Atom--Diatom Collision Processes: Rovibrationally Detailed Cross Sections For Models

摘要

Atom-diatomic molecule collision processes are of particular importance in nonequilibrium numerical models in which rovibrational energy exchange and state-selected dissociation are taken into account by means of rate coefficients. If also translational nonequilibrium is considered, availability of large sets of cross sections is needed. To cope with this issue extended quasiclassical calculations have been performed to obtain translational energy dependent detailed data for hydrogen, nitrogen and oxygen, with particular attention devoted to computational optimization. Problems related to huge memory requirements of large cross section sets when used in numerical models can be effectively solved with an interpolation method proposed by the author, which seems to reach an optimal compromise between accuracy and amount of data storage required. Comparisons with literature are, when available, globally good. An important issue about the exclusion of rotational distribution in both vibrational energy exchange and dissociation rate coefficients is stressed. Rotational distribution can significantly change dynamical results, with obvious consequences in their applications to models, independently of its explicit or implicit consideration into models. Concerning collision induced dissociation/recombination dynamics, a strong rotational dependence is shown using two different mechanisms in the case of hydrogen.