Polaronic satellites in x-ray-absorption spectra

Satellite structure in the 2p absorption spectra of early 3d transition-metal compounds is reported. The spectral shape depends strongly on the local symmetry of the excited atom and gives evidence that in Ti oxides the excitation on the metal is screened by an exciton transition in the oxygen band and not by a charge-transfer or Mott-Hubbard transition as in the case of narrow-band metal compounds. The relative satellite intensities can be used to assess the anisotropy of the local electronic structure and the influence of the excited electron on the screening of the core-hole potential