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 soft 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. (C) 1999 American Institute of Physics. [S0021-9606(99)70433-2].