1
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Affiliation(s)
- Sean D. S. Gordon
- Institute for Chemical Sciences and Engineering (ISIC), Ecole Polytechnique Fédérale de Lausanne (EPFL), Lausanne, Switzerland
- Present address: EPFL Innovation Park, Building C, 1015 Lausanne, Switzerland
| | - Andreas Osterwalder
- Institute for Chemical Sciences and Engineering (ISIC), Ecole Polytechnique Fédérale de Lausanne (EPFL), Lausanne, Switzerland
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2
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Gruber B, Czakó G. Benchmark ab initio characterization of the abstraction and substitution pathways of the OH + CH4/C2H6 reactions. Phys Chem Chem Phys 2020; 22:14560-14569. [DOI: 10.1039/d0cp02560g] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
We report benchmark ab initio stationary-point properties for the hydrogen-abstraction, hydrogen-substitution, and methyl-substitution pathways of the OH + CH4/C2H6 reactions.
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Affiliation(s)
- Balázs Gruber
- MTA-SZTE Lendület Computational Reaction Dynamics Research Group
- Interdisciplinary Excellence Centre and Department of Physical Chemistry and Materials Science
- Institute of Chemistry
- University of Szeged
- Szeged H-6720
| | - Gábor Czakó
- MTA-SZTE Lendület Computational Reaction Dynamics Research Group
- Interdisciplinary Excellence Centre and Department of Physical Chemistry and Materials Science
- Institute of Chemistry
- University of Szeged
- Szeged H-6720
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3
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Papp D, Gruber B, Czakó G. Detailed benchmark ab initio mapping of the potential energy surfaces of the X + C2H6 [X = F, Cl, Br, I] reactions. Phys Chem Chem Phys 2019; 21:396-408. [DOI: 10.1039/c8cp06445h] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
We provide benchmark relative energies for the stationary points of three different channels of the halogen atom + ethane reactions.
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Affiliation(s)
- Dóra Papp
- Interdisciplinary Excellence Centre and Department of Physical Chemistry and Materials Science
- Institute of Chemistry
- University of Szeged
- Szeged H-6720
- Hungary
| | - Balázs Gruber
- Interdisciplinary Excellence Centre and Department of Physical Chemistry and Materials Science
- Institute of Chemistry
- University of Szeged
- Szeged H-6720
- Hungary
| | - Gábor Czakó
- Interdisciplinary Excellence Centre and Department of Physical Chemistry and Materials Science
- Institute of Chemistry
- University of Szeged
- Szeged H-6720
- Hungary
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4
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Thompson JOF, Amarasinghe C, Foley CD, Suits AG. Finite slice analysis (FINA)-A general reconstruction method for velocity mapped and time-sliced ion imaging. J Chem Phys 2018; 147:013913. [PMID: 28688407 DOI: 10.1063/1.4979305] [Citation(s) in RCA: 31] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Since the advent of ion imaging, one of the key issues in the field has been creating methods to reconstruct the initial 3D distribution of particles from its 2D projection. This has led to the development of a number of different numerical methods and fitting techniques to solve this fundamental issue in imaging. In recent years, slice-imaging methods have been developed that permit direct recording of the 3D distribution, i.e., a thin slice of the recoiling fragment distribution. However, in practice, most slice imaging experiments achieve a velocity slice width of around 10%-25% around the center of the distribution. This still carries significant out-of-plane elements that can blur the spectrum, lose fine resolution, and underestimate the contribution from slow recoiling products. To overcome these limitations, we developed a new numerical method to remove these out-of-plane elements from a sliced image. The finite sliced analysis method models the off-axis elements of the 3D particle distribution through the use of radial basis functions. Once applied, the method reconstructs the underlying central slice of the 3D particle distribution. The approach may be applied to arbitrarily sliced or unsliced data and has the further advantage that it neither requires nor enforces full cylindrical symmetry of the data. We demonstrate this reconstruction approach with a broad range of synthetic and experimental data that, at the same time, allows us to examine the impact of finite slicing on the recovered distributions in detail.
