On the broadening of the ESR line in presence of air or oxygen in conducting polymers

Abstract The oxygen-induced ESR line broadening is investigated in the case of the conducting polymer, polyaniline in the powder form. Pumping under vacuum results in a narrowing of the ESR linewidth from 3.3 to 0.95 Gauss (full width at half maximum). Subsequent application of air or oxygen pressures result in a fast broadening to 12 Gauss in both cases. Then, quite different behaviours are observed. In the case of air, after a maximum the linewidth decreases with a time constant of 3 h. This effect gives evidence for different kinetical behaviours for oxygen and nitrogen. In the case of pure oxygen, a decay of the linewidth is also observed, but much slower. These effects are reversible.