Intermediate phase upon alloying Au-Ag nanoparticles under laser exposure of the mixture of individual colloids

The dynamics of Au-Ag alloy formation under laser irradiation of a mixture of the monometallic colloidal solutions are experimentally investigated and the factors influencing the alloy genesis are determined. Ag or Au nanoparticles are obtained by laser ablation of the corresponding metals in water or ethanol. Evidence is presented for the formation of an intermediate Au-Ag phase characterized by a transient red-shifted absorption peak. The changes in absorption spectrum and morphology of the colloidal particles are studied as a function of exposure time to laser radiation. It is found that the rate of alloying depends on both the concentration of nanoparticles and the presence of surface-active substances. (C) 2004 Elsevier B.V. All rights reserved.