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Yang X. Probing state-to-state reaction dynamics using H-atom Rydberg tagging time-of-flight spectroscopy. Phys Chem Chem Phys 2011; 13:8112-21. [DOI: 10.1039/c1cp00005e] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Gustafsson M, Skodje RT, Zhang J, Dai D, Harich SA, Wang X, Yang X. Observing the stereodynamics of chemical reactions using randomly oriented molecular beams. J Chem Phys 2007; 124:241105. [PMID: 16821965 DOI: 10.1063/1.2217015] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
A new method is demonstrated to study the stereodynamics of simple chemical reactions that does not require the use of oriented (or aligned) molecular beams or measurements of the orientation state of product molecules. Instead, it is shown that by numerically combining accurate measurements of the state-to-state differential cross section for two or more rotational states of the reagent molecule, the separate contribution from the individual helicity states can be extracted. New molecular beam experiments are conducted for the D+H(2)-->HD+H reaction that confirm the validity of the method.
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Affiliation(s)
- Magnus Gustafsson
- Institute of Atomic and Molecular Sciences, Academia Sinica, PO Box 23-166, Taipei, Taiwan
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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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Whitney ES, Zolot AM, McCoy AB, Francisco JS, Nesbitt DJ. Reactive scattering dynamics in atom+polyatomic systems: F+C2H6-->HF(v,J)+C2H5. J Chem Phys 2006; 122:124310. [PMID: 15836381 DOI: 10.1063/1.1868553] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
State-to-state scattering dynamics of F+C2H6-->HF(v,J)+C2H5 have been investigated at Ecom=3.2(6) kcalmol under single-collision conditions, via detection of nascent rovibrationally resolved HF(v,J) product states with high-resolution infrared laser absorption methods. State-resolved Doppler absorption profiles are recorded for multiple HF(v,J) transitions originating in the v=0,1,2,3 manifold, analyzed to yield absolute column-integrated densities via known HF transition moments, and converted into nascent probabilities via density-to-flux analysis. The spectral resolution of the probe laser also permits Doppler study of translational energy release into quantum-state-resolved HF fragments, which reveals a remarkable linear correlation between (i) HF(v,J) translational recoil and (ii) the remaining energy available, Eavail=Etot-E(HF(v,J)). The dynamics are interpreted in the context of a simple impulsive model based on conservation of linearangular momentum that yields predictions in good agreement with experiment. Deviations from the model indicate only minor excitation of ethyl vibrations, in contrast with a picture of extensive intramolecular vibrational energy flow but consistent with Franck-Condon excitation of the methylene CH2 bending mode. The results suggest a relatively simple dynamical picture for exothermic atom+polyatomic scattering, i.e., that of early barrier dynamics in atom+diatom systems but modified by impulsive recoil coupling at the transition state between translationalrotational degrees of freedom.
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Affiliation(s)
- Erin S Whitney
- JILA, National Institute of Standards and Technology and University of Colorado, Boulder, Colorado 80309-0440, USA
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Zhang J, Dai D, Wang CC, Harich SA, Wang X, Yang X, Gustafsson M, Skodje RT. State to state to state dynamics of the D+H2 -->HD+H reaction: control of transition-state pathways via reagent orientation. PHYSICAL REVIEW LETTERS 2006; 96:093201. [PMID: 16606261 DOI: 10.1103/physrevlett.96.093201] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/08/2005] [Revised: 02/22/2006] [Indexed: 05/08/2023]
Abstract
The influence of reagent rotation on the dynamics of the D+H2 -->HD+H reaction is studied. The state-resolved differential cross section is measured using the Rydberg-atom scheme in a crossed beam experiment. It is found that the H2 rotation has a strong influence on the results. This effect was traced to the selection of the quantum bottleneck states through reagent orientation, thus suggesting a novel strategy to control the transition-state pathways in direct chemical reactions.
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Affiliation(s)
- Jianyang Zhang
- Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian, China
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Yang * X. State-to-state dynamics of elementary chemical reactions using Rydberg H-atom translational spectroscopy. INT REV PHYS CHEM 2005. [DOI: 10.1080/01442350500163806] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
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Aoiz * FJ, BaÑares L, Herrero VJ. The H+H2reactive system. Progress in the study of the dynamics of the simplest reaction. INT REV PHYS CHEM 2005. [DOI: 10.1080/01442350500195659] [Citation(s) in RCA: 92] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
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Zhou J, Lin JJ, Liu K. Observation of a reactive resonance in the integral cross section of a six-atom reaction: F+CHD3. J Chem Phys 2004; 121:813-8. [PMID: 15260609 DOI: 10.1063/1.1761051] [Citation(s) in RCA: 68] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
The title reaction was investigated under crossed-beam conditions at collisional energies ranging from about 0.4 to 7.5 kcal/mol. Product velocity distributions were measured by a time-sliced, velocity-map imaging technique to explicitly account for the density-to-flux transformation factors. Both the state-resolved, pair-correlated excitation functions and vibrational branching ratios are presented for the two isotopic product channels. An intriguing resonance tunneling mechanism occurring near the reaction threshold for the HF+CD3 product channel is surmized, which echoes the reactive resonances found previously for the F+HD-->HF+D reaction and more recently for the F+CH4 reaction.
