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Pan H, Liu K. State-to-State Dynamics in Mode-Specific Reactions of Cl + CH 3D( v1-I, v1-II, and v4 = 1; |10⟩): Loss of Memory or Not. J Phys Chem Lett 2023; 14:1769-1776. [PMID: 36762846 DOI: 10.1021/acs.jpclett.3c00133] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/18/2023]
Abstract
Several decades of the study of reaction dynamics culminate in the concept of mode specificity and bond selectivity in polyatomic systems. Until very recently, the main concern of those studies has been total reactivity and little attention has been paid to the mode-specific effects on the more detailed product-state and angular distributions. Conventional wisdom would anticipate that the fine detail should reveal a more pronounced mode dependency. However, a few recent studies showed that the product distributions could appear to be surprisingly insensitive to the modes of internal excitation of reagents. This counterintuitive finding led to a concept of loss of memory. Here, we present detailed experimental results in the reactions of the Cl atom with three distinct stretching-excited CH3D(vCH3 = 1) reagents. In conjunction with the previous reports on various aspects of this reaction, such a comprehensive set of data enables us to perform an in-depth examination of the validity of this new concept.
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Affiliation(s)
- Huilin Pan
- Department of Chemistry, Southern University of Science and Technology, Shenzhen 518055, P. R. China
- Institute of Atomic and Molecular Sciences (IAMS), Academia Sinica, Taipei, Taiwan 10617
| | - Kopin Liu
- Institute of Atomic and Molecular Sciences (IAMS), Academia Sinica, Taipei, Taiwan 10617
- State Key Laboratory of Molecular Reaction Dynamics, Dalian Institute of Chemical Physics, CAS, Dalian 116023, P. R. China
- Aerosol Science Research Center, National Sun Yat-sen University, Kaohsiung, Taiwan 80424
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2
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Mondal S, Pan H, Liu K. Stretching-mode specificity in the Cl + CH 3D( v1-I, v1-II, and v4 = 1; | jK〉) reactions: dependency on the initial | jK〉 selectivity. Phys Chem Chem Phys 2022; 24:24050-24061. [PMID: 36168830 DOI: 10.1039/d2cp03614b] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The title reactions were studied at a collisional energy of 5.4 kcal mol-1 in a crossed-beam product-imaging experiment. The dynamics attributes of the dominant ground-state CH2D(00) and the accompanied C-D bend-excited CH2D(61) products were imaged in reactions with totally 16 ro-vibrationally selected states of the CH3D(vi, |jK〉) reagents. We found that all three vibrational excitations yielded marked |jK〉-dependent rate-enhancements in forming the (00, 0/1)s product pairs. Furthermore, for a given rotational |jK〉-mode, a vibrational-mode propensity of v4 > v1-I > v1-II in rate promotion and a clear manifestation of the Fermi-phase-induced interference effect of the latter two were observed. Compared to the reactivity of the rotationless state |jK〉 = |00〉, a minute rotational-excitation of all three stretch-excited CH3D(vi = 1) reagents could yield significantly higher reaction rates for the product pair (00, 0)s, but not so for (00, 1)s. The signals in forming the (61, 0)s pair were clearly notable but smaller than that of the ground-state reaction product pair, (00, 0)g. An opposite propensity of v1-II ≈ v1-I > v4 with a milder dependency on the initial |jK〉-states was observed. The angular distributions of the (00, 0)s pairs were nearly identical for all ro-vibrationally excited reagents, displaying the typical trait for a direct abstraction of the rebound mechanism. Similar distributions were found for the (61, 0)s pairs; yet, both pairs deviated substantially from the peripheral feature of the ground-state reaction pair of (00, 0)g. Those of the (00, 1)s pairs in reactions with v4-excitation featured a prominent forward-peaking distribution-suggestive of a time-delayed, resonance-mediated pathway, again with little dependency on the initial |jK〉-states. As for the reactions with the two Fermi-dyads, v1-I and v1-II, albeit showing globally similar distributions to that for v4, a substantial variation with the initial rotational-mode excitation could be discerned in the forward-peaking features. To unravel the impact of the Fermi-phase on the |jK〉-dependent attributes, we adopted a comparative approach by contrasting the observations in reactions with the Fermi-dyad reagents (the superposition states) to those with the pure-state reagents. Remarkable distinctions are unveiled and elucidated with the unexplained results explicitly pointed out, which call for future theoretical investigations for deeper understanding.
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Affiliation(s)
- Sohidul Mondal
- Institute of Atomic and Molecular Sciences (IAMS), Academia Sinica, P. O. Box 23-166, Taipei, 10699, Taiwan.
| | - Huilin Pan
- Institute of Atomic and Molecular Sciences (IAMS), Academia Sinica, P. O. Box 23-166, Taipei, 10699, Taiwan. .,Department of Chemistry, Southern University of Science and Technology, Shenzhen, 518055, P. R. China
| | - Kopin Liu
- Institute of Atomic and Molecular Sciences (IAMS), Academia Sinica, P. O. Box 23-166, Taipei, 10699, 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, CAS, Dalian, 116023, P. R. China
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3
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Mondal S, Liu K. Imaging the Mode-Specificity in Cl + CH 3D( v1-I, v1-II, v4 = 1; | jK⟩ = |10⟩) → CH 2D(4 1) + HCl( v). J Phys Chem A 2022; 126:2825-2831. [PMID: 35499972 DOI: 10.1021/acs.jpca.2c01852] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
We report a crossed-beam imaging experiment on the title reactions at two collisional energies (Ec) of 5.3 and 10 kcal mol-1. Both the integral cross sections relative to the ground-state reactivity and the differential cross sections were measured and compared. We found that one-quantum excitations of the CH3-stretching vibrations of the CH3D reagent exerted profound mode-specificity in forming the umbrella-mode-excited CH2D(41) products with the vibrational efficacy of v4 > v1-I > v1-II at both Ec values. The concomitantly formed HCl(v) coproducts were vibrationally cold. Interestingly, the branching ratios of (v = 1)/(v = 0) appeared invariant to the initial stretch-modes of excitation at Ec = 5.3 kcal mol-1, yet exhibited a pronounced mode-specific dependency in the order of v1-II > v1-I > v4 at Ec = 10.3 kcal mol-1. This large and Ec-dependent disparity between the two Fermi-coupled reagents, v1-I and v1-II, is particularly significant and could be another facet─in addition to that in the recently reported vibrational enhancement factors─of the Fermi-phase-induced interference effect manifested in the product vibrational branching ratio. The pair-correlated angular distributions (vCH2D, vHCl)s = (41, 0)s in the three stretch-excited reactions were globally alike and resembled that of the ground-state reaction pair (00, 0)g, suggestive of a direct abstraction mechanism of the peripheral type. This is in sharp contrast to all other vibrationally excited pairs of (11, 0)s, (31, 0)s, and (61, 0)s previously reported in the CH2D + HCl isotopic channel, for which both the direct abstraction and a time-delayed resonance pathway partake.
