1
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Schatz GC, Wodtke AM, Yang X. Spiers Memorial Lecture: New directions in molecular scattering. Faraday Discuss 2024. [PMID: 38764350 DOI: 10.1039/d4fd00015c] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/21/2024]
Abstract
The field of molecular scattering is reviewed as it pertains to gas-gas as well as gas-surface chemical reaction dynamics. We emphasize the importance of collaboration of experiment and theory, from which new directions of research are being pursued on increasingly complex problems. We review both experimental and theoretical advances that provide the modern toolbox available to molecular-scattering studies. We distinguish between two classes of work. The first involves simple systems and uses experiment to validate theory so that from the validated theory, one may learn far more than could ever be measured in the laboratory. The second class involves problems of great complexity that would be difficult or impossible to understand without a partnership of experiment and theory. Key topics covered in this review include crossed-beams reactive scattering and scattering at extremely low energies, where quantum effects dominate. They also include scattering from surfaces, reactive scattering and kinetics at surfaces, and scattering work done at liquid surfaces. The review closes with thoughts on future promising directions of research.
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Affiliation(s)
- George C Schatz
- Dept of Chemistry, Northwestern University, Evanston, Illinois 60208, USA
| | - Alec M Wodtke
- Institute for Physical Chemistry, Georg August University, Goettingen, Germany
- Max Planck Institute for Multidisciplinary Natural Sciences, Goettingen, Germany.
- International Center for the Advanced Studies of Energy Conversion, Georg August University, Goettingen, Germany
| | - Xueming Yang
- Dalian Institute for Chemical Physics, Chinese Academy of Sciences, Dalian, China
- Department of Chemistry, College of Science, Southern University of Science and Technology, Shenzhen, China
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2
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Cavallotti C, Della Libera A, Zhou CW, Recio P, Caracciolo A, Balucani N, Casavecchia P. Crossed-beam and theoretical studies of multichannel nonadiabatic reactions: branching fractions and role of intersystem crossing for O(3P)+1,3-butadiene. Faraday Discuss 2022; 238:161-182. [DOI: 10.1039/d2fd00037g] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Atomic oxygen reactions can contribute significantly to the oxidation of unsaturated aliphatic and aromatic hydrocarbons. The reaction mechanism is started by electrophilic O atom addition to the unsaturated bond(s) to...
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3
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Sun G, Zheng X, Xu K, Song Y, Zhang J. Photodissociation Dynamics of Vinoxy Radical via the B̃ 2A″ State: The H + CH 2CO Product Channel. J Phys Chem A 2021; 125:8882-8890. [PMID: 34607427 DOI: 10.1021/acs.jpca.1c07099] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Photodissociation dynamics of the jet-cooled vinoxy radical (CH2CHO) via the B̃2A″ state was studied in the near-ultraviolet (near-UV) region of 308-328 nm using high-n Rydberg H atom time-of-flight (HRTOF) and resonance-enhanced multiphoton ionization (REMPI) techniques. The vinoxy radical beam was produced by 193 nm photolysis of ethyl vinyl ether followed by supersonic expansion. The H + CH2CO product channel was observed directly in the H atom TOF spectra. The H atom photofragment yield (PFY) spectra were obtained by integrating the H atom TOF spectra and measuring the H atom REMPI signals, and showed several vibronic bands of the B̃2A″ state. The translational energy distributions of the H + CH2CO products, P(ET)'s, were obtained at several vibronic transitions. The P(ET) distributions were broad, peaking at a low energy of ∼3500 cm-1. The product translational energy release was moderate; the average translational energy release in the maximum available energy, ⟨fT⟩, was in the range of 0.24-0.27. The product angular distributions in this wavelength region were slightly anisotropic, with the β parameter in the range of 0.10-0.24. The near-UV photodissociation mechanism of the H + CH2CO product channel of the vinoxy radical is consistent with unimolecular dissociation on the electronic ground state (X̃2A″) following internal conversion from the B̃2A″ state to the Ã2A' state and then to the X̃2A″ state (although unimolecular dissociation from the first excited Ã2A' may also contribute).
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Affiliation(s)
- Ge Sun
- Department of Chemistry, University of California at Riverside, Riverside, California 92521, United States
| | - Xianfeng Zheng
- Department of Chemistry, University of California at Riverside, Riverside, California 92521, United States
| | - Kesheng Xu
- Department of Chemistry, University of California at Riverside, Riverside, California 92521, United States
| | - Yu Song
- Department of Chemistry, University of California at Riverside, Riverside, California 92521, United States
| | - Jingsong Zhang
- Department of Chemistry, University of California at Riverside, Riverside, California 92521, United States.,Air Pollution Research Center, University of California at Riverside, Riverside, California 92521, United States
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Vanuzzo G, Caracciolo A, Minton TK, Balucani N, Casavecchia P, de Falco C, Baggioli A, Cavallotti C. Crossed-Beam and Theoretical Studies of the O( 3P, 1D) + Benzene Reactions: Primary Products, Branching Fractions, and Role of Intersystem Crossing. J Phys Chem A 2021; 125:8434-8453. [PMID: 34533308 PMCID: PMC8488941 DOI: 10.1021/acs.jpca.1c06913] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
![]()
Reliable modeling
of hydrocarbon oxidation relies critically on
knowledge of the branching fractions (BFs) as a function of temperature
(T) and pressure (p) for the products
of the reaction of the hydrocarbon with atomic oxygen in its ground
state, O(3P). During the past decade, we have performed
in-depth investigations of the reactions of O(3P) with
a variety of small unsaturated hydrocarbons using the crossed molecular
beam (CMB) technique with universal mass spectrometric
(MS) detection and time-of-flight (TOF) analysis, combined with synergistic
theoretical calculations of the relevant potential energy surfaces
(PESs) and statistical computations of product BFs, including intersystem
crossing (ISC). This has allowed us to determine the primary products,
their BFs, and extent of ISC to ultimately provide theoretical channel-specific
rate constants as a function of T and p. In this work, we have extended this approach to the oxidation of
one of the most important species involved in the combustion of aromatics:
the benzene (C6H6) molecule. Despite extensive
experimental and theoretical studies on the kinetics and dynamics
of the O(3P) + C6H6 reaction, the
relative importance of the C6H5O (phenoxy) +
H open-shell products and of the spin-forbidden C5H6 (cyclopentadiene) + CO and phenol adduct closed-shell products
are still open issues, which have hampered the development of reliable
benzene combustion models. With the CMB technique, we have investigated
the reaction dynamics of O(3P) + benzene at a collision
energy (Ec) of 8.2 kcal/mol, focusing
on the occurrence of the phenoxy + H and spin-forbidden C5H6 + CO and phenol channels in order to shed further light
on the dynamics of this complex and important reaction, including
the role of ISC. Concurrently, we have also investigated the reaction
dynamics of O(1D) + benzene at the same Ec. Synergistic high-level electronic structure calculations
of the underlying triplet/singlet PESs, including nonadiabatic couplings,
have been performed to complement and assist the interpretation of
the experimental results. Statistical (RRKM)/master equation (ME)
computations of the product distribution and BFs on these PESs, with
inclusion of ISC, have been performed and compared to experiment.
In light of the reasonable agreement between the CMB experiment, literature
kinetic experimental results, and theoretical predictions for the
O(3P) + benzene reaction, the so-validated computational
methodology has been used to predict (i) the BF between the C6H5O + H and C5H6 + CO channels
as a function of collision energy and temperature (at 0.1 and 1 bar),
showing that their increase progressively favors radical (phenoxy
+ H)-forming over molecule (C5H6 + CO and phenol
stabilization)-forming channels, and (ii) channel-specific rate constants
as a function of T and p, which
are expected to be useful for improved combustion models.
