1
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Abma G, Parkes MA, Razmus WO, Zhang Y, Wyatt AS, Springate E, Chapman RT, Horke DA, Minns RS. Direct Observation of a Roaming Intermediate and Its Dynamics. J Am Chem Soc 2024; 146:12595-12600. [PMID: 38682306 PMCID: PMC11082896 DOI: 10.1021/jacs.4c01543] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2024] [Revised: 04/11/2024] [Accepted: 04/12/2024] [Indexed: 05/01/2024]
Abstract
Chemical reactions are often characterized by their transition state, which defines the critical geometry the molecule must pass through to move from reactants to products. Roaming provides an alternative picture, where in a dissociation reaction, the bond breaking is frustrated and a loosely bound intermediate is formed. Following bond breaking, the two partners are seen to roam around each other at distances of several Ångstroms, forming a loosely bound, and structurally ill-defined, intermediate that can subsequently lead to reactive or unreactive collisions. Here, we present a direct and time-resolved experimental measurement of roaming. By measuring the photoelectron spectrum of UV-excited acetaldehyde with a femtosecond extreme ultraviolet pulse, we captured spectral signatures of all of the key reactive structures, including that of the roaming intermediate. This provided a direct experimental measurement of the roaming process and allowed us to identify the time scales by which the roaming intermediate is formed and removed and the electronic potential surfaces upon which roaming proceeds.
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Affiliation(s)
- Grite
L. Abma
- Institute
for Molecules and Materials, Radboud University, Heijendaalseweg 135, Nijmegen 6525 AJ, The Netherlands
| | - Michael A. Parkes
- Department
of Chemistry, University College London, 20 Gordon Street, London WC1H 0AJ, U.K.
| | - Weronika O. Razmus
- School
of Chemistry, University of Southampton, Highfield, Southampton SO17 1BJ, U.K.
| | - Yu Zhang
- Central
Laser Facility, STFC Rutherford Appleton
Laboratory, Didcot, Oxfordshire OX11 0QX, U.K.
| | - Adam S. Wyatt
- Central
Laser Facility, STFC Rutherford Appleton
Laboratory, Didcot, Oxfordshire OX11 0QX, U.K.
| | - Emma Springate
- Central
Laser Facility, STFC Rutherford Appleton
Laboratory, Didcot, Oxfordshire OX11 0QX, U.K.
| | - Richard T. Chapman
- Central
Laser Facility, STFC Rutherford Appleton
Laboratory, Didcot, Oxfordshire OX11 0QX, U.K.
| | - Daniel A. Horke
- Institute
for Molecules and Materials, Radboud University, Heijendaalseweg 135, Nijmegen 6525 AJ, The Netherlands
| | - Russell S. Minns
- School
of Chemistry, University of Southampton, Highfield, Southampton SO17 1BJ, U.K.
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2
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Li Z, Fu YL, Luo Z, Yang S, Wu Y, Wu H, Wu G, Zhang W, Fu B, Yuan K, Zhang D, Yang X. Roaming in highly excited states: The central atom elimination of triatomic molecule decomposition. Science 2024; 383:746-750. [PMID: 38359138 DOI: 10.1126/science.adn3357] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2023] [Accepted: 01/18/2024] [Indexed: 02/17/2024]
Abstract
Chemical reactions are generally assumed to proceed from reactants to products along the minimum energy path (MEP). However, straying from the MEP-roaming-has been recognized as an unconventional reaction mechanism and found to occur in both the ground and first excited states. Its existence in highly excited states is however not yet established. We report a dissociation channel to produce electronically excited fragments, S(1D)+O2(a1Δg), from SO2 photodissociation in highly excited states. The results revealed two dissociation pathways: One proceeds through the MEP to produce vibrationally colder O2(a1Δg) and the other yields vibrationally hotter O2(a1Δg) by means of a roaming pathway involving an intramolecular O abstraction during reorientation motion. Such roaming dynamics may well be the rule rather than the exception for molecular photodissociation through highly excited states.
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Affiliation(s)
- Zhenxing Li
- State Key Laboratory of Molecular Reaction Dynamics and Dalian Coherent Light Source, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, 457 Zhongshan Road, Dalian 116023, P. R. China
| | - Yan-Lin Fu
- State Key Laboratory of Molecular Reaction Dynamics and Dalian Coherent Light Source, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, 457 Zhongshan Road, Dalian 116023, P. R. China
| | - Zijie Luo
- State Key Laboratory of Molecular Reaction Dynamics and Dalian Coherent Light Source, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, 457 Zhongshan Road, Dalian 116023, P. R. China
- Marine Engineering College, Dalian Maritime University, Liaoning 116026, P. R. China
| | - Shuaikang Yang
- State Key Laboratory of Molecular Reaction Dynamics and Dalian Coherent Light Source, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, 457 Zhongshan Road, Dalian 116023, P. R. China
| | - Yucheng Wu
- State Key Laboratory of Molecular Reaction Dynamics and Dalian Coherent Light Source, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, 457 Zhongshan Road, Dalian 116023, P. R. China
- University of Chinese Academy of Sciences, Beijing 100049, P. R. China
| | - Hao Wu
- State Key Laboratory of Molecular Reaction Dynamics and Dalian Coherent Light Source, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, 457 Zhongshan Road, Dalian 116023, P. R. China
- University of Chinese Academy of Sciences, Beijing 100049, P. R. China
| | - Guorong Wu
- State Key Laboratory of Molecular Reaction Dynamics and Dalian Coherent Light Source, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, 457 Zhongshan Road, Dalian 116023, P. R. China
| | - Weiqing Zhang
- State Key Laboratory of Molecular Reaction Dynamics and Dalian Coherent Light Source, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, 457 Zhongshan Road, Dalian 116023, P. R. China
| | - Bina Fu
- State Key Laboratory of Molecular Reaction Dynamics and Dalian Coherent Light Source, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, 457 Zhongshan Road, Dalian 116023, P. R. China
- University of Chinese Academy of Sciences, Beijing 100049, P. R. China
- Hefei National Laboratory, Hefei 230088, P. R. China
| | - Kaijun Yuan
- State Key Laboratory of Molecular Reaction Dynamics and Dalian Coherent Light Source, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, 457 Zhongshan Road, Dalian 116023, P. R. China
- University of Chinese Academy of Sciences, Beijing 100049, P. R. China
- Hefei National Laboratory, Hefei 230088, P. R. China
| | - Donghui Zhang
- State Key Laboratory of Molecular Reaction Dynamics and Dalian Coherent Light Source, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, 457 Zhongshan Road, Dalian 116023, P. R. China
- University of Chinese Academy of Sciences, Beijing 100049, P. R. China
- Hefei National Laboratory, Hefei 230088, P. R. China
| | - Xueming Yang
- State Key Laboratory of Molecular Reaction Dynamics and Dalian Coherent Light Source, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, 457 Zhongshan Road, Dalian 116023, P. R. China
- Department of Chemistry and Center for Advanced Light Source Research, College of Science, Southern University of Science and Technology, Shenzhen 518055, P. R. China
- Hefei National Laboratory, Hefei 230088, P. R. China
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3
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Severt T, Weckwerth E, Kaderiya B, Feizollah P, Jochim B, Borne K, Ziaee F, P KR, Carnes KD, Dantus M, Rolles D, Rudenko A, Wells E, Ben-Itzhak I. Initial-site characterization of hydrogen migration following strong-field double-ionization of ethanol. Nat Commun 2024; 15:74. [PMID: 38168047 PMCID: PMC10761976 DOI: 10.1038/s41467-023-44311-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2023] [Accepted: 12/05/2023] [Indexed: 01/05/2024] Open
Abstract
An essential problem in photochemistry is understanding the coupling of electronic and nuclear dynamics in molecules, which manifests in processes such as hydrogen migration. Measurements of hydrogen migration in molecules that have more than two equivalent hydrogen sites, however, produce data that is difficult to compare with calculations because the initial hydrogen site is unknown. We demonstrate that coincidence ion-imaging measurements of a few deuterium-tagged isotopologues of ethanol can determine the contribution of each initial-site composition to hydrogen-rich fragments following strong-field double ionization. These site-specific probabilities produce benchmarks for calculations and answer outstanding questions about photofragmentation of ethanol dications; e.g., establishing that the central two hydrogen atoms are 15 times more likely to abstract the hydroxyl proton than a methyl-group proton to form H[Formula: see text] and that hydrogen scrambling, involving the exchange of hydrogen between different sites, is important in H2O+ formation. The technique extends to dynamic variables and could, in principle, be applied to larger non-cyclic hydrocarbons.
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Affiliation(s)
- Travis Severt
- J. R. Macdonald Laboratory, Physics Department, Kansas State University, Manhattan, KS, 66506, USA
| | - Eleanor Weckwerth
- Department of Physics, Augustana University, Sioux Falls, SD, 57108, USA
| | - Balram Kaderiya
- J. R. Macdonald Laboratory, Physics Department, Kansas State University, Manhattan, KS, 66506, USA
| | - Peyman Feizollah
- J. R. Macdonald Laboratory, Physics Department, Kansas State University, Manhattan, KS, 66506, USA
| | - Bethany Jochim
- J. R. Macdonald Laboratory, Physics Department, Kansas State University, Manhattan, KS, 66506, USA
| | - Kurtis Borne
- J. R. Macdonald Laboratory, Physics Department, Kansas State University, Manhattan, KS, 66506, USA
| | - Farzaneh Ziaee
- J. R. Macdonald Laboratory, Physics Department, Kansas State University, Manhattan, KS, 66506, USA
| | - Kanaka Raju P
- J. R. Macdonald Laboratory, Physics Department, Kansas State University, Manhattan, KS, 66506, USA
- School of Quantum Technology, DIAT (DU), Pune, Maharashtra, 411025, India
| | - Kevin D Carnes
- J. R. Macdonald Laboratory, Physics Department, Kansas State University, Manhattan, KS, 66506, USA
| | - Marcos Dantus
- Department of Chemistry, Michigan State University, East Lansing, MI, 48824, USA
| | - Daniel Rolles
- J. R. Macdonald Laboratory, Physics Department, Kansas State University, Manhattan, KS, 66506, USA
| | - Artem Rudenko
- J. R. Macdonald Laboratory, Physics Department, Kansas State University, Manhattan, KS, 66506, USA
| | - Eric Wells
- Department of Physics, Augustana University, Sioux Falls, SD, 57108, USA.
| | - Itzik Ben-Itzhak
- J. R. Macdonald Laboratory, Physics Department, Kansas State University, Manhattan, KS, 66506, USA.
