2. Experimental methods for studying surface structure

Some experimental techniques [2] used to study solid surface structures are intrinsically surface methods, due to the very limited penetration or escape depth of the probe particles. Other techniques, on the other hand, derive from methods usually applied to volumetric studies, but have been adapted to be surface-sensitive. Any method based on the propagation or diffusion of charged particles (electrons or ions) can only be conceived in a vacuum. Conversely, a near-field technique or one based on photon or neutron scattering can be implemented in air.

The need for vacuum or ultra-high vacuum may also be dictated by the nature of the surfaces to be studied and the structural effects to be analyzed. The surface of a material is particularly exposed to contamination and pollution from the surrounding...