Universal and State-Resolved Imaging of Chemical Dynamics

Townsend, David; Li, Wen; Lee, Suk Kyoung; Gross, Richard L.; Suits, Arthur G.

doi:10.1021/jp0526086

Cited by 52 publications

(32 citation statements)

References 99 publications

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“…However, such a behaviour is not seen experimentally in the reaction NO 2 → O͑ 3 P 2 ͒ + NO; 17,18 despite strong similarities between this process and the previous ones, the measured recoil energy distribution shows a sharp increase from E T Ϸ 0 eV, in agreement with the present calculations. More theoretical and experimental work is therefore necessary to clarify this issue.…”

supporting

confidence: 90%

Classical treatment of molecular collisions: striking improvement of the description of recoil energy distributions using Gaussian weighted trajectories

González-Martínez

Bonnet

Larrégaray

et al. 2007

The Journal of Chemical Physics

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The Gaussian weighting (GW) procedure, recently used in the classical treatment of molecular collisions, is a practical way of taking into account quantization of product vibrational actions. The goal of this brief communication is to show that the GW procedure may drastically improve the predictions of the recoil energy distribution between final fragments, an observable frequently measured in molecular beam experiments.

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supporting

confidence: 90%

Classical treatment of molecular collisions: striking improvement of the description of recoil energy distributions using Gaussian weighted trajectories

González-Martínez

Bonnet

Larrégaray

et al. 2007

The Journal of Chemical Physics

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“…In principle, both reactant beams can be prepared in well-defined quantum states before they cross at a specific collision energy under single collision conditions. The products can be monitored via spectroscopic detection schemes such as laser-induced fluorescence (LIF) 40 or Rydberg tagging, 41 via ion imaging probes, 42,43 or via a quadrupole mass spectrometric detector (QMS) with universal electron impact ionization or photoionization coupled to a mass spectrometric device. Here, the crossed molecular beam method with mass spectrometric detection presents the most versatile technique to study these elementary reactions thus permitting the elucidation of the chemical dynamics and, in the case of polyatomic reactions, the primary products.…”

Section: The Crossed Molecular Beam Approachmentioning

confidence: 99%

Reaction Dynamics of Phenyl Radicals in Extreme Environments: A Crossed Molecular Beam Study

Kaiser

2008

Acc. Chem. Res.

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Polycyclic aromatic hydrocarbons (PAHs)sorganic compounds that consist of fused benzene ringssand their hydrogendeficient precursors have attracted extensive interest from combustion scientists, organic chemists, astronomers, and planetary scientists. On Earth, PAHs are toxic combustion products and a source of air pollution. In the interstellar medium, research suggests that PAHs play a role in unidentified infrared emission bands, diffuse interstellar bands, and the synthesis of precursor molecules to life. To build clean combustion devices and to understand the astrochemical evolution of the interstellar medium, it will be critical to understand the elementary reaction mechanisms under single collision conditions by which these molecules form in the gas phase.Until recently, this work had been hampered by the difficulty in preparing a large concentration of phenyl radicals, but the phenyl radical represents one of the most important radical species to trigger PAH formation in high-temperature environments. However, we have developed a method for producing these radical species and have undertaken a systematic experimental investigation. In this Account, we report on the chemical dynamics of the phenyl radical (C 6 H 5 ) reactions with the unsaturated hydrocarbons acetylene (C 2 H 2 ), ethylene (C 2 H 4 ), methylacetylene (CH 3 CCH), allene (H 2 CCCH 2 ), propylene (CH 3 CHCH 2 ), and benzene (C 6 H 6 ) utilizing the crossed molecular beams approach. For nonsymmetric reactants such as methylacetylene and propylene, steric effects and the larger cones of acceptance drive the addition of the phenyl radical to the nonsubstituted carbon atom of the hydrocarbon reactant. Reaction intermediates decomposed via atomic hydrogen loss pathways. In the phenyl-propylene system, the longer lifetime of the reaction intermediate yielded a more efficient energy randomization compared with the phenyl-methylacetylene system. Therefore, two reaction channels were open: hydrogen losses from the vinyl and from the methyl groups. All fragmentation pathways involved tight exit transition states. In the range of collision energies investigated, the reactions are dictated by phenyl radical addition-hydrogen atom elimination pathways. We did not observe ring closure processes with the benzene ring.Our investigations present an important step toward a systematic investigation of phenyl radical reactions under single collision conditions similar to those found in combustion flames and in high-temperature interstellar environments. Future experiments at lower collision energies may enhance the lifetimes of the reaction intermediates, which could open up competing ring closure channels to form bicyclic reaction products.

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“…As demonstrated in a series of recent papers 1-12 the timesliced ion velocity imaging technique 13 or its variants [14][15][16][17] are a powerful method to reveal the state-specific correlation of coincident product pairs in polyatomic reactions. The reaction systems we have examined so far are of the abstraction type X +CH 4 , with X =F͑ 2 P͒, 1-6 Cl͑ 2 P͒, 7-9 O͑ 3 P͒, 10 and OH.…”

Section: Introductionmentioning

confidence: 99%

Rotationally selected product pair correlation: F+CD4→DF(ν′)+CD3(ν2=and2,N)

Zhou

Shiu

Lin

et al. 2006

The Journal of Chemical Physics

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The product pair correlation of the title reaction was measured with rotational selection for both the vibrationally ground CD3(nu = 0) and umbrella-excited CD3(nu2 = 2) products. A striking linear relationship was found between the rotational energy of the selected CD3 product and the correlated kinetic energy release (or the average vibrational energy of the DF coproduct). Such a linearly correlated (or anticorrelated) dependence appears to be stronger for CD3(nu2 = 2,N) than for CD3(nu = 0,N). The mechanistic implication of the observation is that the rotational motion N of the CD3 product tends to lie antiparallel to the orbital angular momentum l' of the two departing products. The dependency on the K quantum number--the projection of N on the top axis--is, on the other hand, less significant yet noticeable.

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Universal and State-Resolved Imaging of Chemical Dynamics

Cited by 52 publications

References 99 publications

Classical treatment of molecular collisions: striking improvement of the description of recoil energy distributions using Gaussian weighted trajectories

Classical treatment of molecular collisions: striking improvement of the description of recoil energy distributions using Gaussian weighted trajectories

Reaction Dynamics of Phenyl Radicals in Extreme Environments: A Crossed Molecular Beam Study

Rotationally selected product pair correlation: F+CD4→DF(ν′)+CD3(ν2=and2,N)

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