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Affiliation(s)
- Gianmarco Vanuzzo
- Dipartimento di Chimica, Biologia e Biotecnologie, Università degli Studi di Perugia, 06123 Perugia, Italy
| | - Adriana Caracciolo
- Dipartimento di Chimica, Biologia e Biotecnologie, Università degli Studi di Perugia, 06123 Perugia, Italy
| | - Timothy K Minton
- Dipartimento di Chimica, Biologia e Biotecnologie, Università degli Studi di Perugia, 06123 Perugia, Italy
| | - Nadia Balucani
- Dipartimento di Chimica, Biologia e Biotecnologie, Università degli Studi di Perugia, 06123 Perugia, Italy
| | - Piergiorgio Casavecchia
- Dipartimento di Chimica, Biologia e Biotecnologie, Università degli Studi di Perugia, 06123 Perugia, Italy
| | - Carlo de Falco
- MOX - Modellistica e Calcolo Scientifico, Dipartimento di Matematica, Politecnico di Milano, 20133 Milano, Italy
| | - Alberto Baggioli
- Dipartimento di Chimica, Materiali e Ingegneria Chimica, Politecnico di Milano, 20131 Milano, Italy
| | - Carlo Cavallotti
- Dipartimento di Chimica, Materiali e Ingegneria Chimica, Politecnico di Milano, 20131 Milano, Italy
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5
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Li H, Suits AG. Universal crossed beam imaging studies of polyatomic reaction dynamics. Phys Chem Chem Phys 2020; 22:11126-11138. [DOI: 10.1039/d0cp00522c] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Crossed-beam imaging studies of polyatomic reactions show surprising dynamics not anticipated by extrapolation from smaller model systems.
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Affiliation(s)
- Hongwei Li
- Department of Chemistry
- University of Missouri
- Columbia
- USA
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6
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Thomas AM, Dangi BB, Yang T, Kaiser RI, Sun BJ, Chou TJ, Chang AH. A crossed molecular beams investigation of the reactions of atomic silicon (Si(3P)) with C4H6 isomers (1,3-butadiene, 1,2-butadiene, and 1-butyne). Chem Phys 2019. [DOI: 10.1016/j.chemphys.2019.01.001] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
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7
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Pokhilko P, Shannon R, Glowacki D, Wang H, Krylov AI. Spin-Forbidden Channels in Reactions of Unsaturated Hydrocarbons with O(3P). J Phys Chem A 2018; 123:482-491. [DOI: 10.1021/acs.jpca.8b10225] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Affiliation(s)
- Pavel Pokhilko
- Department of Chemistry, University of Southern California, Los Angeles, California 90089-0482, United States
| | - Robin Shannon
- School of Chemistry, University of Bristol, Cantock’s Close, Bristol BS8 1TS, U.K
| | - David Glowacki
- School of Chemistry, University of Bristol, Cantock’s Close, Bristol BS8 1TS, U.K
| | - Hai Wang
- Department of Mechanical Engineering, Stanford University, Stanford, California 94305-3032, United States
| | - Anna I. Krylov
- Department of Chemistry, University of Southern California, Los Angeles, California 90089-0482, United States
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8
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Pan H, Liu K, Caracciolo A, Casavecchia P. Crossed beam polyatomic reaction dynamics: recent advances and new insights. Chem Soc Rev 2017; 46:7517-7547. [DOI: 10.1039/c7cs00601b] [Citation(s) in RCA: 57] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
This review summarizes the developments in polyatomic reaction dynamics, focusing on reactions of unsaturated hydrocarbons with O-atoms and methane with atoms/radicals.
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Affiliation(s)
- Huilin Pan
- Institute of Atomic and Molecular Sciences (IAMS)
- Academia Sinica
- Taipei
- Taiwan
| | - Kopin Liu
- Institute of Atomic and Molecular Sciences (IAMS)
- Academia Sinica
- Taipei
- Taiwan
- Department of Physics
| | - Adriana Caracciolo
- Dipartimento di Chimica
- Biologia e Biotecnologie
- Università degli Studi di Perugia
- 06123 Perugia
- Italy
| | - Piergiorgio Casavecchia
- Dipartimento di Chimica
- Biologia e Biotecnologie
- Università degli Studi di Perugia
- 06123 Perugia
- Italy
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9
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Vanuzzo G, Balucani N, Leonori F, Stranges D, Nevrly V, Falcinelli S, Bergeat A, Casavecchia P, Cavallotti C. Reaction Dynamics of O(3P) + Propyne: I. Primary Products, Branching Ratios, and Role of Intersystem Crossing from Crossed Molecular Beam Experiments. J Phys Chem A 2016; 120:4603-18. [DOI: 10.1021/acs.jpca.6b01563] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Gianmarco Vanuzzo
- Dipartimento di Chimica, Biologia e Biotecnologie, Università degli Studi di Perugia, 06123 Perugia, Italy
| | - Nadia Balucani
- Dipartimento di Chimica, Biologia e Biotecnologie, Università degli Studi di Perugia, 06123 Perugia, Italy
| | - Francesca Leonori
- Dipartimento di Chimica, Biologia e Biotecnologie, Università degli Studi di Perugia, 06123 Perugia, Italy
| | - Domenico Stranges
- Dipartimento di Chimica, Biologia e Biotecnologie, Università degli Studi di Perugia, 06123 Perugia, Italy
| | - Vaclav Nevrly
- Dipartimento di Chimica, Biologia e Biotecnologie, Università degli Studi di Perugia, 06123 Perugia, Italy
| | - Stefano Falcinelli
- Dipartimento di Chimica, Biologia e Biotecnologie, Università degli Studi di Perugia, 06123 Perugia, Italy
| | - Astrid Bergeat
- Dipartimento di Chimica, Biologia e Biotecnologie, Università degli Studi di Perugia, 06123 Perugia, Italy
| | - Piergiorgio Casavecchia
- Dipartimento di Chimica, Biologia e Biotecnologie, Università degli Studi di Perugia, 06123 Perugia, Italy
| | - Carlo Cavallotti
- Dipartimento di Chimica,
Materiali e Ingegneria Chimica “Giulio Natta”, Politecnico di Milano, 20131 Milano, Italy
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10
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Balucani N, Leonori F, Casavecchia P, Fu B, Bowman JM. Crossed Molecular Beams and Quasiclassical Trajectory Surface Hopping Studies of the Multichannel Nonadiabatic O(3P) + Ethylene Reaction at High Collision Energy. J Phys Chem A 2015; 119:12498-511. [DOI: 10.1021/acs.jpca.5b07979] [Citation(s) in RCA: 43] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Nadia Balucani
- Dipartimento
di Chimica, Biologia e Biotecnologie, Università degli Studi di Perugia, 06123 Perugia, Italy
| | - Francesca Leonori
- Dipartimento
di Chimica, Biologia e Biotecnologie, Università degli Studi di Perugia, 06123 Perugia, Italy
| | - Piergiorgio Casavecchia
- Dipartimento
di Chimica, Biologia e Biotecnologie, Università degli Studi di Perugia, 06123 Perugia, Italy
| | - Bina Fu
- State
Key Laboratory of Molecular Reaction Dynamics, Dalian Institute of
Chemical Physics, Chinese Academy of Sciences, Dalian 116023, China
| | - Joel M. Bowman
- Department
of Chemistry and Cherry L. Emerson Center for Scientific Computation, Emory University, Atlanta, Georgia 30322, United States
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11
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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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12
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Rajak K, Maiti B. Trajectory surface hopping study of the O((3)P) + C2H2 reaction dynamics: effect of collision energy on the extent of intersystem crossing. J Chem Phys 2015; 140:044314. [PMID: 25669530 DOI: 10.1063/1.4862407] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Intersystem crossing (ISC) dynamics plays an important role in determining the product branching in the O((3)P) + C2H2 reaction despite the necessarily small spin-orbit coupling constant values. In this study we investigate the effect of collision energy on the extent of the contribution of a spin non-conserving route through ISC dynamics to the product distributions at the initial collision energies 8.2, 9.5, and 13.1 kcal/mol. A direct dynamics trajectory surface hopping method is employed with potential energy surfaces generated at the unrestricted B3LYP/6-31G(d,p) level of theory to perform nonadiabatic dynamics. To make our calculation simpler, nonadibatic transitions were only considered at the triplet-singlet intersections. At the crossing points, Landau-Zener transition probabilities were calculated using spin-orbit coupling constant values computed at the same geometry. The Landau-Zener model for the title reaction is validated against a more rigorous Tully's fewest switches method and found to be working reasonably well as expected because of weak spin-orbit coupling. We have compared our results with the recent crossed molecular beam experiments and observed a very good agreement with respect to the primary product branching ratios. Our calculation revealed that there is no noticeable effect of the initial collision energy on the overall product distributions that corroborates the recent experimental findings. Our calculation indicates, however, that the extent of intersystem crossing contributions varies significantly with collision energy, needed to be verified, experimentally.
