Photoinduced formation of silver colloids in a borosilicate sol-gel system

Silver ions are stabilized in a borosilicate glass sol by complex formation with a bifunctional amine compound. A UV-irradiation induced photochemical process reduced silver to form silver colloids with radii of several nanometers. The mean colloid size was controlled by irradiation time. The colloid concentration increases rapidly with irradiation, reaching a saturation level corresponding to total reduction of silver. Colloid formation was investigated by UV-VIS spectroscopy.