ESR Spectroscopy of Short-Lived Radical Pairs in Solutions

Abstract

Short-lived radical pairs are, presently, the subject of permanent scientific attention caused by both the radical pair chemical transformation proper, and their specific role in the appearance of such phenomena as the chemically-induced polarization of electrons and nuclei, the effect of external magnetic field and the resonance microwave (mw) fields on radical reaction, magnetic isotopic effect (see e.g. (1)). Unfortunately, the ISR spectra of radical pairs in solutions cannot be detected by means of a conventional ESR technique due to their low stationary concentration. The present review is concerned with more sensitive methods based on the radical pair spin state modulation, and, hence, its reaction under the action of the resonance mw radiation, and the intrinsic interactions of the magnetic nature in pair radicals. In the broad sense, they may be referred to the methods based on the reaction yield detected magnetic resonance (2).