Kinetics of field adsorption

The binding energy in field adsorption can be derived from consideration of the kinetics of field adsorption. Specifically, it can be determined from a temperature dependence of the probability of field adsorption on an adsorption site, or the degree of coverage of field adsorption on a plane. As will be shown, a consideration of the probability of field adsorption based on adsorption time and desorption time leads to an equation equivalent to the Langmuir adsorption isotherm, but specific to the problem of field adsorption.112115 Let us focus on one surface atom. The average time it takes to have an image gas atom field adsorbed on the surface atom, ra, is 

Gas species Field v/A Isolated atom model eV Adsorption layer model eV Experimental value eV 

Let us represent the probability of field adsorption at any instant of time t by p(t). This function has to satisfy the difference equation, 

This equation simply states that in dr, p(t) will be reduced by p(t) dr/rd, and increased by dr[l — p(r)]ra. For the case where the surface atom is not field adsorbed with an image gas atom at t = 0, we have p(0) = 0. The solution satisfying this initial condition is 

The equilibrium probability of field adsorption is therefore given by 

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