XPS can often reduce certain metal salts, such as Cu 2+. One method found to help overcome this particular limitation is to use angle-resolved X-ray photoelectron spectroscopy (ARXPS). Eventually, they compared the results to those obtained using the Gaussian/ Lorentzian peak fitting method. They assumed that the Ni in chemical states resulted in the changes in the Ni 2p XPS of the various NMC samples. Caution should be exercised when analyzing polymers, as they are often chemically active and X-rays will provide energy to start degrading the polymer, altering the properties of the sample. The Ni 2+ /Ni 3+ ratio was used to determine the peak position and sharpness. Sample reaction or degredation are important considerations. As an atom absorbs the X-rays, the energy of the X-ray will cause a K-shell electron to be ejected, as illustrated by Figure \(\PageIndex\) Schematic representation of (a) no scattering, (b) inelastic scattering, and (c) elastic scattering. The X-rays penetrate only 5 – 20 Å into the sample, allowing for surface specific, rather than bulk chemical, analysis.
The sample under study is subjected to irradiation by a high energy X-ray source.
It allows the determination of atomic composition of the sample in a non-destructive manner, as well as other chemical information, such as binding constants, oxidation states and speciation. X-Ray photoelectron spectroscopy (XPS), also known as electron spectroscopy for chemical analysis (ESCA), is one of the most widely used surface techniques in materials science and chemistry.
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