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4
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Wu H, Fu Y, Fu B, Zhang DH. Roaming Dynamics in Hydroxymethyl Hydroperoxide Decomposition Revealed by the Full-Dimensional Potential Energy Surface of the CH 2OO + H 2O Reaction. J Phys Chem A 2023; 127:9098-9105. [PMID: 37870501 DOI: 10.1021/acs.jpca.3c05818] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2023]
Abstract
The CH2OO + H2O reaction is an important atmospheric process that leads to the formation of formic acid (HCOOH) and water via the intermediate hydroxymethyl hydroperoxide (HOCH2OOH, HMHP). We investigated the intricacies of this process by employing quasiclassical trajectory calculations on an accurate, full-dimensional ab initio potential energy surface (PES). In addition to the direct mechanism via the transition state (TS), an interesting roaming mechanism was found to play the predominant role in producing H2O and HCOOH. This roaming pathway is featured as the near direct dissociation of HMHP into OH and hydroxymethoxy radical, followed by the retraction of OH and abstraction of the H atom, culminating in the formation of H2O. Due to the longer interaction time of the roaming mechanism, less product translational energy was released, but more internal energies of HCOOH were obtained, as compared with the direct TS mechanism. The enhanced yield of H2O and formic acid achieved through roaming dynamics underscores the significance of dynamics simulations based on an accurate full-dimensional PES. This work provides new insights into the dynamics of the CH2OO + H2O reaction and its implications for atmospheric chemistry.
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Affiliation(s)
- Hao Wu
- State Key Laboratory of Molecular Reaction Dynamics and Center for Theoretical and Computational Chemistry, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian 116023, China
- University of Chinese Academy of Sciences, Beijing 100049, China
| | - Yanlin Fu
- State Key Laboratory of Molecular Reaction Dynamics and Center for Theoretical and Computational Chemistry, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian 116023, China
| | - Bina Fu
- State Key Laboratory of Molecular Reaction Dynamics and Center for Theoretical and Computational Chemistry, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian 116023, China
- University of Chinese Academy of Sciences, Beijing 100049, China
| | - Dong H Zhang
- State Key Laboratory of Molecular Reaction Dynamics and Center for Theoretical and Computational Chemistry, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian 116023, China
- University of Chinese Academy of Sciences, Beijing 100049, China
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5
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Liu R, Zhang Z, Yan L, Yang X, Zhu Y, Su P, Song H, Wang Z. The Influence of Hydrogen Bonds on the Roaming Reaction. J Phys Chem Lett 2023; 14:9351-9356. [PMID: 37820388 DOI: 10.1021/acs.jpclett.3c02133] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/13/2023]
Abstract
Roaming bypasses the conventional transition state and is a significant reaction pathway due to the unusual energy distributions of its products; however, its reaction pathway under external environmental interactions remains unclear. Herein, we report for the first time the roaming process of nitrobenzene, which is influenced by the hydrogen bonds (H-bonds) between nitro- and phenyl radicals and water molecules in the gas phase. Notably, despite the fact that the single water structure produces a higher but narrower barrier, whereas the double water structure leads to a lower but wider barrier, the roaming reaction still occurs. The underlying mechanism responsible for these influences of H-bonds is ascribed to the dramatically changed polarization and correlation interactions between the roaming radicals. The reaction rates and thermal perturbation probabilities are also remarkably influenced due to the presence of the H-bonds, by approximately 2 orders of magnitude. It is anticipated that this work will encourage the promising feasibility of introducing environmental molecules to modulate the roaming reaction.
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Affiliation(s)
- Rui Liu
- Key Laboratory of Material Simulation Methods & Software of Ministry of Education, College of Physics, Jilin University, Changchun 130012, China
| | - Zhiyuan Zhang
- Institute of Atomic and Molecular Physics, Jilin University, Changchun 130012, China
- Institute of Fundamental and Frontier Sciences, University of Electronic Science and Technology of China, Chengdu 610054, China
| | - Longxiang Yan
- The State Key Laboratory of Physical Chemistry of Solid Surfaces, Fujian Provincial Key Laboratory of Theoretical and Computational Chemistry, and College of Chemistry and Chemical Engineering, Xiamen University, Xiamen 361005, China
| | - Xinrui Yang
- Institute of Atomic and Molecular Physics, Jilin University, Changchun 130012, China
| | - Yu Zhu
- Institute of Atomic and Molecular Physics, Jilin University, Changchun 130012, China
- College of Physics and Electronic Engineering, Hainan Normal University, Haikou 571158, China
| | - Peifeng Su
- The State Key Laboratory of Physical Chemistry of Solid Surfaces, Fujian Provincial Key Laboratory of Theoretical and Computational Chemistry, and College of Chemistry and Chemical Engineering, Xiamen University, Xiamen 361005, China
| | - Huajie Song
- Beijing Institute of Applied Physics and Computational Mathematics, Beijing 100094, China
| | - Zhigang Wang
- Key Laboratory of Material Simulation Methods & Software of Ministry of Education, College of Physics, Jilin University, Changchun 130012, China
- Institute of Atomic and Molecular Physics, Jilin University, Changchun 130012, China
- Institute of Theoretical Chemistry, College of Chemistry, Jilin University, Changchun 130023, China
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6
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Alcolado CI, Garcia-Rio L, Mejuto JC, Moreno I, Poblete FJ, Tejeda J. Oxidation of Aldehydes Used as Food Additives by Peroxynitrite. Antioxidants (Basel) 2023; 12:antiox12030743. [PMID: 36978991 DOI: 10.3390/antiox12030743] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2023] [Revised: 03/13/2023] [Accepted: 03/14/2023] [Indexed: 03/30/2023] Open
Abstract
Benzaldehyde and its derivatives are used as food supplements. These substances can be used mainly as flavorings or as antioxidants. Besides, peroxynitrite, an oxidizing agent, could be formed in canned food. Both species could react between them. The present article has focused on the kinetic study of the oxidation of aldehydes by peroxynitrite. A reaction mechanism that justifies all the experimental results is proposed. This mechanism, in acidic media, passes through three competitive pathways: (a) a radical attack that produces benzoic acid. (b) peracid oxidation, and (c) a nucleophilic attack of peroxynitrous acid over aldehyde to form an intermediate, X, that produces benzoic acid, or, through a Cannizzaro-type reaction, benzoic acid and benzyl alcohol. All rate constants involved in the third pathway (c) have been calculated. These results have never been described in the literature in acid media. A pH effect was analyzed.
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Affiliation(s)
- Clara I Alcolado
- Department of Physical Chemistry, Faculty of Chemistry, University of Castilla-La Mancha, Avda. Camilo José Cela s/n, 13071 Ciudad Real, Spain
| | - Luis Garcia-Rio
- Department of Physical Chemistry, Faculty of Chemistry, University of Santiago, Avda. Das Ciencias s/n, 15701 Santiago de Compostela, Spain
| | - Juan C Mejuto
- Department of Physical Chemistry, Faculty of Science, University of Vigo, Campus de As Lagoas, 32004 Ourense, Spain
| | - Inmaculada Moreno
- Department of Physical Chemistry, Faculty of Chemistry, University of Castilla-La Mancha, Avda. Camilo José Cela s/n, 13071 Ciudad Real, Spain
| | - Francisco J Poblete
- Department of Physical Chemistry, Faculty of Chemistry, University of Castilla-La Mancha, Avda. Camilo José Cela s/n, 13071 Ciudad Real, Spain
| | - Juan Tejeda
- Department of Physical Chemistry, Faculty of Chemistry, University of Castilla-La Mancha, Avda. Camilo José Cela s/n, 13071 Ciudad Real, Spain
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7
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Shuber NJ, Tabor DP, North SW. Theoretical Investigation of the Ground State Dissociation Pathways of CH2NO2. Chem Phys 2023. [DOI: 10.1016/j.chemphys.2023.111823] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
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8
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Peng T, Bai Y, Qi J, Fu YL, Han YC. Comparison of the supercollisions of the deuterium atom with acetylene and ethylene. Chem Phys 2022. [DOI: 10.1016/j.chemphys.2022.111610] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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9
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Kasai T, Muthiah B, Po X, Yan C, Lin K, Tanudji J, Diño WA. Pattern analysis of the impact‐parameter dependent trajectories for the H +
H
2
exchange reaction at
T
=
3
and
300 K
: A characteristic propensity for reactive versus nonreactive trajectories found in the time‐dependent interaction potential and a roaming‐like libration motion at cold temperature. J CHIN CHEM SOC-TAIP 2022. [DOI: 10.1002/jccs.202100539] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Affiliation(s)
- Toshio Kasai
- Department of Chemistry National Taiwan University Taipei Taiwan
- Department of Applied Physics Osaka University Suita Japan
| | | | - Xin‐Hui Po
- Department of Chemistry National Taiwan University Taipei Taiwan
- Department of Statistics National Chengchi University Taipei Taiwan
| | - Chu‐Chun Yan
- Department of Chemistry National Taiwan University Taipei Taiwan
| | - King‐Chuen Lin
- Department of Chemistry National Taiwan University Taipei Taiwan
- Department of Chemistry, Institute of Atomic and Molecular Sciences Academia Sinica Taipei Taiwan
| | | | - Wilson Agerico Diño
- Department of Applied Physics Osaka University Suita Japan
- Center for Atomic and Molecular Technologies Osaka University Suita Japan
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10
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Roaming dynamics of the H+C 2D 2 reaction on a fundamental-invariant neural network potential energy surface. CHINESE J CHEM PHYS 2022. [DOI: 10.1063/1674-0068/cjcp2111249] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022]
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11
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Mishra D, Reino-González J, Obaid R, LaForge AC, Díaz-Tendero S, Martín F, Berrah N. Ultrafast molecular dynamics in ionized 1- and 2-propanol: from simple fragmentation to complex isomerization and roaming mechanisms. Phys Chem Chem Phys 2021; 24:433-443. [PMID: 34897321 DOI: 10.1039/d1cp04011a] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Upon photoexcitation, molecules can undergo numerous complex processes, such as isomerization and roaming, leading to changes in the molecular and electronic structure. Here, we report on the time-resolved ultrafast nuclear dynamics, initiated by laser ionization, in the two structural isomers, 1- and 2-propanol, using a combination of pump-probe spectroscopy and coincident Coulomb explosion imaging. Our measurements, paired with quantum chemistry calculations, identify the mechanisms for the observed two- and three-body dissociation channels for both isomers. In particular, the fragmentation channel of 2-propanol associated with the loss of CH3 shows possible evidence of methyl roaming. Moreover, the electronic structure of this roaming methyl fragment could be responsible for the enhanced ionization also observed for this channel. Finally, comparison with similar studies done on ethanol and acetonitrile helps establish a correlation between the length of the alkyl chain and the likelihood of hydrogen migration.
