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Quantum mechanical study of the 16O + 18O18O → 16O18O + 18O exchange reaction: Integral cross sections and rate constants. J Chem Phys 2018; 149:214304. [DOI: 10.1063/1.5053469] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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2
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Dependence on collision energy of the stereodynamical properties of the 18O + 32O 2 exchange reaction. Mol Phys 2018. [DOI: 10.1080/00268976.2018.1438676] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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3
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State-to-state chemistry and rotational excitation of CH + in photon-dominated regions. MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY 2017; 469:612-620. [PMID: 28690343 PMCID: PMC5500105 DOI: 10.1093/mnras/stx892] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
We present a detailed theoretical study of the rotational excitation of CH+ due to reactive and nonreactive collisions involving C+(2P), H2, CH+, H and free electrons. Specifically, the formation of CH+ proceeds through the reaction between C+(2P) and H2(νH2 = 1, 2), while the collisional (de)excitation and destruction of CH+ is due to collisions with hydrogen atoms and free electrons. State-to-state and initial-state-specific rate coefficients are computed in the kinetic temperature range 10-3000 K for the inelastic, exchange, abstraction and dissociative recombination processes using accurate potential energy surfaces and the best scattering methods. Good agreement, within a factor of 2, is found between the experimental and theoretical thermal rate coefficients, except for the reaction of CH+ with H atoms at kinetic temperatures below 50 K. The full set of collisional and chemical data are then implemented in a radiative transfer model. Our Non-LTE calculations confirm that the formation pumping due to vibrationally excited H2 has a substantial effect on the excitation of CH+ in photon-dominated regions. In addition, we are able to reproduce, within error bars, the far-infrared observations of CH+ toward the Orion Bar and the planetary nebula NGC 7027. Our results further suggest that the population of νH2 = 2 might be significant in the photon-dominated region of NGC 7027.
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4
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Effect of internal excitations of reagent diatom on initial state-selected dynamics of C + OH reaction on its second excited (14A″) electronic state. Mol Phys 2017. [DOI: 10.1080/00268976.2017.1296195] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
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5
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A comparative account of quantum dynamics of the H⁺ + H₂ reaction at low temperature on two different potential energy surfaces. J Chem Phys 2015; 141:064306. [PMID: 25134570 DOI: 10.1063/1.4892043] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
Rotationally resolved reaction probabilities, integral cross sections, and rate constant for the H(+) + H2 (v = 0, j = 0 or 1) → H2 (v' = 0, j') + H(+) reaction are calculated using a time-independent quantum mechanical method and the potential energy surface of Kamisaka et al. [J. Chem. Phys. 116, 654 (2002)] (say KBNN PES). All partial wave contributions of the total angular momentum, J, are included to obtain converged cross sections at low collision energies and rate constants at low temperatures. In order to test the accuracy of the KBNN PES, the results obtained here are compared with those obtained in our earlier work [P. Honvault et al., Phys. Rev. Lett. 107, 023201 (2011)] using the accurate potential energy surface of Velilla et al. [J. Chem. Phys. 129, 084307 (2008)]. Integral cross sections and rate constants obtained on the two potential energy surfaces considered here show remarkable differences in terms of magnitude and dependence on collision energy (or temperature) which can be attributed to the differences observed in the topography of the surfaces near to the entrance channel. This clearly shows the inadequacy of the KBNN PES for calculations at low collision energies.
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Time-Dependent Quantum Wave Packet Dynamics of S + OH Reaction on Its Electronic Ground State. J Phys Chem A 2014; 118:5915-26. [DOI: 10.1021/jp504757g] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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9
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Quantum dynamical study of the O(1D) + CH4→ CH3+ OH atmospheric reaction. J Chem Phys 2014; 140:244315. [DOI: 10.1063/1.4885276] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
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10
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Correction to “State-to-State Quantum Mechanical Calculations of Rate Coefficients for the D+ + H2 → HD + H+ Reaction at Low Temperature”. J Phys Chem A 2013. [DOI: 10.1021/jp4113377] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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11
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State-to-state quantum mechanical calculations of rate coefficients for the D+ + H2 → HD + H+ reaction at low temperature. J Phys Chem A 2013; 117:9778-84. [PMID: 23452294 DOI: 10.1021/jp3124549] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The dynamics of the D(+) + H2 → HD + H(+) reaction on a recent ab initio potential energy surface (Velilla, L.; Lepetit, B.; Aguado, A.; Beswick, J. A.; Paniagua, M. J. Chem. Phys. 2008, 129, 084307) has been investigated by means of a time-independent quantum mechanical approach. Cross-sections and rate coefficients are calculated, respectively, for collision energies below 0.1 eV and temperatures up to 100 K for astrophysical application. An excellent accord is found for collision energy above 5 meV, while a disagreement between theory and experiment is observed below this energy. We show that the rate coefficients reveal a slightly temperature-dependent behavior in the upper part of the temperature range considered here. This is in agreement with the experimental data above 80 K, which give a temperature independent value. However, a significant decrease is found at temperatures below 20 K. This decrease can be related to quantum effects and the decay back to the reactant channel, which are not considered by simple statistical approaches, such as the Langevin model. Our results have been fitted to appropriate analytical expressions in order to be used in astrochemical and cosmological models.
