The master equation for internal relaxation in molecules

The use of the master equation to describe the relaxation of internal energy in molecules is, in fact, nothing more than the writing of a set of kinetic rate equations, one equation for each individual rotation-vibration state of the molecule. The simplest case we can consider is that of an assembly of diatomic molecules highly diluted in a monatomic gas under these conditions, we only need to consider the set of processes 

1 For the reader who is interested in the more fundamental aspects of the master equation and its application to problems in chemical physics, a valuable collection of reprints has been assembled, together with a lengthy introduction, by Oppenheim, Shuler, and Weiss [77.0], another good starting point would be the recent book by van Kampen [8I.KI]. 

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