Multiple temperature descriptions of reaction rate constants with regard to consistent chemical-vibrational coupling

Arrhenius descriptions for nonequilibrium reaction rate constants which were introduced in the literature have been studied and analysed in a wide temperature range. Inconsistencies and shortcomings of these models are discussed. In order to derive a consistent multiple temperature Arrhenius description of rate constants, the basic physical assumptions are pointed out. It is assumed that the vibrational excitation of molecules plays a crucial role not only in dissociations but in all types of reactions with molecular participation. As a result, a modified Ford model and an extended Marrone model are proposed, which are suitable to take the vibrational excitation of molecules in exchange reactions and associative ionizations into account. Because thermal relaxation processes are very sensitive to the amounts of vibrational energies which are gained or lost in all types of reactions, these energy amounts are required to be calculated in a consistent way with rate constant formulations. It is shown that energy values and rate constants must not be chosen independently of each other. A proposal is made how to calculate these energy amounts. Comparisons with experimental data are used to discuss the suggested model.