Core x-ray photoelectron shake-up states of model molecules for polyaniline

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Abstract
The shake‐up features of the N 1s and C 1s core‐level x‐ray photoelectron spectra of model molecules of polyaniline are studied theoretically using the intermediate neglect of differential overlap method in combination with configuration interaction. The calculations are performed on N,N’‐diphenyl‐1,4‐phenylenediamine and N,N’‐diphenyl‐1,4‐benzo‐quinondiimine, which are model molecules for fully reduced and fully oxidizedpolyaniline, respectively. The core‐level spectra of these two molecules are also studied experimentally by means of x‐ray photoelectron spectroscopy. Experimental and theoretical results are found to be in excellent agreement, which allows for a detailed interpretation of the observed shake‐up spectra. Core ionization of imine nitrogens is shown to be accompanied by large shake‐up intensity. Our studies of model molecules are compared with recently published core‐level spectra of polyaniline at various oxidation levels. The increase in imine nitrogen content upon oxidation of the polymer give rise to an increase in the N 1s shake‐up intensity, a result which is in agreement with what we find for the model molecules.