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Affiliation(s)
- Sohidul Mondal
- Institute of Atomic and Molecular Sciences (IAMS), Academia Sinica, Taipei, 10617, Taiwan
| | - Kopin Liu
- Institute of Atomic and Molecular Sciences (IAMS), 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, CAS, Dalian, 116023, P. R. China
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4
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Hu J, Zhi Y, Xie JC, Wu CX, Tian SX. Collision-Energy Dependent Stereodynamics of Dissociative Charge Exchange Reaction between Ar + and CO. J Phys Chem Lett 2021; 12:7127-7133. [PMID: 34296886 DOI: 10.1021/acs.jpclett.1c01980] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
Long-distance charge-dipole attraction between atomic ion and randomly oriented polar molecule potentially makes the molecular orientation, which profoundly influences the products' kinetics of collisional reaction. Using the three-dimensional ion velocity map imaging technique, here we report a collision-energy dependent stereodynamics of dissociative charge exchange reaction Ar+ + CO → Ar + O + C+ in a range of 7.46-9.97 eV. At the lowest collision energy, the most C+ products are forward-scattered and are along the collision axis and are attributed to three different dissociation channels including the predominant one experiencing the rotating intermediate ArC+. At the high collision energies, the remarkably diffusive distribution of C+ arises from the prompt dissociation of the rebounded CO+. The different dynamic processes arising from the nearly collinear collision are elaborated explicitly on the basis of the data analyses using the Doppler kinetics models.
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Affiliation(s)
- Jie Hu
- Hefei National Laboratory for Physical Sciences at the Microscale, Collaborative Innovation Center of Chemistry for Energy Materials (iChEM), Department of Chemical Physics, University of Science and Technology of China, Hefei 230026, China
| | - Yaya Zhi
- Hefei National Laboratory for Physical Sciences at the Microscale, Collaborative Innovation Center of Chemistry for Energy Materials (iChEM), Department of Chemical Physics, University of Science and Technology of China, Hefei 230026, China
| | - Jing-Chen Xie
- Hefei National Laboratory for Physical Sciences at the Microscale, Collaborative Innovation Center of Chemistry for Energy Materials (iChEM), Department of Chemical Physics, University of Science and Technology of China, Hefei 230026, China
| | - Chun-Xiao Wu
- Hefei National Laboratory for Physical Sciences at the Microscale, Collaborative Innovation Center of Chemistry for Energy Materials (iChEM), Department of Chemical Physics, University of Science and Technology of China, Hefei 230026, China
| | - Shan Xi Tian
- Hefei National Laboratory for Physical Sciences at the Microscale, Collaborative Innovation Center of Chemistry for Energy Materials (iChEM), Department of Chemical Physics, University of Science and Technology of China, Hefei 230026, China
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5
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Theoretical rate constant of methane oxidation from the conventional transition-state theory. J Mol Model 2018; 24:294. [PMID: 30255207 DOI: 10.1007/s00894-018-3829-y] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2018] [Accepted: 09/12/2018] [Indexed: 10/28/2022]
Abstract
The potential energy surface for the first step of the methane oxidation CH4 + O2➔CH3 + HO2 was studied using the London-Eyring-Polanyi-Sato equation (LEPS) and the conventional transition-state theory (CTST). The calculated activation energy and rate constant values were in good agreement with the experimental and theoretical values reported in the literature using the shock tube technique and coupled cluster method respectively. The rate equation from CTST, although simple, provides good results to study the H-shift between methane and the oxygen molecules.
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6
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Espinosa-Garcia J, Bonnet L, Corchado JC. Theoretical Study of the Pair-Correlated F + CHD3(v = 0,ν1 = 1) Reaction: Effect of CH Stretching Vibrational Excitation. J Phys Chem A 2017; 121:4076-4092. [DOI: 10.1021/acs.jpca.7b02665] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Joaquin Espinosa-Garcia
- Departamento
de Química Física and Instituto de Computatión
Científica Avanzada, Universidad de Extremadura, 06071 Badajoz, Spain
| | - Laurent Bonnet
- CNRS, Institut
des Sciences Moleculaires, UMR 5255, 33405 Talence, and Université
de Bordeaux, Institut des Sciences Moleculaires, UMR 5255, 33405 Talence, France
| | - Jose C. Corchado
- Departamento
de Química Física and Instituto de Computatión
Científica Avanzada, Universidad de Extremadura, 06071 Badajoz, Spain
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7
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Totenhofer AJ, Connor JNL, Nyman G. Angular Scattering Dynamics of the CH4 + Cl → CH3 + HCl Reaction Using Nearside-Farside, Local Angular Momentum, and Resummation Theories. J Phys Chem B 2016; 120:2020-32. [PMID: 26625096 DOI: 10.1021/acs.jpcb.5b10189] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The differential cross section (DCS) for the CH4 + Cl → CH3 + HCl reaction is studied at six total energies where all of the species are in their ground states. The scattering (S) matrix elements have been calculated by the rotating line umbrella method for a dual-level ab initio analytic potential energy surface. We make the first application to this reaction of nearside-farside (NF) and local angular momentum (LAM) techniques, including resummation orders (r) of 0, 1, 2, and 3 for the partial-wave series representation of the full scattering amplitude. We find that resummation usually cleans the NF r = 0 DCSs of unphysical oscillations, especially at small angles. This cleaning effect is typically most pronounced when changing from no resummation (r = 0) to r = 1; further resummations from r = 1 to r = 2 and from r = 2 to r = 3 have smaller effects. The NF DCS analyses show that the reaction is N-dominated at sideward and large angles, whereas at small angles there are oscillations caused by NF interference. The NF LAM analysis provides consistent and complementary information, in particular for the total angular momenta that contribute to the reaction at different scattering angles. The NF analyses also provide justification for simpler N-dominant dynamical theories such as the semiclassical optical model, which provides an explanation for the distorted mirror image effect for the moduli of the S matrix elements and the DCSs, as well as the use of a hard-sphere DCS over limited angular ranges.