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Affiliation(s)
- Karunamoy Rajak
- Department of Chemistry, Faculty of Science, Banaras Hindu University, Varanasi 221005, India
| | - Biswajit Maiti
- Department of Chemistry, Faculty of Science, Banaras Hindu University, Varanasi 221005, India
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13
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Savee JD, Borkar S, Welz O, Sztáray B, Taatjes CA, Osborn DL. Multiplexed Photoionization Mass Spectrometry Investigation of the O(3P) + Propyne Reaction. J Phys Chem A 2015; 119:7388-403. [DOI: 10.1021/acs.jpca.5b00491] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- John D. Savee
- Combustion
Research Facility, Sandia National Laboratories, Mail Stop 9055, Livermore, California 94551-0969, United States
| | - Sampada Borkar
- Department
of Chemistry, University of the Pacific, Stockton, California 95211, United States
| | - Oliver Welz
- Combustion
Research Facility, Sandia National Laboratories, Mail Stop 9055, Livermore, California 94551-0969, United States
| | - Bálint Sztáray
- Department
of Chemistry, University of the Pacific, Stockton, California 95211, United States
| | - Craig A. Taatjes
- Combustion
Research Facility, Sandia National Laboratories, Mail Stop 9055, Livermore, California 94551-0969, United States
| | - David L. Osborn
- Combustion
Research Facility, Sandia National Laboratories, Mail Stop 9055, Livermore, California 94551-0969, United States
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14
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Zhao H, Liu K, Song D, Su H. Nonadiabatic reaction mechanisms of the O((3)P) with cyclopentene. J Mol Graph Model 2014; 51:184-92. [PMID: 24934330 DOI: 10.1016/j.jmgm.2014.05.008] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2014] [Revised: 05/11/2014] [Accepted: 05/23/2014] [Indexed: 10/25/2022]
Abstract
The reaction mechanism of the ground state oxygen atom O((3)P) with cyclopentene is investigated theoretically. The triplet and singlet potential energy surfaces are calculated at the CCSD(T)//MP2/6-311G(d,p) level and the minimum energy crossing points (MECPs) between the two surfaces are located by means of the Newton-Lagrange method, from which the complex nonadiabatic reaction pathways are revealed. Based on the theoretical results, the most probable reaction mechanism of O((3)P) with c-C5H8 is described, which agrees with the experimental results nicely, including the condensed phase experiment. At the same time, the newly revealed reaction mechanism clarifies the previous controversial product distribution, and predicts the possible existence of the new enol product, cyclopentenol.
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Affiliation(s)
- Hongmei Zhao
- State Key Laboratory of Molecular Reaction Dynamics, Beijing National Laboratory for Molecular Sciences (BNLMS), Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190, China
| | - Kunhui Liu
- State Key Laboratory of Molecular Reaction Dynamics, Beijing National Laboratory for Molecular Sciences (BNLMS), Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190, China
| | - Di Song
- State Key Laboratory of Molecular Reaction Dynamics, Beijing National Laboratory for Molecular Sciences (BNLMS), Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190, China
| | - Hongmei Su
- State Key Laboratory of Molecular Reaction Dynamics, Beijing National Laboratory for Molecular Sciences (BNLMS), Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190, China.
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15
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Leonori F, Balucani N, Capozza G, Segoloni E, Volpi GG, Casavecchia P. Dynamics of the O(3P) + C2H2 reaction from crossed molecular beam experiments with soft electron ionization detection. Phys Chem Chem Phys 2014; 16:10008-22. [DOI: 10.1039/c3cp54729a] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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16
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Tesa-Serrate MA, King KL, Paterson G, Costen ML, McKendrick KG. Site and bond-specific dynamics of reactions at the gas–liquid interface. Phys Chem Chem Phys 2014; 16:173-83. [DOI: 10.1039/c3cp54107j] [Citation(s) in RCA: 14] [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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17
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Fu B, Han Y, Bowman JM. Three-state surface hopping calculations of acetaldehyde photodissociation to CH3 + HCO on ab initio potential surfaces. Faraday Discuss 2013; 157:27-39; discussion 113-40. [PMID: 23230762 DOI: 10.1039/c2fd20010d] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
We report Trajectory Surface Hopping (TSH) calculations of CH3CHO photodissociation involving three electronic states, S1, T1, and S0, with a focus on the radical products CH3 + HCO, which can be formed from both T0 and S0. We use previously reported potential energy surfaces and spin-orbit couplings for T1 and S0 and report a new potential and spin-orbit coupling for S1 here. Roughly 32 000 trajectories are performed at energies corresponding to seven photolysis wavelengths between 372 and 230 nm. Motivated by recent experiments, we examine the branching ratio of the T1 to S0 pathways as a function of photolysis energy. We also present the relative translational energy and CH3 vibrational energy distributions from these pathways at a photolysis energy of 100 kcal mol(-1), formed from both the T1 and S0 potentials. As with standard quasiclassical trajectory calculations, violation of zero-point energy for products also occurs in TSH calculations. This is shown to be a serious issue for this branching ratio and one of several methods considered to deal with this issue is shown to give satisfactory results.
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Affiliation(s)
- Bina Fu
- Department of Chemistry and Cherry L. Emerson Center for Scientific Computation, Emory University, Atlanta, Georgia 30322, USA
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18
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Fu B, Han YC, Bowman JM, Leonori F, Balucani N, Angelucci L, Occhiogrosso A, Petrucci R, Casavecchia P. Experimental and theoretical studies of the O(3P) + C2H4reaction dynamics: Collision energy dependence of branching ratios and extent of intersystem crossing. J Chem Phys 2012; 137:22A532. [DOI: 10.1063/1.4746758] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.8] [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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20
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Fu B, Han YC, Bowman JM, Angelucci L, Balucani N, Leonori F, Casavecchia P. Intersystem crossing and dynamics in O(3P) + C2H4 multichannel reaction: experiment validates theory. Proc Natl Acad Sci U S A 2012; 109:9733-8. [PMID: 22665777 PMCID: PMC3382527 DOI: 10.1073/pnas.1202672109] [Citation(s) in RCA: 80] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The O((3)P) + C(2)H(4) reaction, of importance in combustion and atmospheric chemistry, stands out as a paradigm reaction involving triplet- and singlet-state potential energy surfaces (PESs) interconnected by intersystem crossing (ISC). This reaction poses challenges for theory and experiments owing to the ruggedness and high dimensionality of these potentials, as well as the long lifetimes of the collision complexes. Primary products from five competing channels (H + CH(2)CHO, H + CH(3)CO, H(2) + CH(2)CO, CH(3) + HCO, CH(2) + CH(2)O) and branching ratios (BRs) are determined in crossed molecular beam experiments with soft electron-ionization mass-spectrometric detection at a collision energy of 8.4 kcal/mol. As some of the observed products can only be formed via ISC from triplet to singlet PESs, from the product BRs the extent of ISC is inferred. A new full-dimensional PES for the triplet state as well as spin-orbit coupling to the singlet PES are reported, and roughly half a million surface hopping trajectories are run on the coupled singlet-triplet PESs to compare with the experimental BRs and differential cross-sections. Both theory and experiment find almost equal contributions from the two PESs to the reaction, posing the question of how important is it to consider the ISC as one of the nonadiabatic effects for this and similar systems involved in combustion chemistry. Detailed comparisons at the level of angular and translational energy distributions between theory and experiment are presented for the two primary channel products, CH(3) + HCO and H + CH(2)CHO. The agreement between experimental and theoretical functions is excellent, implying that theory has reached the capability of describing complex multichannel nonadiabatic reactions.