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Affiliation(s)
- Jingang Zhou
- The Institute of Atomic and Molecular Sciences (IAMS), Academia Sinica, P.O. Box 23-166, Taipei, Taiwan 106
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Chao SD, Skodje RT. Time delay as a tool to identify the signatures of reactive resonance: F+HD and F+H2 reactions. J Chem Phys 2003. [DOI: 10.1063/1.1582172] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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Dai D, Wang CC, Harich SA, Wang X, Yang X, Der Chao S, Skodje RT. Interference of quantized transition-state pathways in the H + D2 -> D + HD chemical reaction. Science 2003; 300:1730-4. [PMID: 12805543 DOI: 10.1126/science.1084041] [Citation(s) in RCA: 131] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
The collision-energy dependence of the state-resolved differential cross section at a specific backward-scattering angle for the reaction H + D2 --> D + HD is measured with the D-atom Rydberg "tagging" time-of-flight technique. The reaction was modeled theoretically with converged quantum scattering calculations that provided physical interpretation of the observations. Oscillations in the differential cross sections in the backward-scattering direction are clearly observed and are attributed to the transition-state structures that originate from the interferences of different quantized transition-state pathways.
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Affiliation(s)
- Dongxu Dai
- State Key Laboratory of Molecular Reaction Dynamics, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian, China
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Abstract
This review discusses recent quantum scattering calculations on bimolecular chemical reactions in the gas phase. This theory provides detailed and accurate predictions on the dynamics and kinetics of reactions containing three atoms. In addition, the method can now be applied to reactions involving polyatomic molecules. Results obtained with both time-independent and time-dependent quantum dynamical methods are described. The review emphasises the recent development in time-dependent wave packet theories and the applications of reduced dimensionality approaches for treating polyatomic reactions. Calculations on over 40 different reactions are described.
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Chao SD, Harich SA, Xu Dai D, Wang CC, Yang X, Skodje RT. A fully state- and angle-resolved study of the H+HD→D+H2 reaction: Comparison of a molecular beam experiment to ab initio quantum reaction dynamics. J Chem Phys 2002. [DOI: 10.1063/1.1504083] [Citation(s) in RCA: 55] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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Harich SA, Dai D, Wang CC, Yang X, Chao SD, Skodje RT. Forward scattering due to slow-down of the intermediate in the H + HD --> D + H(2) reaction. Nature 2002; 419:281-4. [PMID: 12239562 DOI: 10.1038/nature01068] [Citation(s) in RCA: 162] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Quantum dynamical processes near the energy barrier that separates reactants from products influence the detailed mechanism by which elementary chemical reactions occur. In fact, these processes can change the product scattering behaviour from that expected from simple collision considerations, as seen in the two classical reactions F + H(2) --> HF + H and H + H(2) --> H(2) + H and their isotopic variants. In the case of the F + HD reaction, the role of a quantized trapped Feshbach resonance state had been directly determined, confirming previous conclusions that Feshbach resonances cause state-specific forward scattering of product molecules. Forward scattering has also been observed in the H + D(2) --> HD + D reaction and attributed to a time-delayed mechanism. But despite extensive experimental and theoretical investigations, the details of the mechanism remain unclear. Here we present crossed-beam scattering experiments and quantum calculations on the H + HD --> H(2) + D reaction. We find that the motion of the system along the reaction coordinate slows down as it approaches the top of the reaction barrier, thereby allowing vibrations perpendicular to the reaction coordinate and forward scattering. The reaction thus proceeds, as previously suggested, through a well-defined 'quantized bottleneck state' different from the trapped Feshbach resonance states observed before.
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Affiliation(s)
- Steven A Harich
- Institute of Atomic and Molecular Sciences, Academia Sinica, Taipei, Taiwan
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Althorpe SC. Time-dependent plane wave packet formulation of quantum scattering with application to H+D2→HD+D. J Chem Phys 2002. [DOI: 10.1063/1.1504082] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
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Aoiz FJ, Bañares L, Castillo JF, Sokolovski D. Energy dependence of forward scattering in the differential cross section of the H+D2→HD(v′=3,j′=0)+D reaction. J Chem Phys 2002. [DOI: 10.1063/1.1490920] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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Abstract
Recent studies of state-resolved angular distributions show the participation of reactive scattering resonances in the simplest chemical reaction. This review is intended for those who wish to learn about the state-of-the-art in the study of the H + H2 reaction family that has made this breakthrough possible. This review is also intended for those who wish to gain insight into the nature of reactive scattering resonances. Following a tour across several fields of physics and chemistry where the concept of resonance has been crucial for the understanding of new phenomena, we offer an operational definition and taxonomy of reactive scattering resonances. We introduce simple intuitive models to illustrate each resonance type. We focus next on the last decade of H + H2 reaction dynamics. Emphasis is placed on the various experimental approaches that have been applied to the search for resonance behavior in the H + H2 reaction family. We conclude by sketching the road ahead in the study of H + H2 reactive scattering resonances.
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Affiliation(s)
- Félix Fernández-Alonso
- Istituto di Struttura della Materia-Consiglio Nazionale delle Ricerche, Area della Ricerca di Roma-Tor Vergata, 00133 Rome, Italy.
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Harich SA, Dai D, Yang X, Chao SD, Skodje RT. State-to-state dynamics of H+HD→H[sub 2]+D at 0.5 eV: A combined theoretical and experimental study. J Chem Phys 2002. [DOI: 10.1063/1.1461818] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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Fernández-Alonso F, Bean BD, Zare RN, Aoiz FJ, Bañares L, Castillo JF. Forward scattering in the H+D2→HD+D reaction: Comparison between experiment and theoretical predictions. J Chem Phys 2001. [DOI: 10.1063/1.1390505] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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