8. Conclusion

The applications of interfacial phenomena are extremely numerous and of considerable economic importance: let's just mention the field of heterogeneous catalysis in petrochemistry, for example, or that of the electronics and computer industries, where the miniaturization of systems is making surface properties increasingly more important than volume ones, or the phenomena of corrosion and wear, which cost our developed countries around 5% of their GDP every year.

After some forty years of development, this science of surfaces has fortunately reached maturity, despite the immense difficulties it presents in both its theoretical and experimental aspects. One reason for these difficulties is that, in its vicinity, the solid loses its three-dimensional symmetry without acquiring two-dimensional symmetry, except in special cases (Xe adsorption on graphite, for example,...