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Affiliation(s)
- Debadarshini Mishra
- Department of Physics, University of Connecticut, Storrs, Connecticut, 06269, USA.
| | - Juan Reino-González
- Departamento de Química, Universidad Autónoma de Madrid, Módulo 13, 28049 Madrid, EU, Spain
| | - Razib Obaid
- Department of Physics, University of Connecticut, Storrs, Connecticut, 06269, USA.
| | - Aaron C LaForge
- Department of Physics, University of Connecticut, Storrs, Connecticut, 06269, USA.
| | - Sergio Díaz-Tendero
- Departamento de Química, Universidad Autónoma de Madrid, Módulo 13, 28049 Madrid, EU, Spain.,Condensed Matter Physics Center (IFIMAC), Universidad Autónoma de Madrid, 28049 Madrid, EU, Spain.,Institute for Advanced Research in Chemical Sciences(IAdChem), Universidad Autónoma de Madrid, 28049 Madrid, EU, Spain
| | - Fernando Martín
- Departamento de Química, Universidad Autónoma de Madrid, Módulo 13, 28049 Madrid, EU, Spain.,Condensed Matter Physics Center (IFIMAC), Universidad Autónoma de Madrid, 28049 Madrid, EU, Spain.,Instituto Madrileño de Estudios Avanzados en Nanociencia (IMDEA-Nano), Campus de Cantoblanco, 28049 Madrid, EU, Spain.,Donostia International Physics Center (DIPC), Paseo Manuel de Lardizabal 4, 20018 Donostia-San Sebastián, EU, Spain
| | - Nora Berrah
- Department of Physics, University of Connecticut, Storrs, Connecticut, 06269, USA.
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12
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Filming ultrafast roaming-mediated isomerization of bismuth triiodide in solution. Nat Commun 2021; 12:4732. [PMID: 34354075 PMCID: PMC8342516 DOI: 10.1038/s41467-021-25070-z] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2021] [Accepted: 07/20/2021] [Indexed: 12/19/2022] Open
Abstract
Roaming reaction, defined as a reaction yielding products via reorientational motion in the long-range region (3 - 8 Å) of the potential, is a relatively recently proposed reaction pathway and is now regarded as a universal mechanism that can explain the unimolecular dissociation and isomerization of various molecules. The structural movements of the partially dissociated fragments originating from the frustrated bond fission at the onset of roaming, however, have been explored mostly via theoretical simulations and rarely observed experimentally. Here, we report an investigation of the structural dynamics during a roaming-mediated isomerization reaction of bismuth triiodide (BiI3) in acetonitrile solution using femtosecond time-resolved x-ray liquidography. Structural analysis of the data visualizes the atomic movements during the roaming-mediated isomerization process including the opening of the Bi-Ib-Ic angle and the closing of Ia-Bi-Ib-Ic dihedral angle, each by ~40°, as well as the shortening of the Ib···Ic distance, following the frustrated bond fission.
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13
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Analysis of the roaming trajectories from the dynamic and kinematic perspectives – A representative study of triatomic systems. Chem Phys Lett 2021. [DOI: 10.1016/j.cplett.2021.138599] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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14
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Yang CH, Bhattacharyya S, Liu K. Time-Resolved Pair-Correlated Imaging of the Photodissociation of Acetaldehyde at 267 nm: Pathway Partitioning. J Phys Chem A 2021; 125:6450-6460. [PMID: 34286579 DOI: 10.1021/acs.jpca.1c04773] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Photodissociation of acetaldehyde (CH3CHO) by UV excitation involves interwoven multiple reaction pathways, including nonradiative decay, isomerization, transition-state pathway, roaming, and other dissociation mechanisms. Recently, we employed picosecond time-resolved, pair-correlated product imaging in a study of acetaldehyde photodissociation at 267 nm to disentangle those competing mechanisms and to elucidate the possible roaming pathways (Yang, C. H.; Chem. Sci. 2020, 11, 6423-6430). Here, we complement the pair-correlated product speed distribution of CO(v = 0) at the high-j side of the CO rotational state distribution in the CO + CH4 channel and detail the two-dimensional data analysis of the time-resolved images. As a result, extensive comparisons with other studies can be made and the branching fractions of the previously assigned TScc(S0), non-TScc(S0), and CI(S1/S0) pathways for the CO(v = 0) + CH4 molecular channel are evaluated to be 0.74 ± 0.08, 0.15 ± 0.02, and 0.11 ± 0.02, respectively. Together with the macroscopic branching ratio between the molecular (CO + CH4) and radical (CH3 + HCO) channels at 267 nm from the literature, a global view of the microscopic pathways can then be delineated, which provides invaluable insights and should pave the way for further studies of this interesting system.
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Affiliation(s)
- Chung-Hsin Yang
- International PhD Program for Science, National Sun Yat-sen University, Kaohsiung 80424, Taiwan.,Department of Chemistry, National Sun Yat-sen University, Kaohsiung 80424, Taiwan.,Aerosol Science Research Center, National Sun Yat-sen University, Kaohsiung 80424, Taiwan
| | | | - Kopin Liu
- Institute of Atomic and Molecular Sciences, Academia Sinica, Taipei 10617, Taiwan.,Aerosol Science Research Center, National Sun Yat-sen University, Kaohsiung 80424, Taiwan.,State Key Laboratory of Molecular Reaction Dynamics, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian 116023, P. R. China
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15
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Fu YL, Bai Y, Han YC, Fu B, Zhang DH. Double-Roaming Dynamics in the H + C 2H 2 → H 2 + C 2H Reaction: Acetylene-Facilitated Roaming and Vinylidene-Facilitated Roaming. J Phys Chem Lett 2021; 12:4211-4217. [PMID: 33900762 DOI: 10.1021/acs.jpclett.1c01045] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
We report two novel roaming pathways for the H + C2H2 → H2 + C2H reaction by performing extensive quasiclassical trajectory calculations on a new, global, high-level machine learning-based potential energy surface. One corresponds to the acetylene-facilitated roaming pathway, where the H atom turns back from the acetylene + H channel and abstracts another H atom from acetylene. The other is the vinylidene-facilitated roaming, where the H atom turns back from the vinylidene + H channel and abstracts another H from vinylidene. The "double-roaming" pathways account for roughly 95% of the total cross section of the H2 + C2H products at the collision energy of 70 kcal/mol. These computational results give valuable insights into the significance of the two isomers (acetylene and vinylidene) in chemical reaction dynamics and also the experimental search for roaming dynamics in this bimolecular reaction.
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Affiliation(s)
- Yan-Lin Fu
- School of Physics, Dalian University of Technology, Dalian, China116024
- State Key Laboratory of Molecular Reaction Dynamics and Center for Theoretical and Computational Chemistry, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian, China 116023
| | - Yuyao Bai
- School of Physics, Dalian University of Technology, Dalian, China116024
- State Key Laboratory of Molecular Reaction Dynamics and Center for Theoretical and Computational Chemistry, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian, China 116023
| | - Yong-Chang Han
- School of Physics, Dalian University of Technology, Dalian, China116024
| | - Bina Fu
- State Key Laboratory of Molecular Reaction Dynamics and Center for Theoretical and Computational Chemistry, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian, China 116023
| | - Dong H Zhang
- State Key Laboratory of Molecular Reaction Dynamics and Center for Theoretical and Computational Chemistry, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian, China 116023
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16
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Lin K, Tso C, Kasai T. Beyond the rule of transition state: Identification of roaming routes in some cases of carbonyl compounds. J CHIN CHEM SOC-TAIP 2021. [DOI: 10.1002/jccs.202100039] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Affiliation(s)
- King‐Chuen Lin
- Department of Chemistry National Taiwan University Taipei Taiwan
- Institute of Atomic and Molecular Sciences Academia Sinica Taipei Taiwan
| | - Cheng‐Jui Tso
- Department of Chemistry National Taiwan University Taipei Taiwan
| | - Toshio Kasai
- Department of Chemistry National Taiwan University Taipei Taiwan
- Institute of Scientific and Industrial Research Osaka University Osaka Japan
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17
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Palazzetti F, Tsai PY. Photodissociation Dynamics of CO-Forming Channels on the Ground-State Surface of Methyl Formate at 248 nm: Direct Dynamics Study and Assessment of Generalized Multicenter Impulsive Models. J Phys Chem A 2021; 125:1198-1220. [PMID: 33507759 DOI: 10.1021/acs.jpca.0c10464] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
The photodissociation dynamics of methyl formate in the electronic ground state S0, initiated by a 248 nm-wavelength laser, is studied by direct dynamics simulations. We analyze five channels, where four of them have as products CH3OH + CO, one leading to the formation of three fragments, H2CO + H2 + CO, and a channel characterized by a roaming transition state. The analysis of energy distribution among the degrees of freedom of the product and the comparison with experimental results previously published by other groups provide the ingredients to distinguish the examined dissociation pathways. The interpretation of the results proves that the characterization of dissociation mechanisms must rely on a dynamics approach involving multiple electronic states, including considerations on the features of the S1/S0 conical intersection. Here, we also assess the generalized multicenter impulsive model, GMCIM, that has been designed for dissociation processes with exit barriers, and the energy distribution in the products is predicted on the basis of information from the saddle points and the intrinsic reaction coordinates. Main features, advantages, limits, and future perspectives of the method are reported and discussed.