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Affiliation(s)
- A J Totenhofer
- School of Chemistry, The University of Manchester , Manchester M13 9PL, United Kingdom
| | - J N L Connor
- School of Chemistry, The University of Manchester , Manchester M13 9PL, United Kingdom
| | - Gunnar Nyman
- Department of Chemistry and Molecular Biology, University of Gothenburg , 41296 Gothenburg, Sweden
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8
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Liu N, Yang M. An eight-dimensional quantum dynamics study of the Cl + CH4→ HCl + CH3 reaction. J Chem Phys 2015; 143:134305. [DOI: 10.1063/1.4931833] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Affiliation(s)
- Na Liu
- State Key Laboratory of Magnetic Resonance and Atomic and Molecular Physics, Wuhan Centre for Magnetic Resonance, Wuhan Institute of Physics and Mathematics, Chinese Academy of Sciences, Wuhan 430071, China
| | - Minghui Yang
- State Key Laboratory of Magnetic Resonance and Atomic and Molecular Physics, Wuhan Centre for Magnetic Resonance, Wuhan Institute of Physics and Mathematics, Chinese Academy of Sciences, Wuhan 430071, China
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9
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CHENG DAHAI, YANG TIANGANG, CHEN MAODU. STEREODYNAMICS STUDY OF THE ABSTRACTION REACTION H + CD4 → HD + CD3. JOURNAL OF THEORETICAL & COMPUTATIONAL CHEMISTRY 2013. [DOI: 10.1142/s021963361250109x] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
A new London–Eyring–Polanyi–Sato (LEPS) potential energy surface (PES) is employed in this work to study the stereo properties for the abstraction reaction of hydrogen with methane at its rovibrationally ground state using the quasiclassical trajectory method (QCT). A "quasi-triatomic" approximation is used to treat the CD3 group of CD4 as a pseudoatom. The calculated excitation function of the title reaction can give a good agreement to most experimental and theoretical data at collision energies (Ec =1.5 ~ 2.5 eV ). Further investigation of the product HD in reaction H + CD4 (v = 0, j = 0) → HD + CD3 and D + CH4 (v = 0, j = 0) → HD + CH3 shows the dependence of the product rotational polarization on collision energies and mass factor, but P(θr) is not sensitive to both the collision energies and the mass factor.
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Affiliation(s)
- DAHAI CHENG
- School of Physics and Optoelectronic Technology, and College of Advanced Science and Technology, Dalian University of Technology, Dalian 116024, P. R. China
| | - TIANGANG YANG
- School of Physics and Optoelectronic Technology, and College of Advanced Science and Technology, Dalian University of Technology, Dalian 116024, P. R. China
| | - MAODU CHEN
- School of Physics and Optoelectronic Technology, and College of Advanced Science and Technology, Dalian University of Technology, Dalian 116024, P. R. China
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10
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Zhang B, Liu K, Czakó G, Bowman JM. Translational energy dependence of the Cl + CH4(vb = 0, 1) reactions: a joint crossed-beam and quasiclassical trajectory study. Mol Phys 2012. [DOI: 10.1080/00268976.2012.662600] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/28/2022]
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11
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Revealing the stereospecific chemistry of the reaction of Cl with aligned CHD3(ν1 = 1). Nat Chem 2012; 4:636-41. [DOI: 10.1038/nchem.1383] [Citation(s) in RCA: 69] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2012] [Accepted: 05/17/2012] [Indexed: 11/09/2022]
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12
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Monge-Palacios M, Yang M, Espinosa-García J. QCT and QM calculations of the Cl(2P) + NH3 reaction: influence of the reactant well on the dynamics. Phys Chem Chem Phys 2012; 14:4824-34. [PMID: 22388701 DOI: 10.1039/c2cp00008c] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
A detailed dynamics study, using both quasi-classical trajectory (QCT) and reduced-dimensional quantum mechanical (QM) calculations, was carried out to understand the reactivity and mechanism of the Cl((2)P) + NH(3)→ HCl + NH(2) gas-phase reaction, which evolves through deep wells in the entry and exit channels. The calculations were performed on an analytical potential energy surface recently developed by our group, PES-2010 [M. Monge-Palacios, C. Rangel, J. C. Corchado and J. Espinosa-Garcia, Int. J. Quantum. Chem., 2011], together with a simplified model surface, mod-PES, in which the reactant well is removed to analyze its influence. The main finding was that the QCT and QM methods show a change of the reaction probability with collision energy, suggesting a change of the atomic-level mechanism of reaction with energy. This change disappeared when the mod-PES was used, showing that the behaviour at low energies is a direct consequence of the existence of the reactant well. Analysis of the trajectories showed that different mechanisms operate depending on the collision energy. Thus, while at high energies (E(coll) > 5 kcal mol(-1)) practically all trajectories are direct, at low energies (E(coll) < 3 kcal mol(-1)) the trajectories are indirect, i.e., with the mediation of a trapping complex in the entry and/or the exit wells. The reactant complex allows repeated encounters between the reactants, increasing the reaction probability at low energies. The differential cross section results reinforce this change of mechanism, showing also the influence of the reactant well on this reaction. Thus, the PES-2010 surface yields a forward-backward symmetry in the scattering, while when the reactant well is removed with the mod-PES the shape is more isotropic.
