Observation of a translational energy threshold for a highly exoergic ion-molecule reaction

Wyatt, J. R.; Strattan, L. W.; Snyder, S. C.; Hierl, Peter M.

doi:10.1063/1.1681592

Cited by 7 publications

(1 citation statement)

References 15 publications

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“…Hydrogen atom abstraction reactions of methane with other ions have also been observed to occur in a stripping-like interaction. 2,60,61 The remaining TOF peak in Figure 5b indicates small impact parameter collisions, resulting in backscattered OH + with substantially more translational to internal energy transfer, as evidenced by the relatively small displacement from V CM . The location of this feature corresponds to the region in which the substantial loss of signal is observed in the low-U RF study for CD 3 + /OD + at E T ) 2 eV, in Figure 3b, and suggests that the backscattered OH + may involve a broad angular distribution, tailing to the forward hemisphere, as observed in Figure 5b.…”

Section: Discussionmentioning

confidence: 99%

Hyperthermal Reactions of O⁺(⁴S_3/2) with CD₄ and CH₄: Theory and Experiment

Levandier¹,

Chiu²,

Dressler³

et al. 2004

J. Phys. Chem. A

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Public reporting burden for this collection of information is estimated to average 1 hour per response, including the time for reviewing instructions, searching existing data sources, gathering and maintaining the data needed, and completing and reviewing this collection of Information. Send comments regarding this burden estimate or any other aspect of this collection of Information, including suggestions for reducing this burden to Department of Defense, Washington Headquarters Services, Directorate for Information Operations and Reports (0704-0188), 1215 Jefferson Davis Highway, Suite 1204, Arlington, VA 22202-4302. Respondents should be aware that notwithstanding any other provision of law, no person shall be subject to any penalty for failing to comply with a collection of information if it does not display a currentiy" valid OMB control number. PLEASE DO NOT RETURN YOUR FORM TO THE ABOVE ADDRESS. REPORT DATE (DD-MM-YYYY)2. REPORT SPONSORING I MONITORING AGENCY NAME(S) AND ADDRESS(ES) 10. SPONSOR/MONITOR'S ACRONYM(S) SPONSORIMONITOR'S REPORT NUMBER(S)12 ABSTRACTTheoretical and experihental methods are applied to the study of the reaction dynamics in hyperthermal collisions of 0+ ( 4 S3t) with methane. Measurements of the absolute reaction' cross sections for the interaction of 0+ with CD 4 and CH4 were obtained at collision energies in the range from near-thermal to approximately 15 eV, using the guided-ion beam (GIB) technique. Product recoil velocity distributions, using the GIB timeof-flight (TOF) methods, were determined for several product ions at selected collision energies. The main reaction channel, charge transfer, proceeds via large impact parameter collisions. A number of minor channels, involving more intimate collisions, were also detected. Ab initio electronic structure calcu'lations have been performed with different levels of theory and basis sets, including high-level coupled-cluster calculations to determine the energies of reaction intermediatesand transition states for reaction. Several, reaction paths on both quartet and doublet electronic states of (O.CH4)+ are found, and these provide a reasonable qualitative .interpretation of the experiments. Although most of the products can be produced via spin-allowed pathways, the appearance of CH 3 + at low energies suggests that intersystem crossing plays some role. Chemistry, Northwestern University, Evanston, Illinois 60208-3113 Received: May 10, 2004; In Final Form: June 4, 2004 Theoretical and experimental methods are applied to the study of the reaction dynamics in hyperthermal collisions of 0+ ( 4 S 3 / 2 ) with methane. Measurements of the absolute reaction cross sections for the interaction of 0+ with CD 4 and CH 4 were obtained at collision energies in the range from near-thermal to approximately 15 eV, using the guided-ion beam (GIB) technique. Product recoil velocity distributions, using the GIB timeof-flight (TOF) methods, were determined for several product ions at selected collision energies. The main reaction channel...

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Section: Discussionmentioning

confidence: 99%

Hyperthermal Reactions of O⁺(⁴S_3/2) with CD₄ and CH₄: Theory and Experiment

Levandier¹,

Chiu²,

Dressler³

et al. 2004

J. Phys. Chem. A

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Molecular beam techniques : applications to the study of ion-molecule collisions

Gentry

1979

Gas Phase Ion Chemistry

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Chemical accelerator studies of reaction dynamics: Ar+ + CH4 → ArH+ + CH3

Wyatt

Strattan

Snyder

et al. 1975

The Journal of Chemical Physics

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Chemical accelerator studies on isotopic variants of the reaction Ar+ + CH. --I ArH+ + CH 3 are reported. Velocity and angular distributions of the ionic product as a function of initial translational energy have been measured over the energy range 0.39-25 eV center-of-mass (c.m.). The asymmetry of the product distribution with respect to the center of mass indicates that the reaction is predominantly direct over the energy range studied. The dynamics of the reaction are approximated by the spectator stripping model: The reaction exothermicity appears as product internal energy and product excitation increases with collision energy at the rate predicted by this model. The internal degrees of freedom of the neutral product have little effect on reaction dynamics, and product excitation appears to reside principally in the ionic product. Deviations from the spectator stripping model suggest the existence of a basin in the potential energy hypersurface for this reaction; the ArCH: complex which may be formed at low collision energies, however. preferentially decomposes via reaction channels other than that resulting in ArH+ formation.

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Observation of a translational energy threshold for a highly exoergic ion-molecule reaction

Cited by 7 publications

References 15 publications

Hyperthermal Reactions of O⁺(⁴S_3/2) with CD₄ and CH₄: Theory and Experiment

Hyperthermal Reactions of O⁺(⁴S_3/2) with CD₄ and CH₄: Theory and Experiment

Molecular beam techniques : applications to the study of ion-molecule collisions

Chemical accelerator studies of reaction dynamics: Ar+ + CH4 → ArH+ + CH3

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Observation of a translational energy threshold for a highly exoergic ion-molecule reaction

Cited by 7 publications

References 15 publications

Hyperthermal Reactions of O+(4S3/2) with CD4 and CH4: Theory and Experiment

Hyperthermal Reactions of O+(4S3/2) with CD4 and CH4: Theory and Experiment

Molecular beam techniques : applications to the study of ion-molecule collisions

Chemical accelerator studies of reaction dynamics: Ar+ + CH4 → ArH+ + CH3

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Hyperthermal Reactions of O⁺(⁴S_3/2) with CD₄ and CH₄: Theory and Experiment

Hyperthermal Reactions of O⁺(⁴S_3/2) with CD₄ and CH₄: Theory and Experiment