structure and properties of atomic nanoclusters, 2005, p.427

[...]... Structure and Properties of Atomic Clusters xii 8 9 Clusters of the Transition Metals 8.1 Noble Metal Clusters 8.1.1 Electronic shell effects 8.1.2 Interplay between d and s electrons 8.1.3 Structure 8.1.4 Special properties of gold clusters 8.1.5 Optical properties 8.2 General Bonding Properties in Clusters of Transition Metals 8.3 Electronic and Atomic. .. theoretical studies of their structure and properties The existence of especially stable clusters is sometimes advocated to construct models of amorphous materials 1 2 Structure and Properties o Atomic Clusters f Two discoveries, nearly simultaneous in time, stand at the top of the field of clusters, and have added strong impetus for its development The first one, reported by Knight and coworkers in 1984,... is the existence of electronic shell effects [ 11, discussed in detail in Chapter 4 There is a close connection between geometrical and electronic structure at the beginning of the growth staircase, when the addition of each new atom changes the properties of the system substantially The simplicity of the sp clusters captured the attention of theorists and experimentalists, and a lot of progress has... for nanofabrication, and arrays of clusters have been produced by moving the STM tip The production of arrays and films of atomic clusters would be of great interest for the microelectronics industry [ 111 The possibility of building parts of circuits with nanosize clusters would allow the fabrication of electronic devices at a molecular scale Applications are also envisaged in optical memories and image... Epitaxy is employed nowadays to produce crystalline semiconductor superlattices of high quality Use of a beam of clusters, instead of atoms, would allow the production of more complex superstructures 10 Structure and Properties ofAtomic Ciusiers 2.2 Liquid Metal Ion Source This method has been used to produce clusters of metals with low melting points, like rubidium [12] The metal is first placed... the clusters of the inert gases [4], the excitation of collective modes similar to the giant dipole excitation of nuclei, etc The spatial arrangement of the atoms, that is, the geometrical structure, is the Introduction to Clusters 3 source of the differences between the properties of clusters of similar sizes; sizes that can differ by just one atom In contrast to bulk solids, the structure of clusters... nanoparticles [ 11 consists of the reduction of Fe2+ and Nd3+ salts using borohydride ions in aqueous solution The concentration and speed of addition of the reactants, the control of the pH, the temperature and the atmosphere under which the reaction is carried out are parameters affecting the characteristics of the particles obtained In order to control the growth of the particles and fix their size so... process Structure and Properties of Atomic Clusters 16 x, +X,q +x (2.8) that is, (2.9) () is usually a very sensitive function of N In this equation E(XN-, )and E(XN) indicate the energies of the clusters with N-1 and N atoms, respectively, and E(X) is the energy of the free atom Consequently, very stable clusters with large Evupevaporate atoms at a slower rate than less stable clusters, and this effect... simplicity of the interatomic forces makes them equally popular between theorists, who have used molecular dynamics techniques to simulate and enlighten the difficult problem of the solid to 4 Structure and Properties o Atomic Clusters f liquid phase transition in systems with a small number of atoms Van der Waals clusters are treated in Chapter 3 Molecular clusters, formed as aggregates of closed shell... the properties of clusters, scientists expect to obtain information on the early stages of growth of matter, and on the evolution of the properties towards the bulk An interesting question which still lacks a convincing answer in many cases is the following: how many atoms are required for a cluster to show the properties of the bulk material? To make affairs more complicated, sometimes different properties . between d and s electrons 231 8.1.3 Structure 232 8.1.4 Special properties of gold clusters 234 8.1.5 Optical properties 236 8.2 General Bonding Properties in Clusters of Transition. development of experimental techniques for producing small clusters, as well as a series of experimental and theoretical studies of their structure and properties. The existence of especially. the properties of the bulk material? To make affairs more complicated, sometimes different properties of a given type of clusters appear to converge at a different rate. But, even more important,