SURFACTANT COUNTERION INDUCED PROCESSABILITY OF POLYANILINE - PHOTOINDUCED ABSORPTION STUDIES

We present near steady state photo-induced absorption spectra of two f orms of polyaniline (PANI) processed from solution as PANI-(S-) where S- denotes the surfactant counter-ion (CSA, DBSA, etc.). In the case o f emeraldine base, two well-resolved photo-induced absorption bands ar e observed with maxima at 0.9 eV and 1.47 eV, accompanied by a bleachi ng of the 2 eV absorption edge. The different relaxation of the two ba nds indicates that they arise from two independent photoinduced nonlin ear excitations. Temperature effects on the photoexcited states are ob served both in the emeraldine base and the pernigraniline forms. The r esults are discussed in terms of intra- and interchain excitations. Th e possibility of deep traps on defect sites in pernigraniline is sugge sted.