1
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Ma D, Ma J. Full-dimensional quantum mechanical calculations for the tunneling behavior of HOCO dissociation to H + CO 2. Phys Chem Chem Phys 2022; 24:15321-15329. [PMID: 35703166 DOI: 10.1039/d1cp04269f] [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
The tunneling behavior during HOCO dissociation to H + CO2 was investigated by full-dimensional quantum mechanical calculations based on an accurate global potential energy surface. The tunneling lifetimes for the low-lying 1500 vibrational states were calculated using the low-storage filter diagonalization method after a 1 million-step Chebyshev propagation. In the calculated energy range, the lifetimes of different vibrational states with similar energy are found to differ by 3-4 orders of magnitude, and the lower limit for these tunneling lifetimes is consistent with the experimental results reported by Continetti et al. For the given vibrational progressions, the lifetime of the vibrational states decreases with the increasing energy level, which is consistent with the results of 1D simulation calculations reported by Bowman, but the declining curve obviously fluctuates, and the declining slope is significantly different from that obtained by 1D simulation. Due to a difference in the effective barrier width, the mode-specific behavior of the tunneling effect is manifested in that the O-C-O' and H-O-C bend modes lead to the largest enhancement and an inhibitory effect on the tunneling process, respectively.
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Affiliation(s)
- Dandan Ma
- Institute of Atomic and Molecular Physics, Sichuan University, Chengdu, Sichuan, 610065, China.
| | - Jianyi Ma
- Institute of Atomic and Molecular Physics, Sichuan University, Chengdu, Sichuan, 610065, China.
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2
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Nikitenko SI, Chave T, Virot M, Pflieger R. Simultaneous H/D and 13C/ 12C Anomalous Kinetic Isotope Effects during the Sonolysis of Water in the Presence of Carbon Monoxide. J Phys Chem Lett 2022; 13:42-48. [PMID: 34958222 DOI: 10.1021/acs.jpclett.1c03744] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
Splitting of water molecules driven by ultrasound plays a central role in sonochemistry. While studies of sonoluminescence revealed the formation of a plasma inside the cavitation bubble, much less is known about the contribution of plasma chemical processes to the sonochemical mechanisms. Herein, we report for the first time sonochemical processes in water saturated with pure CO. The presence of CO causes a large increase in the H/D kinetic isotope effect (KIE) to αH = 14.6 ± 1.8 in a 10% H2O/D2O mixture under 20 kHz ultrasound. The anomalous H/D KIE is attributed to electron quantum tunneling in the plasma produced by cavitation. In addition, CO2 formed simultaneously with hydrogen during the sonochemical process is enriched with the 13C isotope, which indicates a V-V pumping mechanism typical for non-equilibrium plasma. Both observed KIEs unambiguously point to the contribution of quantum effects in sonochemical mechanisms.
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Affiliation(s)
- Sergey I Nikitenko
- ICSM, Univ Montpellier, UMR 5257, CEA, CNRS, ENSCM, Marcoule, F-30207 Bagnols sur Cèze Cedex, France
| | - Tony Chave
- ICSM, Univ Montpellier, UMR 5257, CEA, CNRS, ENSCM, Marcoule, F-30207 Bagnols sur Cèze Cedex, France
| | - Matthieu Virot
- ICSM, Univ Montpellier, UMR 5257, CEA, CNRS, ENSCM, Marcoule, F-30207 Bagnols sur Cèze Cedex, France
| | - Rachel Pflieger
- ICSM, Univ Montpellier, UMR 5257, CEA, CNRS, ENSCM, Marcoule, F-30207 Bagnols sur Cèze Cedex, France
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3
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Abstract
Nonstatistical dynamics is important for many chemical reactions. The Rice-Ramsperger-Kassel-Marcus (RRKM) theory of unimolecular kinetics assumes a reactant molecule maintains a statistical microcanonical ensemble of vibrational states during its dissociation so that its unimolecular dynamics are time independent. Such dynamics results when the reactant's atomic motion is chaotic or irregular. Intrinsic non-RRKM dynamics occurs when part of the reactant's phase space consists of quasiperiodic/regular motion and a bottleneck exists, so that the unimolecular rate constant is time dependent. Nonrandom excitation of a molecule may result in short-time apparent non-RRKM dynamics. For rotational activation, the 2J + 1 K levels for a particular J may be highly mixed, making K an active degree of freedom, or K may be a good quantum number and an adiabatic degree of freedom. Nonstatistical dynamics is often important for bimolecular reactions and their intermediates and for product-energy partitioning of bimolecular and unimolecular reactions. Post–transition state dynamics is often highly complex and nonstatistical.