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Affiliation(s)
- J O F Thompson
- Department of Chemistry, University of Missouri, Columbia, Missouri, 65211, USA
| | - C Amarasinghe
- Department of Chemistry, University of Missouri, Columbia, Missouri, 65211, USA
| | - C D Foley
- Department of Chemistry, University of Missouri, Columbia, Missouri, 65211, USA
| | - A G Suits
- Department of Chemistry, University of Missouri, Columbia, Missouri, 65211, USA
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5
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Espinosa-Garcia J, Martinez-Nuñez E, Rangel C. Quasi-Classical Trajectory Dynamics Study of the Cl( 2P) + C 2H 6 → HCl(v,j) + C 2H 5 Reaction. Comparison with Experiment. J Phys Chem A 2018; 122:2626-2633. [PMID: 29489365 DOI: 10.1021/acs.jpca.8b00149] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
To understand and simulate the dynamics behavior of the title reaction, QCT calculations were performed on a recently developed global analytical potential energy surface, PES-2017. These calculations combine the classical description of the dynamics with pseudoquantization in the reactants and products to perform a theoretical/experimental comparison on the same footing. Thus, in the products a series of constraints are included to analyze the HCl(v = 0,j) product, which is experimentally detected. At collision energies of 5.5 and 6.7 kcal mol-1 the largest fraction of available energy is deposited as translation, 67%, while the ethyl radical shows significant internal energy, 27%, and so it does not act as a spectator of the reaction, thus reproducing recent experimental evidence. The HCl(v=0, j) rotational distribution is cold, peaking at j = 2, only one unit hotter than experiment, which represents an error of 0.12 kcal mol-1. At a collision energy of 5.5 kcal mol-1 product translational distribution is slightly hotter than experiment, but at 6.7 kcal mol-1 agreement with recent experiments is practically quantitative, suggesting that the first experiments should be revised. In addition, we observe that the HCl(v=0, j) scattering distribution shifts from isotropic at low values of j to backward at high values of j, which is in agreement with experimental data. Finally, no evidence was found for the "chattering" mechanism suggested to explain the low translational energy of the HCl product in the backward scattering region. In sum, agreement with experiments of a series of sensible dynamic properties permits us to be optimistic on the quality and accuracy of the theoretical tools used in the present work, QCT and PES-2017.
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Affiliation(s)
- Joaquin Espinosa-Garcia
- Departamento de Química Física and Instituto de Computacion Cientifica Avanzada , Universidad de Extremadura , 06071 Badajoz , Spain
| | - Emilio Martinez-Nuñez
- Departamento de Química Física , Universidad de Santiago de Compostela , Santiago de Compostela , Spain
| | - Cipriano Rangel
- Departamento de Química Física and Instituto de Computacion Cientifica Avanzada , Universidad de Extremadura , 06071 Badajoz , Spain
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6
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Espinosa-Garcia J, Corchado JC, Garcia-Chamorro M, Rangel C. F(2P) + C2H6 → HF + C2H5 kinetics study based on a new analytical potential energy surface. Phys Chem Chem Phys 2018; 20:19860-19870. [DOI: 10.1039/c8cp03103g] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
An exhaustive kinetics study was performed for the title reaction using two theoretical approaches: variational transition-state theory and quasi-classical trajectory calculations, based on an original new analytical full-dimensional potential energy surface, named PES-2018, which has been fitted to high-level ab initio calculations.
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Affiliation(s)
- J. Espinosa-Garcia
- Departamento de Química Física and Instituto de Computacion Cientifica Avanzada
- Universidad de Extremadura
- 06071 Badajoz
- Spain
| | - J. C. Corchado
- Departamento de Química Física and Instituto de Computacion Cientifica Avanzada
- Universidad de Extremadura
- 06071 Badajoz
- Spain
| | - M. Garcia-Chamorro
- Departamento de Química Física and Instituto de Computacion Cientifica Avanzada
- Universidad de Extremadura
- 06071 Badajoz
- Spain
| | - C. Rangel
- Departamento de Química Física and Instituto de Computacion Cientifica Avanzada
- Universidad de Extremadura
- 06071 Badajoz
- Spain
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7
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Espinosa-Garcia J, Garcia-Chamorro M. Role of an ethyl radical and the problem of HF(v) bimodal vibrational distribution in the F(2P) + C2H6 → HF(v) + C2H5 reaction. Phys Chem Chem Phys 2018; 20:26634-26642. [DOI: 10.1039/c8cp05242e] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
A theoretical study of the dynamics of the F(2P) + C2H6 hydrogen abstraction reaction was presented using quasi-classical trajectories propagated on an ab initio fitted global potential energy surface, PES-2018.
