Initiating redox reactions by ionizing radiation: A versatile, selective and quantitative tool

The absorption of ionizing radiation initiates redox reactions, producing chemical species resulting from single electron loss or electron gain. Radiation chemists have developed methods to study individual redox species selectively and to monitor their reactions in real time. This has provided an enormous resource of kinetic, thermodynamic and spectroscopic information concerning the characteristics and reactions of free radicals and their redox reactions, mainly in aqueous solution. While the techniques are specialized and exploiting them is certainly more difficult than initiating redox changes by simple mixing of two chemicals or adding a reagent to a biological target, it is useful to gain an understanding of the basic mechanisms and approaches involved in exploiting radiation chemistry in the wider context of redox reactions in biochemistry, chemistry, and biology. This should enable readers both to appreciate the reliance which can be placed on the kinetic and other information resulting from such studies, as well as identify potential new applications of the technique which might be exploited in their research, by seeking partners who have access to the necessary specialized equipment or just basic irradiation facilities. This review outlines how radiation can be used to initiate selective redox reactions, mainly in water, and helps point readers to resources which should be useful in considering such reactions in a wider context.