Electron Spectroscopy for Chemical Analysis (ESCA), also known as X-ray Photoelectron Spectroscopy (XPS), is an effective technique to detect the elements and their bonding states on the surface layers of solid. The method uses soft X-rays to eject electrons from inner-shell orbitals. The kinetic energy of these photoelectrons is determined by the energy of the X-ray radiation, and the electron binding energy. Because the electron binding energies are dependent on the chemical environment of the atom, it makes XPS useful to identify the oxidation state and ligands of an atom. On the other hand, however, the binding energy may shift (up to several eV) reflecting the chemical state of the atom, it is also possible to get information on the valence number and oxidation number, and the type of functional group present. Moreover, the ion etching technique provides the depth profiling from the surface. If the surface is irradiated not by soft X-ray but by electrons, the determination of the kinetic energies of Auger electrons ejected allows the surface elemental analysis of solids, especially, of conductive solids, which is designated Auger Electron Spectroscopy (AES). If irradiated by argon ions, the masses of the secondary ions ejected will also give the surface information of solids, designated Secondary Ion Mass Spectroscopy (SIMS).

The Center has a Shimadzu ESCA-850 instrument for ESCA analysis. The optional functions for AES and SIMS are also available.