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Kopin Liu - One of the best experts on this subject based on the ideXlab platform.
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Differential steric effects in Cl reactions with aligned CHD3(v1 = 1) by the R(0) and Q(1) transitions. II. Abstracting the unexcited D-atoms.
The Journal of Chemical Physics, 2016Co-Authors: Fengyan Wang, Kopin LiuAbstract:A complete set of four polarization-dependent differential cross sections in the reactions of Cl + aligned-CHD3(v1=1,jK)→DCl(v=0)+CHD2(v1=1) is reported here for two different, rotationally polarized states with j = 1: specifically the jK=10 state prepared via the R(0) excitation and the 1±1 state via Q(1). In stark contrast to the complicated situation of the HCl(v) + CD3(v = 0) channel reported in Paper-I, the stereo-requirement of this isotopic channel for both polarized reactants appears quite straightforward and consistent with a direct rebound mechanism. The extent of steric effects is moderate and relatively smaller than the alternative H-atom abstraction channel. All major findings reported here can qualitatively be understood by first noting that the present reaction invokes abstracting a D-atom, which is the spectator in the IR-excitation process. Next, it is recognized that the directional properties of two polarized states of CHD3(v1=1, jK) should manifest primarily in the IR-excited C–H bond, leaving secondary imprints in the unexcited CD3-moiety. The stereo-specificity of the DCl + CHD2 product channel is further reduced by the fact that the abstraction can occur with any one of the three spatially distinct D-atoms.
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differential steric effects in cl reactions with aligned CHD3 v1 1 by the r 0 and q 1 transitions ii abstracting the unexcited d atoms
Journal of Chemical Physics, 2016Co-Authors: Fengyan Wang, Kopin LiuAbstract:A complete set of four polarization-dependent differential cross sections in the reactions of Cl + aligned-CHD3(v1=1,jK)→DCl(v=0)+CHD2(v1=1) is reported here for two different, rotationally polarized states with j = 1: specifically the jK=10 state prepared via the R(0) excitation and the 1±1 state via Q(1). In stark contrast to the complicated situation of the HCl(v) + CD3(v = 0) channel reported in Paper-I, the stereo-requirement of this isotopic channel for both polarized reactants appears quite straightforward and consistent with a direct rebound mechanism. The extent of steric effects is moderate and relatively smaller than the alternative H-atom abstraction channel. All major findings reported here can qualitatively be understood by first noting that the present reaction invokes abstracting a D-atom, which is the spectator in the IR-excitation process. Next, it is recognized that the directional properties of two polarized states of CHD3(v1=1, jK) should manifest primarily in the IR-excited C–H bond, leaving secondary imprints in the unexcited CD3-moiety. The stereo-specificity of the DCl + CHD2 product channel is further reduced by the fact that the abstraction can occur with any one of the three spatially distinct D-atoms.
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correlated dynamics of the o 3p CHD3 v 0 reaction a joint crossed beam and quasiclassical trajectory study
Journal of Physical Chemistry A, 2015Co-Authors: Bailin Zhang, Kopin Liu, Gábor CzakóAbstract:Crossed beam experiments and quasiclassical trajectory computations on an ab initio potential energy surface are performed for the O(3P) + CHD3(v=0) → OH(v′=0) + CD3(v2=0,2) and OD(v′=0,1) + CHD2(v=0) reactions. Both experiment and theory show that the excitation functions display a concave-up behavior and the angular distributions are backward scattered, indicating a direct rebound mechanism and a tight-bend transition state. The reaction produces mainly ground-state products showing the dominance of a vibrationally adiabatic reaction pathway. The standard histogram binning cannot reproduce the observed vibrational adiabaticity, whereas Gaussian binning gives good agreement with experiment.
