Time-resolved investigation of early processes in the reduction of Ag+ on polyacrylate in aqueous solution

Aqueous solutions of AgClO4 (4 x 10(-4) to 10(-2) M) and sodium polyacrylat e (0.1 M, mean chain length of 30) are exposed to a pulse of high-energy ra diation, and the changes in optical absorption are recorded in the time ran ge from microseconds to seconds. The reduction of Ag+ by the hydrated elect ron is slowed by the polyanion, whereas the subsequent reaction of Ag-0 wit h Ag+ is practically not affected. Polymer-bound Ag-2(+) has two absorption bands (310 and 440 nm). The formation of Ag-3(2+) in the reaction of Ag-2( +) with Ag+ is strongly retarded by the polyanion; it occurs in an intercha in process at low Ag+ concentrations and probably also as an intrachain pro cess at higher ones. Polymer-bound Ag-3(2+) has a broad UV absorption taili ng into the visible. At longer times after the pulse (up to seconds), bimol ecular interchain processes take place in which colored complexes are forme d, which at first contain a small number of silver atoms and an approximate ly equal number of Ag+ ions, and are stabilized by the polyanion chains.