Specific Process Knowledge/Characterization/Element analysis: Difference between revisions

During a XPS (X-ray Photoelectron Spectroscopy) analysis, the sample is irradiated with photons of a specific energy (in the Danchip system 1486 eV). When energy of the irradiating X-rays is adsorbed by the atoms in the sample, photoelectrons are edjected [[http://en.wikipedia.org/wiki/Photoelectric_effect]].  

Since the energy of the incomming photons is known, and the energy of the edjected electrons is measured, the binding energy of the electrons in the probed atoms can be known. The binding energy of the electrons are element specific, and is therefor a "finger-print" of the atom. Hence, a measurment of the XPS spectrum gives information of which materials are present in the sample, and at which concentrations.  

XPS is an excellent technique to probe the chemical state of atoms on a surface. The binding eneryg of lower lying atomic levels (for example 1s, 2s and 2p) are at a specific energy, but is slightly affected by the chemical environment of the probed atom. This is known as the '''chemical shift''', and the information from measuring the shift of the electrons binding energies can be used to know the chemical state of atoms.