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Perspective: Vibrational-induced steric effects in bimolecular reactions
The Journal of Chemical Physics, 2015Co-Authors: Kopin LiuAbstract:The concept of preferred collision geometry in a bimolecular reaction is at the heart of reaction dynamics. Exemplified by a series of crossed molecular beam studies on the reactions of a C–H stretch-excited CHD3(v1 = 1) with F, Cl, and O(3P) atoms, two types of steric control of chemical reactivity will be highlighted. A passive control is governed in a reaction with strong anisotropic entry valley that can significantly steer the incoming trajectories. This disorientation effect is illustrated by the F and O(3P) + CHD3(v1 = 1) reactions. In the former case, the long-range anisotropic interaction acts like an optical “negative” lens by deflecting the trajectories away from the favored transition-state geometry, and thus inhibiting the bond rupture of the stretch-excited CHD3. On the contrary, the interaction between O(3P) and CHD3(v1 = 1) behaves as a “positive” lens by funneling the large impact-parameter collisions into the cone of acceptance, and thereby enhances the reactivity. As for reactions with ...
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Correlated Dynamics of the O(3P) + CHD3(v=0) Reaction: A Joint Crossed-Beam and Quasiclassical Trajectory Study
The Journal of Physical Chemistry A, 2014Co-Authors: Bailin Zhang, Kopin Liu, Gábor CzakóAbstract:Crossed beam experiments and quasiclassical trajectory computations on an ab initio potential energy surface are performed for the O(3P) + CHD3(v=0) → OH(v′=0) + CD3(v2=0,2) and OD(v′=0,1) + CHD2(v=0) reactions. Both experiment and theory show that the excitation functions display a concave-up behavior and the angular distributions are backward scattered, indicating a direct rebound mechanism and a tight-bend transition state. The reaction produces mainly ground-state products showing the dominance of a vibrationally adiabatic reaction pathway. The standard histogram binning cannot reproduce the observed vibrational adiabaticity, whereas Gaussian binning gives good agreement with experiment.
J Espinosagarcia - One of the best experts on this subject based on the ideXlab platform.
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theoretical study of the pair correlated f CHD3 v 0 ν1 1 reaction effect of ch stretching vibrational excitation
Journal of Physical Chemistry A, 2017Co-Authors: J Espinosagarcia, L Bonnet, Jose C CorchadoAbstract:The F + CHD3(v) reaction is a benchmark system in polyatomic reactions. Theoretical/experimental comparisons have been reported in recent years that present some controversies, specifically the role of the reactant CH stretching vibrational excitation, CHD3(ν1 = 1), on the reactivity of both isotope channels, DF(v) + CHD2(v′) and HF(v) + CD3(v′). However, in many cases, these comparisons are not made on an equal footing. Previous theoretical studies were concerned with overall reactivity of each isotope channel, while fine velocity map imaging experiments provided results in a product pair-correlated manner. In order to shed some light on these controversies, we perform here a pair-correlated theory/experiment comparison for the title reaction, using quasi-classical trajectory calculations on a full dimensional potential energy surface. When these calculations are analyzed in a quantum spirit, i.e., by discarding those trajectories whose results do not meet quantum-mechanical requirements and aiming to re...
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quasiclassical trajectory study on the role of ch stretching vibrational excitation in the f 2p CHD3 v1 0 1 reactions
Journal of Physical Chemistry A, 2016Co-Authors: J EspinosagarciaAbstract:To analyze the role of CH-stretching vibrational excitation on the reactivity and dynamics of the F(2P) + CHD3(v1=0,1) reactions, quasiclassical trajectory calculations using a full-dimensional analytical potential energy surface at different collision energies were performed. The extra energy of the CH excitation had almost no effect on the reactivity for the DF + CHD2 channel, although it increased the reactivity for the HF + CD3 channel, with the net effect being that CH excitation barely modified overall reactivity. In addition, the DF/HF branching ratio was not far from the statistical value for the ground-state reaction, whereas CH excitation decreased this ratio. These results, intimately related to the topology of the entrance channel, agree with recent theoretical results obtained using different surfaces (although some differences even persist among them) but strongly contradict recent experiments. This controversy will doubtless guarantee more accurate experiments and theoretical calculations i...
