peaks from electrons in 1s will have a greater energy than peaks representing electrons from 2s. The greater the binding energy, the greater the attraction of that electron to the nucleus.As seen in the figure above, the O1s has the largest peak, and it shows that the atomic composition of oxygen is the greatest. Therefore, the peak intensities give information about the percent composition of a material. For example, if a peak, A, is half the height of another peak B, that means there were half as many electrons detected with the binding energy at A compared to the number of electrons detected with the binding energy at B. The shorter the peak, the less electrons represented. Peaks from the XPS spectra give relative number of electrons with a specific binding energy.
(Figure courtesy of the creative commons license. Graph showing the binding energies of electrons from different orbitals (F1s, O1s, Si2p, etc.) and their intensities which tell the atomic composition of the sample based on the amounts of each electron from different orbitals present.
