ABSTRACT
A number of synthesis techniques for synthesis of metallic colloids using metal salts as starting materials, such as chemical (Turkevich et al. 1951; Enustun and Turkevich 1963; Huang et al. 1997), photochemical (Ohtaki and Toshima 1990), electrochemical (Reetz and Helbig 1994), radiolytic (Gutierrez and Henglein 1993; Zhu et al. 1993; Zhang and Mostafavi 1997), and sonochemical (Mizukoshi et al. 1997) reduction, have been reported. Of these techniques, radiation-induced reduction is one of the most promising strategies because there are some important advantages of using irradiation techniques (Mostafavi et al. 1993), as compared to conventional chemical and photochemical methods: (1) The process is simple and clean, (2) reduction of metal ions can be carried out without using excessive reducing agents or producing undesired by-products of the reductant, (3) the rate of reaction can be controlled since the extent of reduction by radiation is well dened, (4) radiation can be employed for reduction irrespective of the presence of light-absorbing solutes and/or products, (5) reducing agent can be uniformly distributed in the solution, and (6) radiationinduced reduction can be made at ambient temperature.
