## surface excess, $$n^{\sigma}$$

https://doi.org/10.1351/goldbook.S06171
For an @I03082@, the adsorption or surface excess of a given component is defined as the difference between the amount of component actually present in the system, and that which would be present (in a reference system) if the bulk concentration in the adjoining phases were maintained up to a chosen geometrical @D01823@ (@G02635@). For a solid/liquid @I03082@ in which no component of the liquid phase penetrates into the solid, the surface excess (or adsorption) of component i is defined as: $n_{i}^{\sigma }=n_{i}- V^{\text{l}}\ c_{i}^{\text{l}}$ where $$n_{i}$$ is the total amount of i in the system, $$V^{\text{l}}$$ is the volume of an arbitrarily chosen amount of bulk liquid (in the framework of the so-called algebraic method) and $$c_{i}^{\text{l}}$$ is its bulk concentration in the liquid.
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