njit-etd2003-111 - New Jersey Institute of Technology

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The overall concept can be expressed by the equations below, where M can
represent a generic bath gas molecule, an added "inert" gas molecule; it may also
represent a second molecule of reactant or product. In the simple Lindemann theory k 1 ,
along with k_1 and k2 are taken to be energy-independent and are calculated from the
simple collision theory equation.
Application of the steady-state hypothesis to the concentration of A*, allows the
unimolecular rate constant and the high-pressure and low-pressure limit rate and rate
constants to be determined as follows:
One can expect the Lindemann theory to predict a linear change in the initial rate
of a unimolecular reaction with respect to concentration of M at low pressure. The
transition from high-pressure rate constant to low pressure is called "falloff region".
The k 1 in the original Lindemann theory is taken from the collision theory