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Affiliation(s)
- Bina Fu
- Department of Chemistry and Cherry L. Emerson Center for Scientific Computation, Emory University, Atlanta, GA 30322; and
| | - Yong-Chang Han
- Department of Chemistry and Cherry L. Emerson Center for Scientific Computation, Emory University, Atlanta, GA 30322; and
| | - Joel M. Bowman
- Department of Chemistry and Cherry L. Emerson Center for Scientific Computation, Emory University, Atlanta, GA 30322; and
| | - Luca Angelucci
- Dipartimento di Chimica—Università degli Studi di Perugia Via Elce di Sotto, 8-06123 Perugia, Italy
| | - Nadia Balucani
- Dipartimento di Chimica—Università degli Studi di Perugia Via Elce di Sotto, 8-06123 Perugia, Italy
| | - Francesca Leonori
- Dipartimento di Chimica—Università degli Studi di Perugia Via Elce di Sotto, 8-06123 Perugia, Italy
| | - Piergiorgio Casavecchia
- Dipartimento di Chimica—Università degli Studi di Perugia Via Elce di Sotto, 8-06123 Perugia, Italy
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West AC, Lynch JD, Sellner B, Lischka H, Hase WL, Windus TL. O + C2H4 potential energy surface: excited states and biradicals at the multireference level. Theor Chem Acc 2012. [DOI: 10.1007/s00214-012-1123-0] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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22
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Thomas PS, Somers MF, Hoekstra AW, Kroes GJ. Chebyshev high-dimensional model representation (Chebyshev-HDMR) potentials: application to reactive scattering of H2 from Pt(111) and Cu(111) surfaces. Phys Chem Chem Phys 2012; 14:8628-43. [DOI: 10.1039/c2cp40173h] [Citation(s) in RCA: 17] [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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23
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Savee JD, Welz O, Taatjes CA, Osborn DL. New mechanistic insights to the O(3P) + propene reaction from multiplexed photoionization mass spectrometry. Phys Chem Chem Phys 2012; 14:10410-23. [DOI: 10.1039/c2cp41200d] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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24
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Albertí M, Lago NF, Pirani F. Ar Solvation Shells in K+–HFBz: From Cluster Rearrangement to Solvation Dynamics. J Phys Chem A 2011; 115:10871-9. [DOI: 10.1021/jp206601m] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- M. Albertí
- IQTCUB, Departament de Química Física, Universitat de Barcelona, Barcelona, Spain
| | - N. Faginas Lago
- Dipartimento di Chimica, Università di Perugia, Perugia, Italy
| | - F. Pirani
- Dipartimento di Chimica, Università di Perugia, Perugia, Italy
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25
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Balucani N, Casavecchia P. Crossed molecular beam studies of astronomically relevant bimolecular reactions. RENDICONTI LINCEI 2011. [DOI: 10.1007/s12210-011-0128-2] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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26
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Yacovitch TI, Kim JB, Garand E, van der Poll DG, Neumark DM. Slow photoelectron velocity-map imaging spectroscopy of the n-methylvinoxide anion. J Chem Phys 2011; 134:134307. [DOI: 10.1063/1.3572269] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
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27
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Balucani N, Leonori F, Petrucci R, Stazi M, Skouteris D, Rosi M, Casavecchia P. Formation of nitriles and imines in the atmosphere of Titan: combined crossed-beam and theoretical studies on the reaction dynamics of excited nitrogen atoms N(2D) with ethane. Faraday Discuss 2011; 147:189-216; discussion 251-82. [PMID: 21302548 DOI: 10.1039/c004748a] [Citation(s) in RCA: 63] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The dynamics of the H-displacement channels in the reaction N(2D) + C2H6 have been investigated by the crossed molecular beam technique with mass spectrometric detection and time-of-flight analysis at two different collision energies (18.0 and 31.4 kJ mol(-1)). From the derived center-of-mass product angular and translational energy distributions the reaction micromechanisms and the product energy partitioning have been obtained. The interpretation of the scattering results is assisted by new ab initio electronic structure calculations of stationary points and product energetics for the C2H6N ground state doublet potential energy surface. C-C bond breaking and NH production channels have been theoretically characterized and the statistical branching ratio derived at the temperatures relevant for the atmosphere of Titan. Methanimine plus CH3 and ethanimine plus H are the main reaction channels. Implications for the atmospheric chemistry of Titan are discussed.
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Affiliation(s)
- Nadia Balucani
- Dipartimento di Chimica, Università degli Studi di Perugia, 06123, Perugia, Italy.
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28
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Bowman JM, Czakó G, Fu B. High-dimensional ab initio potential energy surfaces for reaction dynamics calculations. Phys Chem Chem Phys 2011; 13:8094-111. [DOI: 10.1039/c0cp02722g] [Citation(s) in RCA: 230] [Impact Index Per Article: 17.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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29
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Balucani N, Leonori F, Bergeat A, Petrucci R, Casavecchia P. Crossed-beam dynamics studies of the radical–radical combustion reaction O(3P) + CH3(methyl). Phys Chem Chem Phys 2011; 13:8322-30. [DOI: 10.1039/c0cp01623c] [Citation(s) in RCA: 18] [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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30
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Leonori F, Hickson KM, Le Picard SD, Wang X, Petrucci R, Foggi P, Balucani N, Casavecchia P. Crossed-beam universal-detection reactive scattering of radical beams characterized by laser-induced-fluorescence: the case of C2and CN. Mol Phys 2010. [DOI: 10.1080/00268971003657110] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
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31
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Thomas PS, Chhantyal-Pun R, Kline ND, Miller TA. The Ã-X̃ absorption of vinoxy radical revisited: Normal and Herzberg–Teller bands observed via cavity ringdown spectroscopy. J Chem Phys 2010; 132:114302. [DOI: 10.1063/1.3352976] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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32
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Costes M, Naulin C. Integral and differential cross sections of reactions relevant to astrochemistry. Phys Chem Chem Phys 2010; 12:9154-64. [DOI: 10.1039/c003656k] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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33
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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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34
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West AC, Kretchmer JS, Sellner B, Park K, Hase WL, Lischka H, Windus TL. O(3P) + C2H4 Potential Energy Surface: Study at the Multireference Level. J Phys Chem A 2009; 113:12663-74. [DOI: 10.1021/jp905070z] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Aaron C. West
- Department of Chemistry, Iowa State University, Ames, Iowa 50011, Department of Chemistry, University of California at Berkeley, Berkeley, California 94720, Institute for Theoretical Chemistry, University of Vienna, Waehringerstrasse 17, A-1090 Vienna, Austria, Department of Chemistry and Biochemistry, Texas Tech University, Memorial Circle & Boston, Lubbock, Texas 79409-1061, and Institute of Organic Chemistry and Biochemistry, Academy of Sciences of the Czech Republic, Flemingovo nam. 2, CZ-16610
| | - Joshua S. Kretchmer
- Department of Chemistry, Iowa State University, Ames, Iowa 50011, Department of Chemistry, University of California at Berkeley, Berkeley, California 94720, Institute for Theoretical Chemistry, University of Vienna, Waehringerstrasse 17, A-1090 Vienna, Austria, Department of Chemistry and Biochemistry, Texas Tech University, Memorial Circle & Boston, Lubbock, Texas 79409-1061, and Institute of Organic Chemistry and Biochemistry, Academy of Sciences of the Czech Republic, Flemingovo nam. 2, CZ-16610
| | - Bernhard Sellner
- Department of Chemistry, Iowa State University, Ames, Iowa 50011, Department of Chemistry, University of California at Berkeley, Berkeley, California 94720, Institute for Theoretical Chemistry, University of Vienna, Waehringerstrasse 17, A-1090 Vienna, Austria, Department of Chemistry and Biochemistry, Texas Tech University, Memorial Circle & Boston, Lubbock, Texas 79409-1061, and Institute of Organic Chemistry and Biochemistry, Academy of Sciences of the Czech Republic, Flemingovo nam. 2, CZ-16610
| | - Kyoyeon Park
- Department of Chemistry, Iowa State University, Ames, Iowa 50011, Department of Chemistry, University of California at Berkeley, Berkeley, California 94720, Institute for Theoretical Chemistry, University of Vienna, Waehringerstrasse 17, A-1090 Vienna, Austria, Department of Chemistry and Biochemistry, Texas Tech University, Memorial Circle & Boston, Lubbock, Texas 79409-1061, and Institute of Organic Chemistry and Biochemistry, Academy of Sciences of the Czech Republic, Flemingovo nam. 2, CZ-16610
| | - William L. Hase
- Department of Chemistry, Iowa State University, Ames, Iowa 50011, Department of Chemistry, University of California at Berkeley, Berkeley, California 94720, Institute for Theoretical Chemistry, University of Vienna, Waehringerstrasse 17, A-1090 Vienna, Austria, Department of Chemistry and Biochemistry, Texas Tech University, Memorial Circle & Boston, Lubbock, Texas 79409-1061, and Institute of Organic Chemistry and Biochemistry, Academy of Sciences of the Czech Republic, Flemingovo nam. 2, CZ-16610
| | - Hans Lischka
- Department of Chemistry, Iowa State University, Ames, Iowa 50011, Department of Chemistry, University of California at Berkeley, Berkeley, California 94720, Institute for Theoretical Chemistry, University of Vienna, Waehringerstrasse 17, A-1090 Vienna, Austria, Department of Chemistry and Biochemistry, Texas Tech University, Memorial Circle & Boston, Lubbock, Texas 79409-1061, and Institute of Organic Chemistry and Biochemistry, Academy of Sciences of the Czech Republic, Flemingovo nam. 2, CZ-16610
