A study of chemical systems using signal flow graph theory
Résumé
Photochemistry of giant planets and their satellites is characterized by numerous reactions involving a lot of chemical species. In the present paper, chemical systems are modeled by signal flow graphs. Such a technique evaluates the transmission of any input into the system (solar flux, electrons...) and gives access to the identification of the most important mechanisms in the chemical system. This method is applied to the production of hydrocarbons in the atmospheres of giant planets. In particular, the production of C_2H_6 in the atmosphere of Neptune from the photodissociation of CH_4 is investigated. Different pathways of dissociation of CH_4 are possible from L_alpha radiation. A chemical system containing 14 species and 30 reactions including these different pathways of dissociation is integrated. The main mechanism of production of C_2H_6 is identified and evaluated for each model of dissociation. The importance of various reaction pathways as a function of time is presented.