SURFACTANT COUNTERION INDUCED PROCESSABILITY OF POLYANILINE - PHOTOINDUCED ABSORPTION STUDIES

We present near steady state photo-induced absorption spectra of two forms of polyaniline (PANI) processed from solution as PANI-(S-) where S- denotes the surfactant counter-ion (CSA, DBSA, etc.). In the case of emeraldine base, two well-resolved photo-induced absorption bands are observed with maxima at 0.9 eV and 1.47 eV, accompanied by a bleaching of the 2 eV absorption edge. The different relaxation of the two bands indicates that they arise from two independent photoinduced nonlinear excitations. Temperature effects on the photoexcited states are observed both in the emeraldine base and the pernigraniline forms. The results are discussed in terms of intra- and interchain excitations. The possibility of deep traps on defect sites in pernigraniline is suggested.