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Affiliation(s)
- Bhumika Jayee
- Department of Chemistry and Biochemistry, Texas Tech University, Lubbock, Texas 79409, USA
| | - William L. Hase
- Department of Chemistry and Biochemistry, Texas Tech University, Lubbock, Texas 79409, USA
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4
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Masoumpour MS, Daryanavard M. The kinetics and dynamics of the multichannel multiwell reaction of CO(1Σ+) with OH(2Π): theoretical investigation. SN APPLIED SCIENCES 2020. [DOI: 10.1007/s42452-020-2299-x] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
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5
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Caracciolo A, Lu D, Balucani N, Vanuzzo G, Stranges D, Wang X, Li J, Guo H, Casavecchia P. Combined Experimental-Theoretical Study of the OH + CO → H + CO 2 Reaction Dynamics. J Phys Chem Lett 2018; 9:1229-1236. [PMID: 29470075 DOI: 10.1021/acs.jpclett.7b03439] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
A combined experimental-theoretical study is performed to advance our understanding of the dynamics of the prototypical tetra-atom, complex-forming reaction OH + CO → H + CO2, which is also of great practical relevance in combustion, Earth's atmosphere, and, potentially, Mars's atmosphere and interstellar chemistry. New crossed molecular beam experiments with mass spectrometric detection are analyzed together with the results from previous experiments and compared with quasi-classical trajectory (QCT) calculations on a new, full-dimensional potential energy surface (PES). Comparisons between experiment and theory are carried out both in the center-of-mass and laboratory frames. Good agreement is found between experiment and theory, both for product angular and translational energy distributions, leading to the conclusion that the new PES is the most accurate at present in elucidating the dynamics of this fundamental reaction. Yet, small deviations between experiment and theory remain and are presumably attributable to the QCT treatment of the scattering dynamics.
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Affiliation(s)
- Adriana Caracciolo
- Dipartimento di Chimica, Biologia e Biotecnologie , Università degli Studi di Perugia , 06123 Perugia , Italy
| | - Dandan Lu
- School of Chemistry and Chemical Engineering , Chongqing University , Chongqing 401331 , China
| | - Nadia Balucani
- Dipartimento di Chimica, Biologia e Biotecnologie , Università degli Studi di Perugia , 06123 Perugia , Italy
| | - Gianmarco Vanuzzo
- Dipartimento di Chimica, Biologia e Biotecnologie , Università degli Studi di Perugia , 06123 Perugia , Italy
| | - Domenico Stranges
- Dipartimento di Chimica , Sapienza - Università di Roma , 00185 Roma , Italy
| | - Xingan Wang
- Department of Chemical Physics, School of Chemistry and Materials Science , University of Science and Technology of China , Hefei , Anhui 230026 , China
| | - Jun Li
- School of Chemistry and Chemical Engineering , Chongqing University , Chongqing 401331 , China
| | - Hua Guo
- Department of Chemistry and Chemical Biology , University of New Mexico , Albuquerque , New Mexico 87131 , United States
| | - Piergiorgio Casavecchia
- Dipartimento di Chimica, Biologia e Biotecnologie , Università degli Studi di Perugia , 06123 Perugia , Italy
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6