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the abstraction reaction of h and c h stretch excited CHD3 a qct study on an ab initio based potential energy surface
Computational and Theoretical Chemistry, 2013Co-Authors: J Espinosagarcia, Jose C CorchadoAbstract:Abstract Using a recent ab initio based potential energy surface, PES-2009, quasi-classical trajectory calculations were performed to analyse the effects of the C–H stretch excitation on the reactivity and dynamics of the H + CHD3 abstraction reaction at a collision energy of 1.53 eV. Firstly, we found that the C–H stretch mode excitation has little influence on the product rotational distributions and on the scattering distribution for both channels. However, it has significant influence on the product energy distribution for the CHD2 + HD channel, indicating that the reaction shows mode selectivity, reproducing the experimental evidence. Finally, excitation of the C–H stretch by one quantum increases the reactivity of the vibrational ground-state for both channels reproducing the experimental evidence, although for the H-abstraction channel we report an enhancement of reactivity somewhat lower than other theoretical results.
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state to state dynamics analysis of the f CHD3 reaction a quasiclassical trajectory study
Journal of Physical Chemistry A, 2008Co-Authors: J Espinosagarcia, José Luis BravoAbstract:An exhaustive state-to-state dynamics study was performed to analyze the F + CHD3 → FD(ν′,j′) + CHD2(ν) gas-phase abstraction reaction. Quasiclassical trajectory (QCT) calculations, including corrections to avoid zero-point energy leakage along the trajectories, were performed at different collision energies on an analytical potential energy surface (PES-2006) recently developed by our group. Whereas the CHD2 coproduct appears vibrationally and rotationally cold, most of the available energy appears as FD(ν′) product vibrational energy, peaking at ν′ = 2 and ν′ = 3, with the population in the latter level growing as the energy increases. The excitation function rises from the threshold of the reaction and then levels off at higher energies, with the maximum contribution from the FD(ν′ = 3) level. The state-specific FD(ν′) scattering distributions correlated with the coproduct CHD2 in the ν4 = 2 and ν3 = 1 states, at different collision energies, show a steady change from backward to forward scattering as ...
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role of the c h stretch mode excitation in the dynamics of the cl CHD3 reaction a quasi classical trajectory calculation
Journal of Physical Chemistry A, 2007Co-Authors: J EspinosagarciaAbstract: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(ν=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...
Dong H. Zhang - One of the best experts on this subject based on the ideXlab platform.
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Computing energy levels of CH4, CHD3, CH3D, and CH3F with a direct product basis and coordinates based on the methyl subsystem
The Journal of Chemical Physics, 2018Co-Authors: Zhiqiang Zhao, Dong H. Zhang, Xiao-gang Wang, Tucker Carrington, Jun Chen, Zhaojun Zhang, Fabien GattiAbstract:Quantum mechanical calculations of ro-vibrational energies of CH4, CHD3, CH3D, and CH3F were made with two different numerical approaches. Both use polyspherical coordinates. The computed energy levels agree, confirming the accuracy of the methods. In the first approach, for all the molecules, the coordinates are defined using three Radau vectors for the CH3 subsystem and a Jacobi vector between the remaining atom and the centre of mass of CH3. Euler angles specifying the orientation of a frame attached to CH3 with respect to a frame attached to the Jacobi vector are used as vibrational coordinates. A direct product potential-optimized discrete variable vibrational basis is used to build a Hamiltonian matrix. Ro-vibrational energies are computed using a re-started Arnoldi eigensolver. In the second approach, the coordinates are the spherical coordinates associated with four Radau vectors or three Radau vectors and a Jacobi vector, and the frame is an Eckart frame. Vibrational basis functions are products ...
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Effect of CH stretching excitation on the reaction dynamics of F + CHD3 → DF + CHD2.
