Understanding and Representing the Kinetics of Gas-Phase Reaction Systems in Mixtures

Gas-phase reaction kinetics is at the center of the evolution of reacting systems. Many important reactions in the gas phase proceed through rovibrationally excited complexes AB* that are formed either from the association of two particles A + B or from the activation of thermalized species AB by collisions between AB and inert colliders. The fate of these rovibrationally excited complexes is governed by the competition among energy-transferring collisions, unimolecular decomposition, and bimolecular reactions -- yielding a strong dependence of all emergent rate constants on temperature, pressure, and composition of the surrounding mixture. In nearly all realistic environments critical to combustion and planetary atmospheres, multiple species are present in significant quantities and thus contribute to the evolution of the rovibrationally excited complexes. A substantial fraction of these species is inert in the sense that they merely participate in energy-transferring collisions, and a portion of them are instead reactive, which participate in reactive collisions and induce reactions with the rovibrationally excited complexes rather than merely transferring energy. Most of the ine