Synthesis of tailored composite nanoparticles in the gas phase

We report on a method to obtain tailored nanoparticle aggregates of two com ponents in the gas phase. The method is based on the modification of the Br ownian collision rate by charging the nanoparticles. Particles of different components are charged oppositely in order to obtain composite nanoparticl e aggregates via preferential coagulation. The resulting composite aggregat es are uncharged, which allows for their separation from both, charged unag gregated particles and charged aggregates of only one component. The mean s ize and standard deviation of each particle component can be adjusted by me ans of differential mobility analysis. Experimental results are presented f or composites of PbS and Ag. (C) 2000 American Institute of Physics. [S0003 -6951(01)01301-8].