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Panteleev SV, Masunov AE, Vasu SS. Molecular Dynamics Study of Combustion Reactions in a Supercritical Environment. Part 2: Boxed MD Study of CO + OH → CO2 + H Reaction Kinetics. J Phys Chem A 2018; 122:897-908. [DOI: 10.1021/acs.jpca.7b09774] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Sergey V. Panteleev
- NanoScienece
Technology Center, University of Central Florida, 12424 Research
Parkway, Suite 400, Orlando, Florida 32826, United States
- N. I. Lobachevsky State University of Nizhny Novgorod, Gagarin Av. 23, Nizhny Novgorod 603950, Russia
| | - Artëm E. Masunov
- NanoScienece
Technology Center, University of Central Florida, 12424 Research
Parkway, Suite 400, Orlando, Florida 32826, United States
- Department
of Chemistry, and Department of Physics, University of Central Florida, 4111 Libra Drive, Orlando, Florida 32816, United States
- South Ural State University, Lenin pr. 76, Chelyabinsk 454080, Russia
- National Research Nuclear University MEPhI, Kashirskoye shosse 31, Moscow, 115409, Russia
| | - Subith S. Vasu
- Center for
Advanced Turbomachinery and Energy Research (CATER), Mechanical and
Aerospace Engineering, University of Central Florida, Orlando, Florida 32816, United States
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7
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Bjork BJ, Bui TQ, Heckl OH, Changala PB, Spaun B, Heu P, Follman D, Deutsch C, Cole GD, Aspelmeyer M, Okumura M, Ye J. Direct frequency comb measurement of OD + CO -> DOCO kinetics. Science 2016; 354:444-448. [PMID: 27789837 DOI: 10.1126/science.aag1862] [Citation(s) in RCA: 40] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2016] [Accepted: 09/28/2016] [Indexed: 11/02/2022]
Affiliation(s)
- B J Bjork
- JILA, National Institute of Standards and Technology and University of Colorado, and Department of Physics, University of Colorado, Boulder, CO 80309, USA.
| | - T Q Bui
- JILA, National Institute of Standards and Technology and University of Colorado, and Department of Physics, University of Colorado, Boulder, CO 80309, USA
| | - O H Heckl
- JILA, National Institute of Standards and Technology and University of Colorado, and Department of Physics, University of Colorado, Boulder, CO 80309, USA
| | - P B Changala
- JILA, National Institute of Standards and Technology and University of Colorado, and Department of Physics, University of Colorado, Boulder, CO 80309, USA
| | - B Spaun
- JILA, National Institute of Standards and Technology and University of Colorado, and Department of Physics, University of Colorado, Boulder, CO 80309, USA
| | - P Heu
- Crystalline Mirror Solutions, 114 East Haley Street, Suite G, Santa Barbara, CA 93101, USA
| | - D Follman
- Crystalline Mirror Solutions, 114 East Haley Street, Suite G, Santa Barbara, CA 93101, USA
| | - C Deutsch
- Crystalline Mirror Solutions, Parkring 10, 1010 Vienna, Austria
| | - G D Cole
- Crystalline Mirror Solutions, 114 East Haley Street, Suite G, Santa Barbara, CA 93101, USA. Crystalline Mirror Solutions, Parkring 10, 1010 Vienna, Austria
| | - M Aspelmeyer
- Vienna Center for Quantum Science and Technology, Faculty of Physics, University of Vienna, 1090 Vienna, Austria
| | - M Okumura
- Arthur Amos Noyes Laboratory of Chemical Physics, Division of Chemistry and Chemical Engineering, California Institute of Technology, 1200 East California Boulevard, Pasadena, CA 91125, USA
| | - J Ye
- JILA, National Institute of Standards and Technology and University of Colorado, and Department of Physics, University of Colorado, Boulder, CO 80309, USA.
