Synthesis of copper and silver nanoparticles by molecular beam method.

The paper presents the results of investigation of the structure of porous condensates of Ag-NaCl and Cu-NaCl composition; chemical and phase compositions and dimensions of nanoparticles, produced from the vapour phase by EBPVD method. Silver and copper nanoparticles in a porous matrix, when removed from vacuum, oxidize in air to lower oxides, and have considerable sorption capacity relative to oxygen and moisture. Heating in air is accompanied by lowering of porous condensate mass, primarily, due to desorption of physically sorbed moisture, as well as afteroxidation to higher oxides due to physically adsorbed oxygen. At copper concentrations up to 10 at.%, sorption capacity of the condensate is greatly enhanced, that is attributable to presence of very fine nanoparticles. Increase of copper concentration in the condensate is accompanied by lowering of sorption capacity of nanoparticles with respect to oxygen, and, therefore, also change of phase composition. In addition to concentration change, phase composition of nanoparticles can be also controlled by heat treatment of the initial condensate produced at low condensation temperatures. Silver and copper nanoparticles can be converted into stable colloidal systems.