XANES

Much chemical information can be extracted from the XANES region: formal valence (very difficult to experimentally determine in a nondestructive way); coordination environment (e.g., octahedral, tetrahedral coordination) and subtle geometrical distortions of it.

Transitions to bound vacant states just above the Fermi level can be seen. Thus XANES spectra can be used as a probe of the unoccupied band structure of a material.

The near-edge structure is characteristic of an environment and valence state hence one of its more common uses is in fingerprinting: if you have a mixture of sites/compounds in a sample you can fit the measured spectra with a linear combinations of XANES spectra of known species and determine the proportion of each site/compound in the sample.

 

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Fig.1: Fe K-edge XANES of all measured standards recorded in TXRF geometry. The spectra are displaced vertically for clarity. The vertical line at 7126 eV indicates the edge position of the ferric sulfate (Fe2(SO4)3) standard.