Magnetic Susceptibilities and Exchange Effects in Four Organic Free Radicals

Abstract
Studies of EPR intensity and linewidth in four free radicals at temperatures between 300° and 1.5°K have shown the presence of antiferromagnetic exchange coupling. In two cases a low-temperature paramagnetism occurs following a Curie-Weiss law with positive Weiss constant. A model involving isolated spins in a magnetically dilute system is proposed to explain these results.