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The densities of the valence and conduction band electronic states of thenewly discovered layered superconductors LaOFeAs, LaO$_{0.87}$F$_{0.13}$FeAs(Tc=26 K), SmO$_{0.95}$F$_{0.05}$FeAs and SmO$_{0.85}$F$_{0.15}$FeAs (Tc=43 K)are studied using soft X-ray absorption and emission spectroscopy combined withFP LAPW calculations of LaOFeAs, LaO$_{0.875}$FeAs andLaO$_{0.875}$F${0.125}$FeAs. The Fe 3d-states are localized in energy near thetop of the valence band and are partially hybridized with p-type O (2p), As(4p), and La (6p) states approximately 3 eV below the Fermi energy. The Fe L3X-ray emission spectra do not show any features that would indicate thepresence of the low Hubbard 3d-band or the quasiparticle peak that werepredicted by the DMFT analysis of LaOFeAs. We can conclude that theLaOFeAs-type compounds do not represent strongly correlated systems. Wheneither oxygen vacancies or fluorine dopants are included in numericalelectronic structure calculations the width of O 2p-band decreases, but thedistribution of Fe 3d-states is largely unaffected.

X-ray spectra and electronic structure of FeAs superconductors