XANES in condensed systems.

In this short review of recent advances in XANES we have discussed the use of this spectroscopy to probe the geometry of local structure via multiple scattering effects in the real space and and the local partial unoccupied density of states in metals via the band structure approach. Several important aspects of x-ray absorption spectroscopy have not be considered such as the excitonic effects, the many body infrared singularities in free electron metals and the many body final state configurations in solids with high electronic correlation such as the valence fluctuating metals and correlated oxides as CeO2 and the new high Tc oxide superconsuctors. These effects require to go beyond the one-electron aproximation discussed here but give important information on the local electronic structure of materials. [ABSTRACT FROM AUTHOR]