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Affiliation(s)
- M Monge-Palacios
- Departamento de Química Física, Universidad de Extremadura, 06071 Badajoz, Spain
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13
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Zhang J, Lahankar SA, Garton DJ, Minton TK, Zhang W, Yang X. Crossed-Beams Studies of the Dynamics of the H-Atom Abstraction Reaction, O(3P) + CH4 → OH + CH3, at Hyperthermal Collision Energies. J Phys Chem A 2011; 115:10894-902. [DOI: 10.1021/jp207137t] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Jianming Zhang
- Department of Chemistry and Biochemistry, Montana State University, Bozeman, Montana 59717, United States
| | - Sridhar A. Lahankar
- Department of Chemistry and Biochemistry, Montana State University, Bozeman, Montana 59717, United States
| | - Donna J. Garton
- Department of Chemistry and Biochemistry, Montana State University, Bozeman, Montana 59717, United States
| | - Timothy K. Minton
- Department of Chemistry and Biochemistry, Montana State University, Bozeman, Montana 59717, United States
| | - Weiqing Zhang
- State Key Laboratory of Molecular Reaction Dynamics, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian, Liaoning 116023, P. R. China
| | - Xueming Yang
- State Key Laboratory of Molecular Reaction Dynamics, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian, Liaoning 116023, P. R. China
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14
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Remmert SM, Banks ST, Harvey JN, Orr-Ewing AJ, Clary DC. Reduced dimensionality spin-orbit dynamics of CH3 + HCl ⇌ CH4 + Cl on ab initio surfaces. J Chem Phys 2011; 134:204311. [DOI: 10.1063/1.3592732] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023] Open
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15
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Zhou J, Zhang B, Lin JJ, Liu K. Imaging the isotope effects in the ground state reaction of Cl CH4 and CD4. Mol Phys 2011. [DOI: 10.1080/00268970500064838] [Citation(s) in RCA: 52] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
Affiliation(s)
- J. Zhou
- a The Institute of Atomic and Molecular Sciences (IAMS) , Academia Sinica , Taipei , Taiwan , 106
| | - B. Zhang
- a The Institute of Atomic and Molecular Sciences (IAMS) , Academia Sinica , Taipei , Taiwan , 106
| | - J. J. Lin
- a The Institute of Atomic and Molecular Sciences (IAMS) , Academia Sinica , Taipei , Taiwan , 106
| | - K. Liu
- a The Institute of Atomic and Molecular Sciences (IAMS) , Academia Sinica , Taipei , Taiwan , 106
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16
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Greaves SJ, Rose RA, Abou-Chahine F, Glowacki DR, Troya D, Orr-Ewing AJ. Quasi-classical trajectory study of the dynamics of the Cl + CH4→ HCl + CH3 reaction. Phys Chem Chem Phys 2011; 13:11438-45. [DOI: 10.1039/c0cp02694h] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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17
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Kawamata H, Liu K. Imaging the nature of the mode-specific chemistry in the reaction of Cl atom with antisymmetric stretch-excited CH4. J Chem Phys 2010; 133:124304. [DOI: 10.1063/1.3482628] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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18
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Espinosa-García J, Corchado JC. Quasi-Classical Trajectory Calculations of the Hydrogen Abstraction Reaction H + NH3. J Phys Chem A 2010; 114:6194-200. [DOI: 10.1021/jp101607n] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
| | - José C. Corchado
- Departamento de Química Física, Universidad de Extremadura, 06006 Badajoz (Spain)
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19
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Taylor MS, Ivanic SA, Wood GPF, Easton CJ, Bacskay GB, Radom L. Hydrogen Abstraction by Chlorine Atom from Small Organic Molecules Containing Amino Acid Functionalities: An Assessment of Theoretical Procedures. J Phys Chem A 2009; 113:11817-32. [DOI: 10.1021/jp9029437] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Affiliation(s)
- Mark S. Taylor
- ARC Centre of Excellence for Free Radical Chemistry and Biotechnology, School of Chemistry, University of Sydney, Sydney, NSW 2006, Australia, and Research School of Chemistry, Australian National University, Canberra, ACT 0200, Australia
| | - Sandra A. Ivanic
- ARC Centre of Excellence for Free Radical Chemistry and Biotechnology, School of Chemistry, University of Sydney, Sydney, NSW 2006, Australia, and Research School of Chemistry, Australian National University, Canberra, ACT 0200, Australia
| | - Geoffrey P. F. Wood
- ARC Centre of Excellence for Free Radical Chemistry and Biotechnology, School of Chemistry, University of Sydney, Sydney, NSW 2006, Australia, and Research School of Chemistry, Australian National University, Canberra, ACT 0200, Australia
| | - Christopher J. Easton
- ARC Centre of Excellence for Free Radical Chemistry and Biotechnology, School of Chemistry, University of Sydney, Sydney, NSW 2006, Australia, and Research School of Chemistry, Australian National University, Canberra, ACT 0200, Australia
| | - George B. Bacskay
- ARC Centre of Excellence for Free Radical Chemistry and Biotechnology, School of Chemistry, University of Sydney, Sydney, NSW 2006, Australia, and Research School of Chemistry, Australian National University, Canberra, ACT 0200, Australia
| | - Leo Radom
- ARC Centre of Excellence for Free Radical Chemistry and Biotechnology, School of Chemistry, University of Sydney, Sydney, NSW 2006, Australia, and Research School of Chemistry, Australian National University, Canberra, ACT 0200, Australia
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Riedel J, Yan S, Liu K. Mode Specificity in Reactions of Cl with CH2 Stretch-Excited CH2D2(υ1, υ6 = 1). J Phys Chem A 2009; 113:14270-6. [DOI: 10.1021/jp902629h] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Affiliation(s)
- Jens Riedel
- Institute of Atomic and Molecular Sciences (IAMS), Academia Sinica, P.O. Box 23-166, Taipei, Taiwan 10617
| | - Shannon Yan
- Institute of Atomic and Molecular Sciences (IAMS), Academia Sinica, P.O. Box 23-166, Taipei, Taiwan 10617
| | - Kopin Liu
- Institute of Atomic and Molecular Sciences (IAMS), Academia Sinica, P.O. Box 23-166, Taipei, Taiwan 10617
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21
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Espinosa-García J, Nyman G, Corchado JC. The hydrogen abstraction reaction H+CH[sub 4]. II. Theoretical investigation of the kinetics and dynamics. J Chem Phys 2009; 130:184315. [DOI: 10.1063/1.3132594] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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22
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Wu YT, Liu K. Imaging the pair-correlated dynamics and isotope effects of the Cl+CH2D2 reaction. J Chem Phys 2008; 129:154302. [DOI: 10.1063/1.2993264] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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23
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Wang M, Sun X, Bian W. Quasiclassical trajectory study of the SiH(4)+H-->SiH(3)+H(2) reaction on a global ab initio potential energy surface. J Chem Phys 2008; 129:084309. [PMID: 19044825 DOI: 10.1063/1.2973626] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
The SiH(4)+H-->SiH(3)+H(2) reaction has been investigated by the quasiclassical trajectory (QCT) method on a recent global ab initio potential energy surface [M. Wang et al., J. Chem. Phys. 124, 234311 (2006)]. The integral cross section as a function of collision energy and thermal rate coefficient for the temperature range of 300-1600 K have been obtained. At the collision energy of 9.41 kcalmol, product energy distributions and rovibrational populations are explored in detail, and H(2) rotational state distributions show a clear evidence of two reaction mechanisms. One is the conventional rebound mechanism and the other is the stripping mechanism similar to what has recently been found in the reaction of CD(4)+H [J. P. Camden et al., J. Am. Chem. Soc. 127, 11898 (2005)]. The computed rate coefficients with the zero-point energy correction are in good agreement with the available experimental data.
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Affiliation(s)
- Manhui Wang
- Beijing National Laboratory for Molecular Sciences, State Key Laboratory of Molecular Reaction Dynamics, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190, People's Republic of China
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Abstract
We report a comprehensive study of the quantum-state correlation property of product pairs from reactions of chlorine atoms with both the ground-state and the CH stretch-excited CHD(3). In light of available ab initio theoretical results, this set of experimental data provides a conceptual framework to visualize the energy-flow pattern along the reaction path, to classify the activity of different vibrational modes in a reactive encounter, to gain deeper insight into the concept of vibrational adiabaticity, and to elucidate the intermode coupling in the transition-state region. This exploratory approach not only opens up an avenue to understand polyatomic reaction dynamics, even for motions at the molecular level in the fleeting transition-state region, but it also leads to a generalization of Polanyi's rules to reactions involving a polyatomic molecule.
