Specific Process Knowledge/Characterization/XPS/XPS technique: Difference between revisions
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=XPS technique= | =XPS technique= | ||
XPS is a surface sensitive and non destructive technique used for analysis of the elemental composition of a sample. It relies on the photoelectric effect; X-ray photons irradiated onto a sample will cause electrons bound in the sample atoms to become free electrons inside the the sample. The kinetic energy of these photoelectrons depend on the energy of the X-ray photon and their original binding energy. Escaping into the vacuum and counted in the electron spectrometer as function of their kinetic energy, the photoelectrons make a spectrum if represented in terms of numbers as function of their binding energy. | XPS is a surface sensitive and non destructive technique used for analysis of the elemental composition of a sample. It relies on the photoelectric effect; X-ray photons irradiated onto a sample will cause electrons bound in the sample atoms to become free electrons inside the the sample. The kinetic energy of these photoelectrons depend on the energy of the X-ray photon and their original binding energy. Escaping into the vacuum and counted in the electron spectrometer as function of their kinetic energy, the photoelectrons make a spectrum if represented in terms of numbers as function of their binding energy. What makes the technique extremely useful is: | ||
* the fact the kinetic energy of the photoelectrons may be determined with such high accuracy (the resolution of the spectrometer is roughly 1 eV compared to the ~130 eV resolution of the spectrometer in an EDX X-ray detector ) that the small changes in binding energy of the sample electrons caused by the binding to other atoms makes it capable of chemical analysis. | |||
* the inelastic mean free path of the photoelectrons is very short | |||
The basic principle is shown below (the image is taken from Wikipedia). | The basic principle is shown below (the image is taken from Wikipedia). | ||