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X-ray Photoelectron Spectroscopy
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| | X-ray photoelectron spectroscopy (XPS) is a
powerful method to study chemical properties of a sample and is
often referred to as electron spectroscopy for chemical analysis
(ESCA). In XPS photons with a energy hν are absorbed by a system and core
electrons are emitted. The kinetic energy of these electrons are
measured with an energy analyzer. They are given by
Ekin = hν - EB
- φsp , where
EB is the binding energy and φsp is the work
function of the spectrometer. Since binding energies of core
electrons are characteristic for elements in a certain chemical
environment XPS allows for a determination of the atomic
compositions of a sample or the chemical state of an certain
element. In many cases chemical shifts can be used to draw
direct conclusions on the local coordination in a system. For
adsorbates, this often allows to distinguish different
adsorption sites of molecules adsorbed on a surface.
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