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Affiliation(s)
- J. Espinosa-Garcia
- Departamento de Quimica Fisica
- Instituto de Computacion Cientifica Avanzada
- Universidad de Extremadura
- 06071 Badajoz
- Spain
| | - M. Garcia-Chamorro
- Departamento de Quimica Fisica
- Instituto de Computacion Cientifica Avanzada
- Universidad de Extremadura
- 06071 Badajoz
- Spain
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8
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Rangel C, Espinosa-Garcia J. Full-dimensional analytical potential energy surface describing the gas-phase Cl + C2H6 reaction and kinetics study of rate constants and kinetic isotope effects. Phys Chem Chem Phys 2018; 20:3925-3938. [DOI: 10.1039/c7cp07592h] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Within the Born–Oppenheimer approximation a full-dimensional analytical potential energy surface, PES-2017, was developed for the gas-phase hydrogen abstraction reaction between the chlorine atom and ethane, which is a nine body system.
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Affiliation(s)
- Cipriano Rangel
- Departamento de Química Física and Instituto de Computación Científica Avanzada
- Universidad de Extremadura
- 06071 Badajoz
- Spain
| | - Joaquin Espinosa-Garcia
- Departamento de Química Física and Instituto de Computación Científica Avanzada
- Universidad de Extremadura
- 06071 Badajoz
- Spain
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9
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Affiliation(s)
- Jennifer Meyer
- Institut für Ionenphysik und Angewandte Physik, Universität Innsbruck, 6020 Innsbruck, Austria
| | - Roland Wester
- Institut für Ionenphysik und Angewandte Physik, Universität Innsbruck, 6020 Innsbruck, Austria
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10
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Casavecchia P, Leonori F, Balucani N. Reaction dynamics of oxygen atoms with unsaturated hydrocarbons from crossed molecular beam studies: primary products, branching ratios and role of intersystem crossing. INT REV PHYS CHEM 2015. [DOI: 10.1080/0144235x.2015.1039293] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
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11
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Joalland B, Shi Y, Estillore AD, Kamasah A, Mebel AM, Suits AG. Dynamics of chlorine atom reactions with hydrocarbons: insights from imaging the radical product in crossed beams. J Phys Chem A 2014; 118:9281-95. [PMID: 25076054 DOI: 10.1021/jp504804n] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
We present a comprehensive overview of our ongoing studies applying dc slice imaging in crossed molecular beams to probe the dynamics of chlorine atom reactions with polyatomic hydrocarbons. Our approach consists in measuring the full velocity-flux contour maps of the radical products using vacuum ultraviolet "soft" photoionization at 157 nm. Our overall goal is to extend the range of chemical dynamics investigations from simple triatomic or tetraatomic molecules to systematic investigations of a sequence of isomers or a homologous series of reactants of intermediate size. These experimental investigations are augmented by high-level ab initio calculations which, taken together, reveal trends in product energy and angular momentum partitioning and offer deep insight into the reaction mechanisms as a function of structure, bonding patterns, and kinematics. We explore these issues in alkanes, for which only direct reactive encounters are found, and in unsaturated hydrocarbons, for which an addition-elimination mechanism competes with direct abstraction. The results for alkene addition-elimination in particular suggest a new view of these reactions: The only pathway to HCl elimination is accessed by means of roaming excursions of the Cl atom from the strongly bound adduct.
