Preparation and Properties of Silver Colloids Produced by Laser-Induced Reduction of Silver Nitrate

Silver colloids have been prapared by laser-induced reduction of silver nitrate. The properties of the colloids were studied with transmission electron microscopy, visible-ultraviolet absorption and Raman spectroscopy. We find that the growth of the silver grains is dependent on the laser illumination time. Two characteristic absorption bands of the colloids are located near 390 and 560nm, respectively. Not only are the silver colloids much cleaner than those prepared by chemical reduction methods, but also surface enhanced Raman scattering active. The method may be of interests for ultrafine particle studies as well.