After the invention of molecular-beam techniques, both experimentalists and

theoreticians have been able to study "free" gas-phase clusters. Production of clusters in a

molecular beam generally requires initial vaporization of an atomic or molecular source,

followed by cooling and condensation of the resulting fragments via nucleation, which

may involve the capture of single atoms or the coalescence of larger clusters. Metal

clusters are among the first in which new properties have been found because of the

effects on a nanometer scale1,2. In the last years, bimetallic nanoclusters have become of

greater interest than monometallic ones, both technologically and scientifically. Very

greater interest than monometallic ones, both technologically and scientifically. Very

recently, we have proposed a new way of forming bimetallic nanoclusters of various

structures and chemical composition by means of collision of two metal clusters of

different nature3. Bimetallic nanoclusters of core-shell (Pt?Au, Co-Ag), alloyed (Pd?Au,

Cu-Au), and three-shell onionlike Cu?Ag structures were found after collision of two

Cu-Au), and three-shell onionlike Cu?Ag structures were found after collision of two

clusters with a given initial velocity. While the nature of the emerging nanostructure

(core shell, alloy, and onionlike) is determined by the chemical nature of the colliding

clusters, the initial kinetic energy is an important control parameter.

Structural and dynamic properties are evaluated from atom dynamics and Monte Carlo

simulations.