Monolayers interaction parameters defined

Here Cj (mole/cm ) is the amount of vapours adsorbed per unit surface area, (mole/cm ) is the monolayer adsorption capacity, b represent the vapour-solid adsorption interaction parameter, defined as follows ... 

Since a SAM is a densely packed system where cooperative phenomena may occur, the overall strength of the next-neighbor interactions is difficult to foresee. For this reason, it is not possible to ensure that a feeding solution made of two, or more, thiols in any well-defined molar ratio will produce mixed monolayers with the same composition. The experimental parameters and conditions may be changed to a certain extent to tune the composition of the resulting monolayer. For instance, the solvent may be chosen to favor a polar thiol over an apolar one.40 43 44... 

Attempts are being made to develop phenomenological theories " of the monolayer phases, but the problem of dealing realistically with the many interactions has not been solved. Phase transitions in condensed monolayer phases have also been investigated with two-dimensional lattice models. In such theories, the ordering processes are described in terms of order parameters whose precise physical significance need not be defined. They therefore do not lead to detailed physical descriptions of the monolayer phases. 

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