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25
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Rangel C, Corchado JC, Espinosa-García J. Quasi-classical trajectory calculations in asymmetrically substituted polyatomic systems of the type A + CX3Y → products: the H + CH3Cl hydrogen abstraction reaction channel. Phys Chem Chem Phys 2008; 10:6776-86. [DOI: 10.1039/b809999e] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
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26
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Kawamata H, Tauro S, Liu K. Unravelling the reactivity of antisymmetric stretch-excited CH4 with Cl by-product pair-correlation measurements. Phys Chem Chem Phys 2008; 10:4378-82. [DOI: 10.1039/b809209e] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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27
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Nyman G, Zhou J, Zhang B, Liu K. Crossed-Beam and Quantum Dynamics Studies of the Reaction Cl + CHD3. Isr J Chem 2007. [DOI: 10.1560/ijc.47.1.1] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
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Espinosa-García J. Role of the C-H stretch mode excitation in the dynamics of the Cl + CHD3 reaction: a quasi-classical trajectory calculation. J Phys Chem A 2007; 111:9654-61. [PMID: 17824676 DOI: 10.1021/jp073549u] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
To analyze the effect of the C-H stretch mode excitation on the dynamics of the Cl + CHD3 gas-phase abstraction reaction, an exhaustive state-to-state dynamics study was performed. This reaction can evolve along two channels: H-abstraction, CD3 + ClH, and D-abstraction, CHD2 + ClD. On an analytical potential energy surface constructed previously by our group, named PES-2005, quasi-classical trajectory calculations were performed at a collision energy of 0.18 eV, including corrections to avoid zero-point energy leakage along the trajectories. First, strong coupling between different vibrational modes in the entry valley was observed; i.e., the reaction is vibrationally nonadiabatic. Second, for the ground-state CHD3(nu=0) reaction, the diatomic fragments appeared in their ground states, and the H- and D-abstraction reactions showed similar reactivities. However, when the reactivity per atom is considered, the H is three times more reactive than the D atom. Third, when the C-H stretch mode is excited by one quantum, CHD3(nu1=1), the H-abstraction is strongly favored, and the C-H stretch excitation is maintained in the product CHD2(nu1=1) + ClD channel; i.e., the reaction shows mode selectivity, reproducing the experimental evidence, and also the reactivity of the vibrational ground state is increased, in agreement with experiment. Fourth, the state-to-state angular distributions of the CD3 and CHD2 products showed the products to be practically sideways for the reactant ground state, while the C-H excitation yielded a more forward scattering, reproducing the experimental data. The role of the zero-point energy correction was also analyzed, and we find that the dynamics results are very sensitive on how the ZPE issue is treated. Finally, a comparison is made with the similar H + CHD3(nu1=0,1) and Cl + CH4(nu1=0,1) reactions.
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Affiliation(s)
- J Espinosa-García
- Departamento de Química Física, Universidad de Extremadura, 06071 Badajoz, Spain. joaquin.unex.es
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Espinosa-García J. Quasi-classical trajectory calculations analyzing the dynamics of the C-H stretch mode excitation in the H+CHD3 reaction. J Phys Chem A 2007; 111:5792-9. [PMID: 17567117 DOI: 10.1021/jp072562b] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
A state-to-state dynamics study was performed at a collision energy of 1.53 eV to analyze the effect of the C-H stretch mode excitation on the dynamics of the gas-phase H+CHD3 reaction, which can evolve along two channels, H-abstraction, CD3+H2, and D-abstraction, CHD2+HD. Quasi-classical trajectory calculations were performed on an analytical potential energy surface constructed previously by our group. First, strong coupling between different vibrational modes in the entry channel was observed; i.e., the reaction is non-adiabatic. Second, we found that the C-H stretch mode excitation has little influence on the product rotational distributions for both channels, and on the vibrational distribution for the CD3+H2 channel. However, it has significant influence on the product vibrational distribution for the CHD2+HD channel, where the C-H stretch excitation is maintained in the products, i.e., the reaction shows mode selectivity, reproducing the experimental evidence. Third, the C-H stretch excitation by one quantum increases the reactivity of the vibrational ground-state, in agreement with experiment. Fourth, the state-to-state angular distributions of the CD3 and CHD2 products are reported, finding that for the reactant ground-state the products are practically sideways, whereas the C-H excitation yields a more forward scattering.
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Affiliation(s)
- J Espinosa-García
- Departamento de Química Física, Universidad de Extremadura, 06071 Badajoz, Spain.
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30
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Teslja A, Valentini JJ. State-to-state reaction dynamics: A selective review. J Chem Phys 2006; 125:132304. [PMID: 17029423 DOI: 10.1063/1.2354466] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
A selective review of state-to-state reaction dynamics experiments is presented. The review focuses on three classes of reactions that exemplify the rich history and illustrate the current state of the art in such work. These three reactions are (1) the hydrogen exchange reaction, H+H2-->H2+H and its isotopomers; (2) the H+RH-->H2+R reactions, where RH is an alkane, beginning with H+CH4-->H2+CH3 and extending to much larger alkanes; and (3) the Cl+RH-->HCl+R reactions, principally Cl+CH4-->HCl+CH3. We describe the experiments, discuss their results, present comparisons with theory, and introduce heuristic models.
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Affiliation(s)
- Alexey Teslja
- Department of Chemistry, Columbia University, New York, New York 10027, USA
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Rangel C, Sansón J, Corchado JC, Espinosa-Garcia J, Nyman G. Product Angular Distribution for the H + CD4→ HD + CD3Reaction. J Phys Chem A 2006; 110:10715-9. [PMID: 16970361 DOI: 10.1021/jp063298+] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Using an analytical potential energy surface previously developed by our group, namely PES-2002, we analyzed the gas-phase reaction between a hydrogen atom and perdeuterated methane. We studied the effect of quasiclassical trajectory (QCT) and reduced dimensionality quantum-scattering (QM) calculations, with their respective limitations, on CD3 product angular distributions in the collision energy range 16.1-46.1 kcal x mol(-1). It was found that at low collision energy, 16.1 kcal x mol(-1), both the QCT and QM calculations yielded forward scattered CD3 products, i.e., a rebound mechanism. However, at high energies only the QM calculations on the PES-2002 surface reproduced the angular scattering found experimentally.