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8
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Tachikawa H, Kawabata H. Effects of a Single Water Molecule on the Reaction Barrier of Interstellar CO2 Formation Reaction. J Phys Chem A 2016; 120:6596-603. [DOI: 10.1021/acs.jpca.6b05563] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Hiroto Tachikawa
- Division
of Applied Chemistry, Graduate School of Engineering, Hokkaido University, Sapporo 060-8628, Japan
| | - Hiroshi Kawabata
- Division
of Applied Chemistry, Graduate School of Engineering, Hokkaido University, Sapporo 060-8628, Japan
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9
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Wang J, Li J, Ma J, Guo H. Full-dimensional characterization of photoelectron spectra of HOCO−and DOCO−and tunneling facilitated decay of HOCO prepared by anion photodetachment. J Chem Phys 2014; 140:184314. [DOI: 10.1063/1.4874975] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [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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Wang X, Bowman JM. Mode-Specific Tunneling in the Unimolecular Dissociation of cis-HOCO to H + CO2. J Phys Chem A 2014; 118:684-9. [DOI: 10.1021/jp5000655] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Xiaohong Wang
- Department
of Chemistry, Emory University, Atlanta Georgia 30322, United States
| | - Joel M. Bowman
- Department
of Chemistry, Emory University, Atlanta Georgia 30322, United States
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11
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Johnson CJ, Otto R, Continetti RE. Spectroscopy and dynamics of the HOCO radical: insights into the OH + CO → H + CO2 reaction. Phys Chem Chem Phys 2014; 16:19091-105. [DOI: 10.1039/c4cp02593h] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Photoelectron–photofragment coincidence experiments coupled with quantum chemistry and dynamics calculations have significantly enhanced our understanding of the reactive intermediate HOCO.
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Affiliation(s)
| | - Rico Otto
- Department of Chemistry and Biochemistry
- University of California
- San Diego
- La Jolla, USA
| | - Robert E. Continetti
- Department of Chemistry and Biochemistry
- University of California
- San Diego
- La Jolla, USA
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12
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Walsh C, Herbst E, Nomura H, Millar TJ, Weaver SW. Complex organic molecules along the accretion flow in isolated and externally irradiated protoplanetary disks. Faraday Discuss 2014; 168:389-421. [DOI: 10.1039/c3fd00135k] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The birth environment of the Sun will have influenced the physical and chemical structure of the pre-solar nebula, including the attainable chemical complexity reached in the disk, important for prebiotic chemistry. The formation and distribution of complex organic molecules (COMs) in a disk around a T Tauri star is investigated for two scenarios: (i) an isolated disk, and (ii) a disk irradiated externally by a nearby massive star. The chemistry is calculated along the accretion flow from the outer disk inwards using a comprehensive network which includes gas-phase reactions, gas-grain interactions, and thermal grain-surface chemistry. Two simulations are performed, one beginning with complex ices and one with simple ices only. For the isolated disk, COMs are transported without major chemical alteration into the inner disk where they thermally desorb into the gas reaching an abundance representative of the initial assumed ice abundance. For simple ices, COMs can efficiently form on grain surfaces under the conditions in the outer disk. Gas-phase COMs are released into the molecular layer via photodesorption. For the irradiated disk, complex ices are also transported inwards; however, they undergo thermal processing caused by the warmer conditions in the irradiated disk which tends to reduce their abundance along the accretion flow. For simple ices, grain-surface chemistry cannot efficiently synthesise COMs in the outer disk because the necessary grain-surface radicals, which tend to be particularly volatile, are not sufficiently abundant on the grain surfaces. Gas-phase COMs are formed in the inner region of the irradiated disk via gas-phase chemistry induced by the desorption of strongly bound molecules such as methanol; hence, the abundances are not representative of the initial molecular abundances injected into the outer disk. These results suggest that the composition of comets formed in isolated disks may differ from those formed in externally irradiated disks with the latter composed of more simple ices.