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Affiliation(s)
- Baptiste Joalland
- Department of Chemistry, Wayne State University , Detroit, Michigan 48202, United States
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12
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Kowalewski M, Mikosch J, Wester R, de Vivie-Riedle R. Nucleophilic Substitution Dynamics: Comparing Wave Packet Calculations with Experiment. J Phys Chem A 2014; 118:4661-9. [DOI: 10.1021/jp503974u] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- M. Kowalewski
- Department
of Chemistry, Ludwig-Maximilians-Universität, D-81377 Munich, Germany
- Division
of Scientific Computing, Department of Information Technology, Uppsala University, SE-75105 Uppsala, Sweden
| | - J. Mikosch
- Max-Born-Institute, Max-Born-Strasse 2A, D-12489 Berlin, Germany
| | - R. Wester
- Institut
für Ionenphysik und Angewandte Physik, Universität Innsbruck, Technikerstraße 25/3, 6020 Innsbruck, Austria
| | - R. de Vivie-Riedle
- Department
of Chemistry, Ludwig-Maximilians-Universität, D-81377 Munich, Germany
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13
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Joalland B, Shi Y, Patel N, Van Camp R, Suits AG. Dynamics of Cl + propane, butanes revisited: a crossed beam slice imaging study. Phys Chem Chem Phys 2014; 16:414-20. [DOI: 10.1039/c3cp51785c] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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14
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Joalland B, Van Camp R, Shi Y, Patel N, Suits AG. Crossed-Beam Slice Imaging of Cl Reaction Dynamics with Butene Isomers. J Phys Chem A 2013; 117:7589-94. [DOI: 10.1021/jp403030s] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Affiliation(s)
- Baptiste Joalland
- Department
of Chemistry, Wayne State University, Detroit,
Michigan 48202, United States
| | - Richard Van Camp
- Department
of Chemistry, Wayne State University, Detroit,
Michigan 48202, United States
| | - Yuanyuan Shi
- Department
of Chemistry, Wayne State University, Detroit,
Michigan 48202, United States
| | - Nitin Patel
- Department
of Chemistry, Wayne State University, Detroit,
Michigan 48202, United States
| | - Arthur G. Suits
- Department
of Chemistry, Wayne State University, Detroit,
Michigan 48202, United States
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15
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Mikosch J, Zhang J, Trippel S, Eichhorn C, Otto R, Sun R, de Jong WA, Weidemüller M, Hase WL, Wester R. Indirect dynamics in a highly exoergic substitution reaction. J Am Chem Soc 2013; 135:4250-9. [PMID: 23324058 DOI: 10.1021/ja308042v] [Citation(s) in RCA: 85] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
The highly exoergic nucleophilic substitution reaction F(-) + CH3I shows reaction dynamics strikingly different from that of substitution reactions of larger halogen anions. Over a wide range of collision energies, a large fraction of indirect scattering via a long-lived hydrogen-bonded complex is found both in crossed-beam imaging experiments and in direct chemical dynamics simulations. Our measured differential scattering cross sections show large-angle scattering and low product velocities for all collision energies, resulting from efficient transfer of the collision energy to internal energy of the CH3F reaction product. Both findings are in strong contrast to the previously studied substitution reaction of Cl(-) + CH3I [Science 2008, 319, 183-186] at all but the lowest collision energies, a discrepancy that was not captured in a subsequent study at only a low collision energy [J. Phys. Chem. Lett. 2010, 1, 2747-2752]. Our direct chemical dynamics simulations at the DFT/B97-1 level of theory show that the reaction is dominated by three atomic-level mechanisms, an indirect reaction proceeding via an F(-)-HCH2I hydrogen-bonded complex, a direct rebound, and a direct stripping reaction. The indirect mechanism is found to contribute about one-half of the overall substitution reaction rate at both low and high collision energies. This large fraction of indirect scattering at high collision energy is particularly surprising, because the barrier for the F(-)-HCH2I complex to form products is only 0.10 eV. Overall, experiment and simulation agree very favorably in both the scattering angle and the product internal energy distributions.
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Affiliation(s)
- Jochen Mikosch
- National Research Council of Canada, Ottawa, Ontario K1A 0R6, Canada
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16
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LIU YUFANG, HE XIAOHU, GAO YALI, SUN JINFENG. STEREODYNAMICS STUDY OF THE REACTION Cl(2p3/2) + C2D6 (v = 0, j = 0) → DCl + C2D5. JOURNAL OF THEORETICAL & COMPUTATIONAL CHEMISTRY 2011. [DOI: 10.1142/s0219633610005621] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
The product angular momentum polarization of the Cl + C2D6 → DCl + C2D5 reaction is calculated via the quasiclassical trajectory (QCT) method at the collision energy of 0.25 eV. A new London–Eyring–Polanyi–Sato (LEPS) potential energy surface (PES) is used in this reaction. There is a "late" barrier and a "deep" well on this new LEPS PES. The four polarization-dependent "generalized" differential cross sections (PDDCSs) are presented in the center-of-mass frame. In the meantime, the distributions of P(ϕr), P(θr), and P(θr, ϕr) are calculated. The calculations are in good agreement with the experimental data. In addition, the rotational alignment factors [Formula: see text], [Formula: see text], and [Formula: see text] in the stationary-target frame (STF) are also calculated.