The Journal of Chemical Physics, 2015Co-Authors: Jiayue Yang, Dong H. Zhang, Zhen Chen, Florian Blauert, Bo Jiang, Dongxu Dai, Donghui Zhang, Xueming YangAbstract:The vibrationally excited reaction of F + CHD3(ν1 = 1) → DF + CHD2 at a collision energy of 9.0 kcal/mol is investigated using the crossed-beams and time-sliced velocity map imaging techniques. Detailed and quantitative information of the CH stretching excitation effects on the reactivity and dynamics of the title reaction is extracted with the help of an accurate determination of the fraction of the excited CHD3 reagent in the crossed-beam region. It is found that all vibrational states of the CHD2 products observed in the ground-state reaction, which mainly involve the excitation of the umbrella mode of the CHD2 products, are severely suppressed by the CH stretching excitation. However, there are four additional vibrational states of the CHD2 products appearing in the excited-state reaction which are not presented in the ground-state reaction. These vibrational states either have the CH stretching excitation retained or involve one quantum excitation in the CH stretching and the excitation of the umbrella mode. Including all observed vibrational states, the overall cross section of the excited-state reaction is estimated to be 66.6% of that of the ground-state one. Experimental results also show that when the energy of CH stretching excitation is released during the reaction, it is deposited almost exclusively as the rovibrational energy of the DF products, with little portion in the translational degree of freedom. For vibrational states of the CHD2 products observed in both ground- and excited-state reactions, the CH stretching excitation greatly suppresses the forward scattered products, causing a noticeable change in the product angular distributions.
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effect of ch stretching excitation on the reaction dynamics of f CHD3 df chd2
Journal of Chemical Physics, 2015Co-Authors: Jiayue Yang, Dong H. Zhang, Zhen Chen, Florian Blauert, Bo Jiang, Dongxu Dai, Donghui Zhang, Xueming YangAbstract:The vibrationally excited reaction of F + CHD3(ν1 = 1) → DF + CHD2 at a collision energy of 9.0 kcal/mol is investigated using the crossed-beams and time-sliced velocity map imaging techniques. Detailed and quantitative information of the CH stretching excitation effects on the reactivity and dynamics of the title reaction is extracted with the help of an accurate determination of the fraction of the excited CHD3 reagent in the crossed-beam region. It is found that all vibrational states of the CHD2 products observed in the ground-state reaction, which mainly involve the excitation of the umbrella mode of the CHD2 products, are severely suppressed by the CH stretching excitation. However, there are four additional vibrational states of the CHD2 products appearing in the excited-state reaction which are not presented in the ground-state reaction. These vibrational states either have the CH stretching excitation retained or involve one quantum excitation in the CH stretching and the excitation of the umbrella mode. Including all observed vibrational states, the overall cross section of the excited-state reaction is estimated to be 66.6% of that of the ground-state one. Experimental results also show that when the energy of CH stretching excitation is released during the reaction, it is deposited almost exclusively as the rovibrational energy of the DF products, with little portion in the translational degree of freedom. For vibrational states of the CHD2 products observed in both ground- and excited-state reactions, the CH stretching excitation greatly suppresses the forward scattered products, causing a noticeable change in the product angular distributions.
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Effects of reagent rotational excitation on the H + CHD3 → H2 + CD3 reaction: A seven dimensional time-dependent wave packet study
The Journal of Chemical Physics, 2014Co-Authors: Zhaojun Zhang, Dong H. ZhangAbstract:Seven-dimensional time-dependent wave packet calculations have been carried out for the title reaction to obtain reaction probabilities and cross sections for CHD3 in J0 = 1, 2 rotationally excited initial states with k0 = 0 − J0 (the projection of CHD3 rotational angular momentum on its C3 axis). Under the centrifugal sudden (CS) approximation, the initial states with the projection of the total angular momentum on the body fixed axis (K0) equal to k0 are found to be much more reactive, indicating strong dependence of reactivity on the orientation of the reagent CHD3 with respect to the relative velocity between the reagents H and CHD3. However, at the coupled-channel (CC) level this dependence becomes much weak although in general the K0 specified cross sections for the K0 = k0 initial states remain primary to the overall cross sections, implying the Coriolis coupling is important to the dynamics of the reaction. The calculated CS and CC integral cross sections obtained after K0 averaging for the J0 = 1...