| | - Theresa L. Windus
- Department of Chemistry, Iowa State University, Ames, Iowa 50011, Department of Chemistry, University of California at Berkeley, Berkeley, California 94720, Institute for Theoretical Chemistry, University of Vienna, Waehringerstrasse 17, A-1090 Vienna, Austria, Department of Chemistry and Biochemistry, Texas Tech University, Memorial Circle & Boston, Lubbock, Texas 79409-1061, and Institute of Organic Chemistry and Biochemistry, Academy of Sciences of the Czech Republic, Flemingovo nam. 2, CZ-16610
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Leonori F, Petrucci R, Balucani N, Casavecchia P, Rosi M, Skouteris D, Berteloite C, Le Picard SD, Canosa A, Sims IR. Crossed-Beam Dynamics, Low-Temperature Kinetics, and Theoretical Studies of the Reaction S(1D) + C2H4. J Phys Chem A 2009; 113:15328-45. [DOI: 10.1021/jp906299v] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
| | | | | | | | - Marzio Rosi
- Dipartimento di Ingegneria Civile e Ambientale and ISTM-CNR, c/o Dipartimento di Chimica, Università degli Studi di Perugia, 06123 Perugia, Italy
| | - Dimitris Skouteris
- Dipartimento di Matematica e Informatica and Dipartimento di Chimica, Università degli Studi di Perugia, 06123 Perugia, Italy
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36
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Leonori F, Petrucci R, Balucani N, Hickson KM, Hamberg M, Geppert WD, Casavecchia P, Rosi M. Crossed-beam and theoretical studies of the S(1D) + C2H2 reaction. J Phys Chem A 2009; 113:4330-9. [PMID: 19260670 DOI: 10.1021/jp810989p] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The reaction dynamics of excited sulfur atoms, S((1)D), with acetylene has been investigated by the crossed-beam scattering technique with mass spectrometric detection and time-of-flight (TOF) analysis at the collision energy of 35.6 kJ mol(-1). These studies have been made possible by the development of intense continuous supersonic beams of S((3)P,(1)D) atoms. From product angular and TOF distributions, center-of-mass product angular and translational energy distributions are derived. The S((1)D) + C(2)H(2) reaction is found to lead to formation of HCCS (thioketenyl) + H, while the only other energetically allowed channels, those leading to CCS((3)Sigma(-), (1)Delta) + H(2), are not observed to occur to an appreciable extent. The dynamics of the H-elimination channel is discussed and elucidated. The interpretation of the scattering results is assisted by synergic high-level ab initio electronic structure calculations of stationary points and product energetics for the C(2)H(2)S ground-state singlet potential energy surface. In addition, by exploiting the novel capability of performing product detection by means of a tunable electron-impact ionizer, we have obtained the first experimental information on the ionization energy of thioketenyl radical, HCCS, as synthesized in the reactive scattering experiment. This has been complemented by ab initio calculations of the adiabatic and vertical ionization energies for the ground-state radical. The theoretically derived value of 9.1 eV confirms very recent, accurate calculations and is corroborated by the experimentally determined ionization threshold of 8.9 +/- 0.3 eV for the internally warm HCCS produced from the title reaction.
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Affiliation(s)
- Francesca Leonori
- Dipartimento di Chimica, Universita degli Studi di Perugia, 06123 Perugia, Italy
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37
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Yacovitch TI, Garand E, Neumark DM. Slow photoelectron velocity-map imaging spectroscopy of the vinoxide anion. J Chem Phys 2009; 130:244309. [DOI: 10.1063/1.3157208] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
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38
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Balucani N. Elementary reactions and their role in gas-phase prebiotic chemistry. Int J Mol Sci 2009; 10:2304-2335. [PMID: 19564951 PMCID: PMC2695279 DOI: 10.3390/ijms10052304] [Citation(s) in RCA: 81] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2009] [Revised: 05/13/2009] [Accepted: 05/15/2009] [Indexed: 11/23/2022] Open
Abstract
The formation of complex organic molecules in a reactor filled with gaseous mixtures possibly reproducing the primitive terrestrial atmosphere and ocean demonstrated more than 50 years ago that inorganic synthesis of prebiotic molecules is possible, provided that some form of energy is provided to the system. After that groundbreaking experiment, gas-phase prebiotic molecules have been observed in a wide variety of extraterrestrial objects (including interstellar clouds, comets and planetary atmospheres) where the physical conditions vary widely. A thorough characterization of the chemical evolution of those objects relies on a multi-disciplinary approach: 1) observations allow us to identify the molecules and their number densities as they are nowadays; 2) the chemistry which lies behind their formation starting from atoms and simple molecules is accounted for by complex reaction networks; 3) for a realistic modeling of such networks, a number of experimental parameters are needed and, therefore, the relevant molecular processes should be fully characterized in laboratory experiments. A survey of the available literature reveals, however, that much information is still lacking if it is true that only a small percentage of the elementary reactions considered in the models have been characterized in laboratory experiments. New experimental approaches to characterize the relevant elementary reactions in laboratory are presented and the implications of the results are discussed.
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Affiliation(s)
- Nadia Balucani
- Dipartimento di Chimica, Università degli Studi di Perugia, 06123 Perugia, Italy; E-Mail:
; Tel. +39-075-585-5513; Fax: +39-075-585-5606
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39
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Lee SH, Chen WK, Huang WJ. Exploring the dynamics of reactions of oxygen atoms in states P3 and D1 with ethene at collision energy 3 kcal mol−1. J Chem Phys 2009; 130:054301. [DOI: 10.1063/1.3068716] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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40
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Miyoshi A, Yoshida JI, Shiki N, Koshi M, Matsui H. Product branching fractions for the reaction of O(3P) with ethene. Phys Chem Chem Phys 2009; 11:7318-23. [DOI: 10.1039/b905787k] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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41
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Casavecchia P, Leonori F, Balucani N, Petrucci R, Capozza G, Segoloni E. Probing the dynamics of polyatomic multichannel elementary reactions by crossed molecular beam experiments with soft electron-ionization mass spectrometric detection. Phys Chem Chem Phys 2008; 11:46-65. [PMID: 19081908 DOI: 10.1039/b814709d] [Citation(s) in RCA: 88] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
In this Perspective we highlight developments in the field of chemical reaction dynamics. Focus is on the advances recently made in the investigation of the dynamics of elementary multichannel radical-molecule and radical-radical reactions, as they have become possible using an improved crossed molecular beam scattering apparatus with universal electron-ionization mass spectrometric detection and time-of-flight analysis. These improvements consist in the implementation of (a) soft ionization detection by tunable low-energy electrons which has permitted us to reduce interfering signals originating from dissociative ionization processes, usually representing a major complication, (b) different beam crossing-angle set-ups which have permitted us to extend the range of collision energies over which a reaction can be studied, from very low (a few kJ mol(-1), as of interest in astrochemistry or planetary atmospheric chemistry) to quite high energies (several tens of kJ mol(-1), as of interest in high temperature combustion systems), and (c) continuous supersonic sources for producing a wide variety of atomic and molecular radical reactant beams. Exploiting these new features it has become possible to tackle the dynamics of a variety of polyatomic multichannel reactions, such as those occurring in many environments ranging from combustion and plasmas to terrestrial/planetary atmospheres and interstellar clouds. By measuring product angular and velocity distributions, after having suppressed or mitigated, when needed, the problem of dissociative ionization of interfering species (reactants, products, background gases) by soft ionization detection, essentially all primary reaction products can be identified, the dynamics of each reaction channel characterized, and the branching ratios determined as a function of collision energy. In general this information, besides being of fundamental relevance, is required for a predictive description of the chemistry of these environments via computer models. Examples are taken from recent on-going work (partly published) on the reactions of atomic oxygen with acetylene, ethylene and allyl radical, of great importance in combustion. A reaction of relevance in interstellar chemistry, as that of atomic carbon with acetylene, is also discussed briefly. Comparison with theoretical results is made wherever possible, both at the level of electronic structure calculations of the potential energy surfaces and dynamical computations. Recent complementary CMB work as well as kinetic work exploiting soft photo-ionization with synchrotron radiation are noted. The examples illustrated in this article demonstrate that the type of dynamical results now obtainable on polyatomic multichannel radical-molecule and radical-radical reactions might well complement reaction kinetics experiments and hence contribute to bridging the gap between microscopic reaction dynamics and thermal reaction kinetics, enhancing significantly our basic knowledge of chemical reactivity and understanding of the elementary reactions which occur in real-world environments.