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Affiliation(s)
- Federico Palazzetti
- Dipartimento di Chimica, Biologia e Biotecnologie, Università degli Studi di Perugia, Perugia 06123, Italy
| | - Po-Yu Tsai
- Department of Chemistry, National Chung Hsing University, Taichung 402, Taiwan
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18
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Li C, Chin CH, Zhu T, Hui Zhang JZ. An ab initio/RRKM study of the reaction mechanism and product branching ratios of CH3OH+ and CH3OH++ dissociation. J Mol Struct 2020. [DOI: 10.1016/j.molstruc.2020.128410] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
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19
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Quinn MS, Nauta K, Jordan MJT, Bowman JM, Houston PL, Kable SH. Rotational resonances in the H
2
CO roaming reaction are revealed by detailed correlations. Science 2020; 369:1592-1596. [DOI: 10.1126/science.abc4088] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2020] [Accepted: 07/19/2020] [Indexed: 11/03/2022]
Affiliation(s)
- Mitchell S. Quinn
- School of Chemistry, University of New South Wales, Kensington, NSW, 2052, Australia
| | - Klaas Nauta
- School of Chemistry, University of New South Wales, Kensington, NSW, 2052, Australia
| | | | - Joel M. Bowman
- Department of Chemistry, Emory University, Atlanta, GA, USA
| | - Paul L. Houston
- Department of Chemistry and Biochemistry, Cornell University, Ithaca, NY, USA
| | - Scott H. Kable
- School of Chemistry, University of New South Wales, Kensington, NSW, 2052, Australia
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20
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Pandey A, Poirier B. Plumbing Potentials for Molecules with Up To Tens of Atoms: How to Find Saddle Points and Fix Leaky Holes. J Phys Chem Lett 2020; 11:6468-6474. [PMID: 32687368 DOI: 10.1021/acs.jpclett.0c01435] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Potential energy surfaces (PESs) play an indispensable role in molecular dynamics but are notoriously difficult to flesh out properly in large-dimensional spaces. In particular, the undetected presence of PES holes, i.e., unphysical saddle points beyond which the potential energy drops arbitrarily, can have devastating effects on both classical and quantum dynamics calculations. In this study, the Crystal algorithm is developed as a tool for efficiently and accurately finding PES holes, as well as legitimate saddle points, even in very large-dimensional configuration spaces. The approach is applied to three large-dimensional PESs for molecular systems of current interest: uracil, naphthalene, and formic acid dimer. Low-lying PES holes are discovered and located for the first two systems-including naphthalene, for which no holes were previously suspected, to the best of our knowledge. Likewise, the double-well, double-proton-transfer isomerization saddle point for formic acid dimer is also located.
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Affiliation(s)
- Ankit Pandey
- Department of Chemistry and Biochemistry, Texas Tech University, Lubbock, Texas 79409-1061, United States
| | - Bill Poirier
- Department of Chemistry and Biochemistry, Texas Tech University, Lubbock, Texas 79409-1061, United States
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21
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Abstract
Roaming reactions were first clearly identified in photodissociation of formaldehyde 15 years ago, and roaming dynamics are now recognized as a universal aspect of chemical reactivity. These reactions typically involve frustrated near-dissociation of a quasibound system to radical fragments, followed by reorientation at long range and intramolecular abstraction. The consequences can be unexpected formation of molecular products, depletion of the radical pool in chemical systems, and formation of products with unusual internal state distributions. In this review, I examine some current aspects of roaming reactions with an emphasis on experimental results, focusing on possible quantum effects in roaming and roaming dynamics in bimolecular systems. These considerations lead to a more inclusive definition of roaming reactions as those for which key dynamics take place at long range.
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Affiliation(s)
- Arthur G. Suits
- Department of Chemistry, University of Missouri, Columbia, Missouri 65211, USA
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22
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Roaming Dynamics and Conformational Memory in Photolysis of Formic Acid at 193 nm Using Time-resolved Fourier-transform Infrared Emission Spectroscopy. Sci Rep 2020; 10:4769. [PMID: 32179782 PMCID: PMC7075954 DOI: 10.1038/s41598-020-61642-7] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2019] [Accepted: 11/28/2019] [Indexed: 11/09/2022] Open
Abstract
In photodissociation of trans-formic acid (HCOOH) at 193 nm, we have observed two molecular channels of CO + H2O and CO2 + H2 by using 1 μs-resolved Fourier-transform infrared emission spectroscopy. With the aid of spectral simulation, the CO spectra are rotationally resolved for each vibrational state (v = 1-8). Each of the resulting vibrational and rotational population distributions is characteristic of two Boltzmann profiles with different temperatures, originating from either transition state pathway or OH-roaming to form the same CO + H2O products. The H2O roaming co-product is also spectrally simulated to understand the interplay with the CO product in the internal energy partitioning. Accordingly, this work has evaluated the internal energy disposal for the CO and H2O roaming products; especially the vibrational-state dependence of the roaming signature is reported for the first time. Further, given a 1 μs resolution, the temporal dependence of the CO/CO2 product ratio at v ≥ 1 rises from 3 to 10 of study, thereby characterizing the effect of conformational memory and well reconciling with the disputed results reported previously between absorption and emission methods.
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23
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Strong inverse kinetic isotope effect observed in ammonia charge exchange reactions. Nat Commun 2020; 11:173. [PMID: 31924778 PMCID: PMC6954264 DOI: 10.1038/s41467-019-13976-8] [Citation(s) in RCA: 32] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2019] [Accepted: 12/12/2019] [Indexed: 11/09/2022] Open
Abstract
Isotopic substitution has long been used to understand the detailed mechanisms of chemical reactions; normally the substitution of hydrogen by deuterium leads to a slower reaction. Here, we report our findings on the charge transfer collisions of cold [Formula: see text] ions and two isotopologues of ammonia, [Formula: see text] and [Formula: see text]. Deuterated ammonia is found to react more than three times faster than hydrogenated ammonia. Classical capture models are unable to account for this pronounced inverse kinetic isotope effect. Moreover, detailed ab initio calculations cannot identify any (energetically accessible) crossing points between the reactant and product potential energy surfaces, indicating that electron transfer is likely to be slow. The higher reactivity of [Formula: see text] is attributed to the greater density of states (and therefore lifetime) of the deuterated reaction complex compared to the hydrogenated system. Our observations could provide valuable insight into possible mechanisms contributing to deuterium fractionation in the interstellar medium.
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24
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Fu YL, Lu X, Han YC, Fu B, Zhang DH, Bowman JM. Collision-induced and complex-mediated roaming dynamics in the H + C 2H 4 → H 2 + C 2H 3 reaction. Chem Sci 2020; 11:2148-2154. [PMID: 34123304 PMCID: PMC8150095 DOI: 10.1039/c9sc05951b] [Citation(s) in RCA: 23] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Roaming is a novel mechanism in reaction dynamics. It describes an unusual pathway, which can be quite different from the conventional minimum-energy path, leading to products. While roaming has been reported or suggested in a number of unimolecular reactions, it has been rarely reported for bimolecular reactions. Here, we report a high-level computational study of roaming dynamics in the important bimolecular combustion reaction H + C2H4 → H2 + C2H3, using a new, high-level machine learning-based potential energy surface. In addition to the complex-mediated roaming mechanism, a non-complex forming roaming mechanism is found. It can be described as a direct inelastic collision where the departing H atom roams and then abstracts an H atom. We denoted this as “collision-induced” roaming. These two roaming mechanisms have different angular distributions; however, both produce highly internally excited C2H3. The roaming pathway leads to remarkably different dynamics as compared with the direct abstraction pathway. A clear signature of the roaming mechanism is highly internally excited C2H3, which could be observed experimentally. Collision-induced and complex-mediated roaming mechanisms are revealed for an important bimolecular reaction in combustion.![]()
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Affiliation(s)
- Yan-Lin Fu
- Department of Physics, Dalian University of Technology Dalian China 116024 .,State Key Laboratory of Molecular Reaction Dynamics, Center for Theoretical and Computational Chemistry, Dalian Institute of Chemical Physics, Chinese Academy of Sciences Dalian China 116023
| | - Xiaoxiao Lu
- State Key Laboratory of Molecular Reaction Dynamics, Center for Theoretical and Computational Chemistry, Dalian Institute of Chemical Physics, Chinese Academy of Sciences Dalian China 116023
| | - Yong-Chang Han
- Department of Physics, Dalian University of Technology Dalian China 116024
| | - Bina Fu
- State Key Laboratory of Molecular Reaction Dynamics, Center for Theoretical and Computational Chemistry, Dalian Institute of Chemical Physics, Chinese Academy of Sciences Dalian China 116023
| | - Dong H Zhang
- State Key Laboratory of Molecular Reaction Dynamics, Center for Theoretical and Computational Chemistry, Dalian Institute of Chemical Physics, Chinese Academy of Sciences Dalian China 116023
| | - Joel M Bowman
- Department of Chemistry, Cherry L. Emerson Center for Scientific Computation, Emory University Atlanta Georgia 30322 USA
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25
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Giussani A, Worth GA. How important is roaming in the photodegradation of nitrobenzene? Phys Chem Chem Phys 2020; 22:15945-15952. [DOI: 10.1039/d0cp02077j] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Three pathways have been found for the formation of NO from nitrobenzene photodegradation that lead to either low or high translational energy, with a roaming mechanism involved at high excitation energies.
