Monomolecular reactions in gases

The most important characteristic feature of the effect of nuclear tunneling on the rate of monomolecular reactions in the gas phase seems to be its 

At present there exist [72, 73] different models to describe monomolecular reactions. We use the quantum version of the Kassel model [72], which combines the obviousness and simplicity of the formulae with the high extent of rigour. Within the framework of this model the molecule is considered as a set of equivalent oscillators having the frequency co. Energy exchange between the oscillators is assumed to be fast. The function f(n) of the distribution of the molecules over the energy range is derived from the equation 

The reaction rate constant is obtained by averaging the rate r(n) with the help of the energy distribution 

The rate of decay of molecules having n quanta can be represented as 

If decay is possible only by means of tunneling, then it is most profitable to collect all the quanta on the active oscillator and we have, for r(n) 

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