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Time-dependent quantum wave packet dynamics of the C + OH reaction on the excited electronic state. J Chem Phys 2013; 138:094318. [DOI: 10.1063/1.4793395] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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13
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Quasiclassical Trajectory and Statistical Quantum Calculations for the C + OH → CO + H Reaction on the First Excited 12A″ Potential Energy Surface. J Phys Chem A 2013; 117:1872-9. [DOI: 10.1021/jp309764g] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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14
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H2, H3+ and the age of molecular clouds and prestellar cores. PHILOSOPHICAL TRANSACTIONS. SERIES A, MATHEMATICAL, PHYSICAL, AND ENGINEERING SCIENCES 2012; 370:5200-5212. [PMID: 23028166 DOI: 10.1098/rsta.2012.0027] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
Measuring the age of molecular clouds and prestellar cores is a difficult task that has not yet been successfully accomplished although the information is of paramount importance to help in understanding and discriminating between different formation scenarios. Most chemical clocks suffer from unknown initial conditions and are therefore difficult to use. We propose a new approach based on a subset of deuterium chemistry that takes place in the gas phase and for which initial conditions are relatively well known. It relies primarily on the conversion of H(3)(+) into H(2)D(+) to initiate deuterium enrichment of the molecular gas. This conversion is controlled by the ortho/para ratio of H(2) that is thought to be produced with the statistical ratio of 3 and subsequently slowly decays to an almost pure para-H(2) phase. This slow decay takes approximately 1 Myr and allows us to set an upper limit on the age of molecular clouds. The deuterium enrichment of the core takes longer to reach equilibrium and allows us to estimate the time necessary to form a dense prestellar core, i.e. the last step before the collapse of the core into a protostar. We find that the observed abundance and distribution of DCO(+) and N(2)D(+) argue against quasi-static core formation and favour dynamical formation on time scales of less than 1 Myr. Another consequence is that ortho-H(2) remains comparable to para-H(2) in abundance outside the dense cores.
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An accurate study of the dynamics of the C+OH reaction on the second excited 14A″ potential energy surface. J Chem Phys 2012; 136:164309. [DOI: 10.1063/1.4705426] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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16
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State-to-State Quantum Dynamics Calculations of the C + OH Reaction on the Second Excited Potential Energy Surface. J Phys Chem A 2011; 115:8791-6. [DOI: 10.1021/jp202879n] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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17
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Ortho-para H₂ conversion by proton exchange at low temperature: an accurate quantum mechanical study. PHYSICAL REVIEW LETTERS 2011; 107:023201. [PMID: 21797601 DOI: 10.1103/physrevlett.107.023201] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/20/2011] [Indexed: 05/31/2023]
Abstract
We report extensive, accurate fully quantum, time-independent calculations of cross sections at low collision energies, and rate coefficients at low temperatures for the H⁺ + H₂(v = 0, j) → H⁺ + H₂(v = 0, j') reaction. Different transitions are considered, especially the ortho-para conversion (j = 1 → j' = 0) which is of key importance in astrophysics. This conversion process appears to be very efficient and dominant at low temperature, with a rate coefficient of 4.15 × 10⁻¹⁰ cm³ molecule⁻¹ s⁻¹ at 10 K. The quantum mechanical results are also compared with statistical quantum predictions and the reaction is found to be statistical in the low temperature regime (T < 100 K).
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Quantum mechanical study of the proton exchange in the ortho–para H2 conversion reaction at low temperature. Phys Chem Chem Phys 2011; 13:19089-100. [DOI: 10.1039/c1cp21232j] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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19
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O+OH-->O(2)+H: A key reaction for interstellar chemistry. New theoretical results and comparison with experiment. J Chem Phys 2010; 131:221104. [PMID: 20001016 DOI: 10.1063/1.3274226] [Citation(s) in RCA: 53] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
We report extensive, fully quantum, time-independent (TID) calculations of cross sections at low collision energies and rate constants at low temperatures for the O+OH reaction, of key importance in the production of molecular oxygen in cold, dark, interstellar clouds and in the chemistry of the Earth's atmosphere. Our calculations are compared with TID calculations within the J-shifting approximation, with wave-packet calculations, and with quasiclassical trajectory calculations. The fully quantum TID calculations yield rate constants higher than those from the more approximate methods and are qualitatively consistent with a low-temperature extrapolation of earlier experimental values but not with the most recent experiments at the lowest temperatures.
