What is X-Ray Photoelectron Spectroscopy?
It is a surface-sensitive non-destructive technique that analyzes the outmost ~10 nm of
natural and engineered materials. It is an application of the photoelectric effect described by
Einstein, in which electrons are emitted from atoms in response to impinging
electromagnetic radiation. The kinetic energy of an emitted electron is related to the
binding energy of each electron. Because atoms have multiple orbitals at different energy
states, the resulting response will be a range of emitted electrons with different binding
energies, producing an XPS spectrum.
What can be characterized by the XPS method?
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The composition of material surfaces
The relative abundances of these components on surfaces
The chemical state of polyvalent ions by measuring the binding energies of
elements
Surface characterization
What materials can be characterized by this method?
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Inorganic compounds
Semiconductors
Organic compounds
Thin films and coating on natural and engineered materials
https://serc.carleton.edu/msu_nanotech/methods/xps.html
Instruments of an X-Ray Photoelectron Spectroscopy
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An XPS instrument contains an x-ray source, sample stage, extraction lenses,
analyzer, and detector housed in an ultra-high vacuum environment.
https://mmrc.caltech.edu/XPS%20Info/Practical%20Guides%20to%20XPS/Intro%20to
%20XPS.pdf
How does it work?
X-rays (photons) are shot onto a sample, and when electrons in the sample absorb
enough energy, they are ejected from the sample with a certain kinetic energy. The
energy of those ejected electrons is analyzed by a detector and a plot of these energies
and relative numbers of electrons is produced.
https://www.sciencedirect.com/topics/agricultural-and-biological-sciences/x-rayphotoelectronspectroscopy#:~:text=X%2Drays%20(photons)%20are,et%20al.%2C%202019).
https://www.youtube.com/watch?app=desktop&v=RiaiacbOAQk
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