Synthesis of spherical silver nanoparticles with controllable sizes in aqueous solutions

A new method that combines the seed technique with laser treatment of a synthesized colloid was used to prepare spherical, almost monodisperse silver nanoparticles ranging in diameter from 10 to 80 nm (+/- 10%). Particles in the 10-40 nm size range can easily be produced in a one-step synthesis. Preparation of particles in the 40-60 nm range requires a multistep synthesis that involves laser treatment of the synthesized colloid. Particles larger than 60 nm were produced using a multistep synthesis with laser treatment of intermediate products. Appropriate "soft" conditions were developed for the laser treatment, where "soft" laser fluence was defined as the maximum possible fluence that heats and melts but does not evaporate the spherical particles and, therefore, does not change their sizes. The numerical values for this fluence were calculated for different particle diameters using the particle heating-melting-evaporation model.(35,21) The criteria for application of this model are discussed.