6. Beyond roughness, new microscopes and surface probes

In recent years, instruments with a spatial resolution approaching that of electron microscopes have been developed to go beyond roughness to the structure of surfaces of various materials on the nanometer scale. The microgeometry of solid surfaces is thus being studied at sub-nanometer scale by a category of new instruments: electron or optical scanning tunneling microscopes, near-field microscopes and atomic force microscopes.

• The first scanning tunneling microscope was electronic. A fine conductive fiber (a tungsten tip whose physico-chemical treatment techniques give the tip a radius of a few tens of nanometers) is brought close to the surface at a distance such that no contact is made, and the electrical charges present on the object tunnel through the insulating zone. Variations in this electrical current collected by the tip can give...