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42
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Wang X, Dong W, Xiao C, Che L, Ren Z, Dai D, Wang X, Casavecchia P, Yang X, Jiang B, Xie D, Sun Z, Lee SY, Zhang DH, Werner HJ, Alexander MH. The Extent of Non–Born-Oppenheimer Coupling in the Reaction of Cl(
2
P
) with
para-
H
2. Science 2008; 322:573-6. [DOI: 10.1126/science.1163195] [Citation(s) in RCA: 86] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Affiliation(s)
- Xingan Wang
- State Key Laboratory of Molecular Reaction Dynamics, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian, Liaoning 116023, People's Republic of China
- Institute of Theoretical and Computational Chemistry, Key Laboratory of Mesoscopic Chemistry of Ministry of Education, School of Chemistry and Chemical Engineering, Nanjing University, Nanjing 210093, People's Republic of China
- Division of Chemistry and Biological Chemistry, School of Physical and Mathematical Sciences, Nanyang Technological University, Singapore 637371, Singapore
- School of Physical and Mathematical Sciences, Nanyang Technological University, Singapore 637371, Singapore
- Institute für Theoretische Chemie, Universität Stuttgart, Pfaffenwaldring 55, D-70569 Stuttgart, Germany
| | - Wenrui Dong
- State Key Laboratory of Molecular Reaction Dynamics, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian, Liaoning 116023, People's Republic of China
- Institute of Theoretical and Computational Chemistry, Key Laboratory of Mesoscopic Chemistry of Ministry of Education, School of Chemistry and Chemical Engineering, Nanjing University, Nanjing 210093, People's Republic of China
- Division of Chemistry and Biological Chemistry, School of Physical and Mathematical Sciences, Nanyang Technological University, Singapore 637371, Singapore
- School of Physical and Mathematical Sciences, Nanyang Technological University, Singapore 637371, Singapore
- Institute für Theoretische Chemie, Universität Stuttgart, Pfaffenwaldring 55, D-70569 Stuttgart, Germany
| | - Chunlei Xiao
- State Key Laboratory of Molecular Reaction Dynamics, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian, Liaoning 116023, People's Republic of China
- Institute of Theoretical and Computational Chemistry, Key Laboratory of Mesoscopic Chemistry of Ministry of Education, School of Chemistry and Chemical Engineering, Nanjing University, Nanjing 210093, People's Republic of China
- Division of Chemistry and Biological Chemistry, School of Physical and Mathematical Sciences, Nanyang Technological University, Singapore 637371, Singapore
- School of Physical and Mathematical Sciences, Nanyang Technological University, Singapore 637371, Singapore
- Institute für Theoretische Chemie, Universität Stuttgart, Pfaffenwaldring 55, D-70569 Stuttgart, Germany
| | - Li Che
- State Key Laboratory of Molecular Reaction Dynamics, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian, Liaoning 116023, People's Republic of China
- Institute of Theoretical and Computational Chemistry, Key Laboratory of Mesoscopic Chemistry of Ministry of Education, School of Chemistry and Chemical Engineering, Nanjing University, Nanjing 210093, People's Republic of China
- Division of Chemistry and Biological Chemistry, School of Physical and Mathematical Sciences, Nanyang Technological University, Singapore 637371, Singapore
- School of Physical and Mathematical Sciences, Nanyang Technological University, Singapore 637371, Singapore
- Institute für Theoretische Chemie, Universität Stuttgart, Pfaffenwaldring 55, D-70569 Stuttgart, Germany
| | - Zefeng Ren
- State Key Laboratory of Molecular Reaction Dynamics, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian, Liaoning 116023, People's Republic of China
- Institute of Theoretical and Computational Chemistry, Key Laboratory of Mesoscopic Chemistry of Ministry of Education, School of Chemistry and Chemical Engineering, Nanjing University, Nanjing 210093, People's Republic of China
- Division of Chemistry and Biological Chemistry, School of Physical and Mathematical Sciences, Nanyang Technological University, Singapore 637371, Singapore
- School of Physical and Mathematical Sciences, Nanyang Technological University, Singapore 637371, Singapore
- Institute für Theoretische Chemie, Universität Stuttgart, Pfaffenwaldring 55, D-70569 Stuttgart, Germany
| | - Dongxu Dai
- State Key Laboratory of Molecular Reaction Dynamics, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian, Liaoning 116023, People's Republic of China
- Institute of Theoretical and Computational Chemistry, Key Laboratory of Mesoscopic Chemistry of Ministry of Education, School of Chemistry and Chemical Engineering, Nanjing University, Nanjing 210093, People's Republic of China
- Division of Chemistry and Biological Chemistry, School of Physical and Mathematical Sciences, Nanyang Technological University, Singapore 637371, Singapore
- School of Physical and Mathematical Sciences, Nanyang Technological University, Singapore 637371, Singapore
- Institute für Theoretische Chemie, Universität Stuttgart, Pfaffenwaldring 55, D-70569 Stuttgart, Germany
| | - Xiuyan Wang
- State Key Laboratory of Molecular Reaction Dynamics, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian, Liaoning 116023, People's Republic of China
- Institute of Theoretical and Computational Chemistry, Key Laboratory of Mesoscopic Chemistry of Ministry of Education, School of Chemistry and Chemical Engineering, Nanjing University, Nanjing 210093, People's Republic of China
- Division of Chemistry and Biological Chemistry, School of Physical and Mathematical Sciences, Nanyang Technological University, Singapore 637371, Singapore
- School of Physical and Mathematical Sciences, Nanyang Technological University, Singapore 637371, Singapore
- Institute für Theoretische Chemie, Universität Stuttgart, Pfaffenwaldring 55, D-70569 Stuttgart, Germany
| | - Piergiorgio Casavecchia
- State Key Laboratory of Molecular Reaction Dynamics, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian, Liaoning 116023, People's Republic of China
- Institute of Theoretical and Computational Chemistry, Key Laboratory of Mesoscopic Chemistry of Ministry of Education, School of Chemistry and Chemical Engineering, Nanjing University, Nanjing 210093, People's Republic of China
- Division of Chemistry and Biological Chemistry, School of Physical and Mathematical Sciences, Nanyang Technological University, Singapore 637371, Singapore
- School of Physical and Mathematical Sciences, Nanyang Technological University, Singapore 637371, Singapore
- Institute für Theoretische Chemie, Universität Stuttgart, Pfaffenwaldring 55, D-70569 Stuttgart, Germany
| | - Xueming Yang
- State Key Laboratory of Molecular Reaction Dynamics, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian, Liaoning 116023, People's Republic of China
- Institute of Theoretical and Computational Chemistry, Key Laboratory of Mesoscopic Chemistry of Ministry of Education, School of Chemistry and Chemical Engineering, Nanjing University, Nanjing 210093, People's Republic of China
- Division of Chemistry and Biological Chemistry, School of Physical and Mathematical Sciences, Nanyang Technological University, Singapore 637371, Singapore
- School of Physical and Mathematical Sciences, Nanyang Technological University, Singapore 637371, Singapore
- Institute für Theoretische Chemie, Universität Stuttgart, Pfaffenwaldring 55, D-70569 Stuttgart, Germany
| | - Bin Jiang
- State Key Laboratory of Molecular Reaction Dynamics, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian, Liaoning 116023, People's Republic of China
- Institute of Theoretical and Computational Chemistry, Key Laboratory of Mesoscopic Chemistry of Ministry of Education, School of Chemistry and Chemical Engineering, Nanjing University, Nanjing 210093, People's Republic of China
- Division of Chemistry and Biological Chemistry, School of Physical and Mathematical Sciences, Nanyang Technological University, Singapore 637371, Singapore
- School of Physical and Mathematical Sciences, Nanyang Technological University, Singapore 637371, Singapore
- Institute für Theoretische Chemie, Universität Stuttgart, Pfaffenwaldring 55, D-70569 Stuttgart, Germany
| | - Daiqian Xie
- State Key Laboratory of Molecular Reaction Dynamics, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian, Liaoning 116023, People's Republic of China
- Institute of Theoretical and Computational Chemistry, Key Laboratory of Mesoscopic Chemistry of Ministry of Education, School of Chemistry and Chemical Engineering, Nanjing University, Nanjing 210093, People's Republic of China
- Division of Chemistry and Biological Chemistry, School of Physical and Mathematical Sciences, Nanyang Technological University, Singapore 637371, Singapore
- School of Physical and Mathematical Sciences, Nanyang Technological University, Singapore 637371, Singapore
- Institute für Theoretische Chemie, Universität Stuttgart, Pfaffenwaldring 55, D-70569 Stuttgart, Germany
| | - Zhigang Sun
- State Key Laboratory of Molecular Reaction Dynamics, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian, Liaoning 116023, People's Republic of China
- Institute of Theoretical and Computational Chemistry, Key Laboratory of Mesoscopic Chemistry of Ministry of Education, School of Chemistry and Chemical Engineering, Nanjing University, Nanjing 210093, People's Republic of China
- Division of Chemistry and Biological Chemistry, School of Physical and Mathematical Sciences, Nanyang Technological University, Singapore 637371, Singapore
- School of Physical and Mathematical Sciences, Nanyang Technological University, Singapore 637371, Singapore
- Institute für Theoretische Chemie, Universität Stuttgart, Pfaffenwaldring 55, D-70569 Stuttgart, Germany
| | - Soo-Y. Lee
- State Key Laboratory of Molecular Reaction Dynamics, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian, Liaoning 116023, People's Republic of China
- Institute of Theoretical and Computational Chemistry, Key Laboratory of Mesoscopic Chemistry of Ministry of Education, School of Chemistry and Chemical Engineering, Nanjing University, Nanjing 210093, People's Republic of China