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Quantum Dynamics at the State-to-State Level of the C + OH Reaction on the First Excited Potential Energy Surface. J Phys Chem A 2009; 114:4742-7. [DOI: 10.1021/jp908963k] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
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21
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State-to-State Quantum Reactive Scattering Calculations and Rate Constant for Nitrogen Atoms in Collision with NO Radicals at Low Temperatures. J Phys Chem A 2009; 113:10648-51. [DOI: 10.1021/jp907865a] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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22
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Effects of the rotational excitation of D2 and of the potential energy surface on the H++D2→HD+D+ reaction. J Chem Phys 2009; 131:044315. [DOI: 10.1063/1.3183538] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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23
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Quasi-classical determination of integral cross-sections and rate constants for the N+OH→NO+H reaction. Chem Phys Lett 2009. [DOI: 10.1016/j.cplett.2009.02.029] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
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24
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State-to-State Quantum Dynamical Study of the N + OH → NO + H Reaction. J Phys Chem A 2009; 113:2316-22. [DOI: 10.1021/jp811237z] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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25
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Quasiclassical trajectory scattering calculations for the OH+O→H+O2 reaction: Cross sections and rate constants. Chem Phys Lett 2008. [DOI: 10.1016/j.cplett.2008.07.069] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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26
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Ab initio potential energy surfaces for the study of rotationally inelastic CH(X2Π)+H(2S) collisions. Chem Phys Lett 2008. [DOI: 10.1016/j.cplett.2008.03.005] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
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27
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Quantum mechanical and quasiclassical trajectory scattering calculations for the C(D1)+H2 reaction on the second excited 1A″1 potential energy surface. J Chem Phys 2006; 124:154314. [PMID: 16674233 DOI: 10.1063/1.2187007] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Time-independent quantum mechanical (QM) and quasiclassical trajectory (QCT) scattering calculations have been carried out for the C(1D) + H2 --> CH + H reaction at a collision energy of 80 meV on a newly developed ab initio potential energy surface [B. Bussery-Honvault et al., Phys. Chem. Chem. Phys. 7, 1476 (2005)] of 1 1A" symmetry, corresponding to the second singlet state 1 1B1 of CH2. A general good agreement has been found between the QM and QCT rotational distributions and differential cross sections (DCSs). In both cases, DCSs are strongly peaked in the forward direction with a small contribution in the backward direction in contrast with those obtained on the 1 1A' surface, which are nearly symmetric. Rotational distributions obtained on the 1 1A" surface are somewhat colder than those calculated on the 1 1A' surface. The specific dynamics and the contribution of the 1 1A" surface to the overall reactivity of this system are discussed.
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28
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Quantum mechanical and quasi-classical trajectory reaction probabilities and cross sections for the S(1D) + H2,D2,HD insertion reactions. Phys Chem Chem Phys 2005; 7:627-34. [DOI: 10.1039/b417368f] [Citation(s) in RCA: 59] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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29
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Dynamics of the S(1D) + H2 Insertion Reaction: A Combined Quantum Mechanical and Quasiclassical Trajectory Study. J Phys Chem A 2004. [DOI: 10.1021/jp037109o] [Citation(s) in RCA: 86] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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30
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Quantum mechanical and quasi-classical trajectory study of the C(1D)+H2 reaction dynamics. J Chem Phys 2003. [DOI: 10.1063/1.1527014] [Citation(s) in RCA: 188] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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31
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Experimental and theoretical study of intramultiplet transitions in collisions of C(3P) and Si(3P) with He. J Chem Phys 2002. [DOI: 10.1063/1.1518026] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
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32
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The O(1D)+H2 reaction at 56 meV collision energy: A comparison between quantum mechanical, quasiclassical trajectory, and crossed beam results. J Chem Phys 2002. [DOI: 10.1063/1.1478693] [Citation(s) in RCA: 68] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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33
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A study of the C(1D)+H2→CH+H reaction: Global potential energy surface and quantum dynamics. J Chem Phys 2001. [DOI: 10.1063/1.1417501] [Citation(s) in RCA: 91] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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34
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Insertion and abstraction pathways in the reaction O(1D2) + H2-->OH+H. PHYSICAL REVIEW LETTERS 2001; 86:1729-1732. [PMID: 11290234 DOI: 10.1103/physrevlett.86.1729] [Citation(s) in RCA: 76] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/27/2000] [Indexed: 05/23/2023]
Abstract
Rigorous quantum dynamical calculations have been performed on the ground 1 1A' and first excited 1 1A" electronic states of the title reaction, employing the most accurate potential energy surfaces available. Product rovibrational quantum state populations and rotational angular momentum alignment parameters are reported, and are compared with new experimental, and quasiclassical trajectory calculated results. The quantum calculations agree quantitatively with experiment, and reveal unequivocally that the 1 1A" excited state participates in the reaction.
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Quantum mechanical and quasiclassical trajectory study of state-to-state differential cross sections for the F+D2→DF+D reaction in the center-of-mass and laboratory frames. Phys Chem Chem Phys 1999. [DOI: 10.1039/a902653c] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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36
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Fine structure relaxation of aluminum by atomic argon between 30 and 300 K: An experimental and theoretical study. J Chem Phys 1998. [DOI: 10.1063/1.475342] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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