Adsorption phenomena

International audienceThe notion of a form which is normally associated with a surface is characteristic of a solid. In crystals, each solid can be identified by the arrangement of atoms or molecules composing it. This arrangement, which is specific to each solid, constitutes a solid phase. Generally, this kind of structure (the position of atoms, cohesion energy, etc.) is determined by the finite crystal hypothesis, which involves the same environment for all atoms. Next to the surface, this condition is no longer verified and there is a new local organization of atoms or charges. In the case of ionic environments, in particular, and to respect local electroneutrality, it is often necessary to examine the solid's environment. A balance is established between the material and the different phases in contact with it. This therefore raises the notion of interface, a specific area of the solid from which all kinds of interactions between the solid and the different environmental components in contact with it originate. Depending on the nature of these components, we talk about solid-solid, solid-liquid or solid-gas reactions