- Division of Chemistry and Biological Chemistry, School of Physical and Mathematical Sciences, Nanyang Technological University, Singapore 637371, Singapore
- School of Physical and Mathematical Sciences, Nanyang Technological University, Singapore 637371, Singapore
- Institute für Theoretische Chemie, Universität Stuttgart, Pfaffenwaldring 55, D-70569 Stuttgart, Germany
| | - Dong H. Zhang
- State Key Laboratory of Molecular Reaction Dynamics, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian, Liaoning 116023, People's Republic of China
- Institute of Theoretical and Computational Chemistry, Key Laboratory of Mesoscopic Chemistry of Ministry of Education, School of Chemistry and Chemical Engineering, Nanjing University, Nanjing 210093, People's Republic of China
- Division of Chemistry and Biological Chemistry, School of Physical and Mathematical Sciences, Nanyang Technological University, Singapore 637371, Singapore
- School of Physical and Mathematical Sciences, Nanyang Technological University, Singapore 637371, Singapore
- Institute für Theoretische Chemie, Universität Stuttgart, Pfaffenwaldring 55, D-70569 Stuttgart, Germany
| | - Hans-Joachim Werner
- State Key Laboratory of Molecular Reaction Dynamics, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian, Liaoning 116023, People's Republic of China
- Institute of Theoretical and Computational Chemistry, Key Laboratory of Mesoscopic Chemistry of Ministry of Education, School of Chemistry and Chemical Engineering, Nanjing University, Nanjing 210093, People's Republic of China
- Division of Chemistry and Biological Chemistry, School of Physical and Mathematical Sciences, Nanyang Technological University, Singapore 637371, Singapore
- School of Physical and Mathematical Sciences, Nanyang Technological University, Singapore 637371, Singapore
- Institute für Theoretische Chemie, Universität Stuttgart, Pfaffenwaldring 55, D-70569 Stuttgart, Germany
| | - Millard H. Alexander
- State Key Laboratory of Molecular Reaction Dynamics, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian, Liaoning 116023, People's Republic of China
- Institute of Theoretical and Computational Chemistry, Key Laboratory of Mesoscopic Chemistry of Ministry of Education, School of Chemistry and Chemical Engineering, Nanjing University, Nanjing 210093, People's Republic of China
- Division of Chemistry and Biological Chemistry, School of Physical and Mathematical Sciences, Nanyang Technological University, Singapore 637371, Singapore
- School of Physical and Mathematical Sciences, Nanyang Technological University, Singapore 637371, Singapore
- Institute für Theoretische Chemie, Universität Stuttgart, Pfaffenwaldring 55, D-70569 Stuttgart, Germany
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43
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Leonori F, Petrucci R, Segoloni E, Bergeat A, Hickson KM, Balucani N, Casavecchia P. Unraveling the dynamics of the C(3P,1D) + C2H2 reactions by the crossed molecular beam scattering technique. J Phys Chem A 2008; 112:1363-79. [PMID: 18229899 DOI: 10.1021/jp0776208] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
A detailed investigation of the dynamics of the reactions of ground- and excited-state carbon atoms, C(3P) and C(1D), with acetylene is reported over a wide collision energy range (3.6-49.1 kJ mol-1) using the crossed molecular beam (CMB) scattering technique with electron ionization mass spectrometric detection and time-of-flight (TOF) analysis. We have exploited the capability of (a) generating continuous intense supersonic beams of C(3P, 1D), (b) crossing the two reactant beams at different intersection angles (45, 90, and 135 degrees ) to attain a wide range of collision energies, and (c) tuning the energy of the ionizing electrons to low values (soft ionization) to suppress interferences from dissociative ionization processes. From angular and TOF distribution measurements of products at m/z=37 and 36, the primary reaction products of the C(3P) and C(1D) reactions with C2H2 have been identified to be cyclic (c)-C3H + H, linear (l)-C3H + H, and C3 + H2. From the data analysis, product angular and translational energy distributions in the center-of-mass (CM) system for both the linear and cyclic C3H isomers as well as the C3 product from C(3P) and for l/c-C3H and C3 from C(1D) have been derived as a function of collision energy from 3.6 to 49.1 kJ mol-1. The cyclic/linear C3H ratio and the C3/(C3 + c/l-C3H) branching ratios for the C(3P) reaction have been determined as a function of collision energy. The present findings have been compared with those from previous CMB studies using pulsed beams; here, a marked contrast is noted in the CM angular distributions for both C3H- and C3-forming channels from C(3P) and their trend with collision energy. Consequently, the interpretation of the reaction dynamics derived in the present work contradicts that previously proposed from the pulsed CMB studies. The results have been discussed in the light of the available theoretical information on the relevant triplet and singlet C3H2 ab initio potential energy surfaces (PESs). In particular, the branching ratios for the C(3P) + C2H2 reaction have been compared with the available theoretical predictions (approximate quantum scattering calculations and quasiclassical trajectory calculations on ab initio triplet PESs and, very recent, statistical calculations on ab initio triplet PESs as well as on ab initio triplet/singlet PESs including nonadiabatic effects, that is, intersystem crossing). While the experimental branching ratios have been corroborated by the statistical predictions, strong disagreement has been found with the results of the dynamical calculations. The astrophysical implications of the present results have been noted.
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Affiliation(s)
- Francesca Leonori
- Dipartimento di Chimica, Università degli Studi di Perugia, 06123 Perugia, Italy
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44
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Hu W, Lendvay G, Maiti B, Schatz GC. Trajectory Surface Hopping Study of the O(3P) + Ethylene Reaction Dynamics. J Phys Chem A 2007; 112:2093-103. [DOI: 10.1021/jp076716z] [Citation(s) in RCA: 65] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Affiliation(s)
- Wenfang Hu
- Department of Chemistry, Northwestern University, Evanston Illinois 60208-3113, Chemical Research Center, Hungarian Academy of Sciences, H-1525 Budapest, P.O. Box 17, Hungary, and Department of Chemistry, Faculty of Science, Banaras Hindu University, Varanasi 221005, India
| | - György Lendvay
- Department of Chemistry, Northwestern University, Evanston Illinois 60208-3113, Chemical Research Center, Hungarian Academy of Sciences, H-1525 Budapest, P.O. Box 17, Hungary, and Department of Chemistry, Faculty of Science, Banaras Hindu University, Varanasi 221005, India
| | - Biswajit Maiti
- Department of Chemistry, Northwestern University, Evanston Illinois 60208-3113, Chemical Research Center, Hungarian Academy of Sciences, H-1525 Budapest, P.O. Box 17, Hungary, and Department of Chemistry, Faculty of Science, Banaras Hindu University, Varanasi 221005, India
| | - George C. Schatz
- Department of Chemistry, Northwestern University, Evanston Illinois 60208-3113, Chemical Research Center, Hungarian Academy of Sciences, H-1525 Budapest, P.O. Box 17, Hungary, and Department of Chemistry, Faculty of Science, Banaras Hindu University, Varanasi 221005, India
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45
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DeBoer GD, Dodd JA. Ab Initio Energies and Product Branching Ratios for the O + C3H6 Reaction. J Phys Chem A 2007; 111:12977-84. [DOI: 10.1021/jp0755037] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Gary D. DeBoer
- Department of Chemistry and Physics, LeTourneau University, Longview, Texas 75602
| | - James A. Dodd
- Air Force Research Laboratory/Space Vehicles Directorate, Hanscom AFB, Massachusetts 01731-3010
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46
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Lee SH, Huang WJ, Chen WK. Dynamics of the reaction of atomic oxygen with ethene: Observation of all carbon-containing products by single-photon ionization. Chem Phys Lett 2007. [DOI: 10.1016/j.cplett.2007.08.083] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
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47
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Bennett DIG, Butler LJ, Werner HJ. Comparing electronic structure predictions for the ground state dissociation of vinoxy radicals. J Chem Phys 2007; 127:094309. [PMID: 17824741 DOI: 10.1063/1.2753489] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
This paper reports a series of electronic structure calculations performed on the dissociation pathways of the vinoxy radical (CH(2)CHO). We use coupled-cluster with single, double, and perturbative triple excitations (CCSD(T)), complete active space self-consistent field (CASSCF), multireference configuration interaction (MRCI), and MRCI with the Davidson correction (MRCI+Q) to calculate the barrier heights of the two unimolecular dissociation pathways of this radical. The effect of state averaging on the barrier heights is investigated at the CASSCF, MRCI, and MRCI+Q levels. The change in mixing angle along the reaction path is calculated as a measure of derivative coupling and found to be insufficient to suggest nonadiabatic recrossing. We also present a new analysis of previous experimental data on the unimolecular dissociation of ground state vinoxy. In particular, an error in the internal energy distribution of vinoxy radicals reported in a previous paper is corrected and a new analysis of the experimental sensitivity to the onset energy (barrier height) for the isomerization reaction is given. Combining these studies, a final "worst case" analysis of the product branching ratio is given and a statistical model using each of the calculated transition states is found to be unable to correctly reproduce the experimental data.