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Affiliation(s)
- C Rangel
- Departamento de Química Física, Universidad de Extremadura, 06071 Badajoz, Spain
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Rangel C, Corchado JC, Espinosa-García J. Quasi-Classical Trajectory Calculations Analyzing the Reactivity and Dynamics of Asymmetric Stretch Mode Excitations of Methane in the H + CH4 Reaction. J Phys Chem A 2006; 110:10375-83. [PMID: 16942042 DOI: 10.1021/jp063118w] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
An exhaustive dynamics study was performed at two collision energies, 1.52 and 2.20 eV, analyzing the effects of the asymmetric (nu3) stretch mode excitation in the reactivity and dynamics of the gas-phase H + CH4 reaction. Quasi-classical trajectory (QCT) calculations, including corrections to avoid zero-point energy leakage along the trajectories, were performed on an analytical potential energy surface previously developed by our group. First, strong coupling between different vibrational modes in the entry channel was observed, indicating that energy can flow between these modes, and therefore that they do not preserve their adiabatic character along the reaction path; i.e., the reaction is nonadiabatic. Second, we found that the reactant vibrational excitation has a significant influence on the vibrational and rotational product distributions. With respect to the vibrational distribution, our results confirm the purely qualitative experimental evidence, although the theoretical results presented here are also quantitative. The rotational distributions are predictive, because no experimental data have been reported. Third, with respect to the reactivity, we found that the nu3 mode excitation by one quantum is more reactive than the ground state by a factor of about 2, independently of the collision energy, and in agreement with the experimental measurement of 3.0 +/- 1.5. Fourth, the state-to-state angular distributions of the products reproduce the experimental behavior at 1.52 eV, where the CH3 products scatter sideways and backward. At 2.20 eV this experimental information is not available, and therefore the results reported here are again predictive. The satisfactory reproduction of a great variety of experimental data by the present QCT study lends confidence to the potential energy surface constructed by our group and to those results whose accuracy cannot be checked by comparison with experiment.
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Affiliation(s)
- Cipriano Rangel
- Departamento de Química Física, Universidad de Extremadura, 06071 Badajoz, Spain
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Rangel C, Navarrete M, Corchado JC, Espinosa-García J. Potential energy surface, kinetics, and dynamics study of the Cl+CH4→HCl+CH3 reaction. J Chem Phys 2006; 124:124306. [PMID: 16599673 DOI: 10.1063/1.2179067] [Citation(s) in RCA: 57] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
A modified and recalibrated potential energy surface for the gas-phase Cl+CH4-->HCl+CH3 reaction is reported and tested. It is completely symmetric with respect to the permutation of the four methane hydrogen atoms and is calibrated with respect to updated experimental and theoretical stationary point properties and experimental forward thermal rate constants. From the kinetics point of view, the forward and reverse thermal rate constants and the activation energies were calculated using the variational transition-state theory with semiclassical transmission coefficients over a wide temperature range of 150-2500 K. The theoretical results reproduce the available experimental data, with a small curvature of the Arrhenius plot which indicates the role of tunneling in this hydrogen abstraction reaction. A dynamics study was also performed on this PES using quasiclassical trajectory (QCT) calculations, including corrections to avoid zero-point energy leakage along the trajectories. First, we found a noticeable internal energy in the coproduct methyl radical, both in the ground-state [CH4 (v=0)] and vibrationally excited [CH4 (v=1)] reactions. This CH3 internal energy was directly precluded in some experiments or oversimplified in previous theoretical studies using pseudotriatomic models. Second, our QCT calculations give HCl rotational distributions slightly hotter than those in experiment, but correctly describing the experimental trend of decreasing the HCl product rotation excitation in going from HCl (v'=0) to HCl (v'=1) for the CH4 (v=1) reaction. Third, the state specific scattering distributions present a reasonable agreement with experiment, although they tend to make the reaction more forward and backward scattered than found experimentally probably because of the hotter rotational distribution and the deficiencies of the QCT methods.
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Affiliation(s)
- Cipriano Rangel
- Departamento de Química Física, Universidad de Extremadura, 06071 Badajoz, Spain
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Sansón J, Corchado JC, Rangel C, Espinosa-Garcia J. Quasiclassical trajectory calculations comparing the reactivity and dynamics of symmetric and asymmetric stretch and the role of the bending mode excitations of methane in the Cl+CH4 reaction. J Chem Phys 2006; 124:74312. [PMID: 16497041 DOI: 10.1063/1.2172608] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023] Open
Abstract
To analyze the effects of the symmetric (nu(1)) and asymmetric (nu(3)) stretch mode excitations and the role played by the "umbrella" bending (nu(4)) mode excitation in the reactivity and the dynamics of the gas-phase Cl+CH(4) reaction, an exhaustive dynamics study was performed. Quasiclassical trajectory (QCT) calculations, including corrections to avoid zero-point energy leakage along the trajectories, were used in this work on an analytical potential energy surface previously developed by Espinosa-Garcia et al. [J. Chem. Phys. (to be published)]. First, with respect to the reactivity, we found that the nu(1) mode excitation is more reactive than the nu(3) mode by a factor of 1.20, in agreement with the experimental tendency between these modes. The inclusion of the nu(4) bending mode practically does not affect this relative reactivity, (nu(1+)nu(4))(nu(3+)nu(4)) = 1.16. Second, with respect to the dynamics (rotovibrational and angular distributions of the products), the two stretch modes, nu(1) and nu(3), give very similar pictures, reproducing the experimental behavior, and the nu(4) "umbrella" mode does not affect the dynamics. The satisfactory reproduction (always qualitatively acceptable and sometimes even quantitatively) of a great variety of experimental data by the QCT study presented here lends confidence to the potential energy surface constructed by Espinosa-Garcia et al. [J. Chem. Phys. (to be published)].