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Affiliation(s)
- Angelo Giussani
- Department of Chemistry
- University College London
- London WC1H 0AJ
- UK
| | - Graham A. Worth
- Department of Chemistry
- University College London
- London WC1H 0AJ
- UK
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26
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Gunthardt CE, Aardema MN, Hall GE, North SW. Evidence for lambda doublet propensity in the UV photodissociation of ozone. J Chem Phys 2019; 151:224302. [PMID: 31837678 DOI: 10.1063/1.5131504] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
The photodissociation of O3 at 266 nm has been studied using velocity mapped ion imaging. We report temperature-dependent vector correlations for the O2(a1Δg, v = 0, j = 18-20) fragments at molecular beam temperatures of 70 K, 115 K, and 170 K. Both the fragment spatial anisotropy and the v-j correlations are found to be increasingly depolarized with increasing beam temperature. At all temperatures, the v-j correlations for the j = 19 state were shown to be reduced compared to those of j = 18 and 20, while no such odd/even rotational state difference was observed for the spatial anisotropy, consistent with previous measurements. We find that temperature-dependent differences in the populations and v-j correlations between the odd and even rotational states can be explained by a Λ-doublet propensity model. Although symmetry conservation should lead to formation of only the A' Λ-doublet component, and only even rotational states, out-of-plane rotation of the parent molecule breaks the planar symmetry and permits the formation of the A″ Λ-doublet component and odd rotational states. A simple classical model to treat the effect of parent rotation on the v-j correlation and the odd/even rotational population alternation reproduces both the current measurements and previously reported rotational distributions, suggesting that the "odd" behavior originates from a Λ-doublet propensity, and not from a mass independent curve crossing effect, as previously proposed.
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Affiliation(s)
- Carolyn E Gunthardt
- Department of Chemistry, Texas A&M University, College Station, Texas 77842, USA
| | - Megan N Aardema
- Department of Chemistry, Texas A&M University, College Station, Texas 77842, USA
| | - Gregory E Hall
- Chemistry Division, Brookhaven National Laboratory P.O. Box 5000 Upton, New York 11973-5000, USA
| | - Simon W North
- Department of Chemistry, Texas A&M University, College Station, Texas 77842, USA
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27
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Blackshaw KJ, Quartey NK, Korb RT, Hood DJ, Hettwer CD, Kidwell NM. Imaging the nonreactive collisional quenching dynamics of NO (A 2Σ +) radicals with O 2 (X 3Σ g -). J Chem Phys 2019; 151:104304. [PMID: 31521090 DOI: 10.1063/1.5109112] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Nitric oxide (NO) radicals are ubiquitous chemical intermediates present in the atmosphere and in combustion processes, where laser-induced fluorescence is extensively used on the NO (A2Σ+ ← X2Π) band to report on fuel-burning properties. However, accurate fluorescence quantum yields and NO concentration measurements are impeded by electronic quenching of NO (A2Σ+) to NO (X2Π) with colliding atomic and molecular species. To improve predictive combustion models and develop a molecular-level understanding of NO (A2Σ+) quenching, we report the velocity map ion images and product state distributions of NO (X2Π, v″ = 0, J″, Fn, Λ) following nonreactive collisional quenching of NO (A2Σ+) with molecular oxygen, O2 (X3Σg -). A novel dual-flow pulse valve nozzle is constructed and implemented to carry out the NO (A2Σ+) electronic quenching studies and to limit NO2 formation. The isotropic ion images reveal that the NO-O2 system evolves through a long-lived NO3 collision complex prior to formation of products. Furthermore, the corresponding total kinetic energy release distributions support that O2 collision coproducts are formed primarily in the c1Σu - electronic state with NO (X2Π, v″ = 0, J″, Fn, Λ). The product state distributions also indicate that NO (X2Π) is generated with a propensity to occupy the Π(A″) Λ-doublet state, which is consistent with the NO π* orbital aligned perpendicular to nuclear rotation. The deviations between experimental results and statistical phase space theory simulations illustrate the key role that the conical intersection plays in the quenching dynamics to funnel population to product rovibronic levels.
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Affiliation(s)
- K Jacob Blackshaw
- Department of Chemistry, The College of William and Mary, Williamsburg, Virginia 23187-8795, USA
| | - Naa-Kwarley Quartey
- Department of Chemistry, The College of William and Mary, Williamsburg, Virginia 23187-8795, USA
| | - Robert T Korb
- Department of Chemistry, The College of William and Mary, Williamsburg, Virginia 23187-8795, USA
| | - David J Hood
- Department of Chemistry, The College of William and Mary, Williamsburg, Virginia 23187-8795, USA
| | - Christian D Hettwer
- Department of Chemistry, The College of William and Mary, Williamsburg, Virginia 23187-8795, USA
| | - Nathanael M Kidwell
- Department of Chemistry, The College of William and Mary, Williamsburg, Virginia 23187-8795, USA
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28
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Chen W, Zhang L, Yuan D, Chang Y, Yu S, Wang S, Wang T, Jiang B, Yuan K, Yang X, Wang X. Observation of the Carbon Elimination Channel in Vacuum Ultraviolet Photodissociation of OCS. J Phys Chem Lett 2019; 10:4783-4787. [PMID: 31378065 DOI: 10.1021/acs.jpclett.9b01811] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
The textbook mechanism for OCS photodissociation mainly involves the CO + S or CS + O product channel via a single bond fission. However, a third dissociation channel concerning the cleavage of both C-S and C-O bonds yielding SO + C products, though thermodynamically allowed, has never been verified experimentally to date. By using a tunable vacuum ultraviolet laser light and time-sliced velocity map ion imaging technique, we have clearly observed the SO(X3Σ-) + C(3PJ=0) products as the vacuum ultraviolet laser photon energy gradually exceeds its thermodynamic threshold. The corresponding SO(X3Σ-) coproducts are highly vibrationally excited and show varying angular distributions from isotropic to anisotropic as the excitation photon energy increases. Theoretical analysis suggests that a fast nonadiabatic pathway plays a dominant role in the formation of the anisotropic SO products. That isotropic products arise as the excitation photon energies approach the thermodynamic threshold can be reasonably explained by the "roaming mechanism".
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Affiliation(s)
- Wentao Chen
- Hefei National Laboratory for Physical Sciences at the Microscale and Department of Chemical Physics, University of Science and Technology of China, Hefei 230026, China
| | - Liang Zhang
- Hefei National Laboratory for Physical Sciences at the Microscale and Department of Chemical Physics, University of Science and Technology of China, Hefei 230026, China
| | - Daofu Yuan
- Hefei National Laboratory for Physical Sciences at the Microscale and Department of Chemical Physics, University of Science and Technology of China, Hefei 230026, China
| | - Yao Chang
- Hefei National Laboratory for Physical Sciences at the Microscale and Department of Chemical Physics, University of Science and Technology of China, Hefei 230026, China
- State Key Laboratory of Molecular Reaction Dynamics, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian 116023, China
| | - Shengrui Yu
- Hangzhou Institute of Advanced Studies, Zhejiang Normal University, Hangzhou 311231, China
| | - Siwen Wang
- Hefei National Laboratory for Physical Sciences at the Microscale and Department of Chemical Physics, University of Science and Technology of China, Hefei 230026, China
| | - Tao Wang
- Department of Chemistry, School of Science, Southern University of Science and Technology, Shenzhen 518055, China
| | - Bin Jiang
- Hefei National Laboratory for Physical Sciences at the Microscale and Department of Chemical Physics, University of Science and Technology of China, Hefei 230026, China
| | - Kaijun Yuan
- State Key Laboratory of Molecular Reaction Dynamics, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian 116023, China
| | - Xueming Yang
- State Key Laboratory of Molecular Reaction Dynamics, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian 116023, China
- Department of Chemistry, School of Science, Southern University of Science and Technology, Shenzhen 518055, China
| | - Xingan Wang
- Hefei National Laboratory for Physical Sciences at the Microscale and Department of Chemical Physics, University of Science and Technology of China, Hefei 230026, China
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29
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Ma Y, Liu J, Li F, Wang F, Kitsopoulos TN. Roaming Dynamics in the Photodissociation of Formic Acid at 230 nm. J Phys Chem A 2019; 123:3672-3677. [PMID: 30969120 DOI: 10.1021/acs.jpca.9b00724] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Roaming dynamics is observed in the photodissociation of formic acid (HCOOH) at 230 nm by using the slice imaging method. In combination with rotational state selective (2 + 1) resonance-enhanced multiphoton ionization of the CO fragments, the speed distributions of the CO fragments exhibit a low recoil velocity at low rotational levels of J = 9 and 20, while the velocity distributions of CO at high rotational levels of J = 30 and 48 show a relatively large recoil velocity. The experimental results indicate that the roaming of OH radical should be related with the formation of CO + H2O channel at the present photolysis energy. Unlike the roaming pathways occurring in H2CO that can be described by loose flat potential, our CO speed distribution analysis suggests the presence of a "tight" flat potential in the roaming dynamics of HCOOH molecules.
