1
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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, 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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3
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Pan H, Liu K. Pair-Correlated Imaging of Cl + CH 3D( v4, v1-I, v1-II = 1, | jK⟩) → CH 2D( vi) + HCl( v). J Phys Chem A 2021; 125:6731-6738. [PMID: 34333974 DOI: 10.1021/acs.jpca.1c05373] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The title reactions were studied at a collisional energy of 10.0 kcal mol-1 in a crossed-beam, product-imaging experiment. In terms of integral cross sections, all three CH3-stretching excited CH3D(vCH3 = 1) reagents promote the reactivity in forming the predominant product pair of (vCH2D, vHCl)s = (00, 0/1)s with a prominent mode-propensity of v4 > v1-I > v1-II, where v4 denotes the degenerate mode of CH3 asymmetric stretch and v1-I and v1-II are a pair of Fermi-coupled, symmetric-stretch states. The vibrationally excited CH2D product pairs of (61, 0)s, (11, 0)s, and (31, 0)s appear to be minor channels and display a reverse propensity of v4 < v1-I ≈ v1-II for (61, 0)s, while v4 > v1-I for (11, 0)s. Based on the observed angular distributions, we conjecture that, irrespective of the initial mode of excitation, the (00, 0)s product pair proceeds by a direct abstraction of the peripheral type, whereas the (00,1)s pair is mediated via a resonance pathway. Intriguingly, the angular distributions of the excited product pairs-(61, 0)s, (11, 0)s, and (31, 0)s-are remarkably similar and comprise the traits of both the peripheral mechanism and resonance pathway. Possible interpretation and implication are suggested. In addition, due to the spectral overlap of the REMPI bands and heavily congested image features, a robust data analysis method is developed, which enables us to extract the dynamics attributes of a weak feature buried in the proximate, more intense ones with high fidelity.
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Affiliation(s)
- Huilin Pan
- 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, Chinese Academy of Sciences, Dalian 116023, P. R. China.,Aerosol Science Research Center, National Sun Yat-sen University, Kaohsiung, Taiwan 80424
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4
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Tian L, Song H, Yang M. Effects of bending excitation on the reaction dynamics of fluorine atoms with ammonia. Phys Chem Chem Phys 2021; 23:2715-2722. [PMID: 33491710 DOI: 10.1039/d0cp05790h] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Vibrational excitation has been established as an efficient way to control the chemical reaction outcome. Stretching vibration of polyatomic molecules is believed to be efficient to promote abstraction reactions since energy is placed directly into the breaking bond. In this work, we report on a counterexample showing that exciting the low-frequency umbrella bending mode of ammonia enhances its reaction with fluorine atoms much more than exciting the high-frequency symmetric or asymmetric stretching mode over a wide range of collision energy, validated using both quasiclassical trajectory simulations and full-dimensional quantum dynamics calculations under the centrifugal-sudden approximation. This interesting mode-specific reaction dynamic originates from the increased chance of capturing the fluorine atom by ammonia due to the enlarged attractive interaction between them and the enhancement of the direct stripping reaction mediated by two submerged barriers.
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Affiliation(s)
- Li Tian
- State Key Laboratory of Magnetic Resonance and Atomic and Molecular Physics, Wuhan Institute of Physics and Mathematics, Innovation Academy for Precision Measurement Science and Technology, Chinese Academy of Sciences, Wuhan 430071, China. and College of Physical Science and Technology, Huazhong Normal University, Wuhan 430079, China
| | - Hongwei Song
- State Key Laboratory of Magnetic Resonance and Atomic and Molecular Physics, Wuhan Institute of Physics and Mathematics, Innovation Academy for Precision Measurement Science and Technology, Chinese Academy of Sciences, Wuhan 430071, China.
| | - Minghui Yang
- State Key Laboratory of Magnetic Resonance and Atomic and Molecular Physics, Wuhan Institute of Physics and Mathematics, Innovation Academy for Precision Measurement Science and Technology, Chinese Academy of Sciences, Wuhan 430071, China.
