XANES investigation of chemical states of nitrogen in polyaniline

X-ray absorption and photoelectron spectra of polyaniline were investigated in order to characterize the chemical bonding of its nitrogen atoms. The identification of neutral and charged nitrogen groups is of special interest. X-ray absorption near-edge structure (XANES) at the nitrogen K edge shows characteristic resonance structures reflecting transitions from the N1s core-level into unoccupied states. For comparison N1s X-ray photoelectron spectra were recorded representing the initial state of the N1s(-1)2p(pi*/sigma*) transitions. Due to the increasing energy differences between the N1s initial state and the unoccupied pi and sigma states, discrete final states, originating from the different chemical bonding at the nitrogen atom (=N-,=NH+-and-NH -), were resolved in the N K XANES. (C) 1998 Elsevier Science S.A.