Belay Zeleke Dilnesa - Eawag-Empa Library

CHAPTER 1 INTRODUCTION
Fig. 4 Sample XAS Spectrum of FeO with XANES and EXAFS region [26].
The X-ray absorption near edge structure, XANES, is the part of the spectrum that gives
qualitative data based on modeling and simulation. XANES is used to give information
about the average oxidation state and coordination environment. By taking unknown
spectra and fitting a linear combination of known reference spectra, one can get an
estimate of the contribution of each reference to the unknown spectra.
Extended X-ray absorption fine structure, EXAFS, is the part of spectrum that gives
quantitative data on the local structure around the absorber atom. From EXAFS mainly
information on the type of neighboring atoms, their distance from absorber atom (bond
length), the number of neighboring atoms (coordination numbers) and ordering effects
(Debye-Waller factor) can be extracted. As described above, the photoelectron can be
thought of as a wave centered at an atom. The wave vector of the photoelectron is related
to the difference in binding energy of the electron, E0, and the energy of the photon, E, as
shown below:
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