Simplest bimolecular reactions in condensed media

The mathematical technique of formal chemical kinetics is very useful for qualitative estimates and general analysis of processes in condensed matter. The treatment of a problem begins usually with the analysis of the reaction 

It contains the phenomenological parameter k called reaction rate. (The particle lifetime tq = 1 /k.) 

Such simplest bimolecular reaction, A -1- B —) C, obeys the equation 

This case is called degenerate bimolecular or pseudo-first order reaction. 

Another example of simple bimolecular reaction is mobile exciton annihilation which is well studied in molecular crystals A -I- A 0 (zero means that usually we are not interested what is happening with reaction products) [10]. In this case the kinetic equation is obvious 

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