Fundamental Definitions and Relationships

In the following treatment we shall deal mainly with the overall reversible systems, defined as systems in which the adsorbate is released into the gas phase in the form of the original molecules only (no new 

For the model formulated by the above postulates, the specific desorption rate rd, i.e. the molar rate of release of the adsorbed species under consideration from the unit surface, is in general given by the product of four factors  

the most general expression for the desorption rate in this model is 

The summation extends over all the configurations which give nonzero and different values of kA. 

For a nonassociative desorption, evidently = 1 and fcd is configuration-independent. In other cases, the functions gi(6 y conf) and (conf y) can be combined into a single coverage-dependent function 

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