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5
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Liu R, Song H, Qi J, Yang M. A ten-dimensional quantum dynamics model for the X + YCAB 2 reaction: Application to H + CH 4 reaction. J Chem Phys 2020; 153:224119. [DOI: 10.1063/5.0033851] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Affiliation(s)
- Rui Liu
- Key Laboratory of Magnetic Resonance in Biological Systems, National Center for Magnetic Resonance in Wuhan, State Key Laboratory of Magnetic Resonance and Atomic and Molecular Physics, Innovation Academy for Precision Measurement Science and Technology, Wuhan Institute of Physics and Mathematics, Chinese Academy of Sciences, Wuhan 430071, China
- China Engineering Research Center of Nano-Geomaterials of Ministry of Education, Faculty of Materials Science and Chemistry, China University of Geosciences, Wuhan 430074, China
| | - Hongwei Song
- Key Laboratory of Magnetic Resonance in Biological Systems, National Center for Magnetic Resonance in Wuhan, State Key Laboratory of Magnetic Resonance and Atomic and Molecular Physics, Innovation Academy for Precision Measurement Science and Technology, Wuhan Institute of Physics and Mathematics, Chinese Academy of Sciences, Wuhan 430071, China
| | - Ji Qi
- Key Laboratory of Magnetic Resonance in Biological Systems, National Center for Magnetic Resonance in Wuhan, State Key Laboratory of Magnetic Resonance and Atomic and Molecular Physics, Innovation Academy for Precision Measurement Science and Technology, Wuhan Institute of Physics and Mathematics, Chinese Academy of Sciences, Wuhan 430071, China
| | - Minghui Yang
- Key Laboratory of Magnetic Resonance in Biological Systems, National Center for Magnetic Resonance in Wuhan, State Key Laboratory of Magnetic Resonance and Atomic and Molecular Physics, Innovation Academy for Precision Measurement Science and Technology, Wuhan Institute of Physics and Mathematics, Chinese Academy of Sciences, Wuhan 430071, China
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6
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Xin R, Pan M, Song H, Yang M. Mode- and Bond-Selected Reaction of H with Local Mode Molecule HDS. J Phys Chem A 2020; 124:10162-10170. [PMID: 33252233 DOI: 10.1021/acs.jpca.0c09415] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Understanding mode- and bond-selected dynamics of elementary chemical reactions is of central importance in molecular reaction dynamics. The initial state-selected time-dependent wave packet method is employed to study the mode and bond selectivity, isotopic branching ratio, and temperature dependence of rate constants of the two-channel reaction of H with local mode molecule HDS. For the abstraction channel, fundamental excitation of the HS (DS) bond of the reactant HDS significantly enhances the H-abstraction (D-abstraction) reaction, whose efficacy is higher than the same amount of translational energy except at low energies just above the energy threshold. This is in sharp contrast to the prediction of Polanyi rules: translational energy is more efficient than vibrational energy in enhancing a reaction with an early barrier. The recent sudden vector projection model is then applied to rationalize the observed mode specificity, which, however, shows that the translational mode vector has a larger coupling with the reaction coordinate than the stretching vector of the active bond, implying a reversed relative efficacy on promoting the reaction as well. In contrast, the mode and bond specificity for the exchange channel is not as strong as for the abstraction channel due to the regulation of the shallow well along the reaction path.
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Affiliation(s)
- Rong Xin
- State Key Laboratory of Magnetic Resonance and Atomic and Molecular Physics, Wuhan Institute of Physics and Mathematics, Innovation Academy for Precision Measurement Science and Technology, Chinese Academy of Sciences, Wuhan 430071, China.,College of Physical Science and Technology, Huazhong Normal University, Wuhan 430079, China
| | - Mengyi Pan
- State Key Laboratory of Magnetic Resonance and Atomic and Molecular Physics, Wuhan Institute of Physics and Mathematics, Innovation Academy for Precision Measurement Science and Technology, Chinese Academy of Sciences, Wuhan 430071, China.,College of Physical Science and Technology, Huazhong Normal University, Wuhan 430079, China
| | - Hongwei Song
- State Key Laboratory of Magnetic Resonance and Atomic and Molecular Physics, Wuhan Institute of Physics and Mathematics, Innovation Academy for Precision Measurement Science and Technology, Chinese Academy of Sciences, Wuhan 430071, China
| | - Minghui Yang
- State Key Laboratory of Magnetic Resonance and Atomic and Molecular Physics, Wuhan Institute of Physics and Mathematics, Innovation Academy for Precision Measurement Science and Technology, Chinese Academy of Sciences, Wuhan 430071, China
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7
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Michaelsen T, Bastian B, Strübin P, Meyer J, Wester R. Proton transfer dynamics modified by CH-stretching excitation. Phys Chem Chem Phys 2020; 22:12382-12388. [PMID: 32319988 DOI: 10.1039/d0cp00727g] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Gaining insight how specific rovibrational states influence reaction kinetics and dynamics is a fundamental goal of physical chemistry. Purely statistical approaches often fail to predict the influence of a specific state on the reaction outcome, evident in a great number of both experimental and theoretical studies. Most detailed insight in atomistic reaction mechanisms is achieved using accurate collision experiments and high level dynamics calculations. For ion-molecule reactions such experiments are scarce. Here we show the influence of symmetric CH-stretching vibration on the rate and dynamics of proton transfer in the reaction of F- + CH3I. We find a pronounced shift in the reaction dynamics for excited reactions from indirect to preferred direct dynamics at higher collision energy. Moreover, excited reactions occur at larger impact parameters. Finally, we compare vibrational excitation with collision energy and find that vibration is overall more efficient in promoting reactivity, which agrees with recent theoretical calculations.
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Affiliation(s)
- Tim Michaelsen
- Institut für Ionenphysik und Angewandte Physik, Universität Innsbruck, Technikerstraße 25/3, 6020 Innsbruck, Austria.
| | - Björn Bastian
- Institut für Ionenphysik und Angewandte Physik, Universität Innsbruck, Technikerstraße 25/3, 6020 Innsbruck, Austria.
| | - Patrick Strübin
- Institut für Ionenphysik und Angewandte Physik, Universität Innsbruck, Technikerstraße 25/3, 6020 Innsbruck, Austria.
| | - Jennifer Meyer
- Institut für Ionenphysik und Angewandte Physik, Universität Innsbruck, Technikerstraße 25/3, 6020 Innsbruck, Austria.
| | - Roland Wester
- Institut für Ionenphysik und Angewandte Physik, Universität Innsbruck, Technikerstraße 25/3, 6020 Innsbruck, Austria.
