Radiolysis of silver ion solutions in ethylene glycol: solvated electron and radical scavenging yields

The solvated electron yield in neat ethylene glycol (1,2-ethanediol), measured using pulse radiolysis. is G (e(solv)(-))(10ns) = (1.7 +/- 0.2) x 10(-7) mol J(-1). The rate constant of the reaction of solvated electrons with silver cation is k (e(solv)(-) + Ag+) = (2.8 +/- 0.1) x 10(9) dm(3) mol(-1) s(-1) and the absorption band maximum of Ag-0 is at 350 nm. The surface plasmon band of the silver clusters appears slowly at around 400 nm with a coalescence cascade rate constant of 2 x 10(6) dm(3) mol(-1) s(-1). The free silver ions do not scavenge ethylene glycol radicals. In contrast, the gamma-radiolysis reduction yield of Ag+ into clusters is dose-dependent, changing from G(i)(Ag-n) = (2.5 +/- 0.5) x 10(-7) mol J(-1) at low dose to G(max)(Ag-n) = (7.5 +/- 0.5) x 10(-7) mol J(-1) at higher doses. when clusters accumulate. Silver cations adsorbed on clusters are able to scavenge the ethylene glycol radicals. which also contribute to their reduction for a part of G(rad) = (5.8 +/- 0.5) x 10(-7) mol J(-1). Considering the different ways the reducing radicals car, be produced, it is concluded that they originate from the electron-cation recombination and front the cafion-ethyleneglycol reaction, but that the dissociation of excited states is a negligible path. The formation mechanisms of the radicals and the rate constants in ethylene glycol are compared with those in water and methanol. (C) 2004 Elsevier Ltd. All rights reserved.