Large-scale production of nanocrystals by laser ablation of microparticles in a flowing aerosol

We experimentally demonstrate the production of nanoparticles by laser ablation of microparticles entrained at high density in a flowing aerosol. The currently measured production rate of 20 grams per hour could be scaled to industrially useful rates. We have characterized the size distribution of particles and found nearly monodisperse distributions where mean sizes were smaller and varied less with laser fluence than was observed for ablation of microparticles held on flat plates. Mean size was controlled from 4-20 nm by varying the type and pressure of carrier gas. We found Ag and CdSe nanoparticles were crystalline having few dislocations. Materials tested included metals (Ag, Au, and W), semiconductors (Si, CdSe, GaN, and ZnO), ceramics (WC, SiC, and YBa2Cu3O7), and a ferroelectric. Two types of collection processes are described that preserve the nonagglomerated nature of the particles, even at high mass densities. (C) 2001 American Institute of Physics.