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Affiliation(s)
- Catherine Walsh
- Leiden Observatory
- Leiden University
- 2300 RA Leiden, The Netherlands
| | - Eric Herbst
- Departments of Chemistry, Astronomy, and Physics, University of Virginia
- Charlottesville, USA
| | - Hideko Nomura
- Department of Earth and Planetary Sciences
- Tokyo Institute of Technology
- , Japan
| | - T. J. Millar
- Astrophysics Research Centre
- School of Mathematics and Physics
- Queen's University Belfast
- Belfast, UK
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13
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Weston RE, Nguyen TL, Stanton JF, Barker JR. HO + CO Reaction Rates and H/D Kinetic Isotope Effects: Master Equation Models with ab Initio SCTST Rate Constants. J Phys Chem A 2013; 117:821-35. [DOI: 10.1021/jp311928w] [Citation(s) in RCA: 57] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Ralph E. Weston
- Department
of Chemistry, Brookhaven National Laboratory, Upton, New York 11973,
United States
| | - Thanh Lam Nguyen
- Department
of Chemistry and
Biochemistry, The University of Texas,
Austin, Texas 78712-0165, United States
| | - John F. Stanton
- Department
of Chemistry and
Biochemistry, The University of Texas,
Austin, Texas 78712-0165, United States
| | - John R. Barker
- Department of Atmospheric, Oceanic,
and Space Sciences, University of Michigan, Ann Arbor, Michigan 48109-2143, United States
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14
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Li J, Xie C, Ma J, Wang Y, Dawes R, Xie D, Bowman JM, Guo H. Quasi-Classical Trajectory Study of the HO + CO → H + CO2 Reaction on a New ab Initio Based Potential Energy Surface. J Phys Chem A 2012; 116:5057-67. [DOI: 10.1021/jp302278r] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Jun Li
- Department of Chemistry and
Chemical Biology, University of New Mexico, Albuquerque, New Mexico 87131, United States
| | - Changjian Xie
- Department of Chemistry and
Chemical Biology, University of New Mexico, Albuquerque, New Mexico 87131, United States
- Institute of Theoretical and
Computational Chemistry, Key Laboratory of Mesoscopic Chemistry, School
of Chemistry and Chemical Engineering, Nanjing University, Nanjing 210093, China
| | - Jianyi Ma
- Department of Chemistry and
Chemical Biology, University of New Mexico, Albuquerque, New Mexico 87131, United States
| | - Yimin Wang
- Cherry L. Emerson Center for Scientific
Computation and Department of Chemistry, Emory University, Atlanta, Georgia 30322, United States
| | - Richard Dawes
- Department of Chemistry, Missouri University of Science and Technology, Rolla,
Missouri 65409, United States
| | - Daiqian Xie
- Institute of Theoretical and
Computational Chemistry, Key Laboratory of Mesoscopic Chemistry, School
of Chemistry and Chemical Engineering, Nanjing University, Nanjing 210093, China
| | - Joel M. Bowman
- Cherry L. Emerson Center for Scientific
Computation and Department of Chemistry, Emory University, Atlanta, Georgia 30322, United States
| | - Hua Guo
- Department of Chemistry and
Chemical Biology, University of New Mexico, Albuquerque, New Mexico 87131, United States
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15
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Li J, Wang Y, Jiang B, Ma J, Dawes R, Xie D, Bowman JM, Guo H. Communication: A chemically accurate global potential energy surface for the HO + CO → H + CO2 reaction. J Chem Phys 2012; 136:041103. [DOI: 10.1063/1.3680256] [Citation(s) in RCA: 99] [Impact Index Per Article: 8.3] [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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17
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Garcia E, Saracibar A, Laganà A. On the anomaly of the quasiclassical product distributions of the $$\hbox{OH} +\hbox{CO} \rightarrow\hbox{H} +\hbox{CO}_2$$ reaction. Theor Chem Acc 2010. [DOI: 10.1007/s00214-010-0787-6] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
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18
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Poggi G, Francisco JS. An ab initio study of the reaction of HOCO radicals with NO2: Addition/elimination mechanism. J Chem Phys 2009; 130:124306. [DOI: 10.1063/1.3095757] [Citation(s) in RCA: 10] [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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19
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Lourderaj U, Hase WL. Theoretical and Computational Studies of Non-RRKM Unimolecular Dynamics. J Phys Chem A 2009; 113:2236-53. [DOI: 10.1021/jp806659f] [Citation(s) in RCA: 137] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Upakarasamy Lourderaj
- Department of Chemistry and Biochemistry, Texas Tech University, Lubbock, Texas 79409-1061
| | - William L. Hase
- Department of Chemistry and Biochemistry, Texas Tech University, Lubbock, Texas 79409-1061
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20