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Affiliation(s)
- YUFANG LIU
- Department of Physics, Henan Normal University, Xinjiang 453007, China
| | - XIAOHU HE
- Department of Physics, Henan Normal University, Xinjiang 453007, China
| | - YALI GAO
- Department of Physics, Henan Normal University, Xinjiang 453007, China
| | - JINFENG SUN
- Department of Physics, Henan Normal University, Xinjiang 453007, China
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17
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Rose RA, Greaves SJ, Orr-Ewing AJ. Velocity map imaging the dynamics of the reactions of Cl atoms with neopentane and tetramethylsilane. J Chem Phys 2010; 132:244312. [DOI: 10.1063/1.3447378] [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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18
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Estillore AD, Visger LM, Suits AG. Crossed-beam dc slice imaging of chlorine atom reactions with pentane isomers. J Chem Phys 2010; 132:164313. [DOI: 10.1063/1.3414353] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Affiliation(s)
| | - Laura M. Visger
- Department of Chemistry, Wayne State University, Detroit, Michigan 48202, USA
| | - Arthur G. Suits
- Department of Chemistry, Wayne State University, Detroit, Michigan 48202, USA
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19
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Rose RA, Greaves SJ, Orr-Ewing AJ. Velocity map imaging of the dynamics of the CH3+ HCl → CH4+ Cl reaction using a dual molecular beam method. Mol Phys 2010. [DOI: 10.1080/00268971003610234] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
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20
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Kaiser RI, Maksyutenko P, Ennis C, Zhang F, Gu X, Krishtal SP, Mebel AM, Kostko O, Ahmed M. Untangling the chemical evolution of Titan's atmosphere and surface–from homogeneous to heterogeneous chemistry. Faraday Discuss 2010; 147:429-78; discussion 527-52. [DOI: 10.1039/c003599h] [Citation(s) in RCA: 109] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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21
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Chichinin AI, Gericke KH, Kauczok S, Maul C. Imaging chemical reactions – 3D velocity mapping. INT REV PHYS CHEM 2009. [DOI: 10.1080/01442350903235045] [Citation(s) in RCA: 59] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
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22
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Gu X, Kaiser RI. Reaction dynamics of phenyl radicals in extreme environments: a crossed molecular beam study. Acc Chem Res 2009; 42:290-302. [PMID: 19053235 DOI: 10.1021/ar8001365] [Citation(s) in RCA: 49] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Polycyclic aromatic hydrocarbons (PAHs)organic compounds that consist of fused benzene ringsand their hydrogen-deficient precursors have attracted extensive interest from combustion scientists, organic chemists, astronomers, and planetary scientists. On Earth, PAHs are toxic combustion products and a source of air pollution. In the interstellar medium, research suggests that PAHs play a role in unidentified infrared emission bands, diffuse interstellar bands, and the synthesis of precursor molecules to life. To build clean combustion devices and to understand the astrochemical evolution of the interstellar medium, it will be critical to understand the elementary reaction mechanisms under single collision conditions by which these molecules form in the gas phase. Until recently, this work had been hampered by the difficulty in preparing a large concentration of phenyl radicals, but the phenyl radical represents one of the most important radical species to trigger PAH formation in high-temperature environments. However, we have developed a method for producing these radical species and have undertaken a systematic experimental investigation. In this Account, we report on the chemical dynamics of the phenyl radical (C(6)H(5)) reactions with the unsaturated hydrocarbons acetylene (C(2)H(2)), ethylene (C(2)H(4)), methylacetylene (CH(3)CCH), allene (H(2)CCCH(2)), propylene (CH(3)CHCH(2)), and benzene (C(6)H(6)) utilizing the crossed molecular beams approach. For nonsymmetric reactants such as methylacetylene and propylene, steric effects and the larger cones of acceptance drive the addition of the phenyl radical to the nonsubstituted carbon atom of the hydrocarbon reactant. Reaction intermediates decomposed via atomic hydrogen loss pathways. In the phenyl-propylene system, the longer lifetime of the reaction intermediate yielded a more efficient energy randomization compared with the phenyl-methylacetylene system. Therefore, two reaction channels were open: hydrogen losses from the vinyl and from the methyl groups. All fragmentation pathways involved tight exit transition states. In the range of collision energies investigated, the reactions are dictated by phenyl radical addition-hydrogen atom elimination pathways. We did not observe ring closure processes with the benzene ring. Our investigations present an important step toward a systematic investigation of phenyl radical reactions under single collision conditions similar to those found in combustion flames and in high-temperature interstellar environments. Future experiments at lower collision energies may enhance the lifetimes of the reaction intermediates, which could open up competing ring closure channels to form bicyclic reaction products.
