Nanoclusters: Properties and processes

We present a review of certain aspects of cluster physics and processes occurring with the use of clusters, which are being developed at the Joint Institute of High Temperatures of the Russian Academy of Sciences. The phase transitions in dielectric and metallic clusters, which occur owing to configurational changes in clusters, are investigated in parallel with the general properties of clusters regarded as self-sustained physical objects. It is shown that the coexistence of phases near the melting point leads to a distinct character of phase transitions in clusters and macroscopic systems. In particular, the phase coexistence region of macroscopic systems is infinitely small, causing small changes in entropy jump in this region. Clusters are characterized by significant changes in entropy jump in the phase coexistence region. In addition, the heat capacity of a cluster can be negative near the melting point under adiabatic conditions of cluster excitation. The glassy state of a liquid cluster, as well as void transport-induced growth of the nucleus of a new phase occurring in the old phase, is analyzed by means of the void model. Methods of generation of metallic cluster beams are presented. Processes of cluster deposition on surfaces are discussed. The current state of nanocatalysis, which ensures acceleration of a chemical process owing to adhesion of reacting molecules to the cluster surface, is discussed.