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8
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Michaelsen T, Bastian B, Ayasli A, Strübin P, Meyer J, Wester R. Influence of Vibrational Excitation on the Reaction of F - with CH 3I: Spectator Mode Behavior, Enhancement, and Suppression. J Phys Chem Lett 2020; 11:4331-4336. [PMID: 32383877 PMCID: PMC7277560 DOI: 10.1021/acs.jpclett.0c01095] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2020] [Accepted: 05/04/2020] [Indexed: 06/10/2023]
Abstract
Detailed insight into chemical reaction dynamics can be obtained by probing the effect of mode-specific vibrational excitation. Suppression or enhancement of reactivity is possible as is already known from the Polanyi rules. In the reaction F- + CH3I, we found vibrational enhancement, suppression, and spectator mode dynamics in the four different reaction channels. For this system we have probed the influence of symmetric CH-stretching vibration over a collision energy range of 0.7-2.3 eV. Proton transfer is significantly enhanced, while for the nucleophilic substitution channel the spectator mode dynamics at lower collision energies unexpectedly move toward enhancement at higher collision energies. In contrast, for two halide abstraction channels, forming FI- and FHI-, we found an overall suppression, which stems mainly from a suppression of the FHI- product. We compare these results to quasiclassical trajectory calculations and with the sudden vector projection model.
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Affiliation(s)
- Tim Michaelsen
- Institut für Ionenphysik und Angewandte Physik, Universität Innsbruck, Technikerstraße 25/3, 6020 Innsbruck, Austria
| | - Björn Bastian
- Institut für Ionenphysik und Angewandte Physik, Universität Innsbruck, Technikerstraße 25/3, 6020 Innsbruck, Austria
| | - Atilay Ayasli
- Institut für Ionenphysik und Angewandte Physik, Universität Innsbruck, Technikerstraße 25/3, 6020 Innsbruck, Austria
| | - Patrick Strübin
- Institut für Ionenphysik und Angewandte Physik, Universität Innsbruck, Technikerstraße 25/3, 6020 Innsbruck, Austria
| | - Jennifer Meyer
- Institut für Ionenphysik und Angewandte Physik, Universität Innsbruck, Technikerstraße 25/3, 6020 Innsbruck, Austria
| | - Roland Wester
- Institut für Ionenphysik und Angewandte Physik, Universität Innsbruck, Technikerstraße 25/3, 6020 Innsbruck, Austria
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9
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Liu Y, Li J. An accurate potential energy surface and ring polymer molecular dynamics study of the Cl + CH4→ HCl + CH3reaction. Phys Chem Chem Phys 2020; 22:344-353. [DOI: 10.1039/c9cp05693a] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Thermal rate coefficients for the Cl + CH4/CD4reactions were studied on a new full-dimensional accurate potential energy surface with the spin–orbit corrections considered in the entrance channel.
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Affiliation(s)
- Yang Liu
- School of Chemistry and Chemical Engineering
- Chongqing University
- Chongqing 401331
- China
| | - Jun Li
- School of Chemistry and Chemical Engineering
- Chongqing University
- Chongqing 401331
- China
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10
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Liu R, Song HW, Yang MH. Understanding rotational mode specificity in the O(3P)+CHD3→ OH+CD3 reaction by simple reactant alignment pictures. CHINESE J CHEM PHYS 2019. [DOI: 10.1063/1674-0068/cjcp1810238] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022]
Affiliation(s)
- Rui Liu
- Key Laboratory of Magnetic Resonance in Biological Systems, National Center for Magnetic Resonance in Wuhan, State Key Laboratory of Magnetic Resonance and Atomic and Molecular Physics, Wuhan Institute of Physics and Mathematics, Chinese Academy of Sciences, Wuhan 430071, China
| | - Hong-wei Song
- Key Laboratory of Magnetic Resonance in Biological Systems, National Center for Magnetic Resonance in Wuhan, State Key Laboratory of Magnetic Resonance and Atomic and Molecular Physics, Wuhan Institute of Physics and Mathematics, Chinese Academy of Sciences, Wuhan 430071, China
| | - Ming-hui Yang
- Key Laboratory of Magnetic Resonance in Biological Systems, National Center for Magnetic Resonance in Wuhan, State Key Laboratory of Magnetic Resonance and Atomic and Molecular Physics, Wuhan Institute of Physics and Mathematics, Chinese Academy of Sciences, Wuhan 430071, China
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11
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Shin JY, Shaloski MA, Crim FF, Case AS. First Evidence of Vibrationally Driven Bimolecular Reactions in Solution: Reactions of Br Atoms with Dimethylsulfoxide and Methanol. J Phys Chem B 2017; 121:2486-2494. [DOI: 10.1021/acs.jpcb.7b00035] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Jae Yoon Shin
- Department of Chemistry, University of Wisconsin, Madison, Wisconsin 53706, United States
| | - Michael A. Shaloski
- Department of Chemistry, University of Wisconsin, Madison, Wisconsin 53706, United States
| | - F. Fleming Crim
- Department of Chemistry, University of Wisconsin, Madison, Wisconsin 53706, United States
| | - Amanda S. Case
- Department of Chemistry, University of Wisconsin, Madison, Wisconsin 53706, United States
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12
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Pham VP, Mishra A, Young Yeom G. The enhancement of Hall mobility and conductivity of CVD graphene through radical doping and vacuum annealing. RSC Adv 2017. [DOI: 10.1039/c7ra01330b] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
We report an innovated method for chlorine doping of graphene utilizing an inductively coupled plasma system.