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Affiliation(s)
- Yujie Ma
- Department of Chemistry and Shanghai Key Laboratory of Molecular Catalysis and Innovative Materials, Collaborative Innovation Centre of Chemistry for Energy Materials , Fudan University , Shanghai 200433 , P. R. China
| | - Jiaxing Liu
- Department of Chemistry and Shanghai Key Laboratory of Molecular Catalysis and Innovative Materials, Collaborative Innovation Centre of Chemistry for Energy Materials , Fudan University , Shanghai 200433 , P. R. China
| | - Fangfang Li
- Department of Chemistry and Shanghai Key Laboratory of Molecular Catalysis and Innovative Materials, Collaborative Innovation Centre of Chemistry for Energy Materials , Fudan University , Shanghai 200433 , P. R. China
| | - Fengyan Wang
- Department of Chemistry and Shanghai Key Laboratory of Molecular Catalysis and Innovative Materials, Collaborative Innovation Centre of Chemistry for Energy Materials , Fudan University , Shanghai 200433 , P. R. China
| | - Theofanis N Kitsopoulos
- Department of Dynamics at Surfaces, Max Planck Institute for Biophysical Chemistry, Göttingen, Germany; Institute of Electronic Structure and Laser, FORTH, Heraklion, Greece; Department of Chemistry , University of Crete , Heraklion , Greece
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30
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Ekanayake N, Severt T, Nairat M, Weingartz NP, Farris BM, Kaderiya B, Feizollah P, Jochim B, Ziaee F, Borne K, Raju P K, Carnes KD, Rolles D, Rudenko A, Levine BG, Jackson JE, Ben-Itzhak I, Dantus M. H 2 roaming chemistry and the formation of H 3+ from organic molecules in strong laser fields. Nat Commun 2018; 9:5186. [PMID: 30518927 PMCID: PMC6281587 DOI: 10.1038/s41467-018-07577-0] [Citation(s) in RCA: 52] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2018] [Accepted: 11/06/2018] [Indexed: 11/11/2022] Open
Abstract
Roaming mechanisms, involving the brief generation of a neutral atom or molecule that stays in the vicinity before reacting with the remaining atoms of the precursor, are providing valuable insights into previously unexplained chemical reactions. Here, the mechanistic details and femtosecond time-resolved dynamics of H3+ formation from a series of alcohols with varying primary carbon chain lengths are obtained through a combination of strong-field laser excitation studies and ab initio molecular dynamics calculations. For small alcohols, four distinct pathways involving hydrogen migration and H2 roaming prior to H3+ formation are uncovered. Despite the increased number of hydrogens and possible combinations leading to H3+ formation, the yield decreases as the carbon chain length increases. The fundamental mechanistic findings presented here explore the formation of H3+, the most important ion in interstellar chemistry, through H2 roaming occurring in ionic species. H2 roaming is associated with H3+ formation when certain organic molecules are exposed to strong laser fields. Here, the mechanistic details and time-resolved dynamics of H3+ formation from a series of alcohols were obtained and found that the product yield decreases as the carbon chain length increases.
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Affiliation(s)
- Nagitha Ekanayake
- Department of Chemistry, Michigan State University, East Lansing, MI, 48824, USA
| | - Travis Severt
- J. R. Macdonald Laboratory, Physics Department, Kansas State University, Manhattan, KS, 66506, USA
| | - Muath Nairat
- Department of Chemistry, Michigan State University, East Lansing, MI, 48824, USA
| | - Nicholas P Weingartz
- Department of Chemistry, Michigan State University, East Lansing, MI, 48824, USA
| | - Benjamin M Farris
- Department of Chemistry, Michigan State University, East Lansing, MI, 48824, USA
| | - Balram Kaderiya
- J. R. Macdonald Laboratory, Physics Department, Kansas State University, Manhattan, KS, 66506, USA
| | - Peyman Feizollah
- J. R. Macdonald Laboratory, Physics Department, Kansas State University, Manhattan, KS, 66506, USA
| | - Bethany Jochim
- J. R. Macdonald Laboratory, Physics Department, Kansas State University, Manhattan, KS, 66506, USA
| | - Farzaneh Ziaee
- J. R. Macdonald Laboratory, Physics Department, Kansas State University, Manhattan, KS, 66506, USA
| | - Kurtis Borne
- J. R. Macdonald Laboratory, Physics Department, Kansas State University, Manhattan, KS, 66506, USA
| | - Kanaka Raju P
- J. R. Macdonald Laboratory, Physics Department, Kansas State University, Manhattan, KS, 66506, USA
| | - Kevin D Carnes
- J. R. Macdonald Laboratory, Physics Department, Kansas State University, Manhattan, KS, 66506, USA
| | - Daniel Rolles
- J. R. Macdonald Laboratory, Physics Department, Kansas State University, Manhattan, KS, 66506, USA
| | - Artem Rudenko
- J. R. Macdonald Laboratory, Physics Department, Kansas State University, Manhattan, KS, 66506, USA
| | - Benjamin G Levine
- Department of Chemistry, Michigan State University, East Lansing, MI, 48824, USA
| | - James E Jackson
- Department of Chemistry, Michigan State University, East Lansing, MI, 48824, USA
| | - Itzik Ben-Itzhak
- J. R. Macdonald Laboratory, Physics Department, Kansas State University, Manhattan, KS, 66506, USA
| | - Marcos Dantus
- Department of Chemistry, Michigan State University, East Lansing, MI, 48824, USA. .,Department of Physics and Astronomy, Michigan State University, East Lansing, MI, 48824, USA.
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31
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Nyambo S, Uhler B, Muzangwa L, Ivanov M, Welch BK, Dawes R, Reid SA. Reactive pathways in the bromobenzene-ammonia dimer cation radical: Evidence for a roaming halogen radical. J Mol Struct 2018. [DOI: 10.1016/j.molstruc.2017.11.122] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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32
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Suits AG. Invited Review Article: Photofragment imaging. THE REVIEW OF SCIENTIFIC INSTRUMENTS 2018; 89:111101. [PMID: 30501356 DOI: 10.1063/1.5045325] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/19/2018] [Accepted: 10/25/2018] [Indexed: 06/09/2023]
Abstract
Photodissociation studies in molecular beams that employ position-sensitive particle detection to map product recoil velocities emerged thirty years ago and continue to evolve with new laser and detector technologies. These powerful methods allow application of tunable laser detection of single product quantum states, simultaneous measurement of velocity and angular momentum polarization, measurement of joint product state distributions for the detected and undetected products, coincident detection of multiple product channels, and application to radicals and ions as well as closed-shell molecules. These studies have permitted deep investigation of photochemical dynamics for a broad range of systems, revealed new reaction mechanisms, and addressed problems of practical importance in atmospheric, combustion, and interstellar chemistry. This review presents an historical overview, a detailed technical account of the range of methods employed, and selected experimental highlights illustrating the capabilities of the method.
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Affiliation(s)
- Arthur G Suits
- Department of Chemistry, University of Missouri, Columbia, Missouri 65211, USA
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Lin KC, Tsai PY, Chao MH, Nakamura M, Kasai T, Lombardi A, Palazzetti F, Aquilanti V. Roaming signature in photodissociation of carbonyl compounds. INT REV PHYS CHEM 2018. [DOI: 10.1080/0144235x.2018.1488951] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/28/2022]
Affiliation(s)
- King-Chuen Lin
- Department of Chemistry, National Taiwan University, Taipei, Taiwan (ROC)
- Institute of Atomic and Molecular Sciences, Academia Sinica, Taipei, Taiwan (ROC)
| | - Po-Yu Tsai
- Department of Chemistry, National Chung-Hsing University, Taichung, Taiwan (ROC)
| | - Meng-Hsuan Chao
- Department of Chemistry, National Taiwan University, Taipei, Taiwan (ROC)
| | - Masaaki Nakamura
- Department of Chemistry, National Taiwan University, Taipei, Taiwan (ROC)
| | - Toshio Kasai
- Department of Chemistry, National Taiwan University, Taipei, Taiwan (ROC)
- Institute of Scientific and Industrial Research, Osaka University, Osaka, Japan
| | - Andrea Lombardi
- Dipartimento di Chimica, Biologia e Biotecnologie, Università di Perugia, Perugia, Italy
- Consortium for Computational Molecular and Materials Sciences (CMS)2, Perugia, Italy
| | - Federico Palazzetti
- Dipartimento di Chimica, Biologia e Biotecnologie, Università di Perugia, Perugia, Italy
- Scuola Normale Superiore di Pisa, Pisa, Italy
| | - Vincenzo Aquilanti
- Dipartimento di Chimica, Biologia e Biotecnologie, Università di Perugia, Perugia, Italy
- Istituto di Struttura della Materia, Consiglio Nazionale delle Ricerche, Rome, Italy
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Tsai PY. A generalized unimolecular impulsive model for curved reaction path. J Chem Phys 2018; 148:234101. [PMID: 29935512 DOI: 10.1063/1.5030488] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
This work aims to introduce a generalized impulsive model for unimolecular dissociation processes. This model allows us to take into account the curvature of the reaction path explicitly. It is a generalization of the previously developed multi-center impulsive model [P.-Y. Tsai and K.-C. Lin, J. Phys. Chem. A 119, 29 (2015)]. Several limitations of conventional impulsive models are eliminated by this study: (1) Unlike conventional impulsive models, in which a single molecular geometry is responsible for the impulse determination, the gradients on the whole dissociation path are taken into account. The model can treat dissociation pathways with large curvatures and loose saddle points. (2) The method can describe the vibrational excitation of polyatomic fragments due to the bond formation by multi-center impulse. (3) The available energy in conventional impulsive models is separated into uncoupled statistical and impulsive energy reservoirs, while the interplay between these reservoirs is allowed in the new model. (4) The quantum state correlation between fragments can be preserved in analysis. Dissociations of several molecular systems including the roaming pathways of formaldehyde, nitrate radical, acetaldehyde, and glyoxal are chosen as benchmarks. The predicted photofragment energy and vector distributions are consistent with the experimental results reported previously. In these examples, the capability of the new model to treat the curved dissociation path, loose saddle points, polyatomic fragments, and multiple-body dissociation is verified. As a cheaper computational tool with respect to ab initio on-the-fly direct dynamic simulations, this model can provide detailed information on the energy disposal, quantum state correlation, and stereodynamics in unimolecular dissociation processes.
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Affiliation(s)
- Po-Yu Tsai
- Department of Chemistry, National Chung Hsing University, Taichung 402, Taiwan
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Cofer-Shabica DV, Stratt RM. What is special about how roaming chemical reactions traverse their potential surfaces? Differences in geodesic paths between roaming and non-roaming events. J Chem Phys 2018; 146:214303. [PMID: 28595418 DOI: 10.1063/1.4984617] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
With the notable exception of some illustrative two-degree-of-freedom models whose surprising classical dynamics has been worked out in detail, theories of roaming have largely bypassed the issue of when and why the counterintuitive phenomenon of roaming occurs. We propose that a useful way to begin to address these issues is to look for the geodesic (most efficient) pathways through the potential surfaces of candidate systems. Although roaming manifests itself in an unusual behavior at asymptotic geometries, we found in the case of formaldehyde dissociation that it was the pathways traversing the parts of the potential surface corresponding to highly vibrationally excited reactants that were the most revealing. An examination of the geodesics for roaming pathways in this region finds that they are much less tightly defined than the geodesics in that same region that lead directly to dissociation (whether into closed-shell products or into radical products). Thus, the broader set of options available to the roaming channel gives it an entropic advantage over more conventional reaction channels. These observations suggest that what leads to roaming in other systems may be less the presence of a localized "roaming transition state," than the existence of an entire region of the potential surface conducive to multiple equivalent pathways.
