quantum chemical methods up to the CCSD(T)/CBS//CCSD/cc-pVTZ level of theory. From the topography of the potential energy surface, it follows that reaction R1 proceeds via isomerization of NCN to CNN and subsequent C-N bond fission along a collinear reaction coordinate without a tight transition state. The calculations reproduce the magnitude and temperature dependence of the rate coefficient and confirm that reaction R1 is in the low-pressure regime under our experimental conditions.
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Affiliation(s)
- Anna Busch
- †Institut für Physikalische Chemie, Karlsruher Institut für Technologie (KIT), Kaiserstr. 12, 76131 Karlsruhe, Germany
| | - Núria González-García
- †Institut für Physikalische Chemie, Karlsruher Institut für Technologie (KIT), Kaiserstr. 12, 76131 Karlsruhe, Germany
| | - György Lendvay
- ‡Institute of Materials and Environmental Chemistry, Research Center for Natural Sciences, Hungarian Academy of Sciences, Magyar Tudósok krt. 2, Budapest H-1117, Hungary
| | - Matthias Olzmann
- †Institut für Physikalische Chemie, Karlsruher Institut für Technologie (KIT), Kaiserstr. 12, 76131 Karlsruhe, Germany
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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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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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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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Schmatz S. Approximate calculation of anharmonic densities of vibrational states for very large molecules. Chem Phys 2008. [DOI: 10.1016/j.chemphys.2008.01.020] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
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Van Doren JM, Miller TM, Viggiano AA, Španěl P, Smith D, Bopp JC, Troe J. Experimental and theoretical investigation of electron attachment to SF5Cl. J Chem Phys 2008; 128:094309. [DOI: 10.1063/1.2831767] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
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Troe J, Ushakov VG. SACM/CT Study of the dissociation/recombination dynamics of hydrogen peroxide on an ab initio potential energy surface : Part II. Specific rate constants k(E,J), thermal rate constants k∞(T), and lifetime distributions. Phys Chem Chem Phys 2008; 10:3915-24. [DOI: 10.1039/b803320j] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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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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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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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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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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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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Truhlar DG, Garrett BC, Klippenstein SJ. Current Status of Transition-State Theory. ACTA ACUST UNITED AC 1996. [DOI: 10.1021/jp953748q] [Citation(s) in RCA: 1585] [Impact Index Per Article: 56.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Donald G. Truhlar
- Department of Chemistry and Supercomputer Institute, University of Minnesota, Minneapolis, Minnesota 55455-0431
| | - Bruce C. Garrett
- Environmental Molecular Sciences Laboratory, Pacific Northwest National Laboratory, 902 Battelle Boulevard, MS K1-96, Richland, Washington 99352
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