Technical Documentation

Principe : Photoelectron spectroscopy x – xps – allows to obtain the chemical composition of a surface of a material to a depth ranging from 1 nm to 10 nm.

The interaction of photons of a source x with the subject matter makes unstable the atoms that make it up. this input of energy, for little that it is enough, allows electrons gravitate around the nucleus to break the attraction that keeps them in their orbital. they then leave the atom with a kinetic energy ec. propelled into the matter, they travel a distance that is a function of this energy and material in which they are evolving. if their energy is sufficient, some electrons reach the surface, are extracted from the material and pass into the void. the electrons emitted are collected and counted according to their kinetic energies. the relationship e_l =hv-ec-w_work output is used to determine the binding energy e_l of electrons and identify the atoms from which they come.

Interest/Objective:

This technique gives a direct access to the chemical composition of the surface layers of a material, as well as to the electronic structure of the elements present. it gives information mainly on the relative proportions of the elements present in the first atomic layer, and on their oxidation state.

This technique allows, among other things, determine :

• elements present (except hydrogen)
• atomic percentage of each element,
• nature and quantification of chemical bonds between these elements.
• mapping chemical : resolution 3 µm.