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Affiliation(s)
- Xibin Gu
- Department of Chemistry, University of Hawaii at Manoa, Honolulu, Hawaii 96822
| | - Ralf I. Kaiser
- Department of Chemistry, University of Hawaii at Manoa, Honolulu, Hawaii 96822
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23
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Gu X, Kaiser RI, Mebel AM. Chemistry of energetically activated cumulenes - from allene (H2CCCH2) to hexapentaene (H2CCCCCCH2). Chemphyschem 2008; 9:350-69. [PMID: 18275046 DOI: 10.1002/cphc.200700609] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
During the last decade, experimental and theoretical studies on the unimolecular decomposition of cumulenes (H(2)C(n)H(2)) from propadiene (H(2)CCCH(2)) to hexapentaene (H(2)CCCCCCH(2)) have received considerable attention due to the importance of these carbon-bearing molecules in combustion flames, chemical vapor deposition processes, atmospheric chemistry, and the chemistry of the interstellar medium. Cumulenes and their substituted counterparts also have significant technical potential as elements for molecular machines (nanomechanics), molecular wires (nano-electronics), nonlinear optics, and molecular sensors. In this review, we present a systematic overview of the stability, formation, and unimolecular decomposition of chemically, photo-chemically, and thermally activated small to medium-sized cumulenes in extreme environments. By concentrating on reactions under gas phase thermal conditions (pyrolysis) and on molecular beam experiments conducted under single-collision conditions (crossed beam and photodissociation studies), a comprehensive picture on the unimolecular decomposition dynamics of cumulenes transpires.
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Affiliation(s)
- Xibin Gu
- Department of Chemistry, University of Hawai'i at Manoa, Honolulu, HI 96822, USA
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25
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Pearce JK, Retail B, Greaves SJ, Rose RA, Orr-Ewing AJ. Imaging the Dynamics of Reactions between Cl Atoms and the Cyclic Ethers Oxirane and Oxetane. J Phys Chem A 2007; 111:13296-304. [DOI: 10.1021/jp0773684] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Julie K. Pearce
- School of Chemistry, University of Bristol, Cantock's Close, Bristol BS8 1TS, United Kingdom
| | - Bertrand Retail
- School of Chemistry, University of Bristol, Cantock's Close, Bristol BS8 1TS, United Kingdom
| | - Stuart J. Greaves
- School of Chemistry, University of Bristol, Cantock's Close, Bristol BS8 1TS, United Kingdom
| | - Rebecca A. Rose
- School of Chemistry, University of Bristol, Cantock's Close, Bristol BS8 1TS, United Kingdom
| | - Andrew J. Orr-Ewing
- School of Chemistry, University of Bristol, Cantock's Close, Bristol BS8 1TS, United Kingdom
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26
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Greaves SJ, Kim J, Orr-Ewing AJ, Troya D. Studying ‘chattering collisions’ in the Cl+ethane reaction with classical trajectories. Chem Phys Lett 2007. [DOI: 10.1016/j.cplett.2007.05.010] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
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Huang C, Li W, Suits AG. Rotationally resolved reactive scattering: Imaging detailed Cl+C2H6 reaction dynamics. J Chem Phys 2006; 125:133107. [PMID: 17029433 DOI: 10.1063/1.2202827] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
The hydrogen atom abstraction reaction of Cl (2P3/2) with ethane has been studied using the crossed molecular beam technique with dc slice imaging at collision energies from 3.2 to 10.4 kcal/mol. The products HCl (v,J) (v = 0, J = 0-5) were state-selectively detected using 2+1 resonance enhanced multiphoton ionization. The images were used to obtain the center-of-mass frame product angular distributions and translational energy release distributions. Two general features were found in all probed HCl quantum states at 6.7 kcal/mol collision energy, and these features have distinct translational energy release and angular distributions, as described for HCl (v = 0, J = 2) in a recent preliminary report [Li et al., J. Chem. Phys. 124, 011102 (2006)]. The results for HCl (v = 0, J = 2) at four collision energies were also compared to investigate the energy-dependent dynamics. We discuss the reaction in terms of a variety of models of polyatomic reaction dynamics. The dynamics of this well studied system are more complicated than can be accounted for by a single mechanism, and the results call for further theoretical and experimental investigations.