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effects of reagent rotational excitation on the h CHD3 h2 cd3 reaction a seven dimensional time dependent wave packet study
Journal of Chemical Physics, 2014Co-Authors: Zhaojun Zhang, Dong H. ZhangAbstract:Seven-dimensional time-dependent wave packet calculations have been carried out for the title reaction to obtain reaction probabilities and cross sections for CHD3 in J0 = 1, 2 rotationally excited initial states with k0 = 0 − J0 (the projection of CHD3 rotational angular momentum on its C3 axis). Under the centrifugal sudden (CS) approximation, the initial states with the projection of the total angular momentum on the body fixed axis (K0) equal to k0 are found to be much more reactive, indicating strong dependence of reactivity on the orientation of the reagent CHD3 with respect to the relative velocity between the reagents H and CHD3. However, at the coupled-channel (CC) level this dependence becomes much weak although in general the K0 specified cross sections for the K0 = k0 initial states remain primary to the overall cross sections, implying the Coriolis coupling is important to the dynamics of the reaction. The calculated CS and CC integral cross sections obtained after K0 averaging for the J0 = 1...
Gábor Czakó - One of the best experts on this subject based on the ideXlab platform.
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correlated dynamics of the o 3p CHD3 v 0 reaction a joint crossed beam and quasiclassical trajectory study
Journal of Physical Chemistry A, 2015Co-Authors: Bailin Zhang, Kopin Liu, Gábor CzakóAbstract:Crossed beam experiments and quasiclassical trajectory computations on an ab initio potential energy surface are performed for the O(3P) + CHD3(v=0) → OH(v′=0) + CD3(v2=0,2) and OD(v′=0,1) + CHD2(v=0) reactions. Both experiment and theory show that the excitation functions display a concave-up behavior and the angular distributions are backward scattered, indicating a direct rebound mechanism and a tight-bend transition state. The reaction produces mainly ground-state products showing the dominance of a vibrationally adiabatic reaction pathway. The standard histogram binning cannot reproduce the observed vibrational adiabaticity, whereas Gaussian binning gives good agreement with experiment.
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Correlated Dynamics of the O(3P) + CHD3(v=0) Reaction: A Joint Crossed-Beam and Quasiclassical Trajectory Study
The Journal of Physical Chemistry A, 2014Co-Authors: Bailin Zhang, Kopin Liu, Gábor CzakóAbstract:Crossed beam experiments and quasiclassical trajectory computations on an ab initio potential energy surface are performed for the O(3P) + CHD3(v=0) → OH(v′=0) + CD3(v2=0,2) and OD(v′=0,1) + CHD2(v=0) reactions. Both experiment and theory show that the excitation functions display a concave-up behavior and the angular distributions are backward scattered, indicating a direct rebound mechanism and a tight-bend transition state. The reaction produces mainly ground-state products showing the dominance of a vibrationally adiabatic reaction pathway. The standard histogram binning cannot reproduce the observed vibrational adiabaticity, whereas Gaussian binning gives good agreement with experiment.
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Rotational mode specificity in the Cl + CHD3 → HCl + CD3 reaction.
The Journal of Chemical Physics, 2014Co-Authors: Rui Liu, Bin Jiang, Minghui Yang, Gábor Czakó, Kopin Liu, Fengyan Wang, Hua GuoAbstract:By exciting the rotational modes of vibrationally excited CHD3(nu(1) = 1, JK), the reactivity for the Cl + CHD3 -> HCl + CD3 reaction is observed enhanced by as much as a factor of two relative to the rotationless reactant. To understand the mode specificity, the reaction dynamics was studied using both a reduced-dimensional quantum dynamical model and the conventional quasi-classical trajectory method, both of which reproduced qualitatively the measured enhancements. The mechanism of enhancement was analyzed using a Franck-Condon model and by inspecting trajectories. It is shown that the higher reactivity for higher J states of CHD3 with K = 0 can be attributed to the enlargement of the cone of acceptance. On the other hand, the less pronounced enhancement for the higher J = K states is apparently due to the fact that the rotation along the C-H bond is less effective in opening up the cone of acceptance. (C) 2014 AIP Publishing LLC.
