X-ray Photoelectron Spectroscopy (XPS)
X-ray photoelectron spectroscopy
(XPS) is a surface chemical analysis
technique with the capability of
determining elemental composition,
oxidation state, empirical formula and
impurities present in a sample. XPS
takes advantage of the photoelectric
effect: it measures the kinetic energy
of electrons that are ejected from a
sample after irradiation by x-rays. The
kinetic energy of an ejected electron
is related to the binding energy of that electron for a certain atom. In this way, binding energies
can be used to assign peaks to atoms in a typical
spectrum.
To the left is a typical full scan showing peaks
originating from specific atoms. Below is zoomedin spectrum of the Si(2p) peak. Electron counts
are plotted versus binding energy. Binding energy
(Ebinding) is determined by the following equation
Ebinding = Ephoton – Ekinetic - Φ
where Ephoton is the energy of the incident x-rays,
Ekinetic is the kinetic energy of the ejected electron
and Φ is the work function of the material.
XPS has applications in chemistry, materials
science, electrical engineering, and condensed
matter physics and is routinenly used to study
inorganic
compounds,
metal
alloys,
semiconductors, polymers, pure elements, glasses,
and ceramics. Images obtained from Wikipedia
commons public domain.