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Affiliation(s)
- Cunshun Huang
- Department of Chemistry, Wayne State University, Detroit, Michigan 48202, USA
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28
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Teslja A, Valentini JJ. State-to-state reaction dynamics: A selective review. J Chem Phys 2006; 125:132304. [PMID: 17029423 DOI: 10.1063/1.2354466] [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
A selective review of state-to-state reaction dynamics experiments is presented. The review focuses on three classes of reactions that exemplify the rich history and illustrate the current state of the art in such work. These three reactions are (1) the hydrogen exchange reaction, H+H2-->H2+H and its isotopomers; (2) the H+RH-->H2+R reactions, where RH is an alkane, beginning with H+CH4-->H2+CH3 and extending to much larger alkanes; and (3) the Cl+RH-->HCl+R reactions, principally Cl+CH4-->HCl+CH3. We describe the experiments, discuss their results, present comparisons with theory, and introduce heuristic models.
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Affiliation(s)
- Alexey Teslja
- Department of Chemistry, Columbia University, New York, New York 10027, USA
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Lahankar SA, Chambreau SD, Townsend D, Suits F, Farnum J, Zhang X, Bowman JM, Suits AG. The roaming atom pathway in formaldehyde decomposition. J Chem Phys 2006; 125:44303. [PMID: 16942138 DOI: 10.1063/1.2202241] [Citation(s) in RCA: 82] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
We present a detailed experimental and theoretical investigation of formaldehyde photodissociation to H(2) and CO following excitation to the 2(1)4(1) and 2(1)4(3) transitions in S(1). The CO velocity distributions were obtained using dc slice imaging of single CO rotational states (v=0, j(CO)=5-45). These high-resolution measurements reveal the correlated internal state distribution in the H(2) cofragments. The results show that rotationally hot CO (j(CO) approximately 45) is produced in conjunction with vibrationally "cold" H(2) fragments (v=0-5): these products are formed through the well-known skewed transition state and described in detail in the accompanying paper. After excitation of formaldehyde above the threshold for the radical channel (H(2)CO-->H+HCO) we also find formation of rotationally cold CO (j(CO)=5-28) correlated to highly vibrationally excited H(2) (v=6-8). These products are formed through a novel mechanism that involves near dissociation followed by intramolecular H abstraction [D. Townsend et al., Science 306, 1158 (2004)], and that avoids the region of the transition state entirely. The dynamics of this "roaming" mechanism are the focus of this paper. The correlations between the vibrational states of H(2) and rotational states of CO formed following excitation on the 2(1)4(3) transition allow us to determine the relative contribution to molecular products from the roaming atom channel versus the conventional molecular channel.
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Affiliation(s)
- Sridhar A Lahankar
- Department of Chemistry, Wayne State University, Detroit, Michigan 48202, USA
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Balucani N, Capozza G, Leonori F, Segoloni E, Casavecchia P. Crossed molecular beam reactive scattering: from simple triatomic to multichannel polyatomic reactions. INT REV PHYS CHEM 2006. [DOI: 10.1080/01442350600641305] [Citation(s) in RCA: 68] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
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31
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Mikosch J, Frühling U, Trippel S, Schwalm D, Weidemüller M, Wester R. Velocity map imaging of ion–molecule reactive scattering: The Ar++ N2charge transfer reaction. Phys Chem Chem Phys 2006; 8:2990-9. [PMID: 16880912 DOI: 10.1039/b603109a] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
We present a velocity map imaging spectrometer for the study of crossed-beam reactive collisions between ions and neutrals at (sub-)electronvolt collision energies. The charge transfer reaction of Ar(+) with N(2) is studied at 0.6, 0.8 and 2.5 eV relative collision energies. Energy and angular distributions are measured for the reaction product N. The differential cross section, as analyzed with a Monte Carlo reconstruction algorithm, shows significant large angle scattering for lower collision energies in qualitative agreement with previous experiments. Significant vibrational excitation of N(+)(2) is also observed. This theoretically still unexplained feature indicates the presence of a low energy scattering resonance.
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Affiliation(s)
- J Mikosch
- Physikalisches Institut, Universität Freiburg, Hermann-Herder-Strasse 3, 79104 Freiburg, Germany
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