Knowledge-based probabilistic representations of branching ratios in chemical networks: The case of dissociative recombinations

Journal Article · Thu Oct 07 00:00:00 EDT 2010 · Journal of Chemical Physics

DOI:https://doi.org/10.1063/1.3479907· OSTI ID:21559922

Plessis, Sylvain ^[1]; Carrasco, Nathalie ^[2]; Pernot, Pascal ^[1]; CNRS, Orsay F-91405 ^[3]

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1. Laboratoire de Chimie Physique, Univ Paris-Sud, UMR 8000, Orsay F-91405 (France)
2. Laboratoire Atmospheres, Milieux, Observations Spatiales, Universite de Versailles Saint-Quentin, UMR 8190, 78280 Guancourt (France)
3. France

Experimental data about branching ratios for the products of dissociative recombination of polyatomic ions are presently the unique information source available to modelers of natural or laboratory chemical plasmas. Yet, because of limitations in the measurement techniques, data for many ions are incomplete. In particular, the repartition of hydrogen atoms among the fragments of hydrocarbons ions is often not available. A consequence is that proper implementation of dissociative recombination processes in chemical models is difficult, and many models ignore invaluable data. We propose a novel probabilistic approach based on Dirichlet-type distributions, enabling modelers to fully account for the available information. As an application, we consider the production rate of radicals through dissociative recombination in an ionospheric chemistry model of Titan, the largest moon of Saturn. We show how the complete scheme of dissociative recombination products derived with our method dramatically affects these rates in comparison with the simplistic H-loss mechanism implemented by default in all recent models.

• OSTI ID: 21559922
• Journal Information: Journal of Chemical Physics, Journal Name: Journal of Chemical Physics Journal Issue: 13 Vol. 133; ISSN JCPSA6; ISSN 0021-9606
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
ATMOSPHERES
ATOMS
BOUNDARY-VALUE PROBLEMS
BRANCHING RATIO
CALCULATION METHODS
CHARGED PARTICLES
COMPARATIVE EVALUATIONS
DIMENSIONLESS NUMBERS
DIRICHLET PROBLEM
DISSOCIATION
ELEMENTS
EVALUATION
HYDROCARBONS
HYDROGEN
IONS
MOON
NONMETALS
ORGANIC COMPOUNDS
PLANETARY ATMOSPHERES
PLANETS
PLASMA
PROBABILISTIC ESTIMATION
PROBABILITY
RECOMBINATION
SATELLITES
SATURN PLANET