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Affiliation(s)
- Viet Phuong Pham
- School of Advanced Materials Science and Engineering
- Sungkyunkwan University (SKKU)
- Suwon
- Republic of Korea
- SKKU Advanced Institute of Nano Technology (SAINT)
| | - Anurag Mishra
- School of Advanced Materials Science and Engineering
- Sungkyunkwan University (SKKU)
- Suwon
- Republic of Korea
- Etch Division
| | - Geun Young Yeom
- School of Advanced Materials Science and Engineering
- Sungkyunkwan University (SKKU)
- Suwon
- Republic of Korea
- SKKU Advanced Institute of Nano Technology (SAINT)
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13
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Liu K. Vibrational Control of Bimolecular Reactions with Methane by Mode, Bond, and Stereo Selectivity. Annu Rev Phys Chem 2016; 67:91-111. [DOI: 10.1146/annurev-physchem-040215-112522] [Citation(s) in RCA: 76] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Affiliation(s)
- Kopin Liu
- Institute of Atomic and Molecular Sciences, Academia Sinica, Taipei 10617, Taiwan;
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14
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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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15
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Liu K. Perspective: Vibrational-induced steric effects in bimolecular reactions. J Chem Phys 2015; 142:080901. [DOI: 10.1063/1.4913323] [Citation(s) in RCA: 45] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Affiliation(s)
- Kopin Liu
- Institute of Atomic and Molecular Sciences (IAMS), Academia Sinica, P.O. Box 23-166, Taipei 10617, Taiwan
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16
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Jiang B, Guo H. Mode Specificity, Bond Selectivity, and Product Energy Disposal in X + CH4/CHD3(X=H, F, O(3P), Cl, and OH) Hydrogen Abstraction Reactions: Perspective from Sudden Vector Projection Model. J CHIN CHEM SOC-TAIP 2014. [DOI: 10.1002/jccs.201400158] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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17
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Pan H, Yang J, Zhang D, Shuai Q, Dai D, Wu G, Jiang B, Yang X. Effect of antisymmetric C–H stretching excitation on the dynamics of O(1D) + CH4 → OH + CH3. J Chem Phys 2014. [DOI: 10.1063/1.4871135] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [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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Berke AE, Volpa EH, Annesley CJ, Crim FF. The influence of translational and vibrational energy on the reaction of Cl with CH3D. J Chem Phys 2013; 138:224306. [DOI: 10.1063/1.4808378] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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19
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Wang F, Liu K. Imaging the Effects of Bend-Excitation in the F + CD4(vb=0,1) → DF(v) + CD3(v2=1,2) Reactions. J Phys Chem A 2013; 117:8536-44. [DOI: 10.1021/jp4014866] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Fengyan Wang
- Institute of Atomic
and Molecular
Sciences (IAMS), Academia Sinica, P.O.
Box 23-166, Taipei, Taiwan 10617
- Department of Chemistry, Fudan University, Shanghai 200433, China
| | - Kopin Liu
- Institute of Atomic
and Molecular
Sciences (IAMS), Academia Sinica, P.O.
Box 23-166, Taipei, Taiwan 10617
- Department of Physics, National Taiwan University, Taipei,
Taiwan 10617
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20
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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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21
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22
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Bowman JM, Czakó G, Fu B. High-dimensional ab initio potential energy surfaces for reaction dynamics calculations. Phys Chem Chem Phys 2011; 13:8094-111. [DOI: 10.1039/c0cp02722g] [Citation(s) in RCA: 230] [Impact Index Per Article: 17.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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23
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Czakó G, Shuai Q, Liu K, Bowman JM. Communication: Experimental and theoretical investigations of the effects of the reactant bending excitations in the F+CHD3 reaction. J Chem Phys 2010; 133:131101. [DOI: 10.1063/1.3490795] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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24
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Rose RA, Greaves SJ, Orr-Ewing AJ. Velocity map imaging the dynamics of the reactions of Cl atoms with neopentane and tetramethylsilane. J Chem Phys 2010; 132:244312. [DOI: 10.1063/1.3447378] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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25
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Wu G, Zhang W, Pan H, Shuai Q, Yang J, Jiang B, Dai D, Yang X. Crossed molecular beam ion-imaging study of the Cl + SiH4→ HCl + SiH3 reaction: product vibrational state-to-state correlation. Phys Chem Chem Phys 2010; 12:9469-74. [DOI: 10.1039/b927455c] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Huarte-Larrañaga F, Manthe U. Thermal Rate Constants for Polyatomic Reactions: First Principles Quantum Theory. ACTA ACUST UNITED AC 2009. [DOI: 10.1524/zpch.2007.221.2.171] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
The truly accurate knowledge of molecular dynamics phenomena is generally achieved through a combination of detailed experiments and first principle theory. The complexity of such a level of description had until recently restricted accurate studies to rather small systems. However, the sophistication of theoretical methods and massive technological developments have provided remarkable progress in the detailed knowledge of reactive events during the past three decades. Moreover, significant progress towards the detailed understanding of polyatomic reaction has been made in recent years. Detailed experimental and accurate theoretical studies of reactions involving more than only three or four atoms are becoming increasingly available. In this work, aspects of the theoretical work aiming at the accurate description of polyatomic reactions are reviewed.
