![]() Unless very high resolutions are used then some spin-orbit splitting cannot always be resolved or is obscured by peak broadening in difference chemical states of the same element ( e.g. The table below shows the different spin combinations that can give rise to the total j and the expected area ratio. It is highly important these ratios are taken in to account when analysing XPS spectra of p, d and f -levels. Na(1s) and Cl(2p) orbitals for NaCl, showing absence of spin-orbit splitting for the s-orbital, but splitting is present in the p-orbital of Cl. The area ratio, or degeneracy, between these spin-orbit split peaks is then given by 2 j + 1, or 1:2 This corresponds to 2 electrons in the 2p 1/2 level and 4 electrons in the 2p 3/2 level. In this example, for the Cl(2p) spectrum, n = 2 and l = 1, therefore j = 1/ 2 and j = 3/ 2. This can be seen in the figure for NaCl below. j = l + s (where s is the spin angular momentum number and equals ±½).Īll orbitals except the s-orbitals ( l = 0), yield a doublet with the two possible states having different binding energies – this differece between the peaks is termed spin-orbit splitting (also known as j-j coupling).ĭue to the physics of this phenomena, the peaks will have a defined area ratio based on the degeneracy of each spin state.l is the angular momentum quantum number. ![]()
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