X-ray absorption fine structure spectroscopy

X-ray Absorption Fine Structure (XAFS) spectroscopy is a structural probe for the local atomic environment around selected chemical species.

 

X-ray absorption spectroscopy shows a steep rise at the core-level X-ray energy of X-ray-absorbing atoms and attenuates gradually with the X-ray energy. An observed fine structure near the absorption edges called X-ray absorption near-edge structure (XANES) corresponds to the transition from a core-level to an unoccupied orbital or band and mainly reflects the electronic state of the absorbing atom. In contrast, an oscillatory structure extending for hundreds of electron volts past the edges, called extended X-ray absorption fine structure (EXAFS) results from the interference effect between an emitted electron from an X-ray-absorbing atom and scattered electrons by surrounding atoms and provides information on the local structures around an X-ray absorbing atom.

 

Nearly all elements can be studied with XAFS, though the emphasis has traditionally been on the heavier elements.