The present article focuses on the development of the first principle theory of reaction rates. It reviews theoretical developments and benchmark applications to reactions as CH4 + H → CH3 + H2 and CH4 + O → CH3 + OH. The importance of quantum effects for the thermal rate constants in different temperature regimes is discussed in detail. The accuracy of the classical transition state theory and of different approximate quantum theories is investigated in detail. A quantum transition state concept which facilitates accurate reaction rate calculations for polyatomic reaction is described. Benchmark results for the CH4 + H → CH3 + H2 reaction are shown which demonstrate that the accuracy of thermal rate constants calculated by first principle theory can rival the accuracy of available experimental data. The perspectives offered by these developments are discussed.
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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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28
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Neumark DM. Slow electron velocity-map imaging of negative ions: applications to spectroscopy and dynamics. J Phys Chem A 2009; 112:13287-301. [PMID: 19032143 DOI: 10.1021/jp807182q] [Citation(s) in RCA: 186] [Impact Index Per Article: 12.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Anion photoelectron spectroscopy (PES) has become one of the most versatile techniques in chemical physics. This article briefly reviews the history of anion PES and some of its applications. It describes efforts to improve the resolution of this technique, including anion zero electron kinetic energy (ZEKE) and the recently developed method of slow electron velocity-map imaging (SEVI). Applications of SEVI to studies of vibronic coupling in open-shell systems and the spectroscopy of prereactive van der Waals complexes are then discussed.
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Affiliation(s)
- Daniel M Neumark
- Department of Chemistry, University of California, Berkeley, and Chemical Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA.
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29
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Golan A, Mayorkas N, Rosenwaks S, Bar I. A new method for determining absorption cross sections out of initially excited vibrational states. J Chem Phys 2009; 130:054303. [DOI: 10.1063/1.3067923] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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30
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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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31
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Crim FF. Chemical dynamics of vibrationally excited molecules: Controlling reactions in gases and on surfaces. Proc Natl Acad Sci U S A 2008; 105:12654-61. [PMID: 18765816 PMCID: PMC2529117 DOI: 10.1073/pnas.0803010105] [Citation(s) in RCA: 134] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2008] [Indexed: 11/18/2022] Open
Abstract
Experimental studies of the chemical reaction dynamics of vibrationally excited molecules reveal the ability of different vibrations to control the course of a reaction. This Perspective describes those studies for the prototypical reaction of vibrationally excited methane and its isotopologues in gases and on surfaces and looks to the prospects of similar studies in liquids. The influences of vibrational excitation on the C-H bond cleavage in a single collision reaction with Cl and in dissociative adsorption on a Ni surface bear some striking similarities. Both reactions are bond-selective processes in which the initial preparation of a molecular eigenstate containing a large component of C-H stretching results in preferential cleavage of that bond. It is possible to cleave either the C-H bond or C-D bond in the reaction of Cl with CH3D, CH2D2, or CHD3 and, similarly, to use initial excitation of the C-H stretch to promote dissociation of CHD3 to CD3 and H on a Ni surface. Different vibrational modes, such as the symmetric and antisymmetric stretches in CH3D or CH4, lead to very different reactivities, and molecules with the symmetric stretching vibration excited can be as much as 10 times more reactive than ones with the antisymmetric stretch excited. The origin of this behavior lies in the change in the vibrational motion induced by the interaction with the atomic reaction partner or the surface.
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Affiliation(s)
- F Fleming Crim
- Department of Chemistry, University of Wisconsin, Madison, WI 53706, USA.
