The characterisation of solids by adsorption and immersion techniques and by AFM/STM

The surface of porous and non-porous solids can be characterised by a variety of techniques. Basic information is provided by the interpretation of adsorption isotherms, which can be combined with immersion calorimetry. Adsorption in micropores is described by Dubinin's theory, which applies to carbons, as well as other solids, but it appears that this theory can also be extended to non-porous solids. In this case, it takes the form of the Dubinin-Radushkevich and Kaganer (DRK) equation. For a number of systems, a good agreement is found with the BET method and the data obtained from vapour adsorption and from immersion calorimetry shows selfconsistency. The structural data derived from adsorption and immersion techniques is also compared with the direct observation of the surface by atomic force and scanning tunnelling microscopies. The relation with the fractal character D of a surface is also considered.