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Affiliation(s)
- Doran I G Bennett
- The James Franck Institute and The Department of Chemistry, The University of Chicago, Chicago, Illinois 60637, USA
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48
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Su H, Zhao S, Liu K, Xiang T. The Reactions of O(3P) with Terminal Alkenes: The H2CO Channel via 3,2 H-Atom Shift. J Phys Chem A 2007; 111:9600-5. [PMID: 17705461 DOI: 10.1021/jp073993x] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The step-scan time-resolved FTIR emission spectroscopy is used to characterize systematically the H(2)CO channel for the reactions of O((3)P) with various alkenes. IR emission bands due to the products of CO, CO(2), and H(2)CO have been observed in the spectra. H(2)CO is identified to be the primary reaction product whereas CO and CO(2) are secondary reaction products of O((3)P) with alkenes. A general trend is observed in which the fraction yield of the H(2)CO product increases substantially as the reactant alkene varies from C(2)H(4), C(3)H(6), 1-C(4)H(8), iso-C(4)H(8), to 1-C(5)H(10). The formation mechanism of the H(2)CO is therefore elucidated to arise from a 3,2 H-atom shift followed by breaking of the C(1)-C(2) bond in the initially formed energized diradical RCH(2)CHCH(2)O*. The 3,2 H-atom shift may become the dominant process with the more rapid delocalization of the energy when the hydrocarbon chain of the alkene molecule is lengthened.
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Affiliation(s)
- Hongmei Su
- State Key Laboratory of Molecular Reaction Dynamics, and Beijing National Laboratory for Molecular Sciences (BNLMS), Institute of Chemistry, Chinese Academy of Sciences, Beijing 100080, People's Republic of China.
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49
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Lu IC, Huang WJ, Chaudhuri C, Chen WK, Lee SH. Development of a stable source of atomic oxygen with a pulsed high-voltage discharge and its application to crossed-beam reactions. THE REVIEW OF SCIENTIFIC INSTRUMENTS 2007; 78:083103. [PMID: 17764309 DOI: 10.1063/1.2772090] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/17/2023]
Abstract
To investigate the reactions of oxygen atoms with ethene and silane in a crossed-beam condition, we developed a stable, highly intense, and short-pulsed source of atomic oxygen with a transient high-voltage discharge. Mixtures of O(2) and He served as discharge media. Utilizing a crossed molecular-beam apparatus and direct vacuum-ultraviolet ionization, we measured the temporal profiles of oxygen atoms and the time-of-flight spectra of reaction products. With O(2) 3% seeded in He as a discharge medium, oxygen atoms might have a full width as small as 13.5 micros at half maximum at a location 193 mm downstream from the discharge region. Most population of oxygen atoms is in the ground state (3)P but some in the first excited state (1)D, depending on the concentration of precursor O(2). This discharge device analogously generates carbon, nitrogen, and fluorine atoms from precursors CO, N(2), and F(2), respectively.
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Affiliation(s)
- I-Chung Lu
- Department of Chemistry, National Tsing Hua University, Hsinchu, Taiwan
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50
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Costes M, Daugey N, Naulin C, Bergeat A, Leonori F, Segoloni E, Petrucci R, Balucani N, Casavecchia P. Crossed-beam studies on the dynamics of the C + C2H2 interstellar reaction leading to linear and cyclic C3H + H and C3 + H2. Faraday Discuss 2007; 133:157-76; discussion 191-230, 449-52. [PMID: 17191448 DOI: 10.1039/b518300f] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
The dynamics of the C + C2H2 reaction has been investigated using two crossed molecular beam apparatus of different concepts. Differential cross sections have been obtained for the C(3PJ) + C2H2(X1sigmag+) --> l/c-C3H + H(2S1/2) reaction in experiments conducted with pulsed supersonic beams and variable beam crossing angle configuration at two relative translational energies ET = 0.80 and 3.5 kJ mol(-1). H(2S1/2) atoms were detected by time-of-flight mass spectrometry with sequential excitation to the 2PJ(o) state using a laser beam tuned at the Lyman-alpha transition around 121.567 nm and ionisation by a second laser beam at 364.7 nm. Doppler-Fizeau spectra of the H atoms were recorded with the Lyman-alpha laser beam parallel to the relative velocity vector of the reagents. These spectra could be fitted using a forward convolution process including two contributions. The recoil energy distribution functions of both contributions were taken as statistical, with total energies corresponding to a reaction exoergicity deltaH0(o) = -11 kJ mol(-1) for the major one, assigned to the c-C3H + H path, and -1.5 kJ mol(-1) for the minor one, assigned to the l-C3H + H path. The angular distribution was taken as also statistical (uniform) for the minor contribution but somewhat backward peaked for the major one. Differential cross sections have been obtained for the three energetically allowed and competitive C(3PJ) + C2H2(X1sigmag+) --> l/c-C3H + H(2S1/2) and C(3PJ) + C2H2(X1sigmag+) --> C3(X1sigmag+) + H2(X1sigmag+) reaction channels in experiments conducted with supersonic continuous beams under 45 degrees crossing angle configuration using "soft" electron-ionisation mass spectrometry time-of-flight detection at ET = 3.5 and 18.5 kJ mol(-1). From measurements of angular and time-of-flight distributions at the mass-to-charge ratios m/z = 37 and 36, product angular and translational energy distributions have been determined in the centre-of-mass system for both linear- and cyclic-C3H isomer formation as well as for C3 production. The variations of the dynamics and product branching ratios with collision energy have been characterized. The ratios c-C3H/l-C3H and C3/C3H from the C(3P) reactions have been both found to decrease with increasing ET. Formation of C3(X1sigmag+) from the C(3P) reaction has been rationalized in terms of intersystem crossing between triplet and singlet C3H2 potential energy surfaces. There is good agreement between the results at ET = 3.5 kJ mol(-1) obtained with the two different crossed molecular beam techniques for the C(3PJ) + C2H2(X1sigmag+) --> l/c-C3H + H(2S1/2) channels. An estimate of the exoergicity of the C(3PJ) + C2H2(X1sigmag+) --> c-C3H + H (2S1/2) pathway from the extent of the translational energy release corroborates the value of deltaH0(o) = -11 kJ mol(-1) obtained from the Doppler-Fizeau measurements. The overall results have been discussed in the light of the available theoretical information on the relevant triplet and singlet C3H2 potential energy surfaces, and compared with the results of previous related kinetic and dynamic work as well as of theoretical calculations of the reaction dynamics.
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Affiliation(s)
- Michel Costes
- Laboratoire de Physico-Chimie Moléculaire, Université Bordeaux 1, 351, Cours de la Liberation, France
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