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32
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Annesley CJ, Berke AE, Crim FF. Reaction Dynamics and Vibrational Spectroscopy of CH3D Molecules with Both C−H and C−D Stretches Excited. J Phys Chem A 2008; 112:9448-53. [DOI: 10.1021/jp803901p] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
| | - Andrew E. Berke
- Department of Chemistry, University of Wisconsin—Madison, Madison, Wisconsin 53706
| | - F. Fleming Crim
- Department of Chemistry, University of Wisconsin—Madison, Madison, Wisconsin 53706
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33
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Teramoto H, Komatsuzaki T. Probing remnants of invariants to mediate energy exchange in highly chaotic many-dimensional systems. PHYSICAL REVIEW. E, STATISTICAL, NONLINEAR, AND SOFT MATTER PHYSICS 2008; 78:017202. [PMID: 18764083 DOI: 10.1103/physreve.78.017202] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/29/2007] [Revised: 04/24/2008] [Indexed: 05/26/2023]
Abstract
A technique is presented to scrutinize a piece of remnants of invariants [R. B. Shirts and W. P. Reinhardt, J. Chem. Phys. 77, 15 (1982)] buried in chaos in many degrees of freedom (DOF) dynamical systems in terms of canonical perturbation theory based on Lie transforms. The transformed canonical variables are often evaluated by the truncation of the coordinate transformation at a finite order in the original Hamiltonian system. However, the truncation of canonical variables gives rise to a loss of the symplectic property of the system. This results in apparent abrupt fluctuation of the action integrals, which yields a misinterpretation. We demonstrate, in a three-DOF Hamiltonian system of HCN isomerization reaction, that our technique can detect remnants of invariants buried in the potential well even at energies higher than the potential barrier, although the conventional truncation scheme fails to do so. This technique makes it possible to shed light on the physical insight into how the reactive mode exchanges its energy with the other modes and through which resonance the energy exchange takes place in reacting systems.
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Affiliation(s)
- Hiroshi Teramoto
- Research Institute for Electronic Science, Hokkaido University, Kita 12 Nishi 6, Kita-ku, Sapporo 060-0812, Japan
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34
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Retail B, Pearce JK, Greaves SJ, Rose RA, Orr-Ewing AJ. Adiabatic and nonadiabatic dynamics in the CH3(CD3)+HCl reaction. J Chem Phys 2008; 128:184303. [DOI: 10.1063/1.2913516] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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35
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Retail B, Rose RA, Pearce JK, Greaves SJ, Orr-Ewing AJ. The dynamics of reaction of Cl atoms with tetramethylsilane. Phys Chem Chem Phys 2008; 10:1675-80. [DOI: 10.1039/b716512a] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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36
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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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37
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Yan S, Wu YT, Zhang B, Yue XF, Liu K. Do Vibrational Excitations of CHD3 Preferentially Promote Reactivity Toward the Chlorine Atom? Science 2007; 316:1723-6. [PMID: 17588925 DOI: 10.1126/science.1142313] [Citation(s) in RCA: 237] [Impact Index Per Article: 13.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
The influence of vibrational excitation on chemical reaction dynamics is well understood in triatomic reactions, but the multiple modes in larger systems complicate efforts toward the validation of a predictive framework. Although recent experiments support selective vibrational enhancements of reactivities, such studies generally do not properly account for the differing amounts of total energy deposited by the excitation of different modes. By precise tuning of translational energies, we measured the relative efficiencies of vibration and translation in promoting the gas-phase reaction of CHD3 with the Cl atom to form HCl and CD3. Unexpectedly, we observed that C-H stretch excitation is no more effective than an equivalent amount of translational energy in raising the overall reaction efficiency; CD3 bend excitation is only slightly more effective. However, vibrational excitation does have a strong impact on product state and angular distributions, with C-H stretch-excited reactants leading to predominantly forward-scattered, vibrationally excited HCl.
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Affiliation(s)
- Shannon Yan
- Institute of Atomic and Molecular Sciences, Academia Sinica, Post Office Box 23-166, Taipei, Taiwan 10617
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38
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Abstract
The study of state-to-state dynamics of elementary bimolecular reactions has provided remarkable insights into chemical reactivity at the most fundamental level. This review covers exciting developments in this important field in the past decade. I focus on recent studies of quantum-state-resolved molecular-beam reactive-scattering studies of elementary chemical reactions, from triatomic to polyatomic systems. Researchers have made great advances in the fundamental understanding of many elementary chemical reactions through state-to-state dynamics studies. The strong interaction between theory and experiment has significantly enhanced our understanding of the dynamics of these reactions. I hope this review provides a glimpse of this exciting research field to both experts and beginners.
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Affiliation(s)
- Xueming Yang
- State Key Laboratory of Molecular Reaction Dynamics, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian, P.R. China.
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39
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Retail B, Greaves SJ, Pearce JK, Rose RA, Orr-Ewing AJ. Imaging the nonadiabatic dynamics of the CH3 + HCl reaction. Phys Chem Chem Phys 2007; 9:3261-7. [PMID: 17579734 DOI: 10.1039/b704463a] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
LAB-frame velocity distributions of Cl-atoms produced in the photoinitiated reaction of CH(3) radicals with HCl have been measured for both the ground Cl ((2)P(3/2)) and excited Cl* ((2)P(1/2)) spin-orbit states using a DC slice velocity-map ion imaging technique. The similarity of these distributions, as well as the average internal excitation of methane co-products for both Cl and Cl* pathways, suggest that all the reactive flux proceeds through the same transition state on the ground potential energy surface (PES) and that the couplings which promote nonadiabatic transitions to the excited PES correlating to Cl* occur later in the exit channel, beyond the TS region. The nature of these couplings is discussed in light of initial vibrational excitation of CH(3) radicals as well as previously reported nonadiabatic reactivity in other polyatomic molecule reactions. Furthermore, the scattering of the reaction products, derived using the photoloc method, suggests that at the high collision energy of our experiment (E(coll) = 22.3 kcal mol(-1)), large impact parameter collisions are favoured with a reduced kinematic constraint on the internal excitation of the methane co-product.
