ESR IN CONDUCTING POLYMERS - OXYGEN-INDUCED CONTRIBUTION TO THE LINEWIDTH

The oxygen-induced ESR line broadening has been investigated in the ca se of the conducting polymer polyaniline in powder and in film form. P umping under vacuum results in a narrowing of the ESR linewidth. After initial pumping various oxygen containing gases have been applied to the sample (pure O-2, ambient air, dry air) and the linewidth has been measured as a function of time. The residual water in these gases was found to seriously affect the narrowing behavior of the linewidth. A theoretical calculation is proposed showing that the line broadening i s proportional to the oxygen concentration and to the polaron mobility . Considering the linewidth dependence upon applied oxygen pressure an evaluation of the polaron mobility is obtained. This value is consist ent with the values estimated from previous spin dynamics studies. An evaluation of the exchange integral is also given.