The Arrhenius Equation: Limits of Validity under Extreme Reaction Conditions

Abstract

Photon‐induced molecular dissociation increases the portion of radical reactions which in general can be treated in the framework of chemical equilibrium kinetics of the translational degrees of freedom of the reagents. In particular an “inversion” of the Arrhenius equation gives a reactive “Arrhenius” cross section which shows a wide (but limited) spectrum of possibilities describing bimolecular gas phase reactions in the framework of Arrhenius kinetics. The occurrence of charged particles and energy‐rich cosmic, solar and magnetospheric species and the presence of electromagnetic fields lead to nonequilibrium situations which have to be described by the chemical nonequilibrium kinetics deviating from Arrhenius kinetics.