ESR in conducting polymers: effect of oxygen and air

Summary form only given. It has been known since the fifties that the ESR signal of the free spins in various compounds is reversibly broadened in presence of air. In conducting polymers such an effect has been reported/sup 1/ to be a signature of the conducting state : in the conducting state, the spin/charge carriers can move to the surface and come into contact with the paramagnetic molecular oxygen. The mechanism of the line broadening will be discussed in relationship with the material properties, and new data obtained on emeraldine salt samples will be reported. In particular, in the case of powders or thin films, quite different behaviors are observed upon exposure to air or to oxygen gas. The kinetics appears to be at least 2 orders of magnitude faster with oxygen than with nitrogen.