The electronic structure of polyaniline and doped phases studied by soft   X-ray absorption and emission spectroscopies
  The electronic structure of the conjugated polymer, polyaniline, has been studied by resonant and nonresonant X-ray emission spectroscopy using synchrotron radiation for the excitation. The measurements were made on polyaniline and a few doped (protonated) phases for both the carbon and nitrogen contents. The resonant X-ray emission spectra show depletion of the {\pi} electron bands due to the selective excitation which enhances the effect of symmetry selection rules. The valence band structures in the X-ray emission spectra attributed to the {\pi} bands show unambiguous changes of the electronic structure upon protonation. By comparing to X-ray absorption measurements, the chemical bonding and electronic configuration is characterized. 
M. Magnuson, J.-H. Guo, S. M. Butorin, A. Agui, C. S{\aa}the, J.   Nordgren and A. P. Monkman
cond-mat.mtrl-sci physics.chem-ph