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rotational mode specificity in the cl CHD3 hcl cd3 reaction
Journal of Chemical Physics, 2014Co-Authors: Rui Liu, Bin Jiang, Minghui Yang, Gábor Czakó, Kopin Liu, Fengyan Wang, Hua GuoAbstract:By exciting the rotational modes of vibrationally excited CHD3(nu(1) = 1, JK), the reactivity for the Cl + CHD3 -> HCl + CD3 reaction is observed enhanced by as much as a factor of two relative to the rotationless reactant. To understand the mode specificity, the reaction dynamics was studied using both a reduced-dimensional quantum dynamical model and the conventional quasi-classical trajectory method, both of which reproduced qualitatively the measured enhancements. The mechanism of enhancement was analyzed using a Franck-Condon model and by inspecting trajectories. It is shown that the higher reactivity for higher J states of CHD3 with K = 0 can be attributed to the enlargement of the cone of acceptance. On the other hand, the less pronounced enhancement for the higher J = K states is apparently due to the fact that the rotation along the C-H bond is less effective in opening up the cone of acceptance. (C) 2014 AIP Publishing LLC.
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Communication: Experimental and theoretical investigations of the effects of the reactant bending excitations in the F+CHD3 reaction
The Journal of Chemical Physics, 2010Co-Authors: Gábor Czakó, Kopin Liu, Quan Shuai, Joel M. BowmanAbstract:The effects of the reactant bending excitations in the F+CHD3 reaction are investigated by crossed molecular beam experiments and quasiclassical trajectory (QCT) calculations using a high-quality ab initio potential energy surface. The collision energy (Ec) dependence of the cross sections of the F+CHD3(vb=0,1) reactions for the correlated product pairs HF(v′)+CD3(v2=0,1) and DF(v′)+CHD2(v4=0,1) is obtained. Both experiment and theory show that the bending excitation activates the reaction at low Ec and begins to inactivate at higher Ec. The experimental F+CHD3(vb=1) excitation functions display surprising peak features, especially for the HF(v′=3)+CD3(v2=0,1) channels, indicating reactive resonances (quantum effects), which cannot be captured by quasiclassical calculations. The reactant state-specific QCT calculations predict that the v5(e) bending mode excitation is the most efficient to drive the reaction and the v6(e) and v5(e) modes enhance the DF and HF channels, respectively.
Fengyan Wang - One of the best experts on this subject based on the ideXlab platform.
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Differential steric effects in Cl reactions with aligned CHD3(v1 = 1) by the R(0) and Q(1) transitions. II. Abstracting the unexcited D-atoms.
The Journal of Chemical Physics, 2016Co-Authors: Fengyan Wang, Kopin LiuAbstract:A complete set of four polarization-dependent differential cross sections in the reactions of Cl + aligned-CHD3(v1=1,jK)→DCl(v=0)+CHD2(v1=1) is reported here for two different, rotationally polarized states with j = 1: specifically the jK=10 state prepared via the R(0) excitation and the 1±1 state via Q(1). In stark contrast to the complicated situation of the HCl(v) + CD3(v = 0) channel reported in Paper-I, the stereo-requirement of this isotopic channel for both polarized reactants appears quite straightforward and consistent with a direct rebound mechanism. The extent of steric effects is moderate and relatively smaller than the alternative H-atom abstraction channel. All major findings reported here can qualitatively be understood by first noting that the present reaction invokes abstracting a D-atom, which is the spectator in the IR-excitation process. Next, it is recognized that the directional properties of two polarized states of CHD3(v1=1, jK) should manifest primarily in the IR-excited C–H bond, leaving secondary imprints in the unexcited CD3-moiety. The stereo-specificity of the DCl + CHD2 product channel is further reduced by the fact that the abstraction can occur with any one of the three spatially distinct D-atoms.
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differential steric effects in cl reactions with aligned CHD3 v1 1 by the r 0 and q 1 transitions ii abstracting the unexcited d atoms
Journal of Chemical Physics, 2016Co-Authors: Fengyan Wang, Kopin LiuAbstract:A complete set of four polarization-dependent differential cross sections in the reactions of Cl + aligned-CHD3(v1=1,jK)→DCl(v=0)+CHD2(v1=1) is reported here for two different, rotationally polarized states with j = 1: specifically the jK=10 state prepared via the R(0) excitation and the 1±1 state via Q(1). In stark contrast to the complicated situation of the HCl(v) + CD3(v = 0) channel reported in Paper-I, the stereo-requirement of this isotopic channel for both polarized reactants appears quite straightforward and consistent with a direct rebound mechanism. The extent of steric effects is moderate and relatively smaller than the alternative H-atom abstraction channel. All major findings reported here can qualitatively be understood by first noting that the present reaction invokes abstracting a D-atom, which is the spectator in the IR-excitation process. Next, it is recognized that the directional properties of two polarized states of CHD3(v1=1, jK) should manifest primarily in the IR-excited C–H bond, leaving secondary imprints in the unexcited CD3-moiety. The stereo-specificity of the DCl + CHD2 product channel is further reduced by the fact that the abstraction can occur with any one of the three spatially distinct D-atoms.