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Affiliation(s)
- Bertrand Retail
- School of Chemistry, University of Bristol, Cantock's Close, Bristol, UKBS8 1TS
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40
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Abstract
The vast majority of chemical reactions involve polyatomic species as reactants and/or products. The added degree of complexity offers opportunities to address dynamical questions other than those already encountered in a typical atom + diatom reaction. Product pair correlation is one of them. This article introduces the basic concept, outlines the experimental approach we developed and then highlights some of the applications to bimolecular reaction dynamics. Particular emphasis is placed on the information contents and unique insights gained from this type of measurements, which otherwise would have been lost by the conventional approach.
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Affiliation(s)
- Kopin Liu
- Institute of Atomic and Molecular Sciences (IAMS), Academia Sinica, P.O. Box 23-166, Taipei, 10617, Taiwan
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41
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Yan SS, Wu YT, Liu K. Disentangling mode-specific reaction dynamics from overlapped images. Phys Chem Chem Phys 2007; 9:250-4. [PMID: 17186068 DOI: 10.1039/b614307e] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The hydrogen abstraction reaction between atomic chlorine and C-H stretch-excited CHD(3) was studied under crossed-beam conditions. Prior to collisions, an infrared (IR) laser was used to pump up a fraction of CHD(3) to nu(1) = 1. A time-sliced velocity imaging technique was exploited to image the recoil velocity distribution of the state-selected product CD(3)(nu = 0). For energetic reasons, the IR-on image shows severely overlapped features arising from both the excited and the un-pumped ground-state reagents. A novel threshold method was then developed to directly determine the fraction of IR-excited CHD(3) reagents, which in turn enables us to disentangle the state-selected dynamics from the overlapped images. The results reveal significant differences from previous experimental reports.
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Affiliation(s)
- Shannon Shiuan Yan
- Institute of Atomic and Molecular Sciences, Academia Sinica, PO Box 23-166, Taipei, 10617, Taiwan
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42
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Golan A, Rosenwaks S, Bar I. Mode-dependent enhancement of photodissociation and photoionization in a seven atom molecule. J Chem Phys 2006; 125:151103. [PMID: 17059232 DOI: 10.1063/1.2362816] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
We report the first experimental demonstration of vibrational mode-dependent enhancement in photodissociation and photoionization of a seven atom molecule, methylamine (CH(3)NH(2)). The fundamental C-H stretches and the overtones or combinations of CH(3) bends were prepared via stimulated Raman excitation (SRE) prior to their 243.135 nm one-photon dissociation or two-photon ionization. The photodissociation or photoionization of the vibrationally excited molecules was achieved via 10 ns delayed or temporally overlapping SRE and UV pulses, respectively. It is shown that bending modes are more effective than stretches in promoting photodissociation and photoionization, since their UV excitation is favored by larger Franck Condon factors. This behavior provides clear evidence for vibrational mode-dependence in a relatively large molecule with a torsional degree of freedom, indicating that these modes survive intramolecular vibrational redistribution on a time scale considerably longer than hitherto inferred from previous studies.
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Affiliation(s)
- Amir Golan
- Department of Physics, Ben-Gurion University of the Negev, Beer-Sheva 84105, Israel
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43
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Abstract
A critical overview of the recent progress in crossed-beam reactive scattering is presented. This review is not intended to be an exhaustive nor a comprehensive one, but rather a critical assessment of what we have been learning about bimolecular reaction dynamics using crossed molecular beams since year 2000. Particular emphasis is placed on the information content encoded in the product angular distribution-the trait of a typical molecular beam scattering experiment-and how the information can help in answering fundamental questions about chemical reactivity. We will start with simple reactions by highlighting a few benchmark three-atom reactions, and then move on progressively to the more complex chemical systems and with more sophisticated types of measurements. Understanding what cause the experimental observations is more than computationally simulating the results. The give and take between experiment and theory in unraveling the physical picture of the underlying dynamics is illustrated throughout this review.
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Affiliation(s)
- Kopin Liu
- Institute of Atomic and Molecular Sciences (IAMS), Academia Sinica, Taipei 10617, Taiwan.
