A quasiclassical trajectory study of H + CO sub 2 yields OH + CO: Bulk reaction dynamics and the effect of van der Waals precursor formation

Journal Article · Thu Oct 17 04:00:00 EDT 1991 · Journal of Physical Chemistry; (United States)

DOI:https://doi.org/10.1021/j100174a047· OSTI ID:7274000

Kudla, K; Schatz, G C ^[1]

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1. Northwestern Univ., Evanston, IL (United States)

The authors present the results of a quasiclassical trajectory study of the H+CO{sub 2} {yields} OH+CO reaction, with particular emphasis on comparing the bulk reaction dynamics (isolated bimolecular collisions) with results for the van der Waals precursor photoinduced reaction HBr{center dot}CO{sub 2} hv {yields} OH+CO+Br. All calculations are based on a full-dimensional HCO{sub 2} potential surface that was derived from ab initio calculations. The T-shaped HBr{center dot}CO{sub 2} system was modeled by adding HBr, BrC, and BrO pair potentials to the HCO{sub 2} potential. Their cross sections and OH product distributions for the bulk reaction are generally in good agreement with experiment over a wide range of collision energies. The agreement is especially good close to the effective threshold for reaction. The trajectory CO product distributions are in good agreement with recent measurements at 300 K, but there are important differences in the dependence of the distributions on initial rotational temperature. In modeling the van der Waals reaction, the experimental geometry for the heavy atoms is used to define initial conditions, with the orientation of the HBr relative to CO{sub 2} treated as a variable. The authors find that reaction occurs efficiently over angular regions in which the H atoms is directed into either HOCO or HCO{sub 2} wells. Overall energy available to the OH+CO products is about 80% of the bulk value, which is consistent with the major component of the energy distribution that has been inferred from experiment. However, the trajectory calculations indicate that the energy in products is not reduced equally for all degrees of freedom. In particular, OH rotation is not necessarily colder than in the bulk, in contrast to the experimental result. The energy dependence of the reaction probability is found in the calculations to be stronger in the complexes than in the bulk, while it is about the same in the experimental results.

• OSTI ID: 7274000
• Journal Information: Journal of Physical Chemistry; (United States), Journal Name: Journal of Physical Chemistry; (United States) Vol. 95:21; ISSN 0022-3654; ISSN JPCHA
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
400201* -- Chemical & Physicochemical Properties
ATOM COLLISIONS
ATOM-MOLECULE COLLISIONS
CARBON COMPOUNDS
CARBON DIOXIDE
CARBON OXIDES
CHALCOGENIDES
CHEMICAL REACTIONS
COLLISIONS
CROSS SECTIONS
DYNAMICS
ELEMENTS
HYDROGEN
MECHANICS
MOLECULE COLLISIONS
NONMETALS
OXIDES
OXYGEN COMPOUNDS
PHOTOCHEMICAL REACTIONS
TRAJECTORIES