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Rotational mode specificity in the Cl + CHD3 → HCl + CD3 reaction.
The Journal of Chemical Physics, 2014Co-Authors: Rui Liu, Bin Jiang, Minghui Yang, Gábor Czakó, Kopin Liu, Fengyan Wang, Hua GuoAbstract:By exciting the rotational modes of vibrationally excited CHD3(nu(1) = 1, JK), the reactivity for the Cl + CHD3 -> HCl + CD3 reaction is observed enhanced by as much as a factor of two relative to the rotationless reactant. To understand the mode specificity, the reaction dynamics was studied using both a reduced-dimensional quantum dynamical model and the conventional quasi-classical trajectory method, both of which reproduced qualitatively the measured enhancements. The mechanism of enhancement was analyzed using a Franck-Condon model and by inspecting trajectories. It is shown that the higher reactivity for higher J states of CHD3 with K = 0 can be attributed to the enlargement of the cone of acceptance. On the other hand, the less pronounced enhancement for the higher J = K states is apparently due to the fact that the rotation along the C-H bond is less effective in opening up the cone of acceptance. (C) 2014 AIP Publishing LLC.
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rotational mode specificity in the cl CHD3 hcl cd3 reaction
Journal of Chemical Physics, 2014Co-Authors: Rui Liu, Bin Jiang, Minghui Yang, Gábor Czakó, Kopin Liu, Fengyan Wang, Hua GuoAbstract:By exciting the rotational modes of vibrationally excited CHD3(nu(1) = 1, JK), the reactivity for the Cl + CHD3 -> HCl + CD3 reaction is observed enhanced by as much as a factor of two relative to the rotationless reactant. To understand the mode specificity, the reaction dynamics was studied using both a reduced-dimensional quantum dynamical model and the conventional quasi-classical trajectory method, both of which reproduced qualitatively the measured enhancements. The mechanism of enhancement was analyzed using a Franck-Condon model and by inspecting trajectories. It is shown that the higher reactivity for higher J states of CHD3 with K = 0 can be attributed to the enlargement of the cone of acceptance. On the other hand, the less pronounced enhancement for the higher J = K states is apparently due to the fact that the rotation along the C-H bond is less effective in opening up the cone of acceptance. (C) 2014 AIP Publishing LLC.
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enlarging the reactive cone of acceptance by exciting the c h bond in the o 3p CHD3 reaction
Chemical Science, 2010Co-Authors: Fengyan Wang, Kopin LiuAbstract:The effects of the CH stretching vibration of methane on the O(3P) + CHD3 reaction are elucidated in a crossed-beam imaging experiment. For the H-atom abstraction channel, the ground state reaction leads mainly to the vibrational ground states of products, OH(v = 0) + CD3(v = 0). When the reactant CHD3 is prepared with one-quantum excitation of CH stretching vibration (v1 = 1), more than 90% of OH coproducts that formed concomitantly with the CD3(v = 0) product are in v = 1. Significant vibrational enhancement in the reaction rate is observed, and the product angular distribution shifts from a backward-dominance in O(3P) + CHD3(v = 0) to a sideways-peaking upon CH stretching excitation. As to the D-atom abstraction channel, the C–H bond excitation, despite being conserved in the CHD2 product, unexpectedly hinders the overall reactivity of the unexcited C–D bond. We interpret the experimental findings as the result of enlarging the reactive cone of acceptance in abstracting the H atom at the expense of the cone for the D-atom transfer channel.