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44
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Holiday RJ, Kwon CH, Annesley CJ, Fleming Crim F. Mode- and bond-selective reaction of Cl(P3∕22) with CH3D: C–H stretch overtone excitation near 6000cm−1. J Chem Phys 2006; 125:133101. [PMID: 17029427 DOI: 10.1063/1.2352742] [Citation(s) in RCA: 57] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
Experiments explore the influence of different C-H stretching eigenstates of CH3D on the reaction of CH3D with Cl(2P3/2). We prepare the mid |110>|0>(A1,E), mid |200>|>0(E), and mid |100>|0> +nu3 +nu5 eigenstates by direct midinfrared absorption near 6000 cm(-1). The vibrationally excited molecules react with photolytic Cl atoms, and we monitor the vibrational states of the CH2D or CH3 radical products by 2+1 resonance enhanced multiphoton ionization. Initial excitation of the |200>|0>(E) state leads to a twofold increase in CH2D products in the vibrational ground state compared to|100>|0> +nu3 +nu5 excitation, indicating mode-selective chemistry in which the C-H stretch motion couples more effectively to the H-atom abstraction coordinate than bend motion. For two eigenstates that differ only in the symmetry of the vibrational wave function, |110>|0>(A1) and |110>|0>(E), the ratio of reaction cross sections is 1.00 +/- 0.05, showing that there is no difference in enhancement of the H-atom abstraction reaction. Molecules with excited local modes corresponding to one quantum of C-H stretch in each of two distinct oscillators react exclusively to form C-H stretch excited CH2D products. Conversely, eigenstates containing stretch excitation in a single C-H oscillator form predominantly ground vibrational state CH2D products. Analyzing the product state yields for reaction of the |110>|0>(A1) state of CH3D yields an enhancement of 20 +/- 4 over the thermal reaction. A local mode description of the vibrational motion along with a spectator model for the reactivity accounts for all of the observed dynamics.
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Affiliation(s)
- Robert J Holiday
- Department of Chemistry, University of Wisconsin-Madison, Madison, Wisconsin 53706, USA
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45
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Camden JP, Bechtel HA, Ankeny Brown DJ, Zare RN. Comparing reactions of H and Cl with C–H stretch-excited CHD3. J Chem Phys 2006; 124:034311. [PMID: 16438587 DOI: 10.1063/1.2155434] [Citation(s) in RCA: 52] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
We report the methyl radical product state distributions for the reactions of H and Cl with CHD3(nu1 = 1,2) at collision energies of 1.53 and 0.18 eV, respectively. Both reactions demonstrate mode selectivity. The resulting state distributions from the H+CHD3(nu1 = 1,2) reactions are well described by a spectator model. The reactions Cl + CHD3(nu1 = 1,2) exhibit similar behavior, but in some aspects the spectator model breaks down. We attribute this breakdown to enhanced intramolecular vibrational redistribution in the Cl + CHD3(nu1 = 1,2) reactions compared to the H + CHD3(nu1 = 1,2) reactions, caused by the interaction of the slower Cl atom with the vibrationally excited CHD3, which is promoted either by its longer collision duration, its stronger coupling, or both.
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Affiliation(s)
- Jon P Camden
- Department of Chemistry, Stanford University, Stanford, California 94305-5080, USA
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46
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Camden JP, Bechtel HA, Brown DJA, Zare RN. Effects of C–H stretch excitation on the H+CH4 reaction. J Chem Phys 2005; 123:134301. [PMID: 16223282 DOI: 10.1063/1.2034507] [Citation(s) in RCA: 63] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
We have investigated the effects of C-H stretching excitation on the H+CH4-->CH3+H2 reaction dynamics using the photo-LOC technique. The CH3 product vibrational state and angular distribution are measured for the reaction of fast H atoms with methane excited in either the antisymmetric stretching fundamental (nu3=1) or first overtone (nu3=2) with a center-of-mass collision energy of Ecoll ranging from 1.52 to 2.20 eV. We find that vibrational excitation of the nu3=1 mode enhances the overall reaction cross section by a factor of 3.0+/-1.5 for Ecoll=1.52 eV, and this enhancement factor is approximately constant over the 1.52-2.20-eV collision energy range. A local-mode description of the CH4 stretching vibration, in which the C-H oscillators are uncoupled, is used to describe the observed state distributions. In this model, the interaction of the incident H atom with either a stretched or an unstretched C-H oscillator determines the vibrational state of the CH3 product. We also compare these results to the similar quantities obtained previously for the Cl+CH4-->CH3+HCl reaction at Ecoll=0.16 eV [Z. H. Kim, H. A. Bechtel, and R. N. Zare, J. Chem. Phys. 117, 3232 (2002); H. A. Bechtel, J. P. Camden, D. J. A. Brown, and R. N. Zare, ibid. 120, 5096 (2004)] in an attempt to elucidate the differences in reactivity for the same initially prepared vibration.
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Affiliation(s)
- Jon P Camden
- Department of Chemistry, Stanford University, Stanford, California 94305-5080, USA
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47
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Zhang B, Liu K. How Active Is the Bend Excitation of Methane in the Reaction with O(3P)? J Phys Chem A 2005; 109:6791-5. [PMID: 16834033 DOI: 10.1021/jp052963w] [Citation(s) in RCA: 53] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The role of bending excitation of methane in the reaction with O(3P) is investigated in a crossed-beam experiment. Previous theories predicted that either stretch or bend excitation of the reactant promotes chemical reactivity and that initial bending excitation of CH4 preferentially yields umbrella-excited CH3 products. Experimentally, both predictions for bend-excited reagent were not borne out in this investigation. We found instead that compared to the ground-state reagent, bend-excited methane yields more vibrational excitation of the hydroxyl coproduct. The first reported product angular distributions show predominant backward scatterings for both ground-state and bend-excited methanes, which corroborate well with a direct rebound reaction mechanism.
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