Cohesive energies from monolayer desorption

Cohesive Energies from Monolayer Desorption Studies... 

Measurement of the free energies of monolayer desorption from the rates of desorption depends on whether equilibrium exists between the monolayer and a thin region of solution immediately beneath the film. The relation which tests this condition (Equation 8) must correctly predict the dependence of the rate constant for desorption, k8, on 7r. For the sulfate, phosphonate, and carboxyl films in this study Equation 8 is obeyed within the range of experimental error (2 to 5%). Therefore, it is reasonable to assume that the necessary equilibrium condition does exist. The cohesive forces in the monolayer follow directly from the evaluation of the free energies of desorption. 

Implicit in the determination of Wr, the cohesive energy in the hydrocarbon region of the long-chain monolayer, is the assumption that W0, the free energy of desorption for one —CH2— group, obtained with relatively short hydrocarbon chains, is independent of the length of the hydrocarbon moiety. The validity of this assumption can be checked for sulfate films where W(. may be obtained from desorption studies as... 

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