Introduction

Abstract

The properties of clusters depend on the number of their constituents: by controlling the size of a cluster one can change the electronic, optical, structural and chemical characteristics of an aggregate. Moreover, by assembling clusters, one can produce a material with novel functional and structural properties. This is easy to say but difficult to do: among different aspects that characterize clusters, high reactivity can be considered universal. The interaction and coalescence of aggregates deposited on a substrate are largely unknown so that one can wonder to what extent clusters retain their individuality in cluster-assembled materials. Another major problem is the production of large quantities of particles with well defined properties (number of components, structure, etc.).