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? - 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? - 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 - 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