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Yu HG, Francisco JS, Muckerman JT. Ab initioand direct dynamics study of the reaction of Cl atoms with HOCO. J Chem Phys 2008; 129:064301. [DOI: 10.1063/1.2965523] [Citation(s) in RCA: 19] [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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21
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Mass-Independent Oxygen Isotope Fractionation in Selected Systems. Mechanistic Considerations. ADVANCES IN QUANTUM CHEMISTRY 2008. [DOI: 10.1016/s0065-3276(07)00202-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 03/11/2023]
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22
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Lu Z, Hu Q, Oakman JE, Continetti RE. Dynamics on the HOCO potential energy surface studied by dissociative photodetachment of HOCO− and DOCO−. J Chem Phys 2007; 126:194305. [PMID: 17523802 DOI: 10.1063/1.2731787] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
An experimental study of the dissociative photodetachment (DPD) dynamics of HOCO(-) and DOCO(-) at a photon energy of 3.21 eV has been carried out to probe the potential energy surface of the HOCO free radical and the dynamics of the OH+CO-->H+CO(2) reaction. These photoelectron-photofragment coincidence experiments allow the identification of photodetachment processes leading to the production of stable HOCO free radicals and both the H+CO(2) and OH+CO dissociation channels on the neutral surface. Isotopic substitution by deuterium in the parent ion is observed to reduce the product branching ratio for the D+CO(2) channel, consistent with tunneling playing a role in this dissociation pathway. Other isotope effects on the detailed partitioning of kinetic energy between photoelectrons and photofragments are also discussed. The results are compared to recent theoretical predictions of this DPD process, and evidence for the involvement of vibrationally excited HOCO(-) anions is discussed.
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Affiliation(s)
- Zhou Lu
- Department of Chemistry and Biochemistry, University of California, San Diego, La Jolla, California 92093-0340, USA
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23
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Ochando-Pardo M, Nebot-Gil I, González-Lafont A, Lluch JM. Methyl Vinyl Ketone+OH and Methacrolein+OH Oxidation Reactions: A Master Equation Analysis of the Pressure- and Temperature-Dependent Rate Constants. Chemistry 2007; 13:1180-90. [PMID: 17066494 DOI: 10.1002/chem.200600529] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
High-level electronic structure calculations and master equation analyses were carried out to obtain the pressure- and temperature-dependent rate constants of the methyl vinyl ketone+OH and methacrolein+OH reactions. The balance between the OH addition reactions at the high-pressure limit, the OH addition reactions in the fall-off region, and the pressure-independent hydrogen abstractions involved in these multiwell and multichannel systems, has been shown to be crucial to understand the pressure and temperature dependence of each global reaction. In particular, the fall-off region of the OH addition reactions contributes to the inverse temperature dependence of the rate constants in the Arrhenius plots, leading to pressure-dependent negative activation energies. The pressure dependence of the methyl vinyl ketone+OH reaction is clearly more important than in the case of the methacrolein+OH reaction owing to the weight of the hydrogen abstraction process in this second system. Comparison of the theoretical rate constants and the experimental measurements shows quite good agreement.
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24
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Chen WC, Marcus RA. On the theory of the reaction rate of vibrationally excited CO molecules with OH radicals. J Chem Phys 2006; 124:024306. [PMID: 16422582 DOI: 10.1063/1.2148408] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
The dependence of the rate of the reaction CO+OH-->H+CO2 on the CO-vibrational excitation is treated here theoretically. Both the Rice-Ramsperger-Kassel-Marcus (RRKM) rate constant kRRKM and a nonstatistical modification knon [W.-C. Chen and R. A. Marcus, J. Chem. Phys. 123, 094307 (2005).] are used in the analysis. The experimentally measured rate constant shows an apparent (large error bars) decrease with increasing CO-vibrational temperature Tv over the range of Tv's studied, 298-1800 K. Both kRRKM(Tv) and knon(Tv) show the same trend over the Tv-range studied, but the knon(Tv) vs Tv plot shows a larger effect. The various trends can be understood in simple terms. The calculated rate constant kv decreases with increasing CO vibrational quantum number v, on going from v=0 to v=1, by factors of 1.5 and 3 in the RRKM and nonstatistical calculations, respectively. It then increases when v is increased further. These results can be regarded as a prediction when v state-selected rate constants become available.
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Affiliation(s)
- Wei-Chen Chen
- Noyes Laboratory 127-72, California Institute of Technology, Pasadena, California 91125, USA
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