Mass action expressions surface reaction kinetics

In the Surface Chemkin formalism, surface processes are written as balanced chemical reactions governed by the law of mass-action kinetics. The framework was developed to provide a very general way to describe heterogeneous processes. In this section many of the standard surface rate expressions are introduced. The connection between these common forms and the explicit mass-action kinetics approach is shown in each case. 

The expression for the rate of a bimolecular reaction of adsorbed particles when the latter have a rapid surface mobility can be obtained in the traditional way for chemical kinetics if the law of mass action is used for large quasi-particles. Let us consider the reaction AZ+BZ on a homogeneous surface containing three species of particles (s = 3) A, B, and Y (the real properties of the vacant sites Y are taken into account in the final expressions). Particles of A and B are at neighboring sites of a lattice and enter the c.s. of one another. 

PM AX corresponds to the reaction rate constant, called maximal production rate in the present context, TEMP expresses a kind of dependence on time through temperature (a phenomenon common in nonisothermal reactions), it is called here temperature limitation, Iq is an external forcing function it is the global radiation on the water surface, U2 is a joint limitation factor describing light- and nutrient-dependence of primary production, or to use the language of reaction kinetics it expresses the deviation from mass-action type kinetics. 

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