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X-ray photoelectron spectroscopy (XPS)Principles
X-ray photoelectron spectroscopy (XPS - ESCA) was developped in the mid 1960s by the K. Siegbahn group (University of Upsalla, Sweden). The first Belgian XPS system was installed in our laboratory beginning 1970s. A sample, introduced in an ultra high vacuum chamber, is bombarded with an X-ray beam. The kinetic energy (in electron volts, eV) of emitted electrons of all elements (except H and He) present at the surface (analyzed depth between 1 and 10 nm) is measured with a precision of about 0.2 eV. Shape and position of peaks depend on the chemical state of the element (the so-called " chemical shift " effect). Area of peaks used in combination with sensitivity factors allow to calculate atom fractions with a detection limit of a few tenths of atom percent. A detailed analysis of certain well-resolved peaks allows to quantify functionalities present at the surface. On most recent systems the minimum spatial resolution is of about 15 µm and 5 µm for XPS analysis and XPS imaging respectively. In most cases XPS can be considered as a non-destructive technique. Applications XPS can be used to characterize the surface of all types of materials, quite exclusively solids (powders or bulk specimen) as it is the case in our group: biomaterials, catalysts, ceramics, fibers, glass, metals, minerals, polymers... The laboratories sharing the XPS facilities have an uncommon expertise in using the method for analysis of microbial cells and adsorbed phases on one hand and of catalysts and dispersed materials on the other hand. Systems
Kratos Axis Ultra Access Our XPS systems are accessible to academic and industrial research teams. For additional information please contact Useful links
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16/07/2008
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