Photochemical and radiation chemistry techniques in the study of colloidal systems

Abstract

The use of radiation chemical and photochemical techniques in the chracterization and understanding of the mechanistics and dynamics of colloidal systems is described through recent examples from our own studies. Determination of thermodynamic properties, such as ion exchange capacity of polyelectrolytes and charged colloids, the number of pendent groups that bind to each metal ion, redox potentials of solubilizates in micelles and flat band potentials of colloidal semiconductors, and kinetic determinations of particle sizes, using these techniques are described in detail. More commonly, these techniques are utilized to unravel mechanistic questions of colloidal processes. These include rates of entrance/exit into/out of the colloidal aggregate, redox catatlysis by metallic colloids, reductive dissolution of transition metal oxide colloids, free radical reactions on chalcogenide colloids, and growth processes of metallic, metal-oxide and silver halide colloids. Recent specific examples include: interactions of actinide ions with polycarboxylic acids, formation of layered semiconductor iodides of quantum size dimensions, dissolution of iron (III) and Mn (IV) oxides, dissolution of CdS and As 2S 3 through reactions of S . ̄ , 02 . ̄ and MV + radicals and growth of silver halide colloids.