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

We experimentally demonstrate the production of nanoparticles by laser abla tion 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 p articles and found nearly monodisperse distributions where mean sizes were smaller and varied less with laser fluence than was observed for ablation o f 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 nano particles were crystalline having few dislocations. Materials tested includ ed metals (Ag, Au, and W), semiconductors (Si, CdSe, GaN, and ZnO), ceramic s (WC, SiC, and YBa2Cu3O7), and a ferroelectric. Two types of collection pr ocesses are described that preserve the nonagglomerated nature of the parti cles, even at high mass densities. (C) 2001 American Institute of Physics.