Microcanonical statistical study of orthopara conversion in the reaction H{sub 3}{sup +}+H{sub 2}{yields}(H{sub 5}{sup +}){sup *}{yields}H{sub 3}{sup +}+H{sub 2} at very low energies
Abstract
The orthopara conversion of H{sub 3}{sup +} and H{sub 2} in the reaction H{sub 3}{sup +}+H{sub 2}{yields}(H{sub 5}{sup +}){sup *}{yields}H{sub 3}{sup +}+H{sub 2} in interstellar space is possible by scrambling the five protons via (H{sub 5}{sup +}){sup *} complex formation. The product distribution of the orthopara conversion reaction can be given by ratios of cumulative reaction probabilities (CRP) calculated by microcanonical statistical theory with conservation of energy, motional angular momentum, nuclear spin, and parity. A statistical method to calculate the statetostate reaction probabilities for given initial nuclear spin species, rotational states, and collision energies is developed using a simple semiclassical approximation of tunneling and abovebarrier reflection. A new calculation method of branching ratios for given total nuclear spins and scrambling mechanisms is also developed. The anisotropic longrange electrostatic interaction potential of H{sub 2} in the Coulomb field of H{sub 3}{sup +} is taken into account using the firstorder perturbation theory in forming the complex. The CRPs and the product distribution of the orthopara conversion reaction at very low energies with reactants in their ground vibronic and lowest rotational states for given initial nuclear spin species are presented as a function of collision energy assuming complete proton scrambling or incomplete protonmore »
 Authors:
 Department of Chemistry, University of Chicago, Chicago, Illinois 60637 and James Franck Institute, University of Chicago, Chicago, Illinois 60637 (United States)
 Publication Date:
 OSTI Identifier:
 20991209
 Resource Type:
 Journal Article
 Resource Relation:
 Journal Name: Journal of Chemical Physics; Journal Volume: 126; Journal Issue: 4; Other Information: DOI: 10.1063/1.2430711; (c) 2007 American Institute of Physics; Country of input: International Atomic Energy Agency (IAEA)
 Country of Publication:
 United States
 Language:
 English
 Subject:
 37 INORGANIC, ORGANIC, PHYSICAL AND ANALYTICAL CHEMISTRY; CONVERSION; HYDROGEN; HYDROGEN IONS 3 PLUS; IONMOLECULE COLLISIONS; PARITY; PERTURBATION THEORY; PROTONS; REACTION KINETICS; ROTATIONAL STATES; SEMICLASSICAL APPROXIMATION; SPIN; STATISTICAL MODELS; TUNNEL EFFECT
Citation Formats
Park, Kisam, and Light, John C. Microcanonical statistical study of orthopara conversion in the reaction H{sub 3}{sup +}+H{sub 2}{yields}(H{sub 5}{sup +}){sup *}{yields}H{sub 3}{sup +}+H{sub 2} at very low energies. United States: N. p., 2007.
Web. doi:10.1063/1.2430711.
Park, Kisam, & Light, John C. Microcanonical statistical study of orthopara conversion in the reaction H{sub 3}{sup +}+H{sub 2}{yields}(H{sub 5}{sup +}){sup *}{yields}H{sub 3}{sup +}+H{sub 2} at very low energies. United States. doi:10.1063/1.2430711.
Park, Kisam, and Light, John C. Sun .
"Microcanonical statistical study of orthopara conversion in the reaction H{sub 3}{sup +}+H{sub 2}{yields}(H{sub 5}{sup +}){sup *}{yields}H{sub 3}{sup +}+H{sub 2} at very low energies". United States.
doi:10.1063/1.2430711.
@article{osti_20991209,
title = {Microcanonical statistical study of orthopara conversion in the reaction H{sub 3}{sup +}+H{sub 2}{yields}(H{sub 5}{sup +}){sup *}{yields}H{sub 3}{sup +}+H{sub 2} at very low energies},
author = {Park, Kisam and Light, John C.},
abstractNote = {The orthopara conversion of H{sub 3}{sup +} and H{sub 2} in the reaction H{sub 3}{sup +}+H{sub 2}{yields}(H{sub 5}{sup +}){sup *}{yields}H{sub 3}{sup +}+H{sub 2} in interstellar space is possible by scrambling the five protons via (H{sub 5}{sup +}){sup *} complex formation. The product distribution of the orthopara conversion reaction can be given by ratios of cumulative reaction probabilities (CRP) calculated by microcanonical statistical theory with conservation of energy, motional angular momentum, nuclear spin, and parity. A statistical method to calculate the statetostate reaction probabilities for given initial nuclear spin species, rotational states, and collision energies is developed using a simple semiclassical approximation of tunneling and abovebarrier reflection. A new calculation method of branching ratios for given total nuclear spins and scrambling mechanisms is also developed. The anisotropic longrange electrostatic interaction potential of H{sub 2} in the Coulomb field of H{sub 3}{sup +} is taken into account using the firstorder perturbation theory in forming the complex. The CRPs and the product distribution of the orthopara conversion reaction at very low energies with reactants in their ground vibronic and lowest rotational states for given initial nuclear spin species are presented as a function of collision energy assuming complete proton scrambling or incomplete proton scrambling. The authors show that the product distribution at very low energies (or very low temperatures) differs substantially from the high energy (or high temperature) limit branching ratios.},
doi = {10.1063/1.2430711},
journal = {Journal of Chemical Physics},
number = 4,
volume = 126,
place = {United States},
year = {Sun Jan 28 00:00:00 EST 2007},
month = {Sun Jan 28 00:00:00 EST 2007}
}

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