Separation of the ultraviolet-visible spectra of the redox states of conducting polymers by simultaneous use of electron-spin resonance and ultraviolet-visible spectroscopy

The electrochemical oxidation of polyaniline (PAni) films on gold electrode s is studied by simultaneous electron spin resonance (ESR) and UV-vis spect roelectrochemistry. The technique permits the separation of the superimpose d UV-vis spectra of three redox states: the protonated reduced polyaniline chains, the deprotonated polaronic state, and the bipolaronic state. The se parated UV-vis spectra as well as the potential dependence of each redox st ate concentration enables a more precise determination of the energy levels and the stability of paramagnetic species.