Electron Paramagnetic Resonance of Free Radicals

Abstract

Among the many techniques of investigation that have been developed during the last decade, electron paramagnetic resonance (EPR) is one of the most significant for chemists. It is expected to play a role comparable to that played by optical spectroscopy during the first half of this century. It has already proved t~o he part,icularly fruitful in two fields: the study of the electronic configuration of the transition metal ions in relat,ion to the crystalline field, and the study of the products of irradiation of matter, especially free radicals and color centers. For example, EPR studies made on iron(I1) and iron(II1) romplexes suggested hypotheses for the mechanism of transport, of oxygen by hemoglobin; also, studies on irradiated plastics have led to the explanation that their improved mechanical properties are due to cross-linking hetween their molecular chains.