Production and controlled collection of nanoparticles: toward manufacturing of nanostructured materials

Here we detail the development of the laser ablation of microparticles (LAM) technique into a continuous flowing process for generating nanoparticles. The design and operation of the feedstock aerosol generator, the laser ablation cell and collection chambers are discussed and demonstrated to produce individual nanoparticles at high number densities. Through the adjustment of process parameters such as gas pressure and laser fluence we show that the size and size distribution of silver nanoparticles can be sensitively controlled from 4-18 nm. It is demonstrated that the application of an electric field during the ablation significantly influences the formation and agglomeration of nanoparticles as shown for silicon nanoparticles. Supersonic expansion of the nanoparticle aerosol through a micronozzle orifice allows narrow, well defined patterns to be directly written onto room temperature substrates with uniform widths down to 33 µm. Choice of carrier gas enables the control of kinetic energy of impacting particles. It is shown argon gas leads to soft landings and helium yields harder impacts. The supersonic technique makes possible the deposition of micrometer-scale features containing controllable nanostructure.Physic