Chain reactions critical branching factor

Such reactions have been used to explain the three limits found in some oxidation reactions, such as those of hydrogen or of carbon monoxide with oxygen, with an "explosion peninsula between the lower and the second limit. However, the phenomenon of the explosion limit itself is not a criterion for a choice between the critical reaction rate of the thermal theory and the critical chain-branching coefficient of the isothermal-chain-reaction theory (See Ref). For exothermic reactions, the temperature rise of the reacting system due to the heat evolved accelerates the reaction rate. In view of the subsequent modification of the Arrhenius factor during the development of the reaction, the evolution of the system is quite similar to that of the branched-chain reactions, even if the system obeys a simple kinetic law. It is necessary in each individual case to determine the reaction mechanism from the whole... 

A pressure variation can lead to a change in the relative importance of the different channels in multichannel reactions, for example, in reactions of biradicals with unsaturated hydrocarbons [115], to an increase in the yield of radical recombination products, and to a deactivation of excited molecules. Lastly, the pressure is a critical factor for branched-chain reactions. Some of the authors [79] also discussed the possibility of the appearance of fundamentally new reaction channels associated with the manifestation of the cage effect when the resulting short-lived molecular complex has time to interact with other agents before decaying. 

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