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Affiliation(s)
| | - Richard M Stratt
- Department of Chemistry, Brown University, Providence, Rhode Island 02912, USA
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36
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Pu M, Heshmat M, Privalov T. Liberation of H 2 from (o-C 6H 4Me) 3P-H (+) + (-)H-B(p-C 6F 4H) 3 ion-pair: A transition-state in the minimum energy path versus the transient species in Born-Oppenheimer molecular dynamics. J Chem Phys 2018; 147:014303. [PMID: 28688388 DOI: 10.1063/1.4989672] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Using Born-Oppenheimer molecular dynamics (BOMD) with density functional theory, transition-state (TS) calculations, and the quantitative energy decomposition analysis (EDA), we examined the mechanism of H2-liberation from LB-H(+) + (-)H-LA ion-pair, 1, in which the Lewis base (LB) is (o-C6H4Me)3P and the Lewis acid (LA) is B(p-C6F4H)3. BOMD simulations indicate that the path of H2 liberation from the ion-pair 1 goes via the short-lived transient species, LB⋯H2⋯LA, which are structurally reminiscent of the TS-structure in the minimum-energy-path describing the reversible reaction between H2 and (o-C6H4Me)3P/B(p-C6F4H)3 frustrated Lewis pair (FLP). With electronic structure calculations performed on graphics processing units, our BOMD data-set covers more than 1 ns of evolution of the ion-pair 1 at temperature T ≈ 400 K. BOMD simulations produced H2-recombination events with various durations of H2 remaining fully recombined as a molecule within a LB/LA attractive "pocket"-from very short vibrational-time scale to time scales in the range of a few hundred femtoseconds. With the help of perturbational approach to trajectory-propagation over a saddle-area, we directly examined dynamics of H2-liberation. Using EDA, we elucidated interactions between the cationic and anionic fragments in the ion-pair 1 and between the molecular fragments in the TS-structure. We have also considered a model that qualitatively takes into account the potential energy characteristics of H-H recombination and H2-release plus inertia of molecular motion of the (o-C6H4Me)3P/B(p-C6F4H)3 FLP.
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Affiliation(s)
- Maoping Pu
- Institute of Organic Chemistry, RWTH Aachen University, Landoltweg 1, 52074 Aachen, Germany
| | - Mojgan Heshmat
- Arrhenius Laboratory, Department of Organic Chemistry, Stockholm University, SE-106 91 Stockholm, Sweden
| | - Timofei Privalov
- Arrhenius Laboratory, Department of Organic Chemistry, Stockholm University, SE-106 91 Stockholm, Sweden
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Lee KLK, Quinn MS, Kolmann SJ, Kable SH, Jordan MJT. Zero-point energy conservation in classical trajectory simulations: Application to H2CO. J Chem Phys 2018; 148:194113. [DOI: 10.1063/1.5023508] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Affiliation(s)
| | - Mitchell S. Quinn
- School of Chemistry, The University of Sydney, Sydney, NSW 2006, Australia
- School of Chemistry, The University of New South Wales, Sydney, NSW 2052, Australia
| | - Stephen J. Kolmann
- School of Chemistry, The University of Sydney, Sydney, NSW 2006, Australia
| | - Scott H. Kable
- School of Chemistry, The University of New South Wales, Sydney, NSW 2052, Australia
| | - Meredith J. T. Jordan
- School of Chemistry, The University of Sydney, Sydney, NSW 2006, Australia
- School of Chemistry, The University of New South Wales, Sydney, NSW 2052, Australia
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38
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Farantos SC. Hamiltonian flow over saddles for exploring molecular phase space structures. PHILOSOPHICAL TRANSACTIONS. SERIES A, MATHEMATICAL, PHYSICAL, AND ENGINEERING SCIENCES 2018; 376:rsta.2017.0148. [PMID: 29431676 DOI: 10.1098/rsta.2017.0148] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Accepted: 10/25/2017] [Indexed: 06/08/2023]
Abstract
Despite using potential energy surfaces, multivariable functions on molecular configuration space, to comprehend chemical dynamics for decades, the real happenings in molecules occur in phase space, in which the states of a classical dynamical system are completely determined by the coordinates and their conjugate momenta. Theoretical and numerical results are presented, employing alanine dipeptide as a model system, to support the view that geometrical structures in phase space dictate the dynamics of molecules, the fingerprints of which are traced by following the Hamiltonian flow above saddles. By properly selecting initial conditions in alanine dipeptide, we have found internally free rotor trajectories the existence of which can only be justified in a phase space perspective.This article is part of the theme issue 'Modern theoretical chemistry'.
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Affiliation(s)
- Stavros C Farantos
- Department of Chemistry, University of Crete, 70013 Heraklion-Crete, Greece
- Institute of Electronic Structure and Laser, Foundation for Research and Technology-Hellas, 71110 Heraklion-Crete, Greece
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Abstract
The phenomenon of roaming in chemical reactions has now become both commonly observed in experiment and extensively supported by theory and simulations. Roaming occurs in highly-excited molecules when the trajectories of atomic motion often bypass the minimum energy pathway and produce reaction in unexpected ways from unlikely geometries. The prototypical example is the unimolecular dissociation of formaldehyde (H2CO), in which the "normal" reaction proceeds through a tight transition state to yield H2 + CO but for which a high fraction of dissociations take place via a "roaming" mechanism in which one H atom moves far from the HCO, almost to dissociation, and then returns to abstract the second H atom. We review below the theories and simulations that have recently been developed to address and understand this new reaction phenomenon.
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Affiliation(s)
- Joel M Bowman
- Department of Chemistry and Cherry L. Emerson Center for Scientific Computation, Emory University Atlanta, Georgia 30322, USA.
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40
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Gao Z, Karman T, Vogels SN, Besemer M, van der Avoird A, Groenenboom GC, van de Meerakker SYT. Observation of correlated excitations in bimolecular collisions. Nat Chem 2018; 10:469-473. [DOI: 10.1038/s41557-018-0004-0] [Citation(s) in RCA: 27] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2017] [Accepted: 12/20/2017] [Indexed: 11/09/2022]
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41
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Ma X, Hase WL. Perspective: chemical dynamics simulations of non-statistical reaction dynamics. PHILOSOPHICAL TRANSACTIONS. SERIES A, MATHEMATICAL, PHYSICAL, AND ENGINEERING SCIENCES 2017; 375:rsta.2016.0204. [PMID: 28320906 PMCID: PMC5360902 DOI: 10.1098/rsta.2016.0204] [Citation(s) in RCA: 53] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Accepted: 01/05/2017] [Indexed: 06/06/2023]
Abstract
Non-statistical chemical dynamics are exemplified by disagreements with the transition state (TS), RRKM and phase space theories of chemical kinetics and dynamics. The intrinsic reaction coordinate (IRC) is often used for the former two theories, and non-statistical dynamics arising from non-IRC dynamics are often important. In this perspective, non-statistical dynamics are discussed for chemical reactions, with results primarily obtained from chemical dynamics simulations and to a lesser extent from experiment. The non-statistical dynamical properties discussed are: post-TS dynamics, including potential energy surface bifurcations, product energy partitioning in unimolecular dissociation and avoiding exit-channel potential energy minima; non-RRKM unimolecular decomposition; non-IRC dynamics; direct mechanisms for bimolecular reactions with pre- and/or post-reaction potential energy minima; non-TS theory barrier recrossings; and roaming dynamics.This article is part of the themed issue 'Theoretical and computational studies of non-equilibrium and non-statistical dynamics in the gas phase, in the condensed phase and at interfaces'.
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Affiliation(s)
- Xinyou Ma
- Department of Chemistry and Biochemistry, Texas Tech University, Lubbock, TX 79409, USA
| | - William L Hase
- Department of Chemistry and Biochemistry, Texas Tech University, Lubbock, TX 79409, USA
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42
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Zhang M, Guo H, Zhang L. Roaming-Mediated CH 2NH Elimination from the Ionization of Aromatic Ethylamines. ChemistryOpen 2017; 6:40-45. [PMID: 28168149 PMCID: PMC5288767 DOI: 10.1002/open.201600144] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2016] [Revised: 12/12/2016] [Indexed: 12/02/2022] Open
Abstract
The ionization of aromatic ethylamines by photons or electrons leads to elimination of CH2NH fragments, supposedly deriving from the McLafferty rearrangement involving intramolecular γ‐hydrogen transfer. Using tryptamine and phenethylamine as examples, the results reported here suggest that the McLafferty mechanism is inadequate for interpreting the observations of CH2NH elimination due to much higher calculated appearance energy than experimentally measured values. Furthermore, by considering the roaming‐mediated effect, the calculated appearance energy for the elimination of CH2NH fragments is reduced and matches well with the experimental results and verifies the existence of roaming‐mediated effect. This effect could potentially be extended to explain the general CH2NH elimination of aromatic ethylamines. Due to the similar hydrogen transfer to that of the McLafferty mechanism, the roaming‐mediated effect was taken into account to suggest a novel mechanism, termed the “roaming‐modified McLafferty rearrangement”, that explains the observations of CH2NH elimination in the ionization of aromatic ethylamines. This is a reasonable modification of the McLafferty rearrangement mechanism.