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Affiliation(s)
- J Sansón
- Departamento de Química Física, Universidad de Extremadura, Badajoz, Spain
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35
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Rangel C, Espinosa-García J, Corchado JC. On the Accuracy of an Analytical Potential Energy Surface for the CH4 + Cl Reaction and the Quasi-Classical Trajectory Calculations for Thermal Rate Constants. J Phys Chem A 2005. [DOI: 10.1021/jp053481n] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Cipriano Rangel
- Departamento de Química Física, Universidad de Extremadura, 06071 Badajoz, Spain
| | | | - José C. Corchado
- Departamento de Química Física, Universidad de Extremadura, 06071 Badajoz, Spain
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36
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Garcia E, Sánchez C, Saracibar A, Laganà A. A Full Dimensional Quasiclassical Trajectory Study of Cl + CH4 Rate Coefficients. J Phys Chem A 2004. [DOI: 10.1021/jp049154h] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Ernesto Garcia
- Departamento de Química Física, Universidad del País Vasco, 01006 Vitoria, Spain
| | - Carlos Sánchez
- Departamento de Química Física, Universidad del País Vasco, 01006 Vitoria, Spain
| | - Amaia Saracibar
- Departamento de Química Física, Universidad del País Vasco, 01006 Vitoria, Spain
| | - Antonio Laganà
- Departamento de Química Física, Universidad del País Vasco, 01006 Vitoria, Spain
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37
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Murray C, Orr-Ewing * AJ. The dynamics of chlorine-atom reactions with polyatomic organic molecules. INT REV PHYS CHEM 2004. [DOI: 10.1080/01442350412331329166] [Citation(s) in RCA: 77] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
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38
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Zhou J, Lin JJ, Zhang B, Liu K. On the Cl*(2P1/2) Reactivity and the Effect of Bend Excitation in the Cl + CH4/CD4 Reactions. J Phys Chem A 2004. [DOI: 10.1021/jp040128t] [Citation(s) in RCA: 78] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Jingang Zhou
- Institute of Atomic and Molecular Sciences (IAMS), Academia Sinica, P.O. Box 23-166, Taipei, Taiwan 106, Department of Applied Chemistry, National Chiao Tung University, Hsinchu, Taiwan 300, and Department of Chemistry, National Taiwan University, Taipei, Taiwan 106
| | - Jim J. Lin
- Institute of Atomic and Molecular Sciences (IAMS), Academia Sinica, P.O. Box 23-166, Taipei, Taiwan 106, Department of Applied Chemistry, National Chiao Tung University, Hsinchu, Taiwan 300, and Department of Chemistry, National Taiwan University, Taipei, Taiwan 106
| | - Bailin Zhang
- Institute of Atomic and Molecular Sciences (IAMS), Academia Sinica, P.O. Box 23-166, Taipei, Taiwan 106, Department of Applied Chemistry, National Chiao Tung University, Hsinchu, Taiwan 300, and Department of Chemistry, National Taiwan University, Taipei, Taiwan 106
| | - Kopin Liu
- Institute of Atomic and Molecular Sciences (IAMS), Academia Sinica, P.O. Box 23-166, Taipei, Taiwan 106, Department of Applied Chemistry, National Chiao Tung University, Hsinchu, Taiwan 300, and Department of Chemistry, National Taiwan University, Taipei, Taiwan 106
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Bechtel HA, Camden JP, Brown DJA, Zare RN. Comparing the dynamical effects of symmetric and antisymmetric stretch excitation of methane in the Cl+CH4 reaction. J Chem Phys 2004; 120:5096-103. [PMID: 15267378 DOI: 10.1063/1.1647533] [Citation(s) in RCA: 74] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
The effects of two nearly isoenergetic C-H stretching motions on the gas-phase reaction of atomic chlorine with methane are examined. First, a 1:4:9 mixture of Cl(2), CH(4), and He is coexpanded into a vacuum chamber. Then, either the antisymmetric stretch (nu(3)=3019 cm(-1)) of CH(4) is prepared by direct infrared absorption or the infrared-inactive symmetric stretch (nu(1)=2917 cm(-1)) of CH(4) is prepared by stimulated Raman pumping. Photolysis of Cl(2) at 355 nm generates fast Cl atoms that initiate the reaction with a collision energy of 1290+/-175 cm(-1) (0.16+/-0.02 eV). Finally, the nascent HCl or CH(3) products are detected state-specifically via resonance enhanced multiphoton ionization and separated by mass in a time-of-flight spectrometer. We find that the rovibrational distributions and state-selected differential cross sections of the HCl and CH(3) products from the two vibrationally excited reactions are nearly indistinguishable. Although Yoon et al. [J. Chem. Phys. 119, 9568 (2003)] report that the reactivities of these two different types of vibrational excitation are quite different, the present results indicate that the reactions of symmetric-stretch excited or antisymmetric-stretch excited methane with atomic chlorine follow closely related product pathways. Approximately 37% of the reaction products are formed in HCl(v=1,J) states with little rotational excitation. At low J states these products are sharply forward scattered, but become almost equally forward and backward scattered at higher J states. The remaining reaction products are formed in HCl(v=0,J) and have more rotational excitation. The HCl(v=0,J) products are predominantly back and side scattered. Measurements of the CH(3) products indicate production of a non-negligible amount of umbrella bend excited methyl radicals primarily in coincidence with the HCl(v=0,J) products. The data are consistent with a model in which the impact parameter governs the scattering dynamics.
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Affiliation(s)
- Hans A Bechtel
- Department of Chemistry, Stanford University, Stanford, California 94305-5080, USA
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Bechtel HA, Kim ZH, Camden JP, Zare RN. Bond and mode selectivity in the reaction of atomic chlorine with vibrationally excited CH2D2. J Chem Phys 2004; 120:791-9. [PMID: 15267915 DOI: 10.1063/1.1630961] [Citation(s) in RCA: 62] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023] Open
Abstract
The title reaction is investigated by co-expanding a mixture of Cl2 and CH2D2 into a vacuum chamber and initiating the reaction by photolyzing Cl2 with linearly polarized 355 nm light. Excitation of the first C-H overtone of CH2D2 leads to a preference for hydrogen abstraction over deuterium abstraction by at least a factor of 20, whereas excitation of the first C-D overtone of CH2D2 reverses this preference by at least a factor of 10. Reactions with CH2D2 prepared in a local mode containing two quanta in one C-H oscillator /2000>- or in a local mode containing one quantum each in two C-H oscillators /1100> lead to products with significantly different rotational, vibrational, and angular distributions, although the vibrational energy for each mode is nearly identical. The Cl+CH2D2/2000>- reaction yields methyl radical products primarily in their ground state, whereas the Cl+CH2D2/1100> reaction yields methyl radical products that are C-H stretch excited. The HCl(v=1) rotational distribution from the Cl+CH2D2/2000>- reaction is significantly hotter than the HCl(v=1) rotational distribution from the Cl+CH2D2/1100> reaction, and the HCl(v=1) differential cross-section (DCS) of the Cl+CH2D2/2000>- reaction is more broadly side scattered than the HCl(v=1) DCS of the Cl+CH2D2/1100> reaction. The results can be explained by a simple spectator model and by noting that the /2000>- mode leads to a wider cone of acceptance for the reaction than the /1100> mode. These measurements represent the first example of mode selectivity observed in a differential cross section, and they demonstrate that vibrational excitation can be used to direct the reaction pathway of the Cl+CH2D2 reaction.