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Affiliation(s)
- Mengxing Zhang
- National Synchrotron Radiation Laboratory; University of Science and Technology of China; Hefei Anhui 230029 P.R. China
| | - Huijun Guo
- Vacree Technologies Co., Ltd; Hefei Anhui 230088 P.R. China
- University of Science and Technology of China; Hefei Anhui 230029 P.R. China
| | - Lidong Zhang
- National Synchrotron Radiation Laboratory; University of Science and Technology of China; Hefei Anhui 230029 P.R. China
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43
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Chen LW, Hung CM, Matsui H, Lee YP. New experimental evidence to support roaming in the reaction Cl + isobutene (i-C 4H 8). Sci Rep 2017; 7:40105. [PMID: 28079173 PMCID: PMC5228202 DOI: 10.1038/srep40105] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2016] [Accepted: 11/30/2016] [Indexed: 12/05/2022] Open
Abstract
The reaction Cl + isobutene (i-C4H8) was reported by Suits et al. to proceed via, in addition to abstraction, an addition-elimination path following a roaming excursion of Cl; a near-zero translational energy release and an isotropic angular distribution observed at a small collision energy characterized this mechanism. We employed a new experimental method to further characterize this roaming mechanism through observation of the internal distribution of HCl (v, J) and their temporal behavior upon irradiation of a mixture of Cl2C2O2 and i-C4H8 in He or Ar buffer gas. With 1–3 Torr buffer gas added to approach the condition of small collision energy, the intensities of emission of HCl (v = 1, 2) and the HCl production rates increased significantly; Ar shows a more significant effect than He because Ar quenches Cl more efficiently to reduce the collisional energy and facilitate the roaming path. According to kinetic modeling, the rate of addition-elimination (roaming) increased from kE ≈ 2 × 105 s−1 when little buffer gas was present to ~1.9 × 106 s−1 when 2–3 Torr of Ar was added, and the branching ratio for formation of [HCl (v = 2)]/[HCl (v = 1)] increased from 0.02 ± 0.01 for abstraction to 0.06 ± 0.01 for roaming.
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Affiliation(s)
- Li-Wei Chen
- Department of Applied Chemistry and Institute of Molecular Science, National Chiao Tung University, 1001 Ta-Hsueh Rd., Hsinchu 30010, Taiwan
| | - Ching-Ming Hung
- Department of Applied Chemistry and Institute of Molecular Science, National Chiao Tung University, 1001 Ta-Hsueh Rd., Hsinchu 30010, Taiwan
| | - Hiroyuki Matsui
- Department of Applied Chemistry and Institute of Molecular Science, National Chiao Tung University, 1001 Ta-Hsueh Rd., Hsinchu 30010, Taiwan
| | - Yuan-Pern Lee
- Department of Applied Chemistry and Institute of Molecular Science, National Chiao Tung University, 1001 Ta-Hsueh Rd., Hsinchu 30010, Taiwan.,Institute of Atomic and Molecular Sciences, Academia Sinica, Taipei 10617, Taiwan
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Hochlaf M. Advances in spectroscopy and dynamics of small and medium sized molecules and clusters. Phys Chem Chem Phys 2017; 19:21236-21261. [DOI: 10.1039/c7cp01980g] [Citation(s) in RCA: 38] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Investigations of the spectroscopy and dynamics of small- and medium-sized molecules and clusters represent a hot topic in atmospheric chemistry, biology, physics, atto- and femto-chemistry and astrophysics.
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Affiliation(s)
- Majdi Hochlaf
- Université Paris-Est
- Laboratoire Modélisation et Simulation Multi Echelle
- MSME UMR 8208 CNRS
- 77454 Marne-la-Vallée
- France
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45
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Roaming mediated nonadiabatic dynamics in molecular hydrogen elimination from propane at 157 nm. Chem Phys Lett 2016. [DOI: 10.1016/j.cplett.2016.08.057] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
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46
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Mauguière FAL, Collins P, Stamatiadis S, Li A, Ezra GS, Farantos SC, Kramer ZC, Carpenter BK, Wiggins S, Guo H. Toward Understanding the Roaming Mechanism in H + MgH → Mg + HH Reaction. J Phys Chem A 2016; 120:5145-54. [PMID: 26918375 DOI: 10.1021/acs.jpca.6b00682] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The roaming mechanism in the reaction H + MgH →Mg + HH is investigated by classical and quantum dynamics employing an accurate ab initio three-dimensional ground electronic state potential energy surface. The reaction dynamics are explored by running trajectories initialized on a four-dimensional dividing surface anchored on three-dimensional normally hyperbolic invariant manifold associated with a family of unstable orbiting periodic orbits in the entrance channel of the reaction (H + MgH). By locating periodic orbits localized in the HMgH well or involving H orbiting around the MgH diatom, and following their continuation with the total energy, regions in phase space where reactive or nonreactive trajectories may be trapped are found. In this way roaming reaction pathways are deduced in phase space. Patterns similar to periodic orbits projected into configuration space are found for the quantum bound and resonance eigenstates. Roaming is attributed to the capture of the trajectories in the neighborhood of certain periodic orbits. The complex forming trajectories in the HMgH well can either return to the radical channel or "roam" to the MgHH minimum from where the molecule may react.
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Affiliation(s)
| | - Peter Collins
- School of Mathematics, University of Bristol , Bristol BS8 1TW, United Kingdom
| | - Stamatis Stamatiadis
- Department of Materials Science and Technology, University of Crete , Iraklion 710 03, Greece
| | - Anyang Li
- Department of Chemistry and Chemical Biology, University of New Mexico , Albuquerque, New Mexico 87131, United States
| | - Gregory S Ezra
- Baker Laboratory, Department of Chemistry and Chemical Biology, Cornell University , Ithaca, New York 14853, United States
| | - Stavros C Farantos
- Institute of Electronic Structure and Laser, Foundation for Research and Technology-Hellas, and Department of Chemistry, University of Crete, Iraklion 711 10, Greece
| | - Zeb C Kramer
- Baker Laboratory, Department of Chemistry and Chemical Biology, Cornell University , Ithaca, New York 14853, United States
| | - Barry K Carpenter
- School of Chemistry, Cardiff University , Cardiff CF10 3AT, United Kingdom
| | - Stephen Wiggins
- School of Mathematics, University of Bristol , Bristol BS8 1TW, United Kingdom
| | - Hua Guo
- Department of Chemistry and Chemical Biology, University of New Mexico , Albuquerque, New Mexico 87131, United States
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47
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Xiao H, Maeda S, Morokuma K. Theoretical insight into the wavelength-dependent photodissociation mechanism of nitric acid. Phys Chem Chem Phys 2016; 18:24582-90. [DOI: 10.1039/c6cp04713k] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The MS-CASPT2 method is used to study O(1D) + HONO and OH + NO2 photodissociation pathways of HNO3 in the four lowest electronic singlet states.
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Affiliation(s)
- Hongyan Xiao
- Key Laboratory of Photochemical Conversion and Optoelectronic Materials
- Technical Institute of Physics and Chemistry
- Chinese Academy of Sciences
- Beijing 100190
- People's Republic of China
| | - Satoshi Maeda
- Department of Chemistry
- Faculty of Science
- Hokkaido University
- Sapporo 060-0810
- Japan
| | - Keiji Morokuma
- Fukui Institute for Fundamental Chemistry
- Kyoto University
- Kyoto 606-8103
- Japan
- Cherry L. Emerson Center for Scientific Computation and Department of Chemistry
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48
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Yosa Reyes J, Brickel S, Unke OT, Nagy T, Meuwly M. HSO3Cl: a prototype molecule for studying OH-stretching overtone induced photodissociation. Phys Chem Chem Phys 2016; 18:6780-8. [DOI: 10.1039/c5cp07319g] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Vibrationally induced photodissociation in sulfurochloridic acid (HSO3Cl) is found to be a viable process to form SO3and HCl from excitations of the OH-stretching overtone starting atνOH= 4.
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Affiliation(s)
- Juvenal Yosa Reyes
- Department of Chemistry
- University of Basel
- Basel
- Switzerland
- Industrial and Systems Engineering Department
| | | | - Oliver T. Unke
- Department of Chemistry
- University of Basel
- Basel
- Switzerland
| | - Tibor Nagy
- Department of Chemistry
- University of Basel
- Basel
- Switzerland
- IMEC
| | - Markus Meuwly
- Department of Chemistry
- University of Basel
- Basel
- Switzerland
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49
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50
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Mauguière FAL, Collins P, Kramer ZC, Carpenter BK, Ezra GS, Farantos SC, Wiggins S. Phase Space Structures Explain Hydrogen Atom Roaming in Formaldehyde Decomposition. J Phys Chem Lett 2015; 6:4123-4128. [PMID: 26499774 DOI: 10.1021/acs.jpclett.5b01930] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
We re-examine the prototypical roaming reaction--hydrogen atom roaming in formaldehyde decomposition--from a phase space perspective. Specifically, we address the question "why do trajectories roam, rather than dissociate through the radical channel?" We describe and compute the phase space structures that define and control all possible reactive events for this reaction, as well as provide a dynamically exact description of the roaming region in phase space. Using these phase space constructs, we show that in the roaming region, there is an unstable periodic orbit whose stable and unstable manifolds define a conduit that both encompasses all roaming trajectories exiting the formaldehyde well and shepherds them toward the H2···CO well.
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Affiliation(s)
| | - Peter Collins
- School of Mathematics, University of Bristol , Bristol BS8 1TW, United Kingdom
| | - Zeb C Kramer
- Department of Chemistry and Chemical Biology, Baker Laboratory, Cornell University , Ithaca, New York 14853, United States
| | - Barry K Carpenter
- School of Chemistry, Cardiff University , Cardiff CF10 3AT, United Kingdom
| | - Gregory S Ezra
- Department of Chemistry and Chemical Biology, Baker Laboratory, Cornell University , Ithaca, New York 14853, United States
| | - Stavros C Farantos
- Department of Chemistry, University of Crete and Institute of Electronic Structure and Laser, Foundation for Research and Technology - Hellas , Iraklion 711 10, Crete, Greece
| | - Stephen Wiggins
- School of Mathematics, University of Bristol , Bristol BS8 1TW, United Kingdom
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