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Affiliation(s)
- Hans A Bechtel
- Department of Chemistry, Stanford University, Stanford, California 94305-5080, USA
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41
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Rudić S, Murray C, Harvey JN, Orr-Ewing AJ. On-the-flyab initiotrajectory calculations of the dynamics of Cl atom reactions with methane, ethane and methanol. J Chem Phys 2004; 120:186-98. [PMID: 15267276 DOI: 10.1063/1.1629670] [Citation(s) in RCA: 62] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
The dynamics of Cl atom reactions with methane, ethane, and methanol have been studied by calculation of quasi-classical trajectories, with computation of potential energies and gradients only at the geometries through which the trajectories pass. Trajectories were started from the transition state, with 2 kcal mol(-1) of energy given to the mode with an imaginary frequency (representing the reaction coordinate at the transition state) and inclusion of zero-point energy in some or all of the remaining vibrational modes. The trajectories were propagated as far as separated products, with the majority of potential energy calculations performed at the HF/6-31G level of theory. The rotational quantum state population distributions of the HCl products from the reactions of Cl atoms with methane, ethane and methanol peaked at J'=1, 2, and 6, respectively. The calculations thereby exhibit somewhat greater rotational excitation than is found experimentally, but correctly describe the trend of increasing HCl product rotation for the three respective reactions. In agreement with previous observations, only 4% of the energy available to the products of the reaction of Cl atoms with methane was channeled into CH3 radical internal energy, and 1% into HCl rotation, with 92% ending up as translational energy. For the reaction of Cl atoms with ethane and with methanol, the corresponding values for radical internal energy, HCl rotation and product translation are 21, 3, and 78%, and 46, 13, and 42%, respectively. For the latter two reactions, the radical internal energy is mostly accounted for by rotational motion. The clear increase in rotational excitation of the HCl products from the Cl atom reaction with methanol is explained in terms of a dipole-dipole interaction between the departing polar fragments. A smaller set of more computationally expensive trajectory calculations using potentials and gradients from the MP2/6-311G(d,p) level of theory were performed for reactions of Cl atoms with methanol, and give results in better agreement with experimentally measured HCl rotational excitation, consistent with the model of dipole-induced product rotation because the MP2/6-311G(d,p) calculations give smaller dipole moments for both products than the HF/6-31G calculations. The calculated angles between the rotational angular momentum vectors and recoil velocities of the radical peak sharply at 90 degrees for the reactions of Cl atoms with ethane and methanol, but exhibit a much broader distribution for reaction with methane.
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Affiliation(s)
- Svemir Rudić
- School of Chemistry, University of Bristol, Cantock's Close, Bristol BS8 1TS, United Kingdom
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42
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Kim ZH, Bechtel HA, Zare RN. Channel-specific angular distributions of HCl and CH3 products from the reaction of atomic chlorine with stretch-excited methane. J Chem Phys 2002. [DOI: 10.1063/1.1493192] [Citation(s) in RCA: 54] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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Abstract
This paper presents an analysis of the reaction of Cl with CH(4) by combining measurements of thermal rate constants and state-dependent reaction cross sections. State-dependent measurements have shown that the reaction probability is enhanced by vibrational excitation of CH(4). Measured thermal rate constants were fit with a model incorporating this information. The results provide estimates of rate constants at extreme temperatures and information about the temperature and collision energy dependence of the vibrational enhancement.
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Affiliation(s)
- H A Michelsen
- Combustion Research Facility, Sandia National Laboratories, MS 9055, P.O. Box 969, Livermore, California 94551, USA
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Liu K. Crossed-beam studies of neutral reactions: state-specific differential cross sections. Annu Rev Phys Chem 2001; 52:139-64. [PMID: 11326062 DOI: 10.1146/annurev.physchem.52.1.139] [Citation(s) in RCA: 201] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Crossed-molecular-beam and laser techniques have enabled experimentalists to measure the state-resolved differential cross sections of elementary chemical reactions. This article reviews recent progress in this area. Particular emphasis is placed on some intriguing physical phenomena associated with a few benchmark reactions and how these measurements help in answering fundamental questions about reaction dynamics. We examine specifically the geometric phase effects in the reaction H + D2, the dynamical resonance phenomenon in F + HD, the unusually large spin-orbit reactivity in Cl((2)P) + H2, the insertion reaction O((1)D) + H2, and the mode-specific reactivity in Cl + CH4(nu). The give-and-take between experiment and theory in unraveling the physical picture of the dynamics is illustrated throughout this review.
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Affiliation(s)
- K Liu
- Institute of Atomic and Molecular Sciences, Academia Sinica, Taipei, Taiwan 10764, Republic of China.
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Valentini JJ. State-to-state chemical reaction dynamics in polyatomic systems: case studies. Annu Rev Phys Chem 2001; 52:15-39. [PMID: 11326057 DOI: 10.1146/annurev.physchem.52.1.15] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
This review illustrates the experimental study of chemical reaction dynamics using methods that select the quantum states and energy of the reactants and determine the quantum states and energy of the products. The focus is reaction dynamics in systems in which at least one of the reactants or products is a polyatomic molecule. The approach taken is to select four prototype reaction systems as case studies to demonstrate the detail of information and insight that can come from such experiments. Thus, the review is selective and neither claims nor attempts to be comprehensive. Reference to and discussion of theoretical reaction dynamics are included where computational results directly connect with the experiments.
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Affiliation(s)
- J J Valentini
- Department of Chemistry, Columbia University, New York, New York 10027, USA.
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Kornweitz H, Persky A. Three-center semi-empirical potential energy surfaces for the reactions F+H2O and F+OH. Chem Phys Lett 2000. [DOI: 10.1016/s0009-2614(00)01177-5] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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Michelsen HA, Simpson WR. Relating State-Dependent Cross Sections to Non-Arrhenius Behavior for the Cl + CH4 Reaction. J Phys Chem A 2000. [DOI: 10.1021/jp0016784] [Citation(s) in RCA: 38] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Affiliation(s)
- Hope A. Michelsen
- Combustion Research Facility, Sandia National Laboratories, MS 9055, P.O. Box 969, Livermore, California 94551
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Skokov S, Bowman JM. Quantum calculations of the effect of bend excitation in methane on the HCl rotational distribution in the reaction CH4+Cl→CH3+HCl. J Chem Phys 2000. [DOI: 10.1063/1.1308049] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
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Zhang L, Chen MD, Wang ML, Han KL. Product rotational polarization: Stereodynamics of the reaction Cl(2P3/2)+CD4(v=0,j=0)→DCl(v′=0,j′=1)+CD3. J Chem Phys 2000. [DOI: 10.1063/1.480523] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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