Cluster assembly energy

Another approach to the stability of the metal-polymer interface proves useful as well. Here, the energy of all individual atomic constituents is subtracted from the total energy of the metal-polymer complex. This is referred to as the cluster assembly energy (CAE) and is representative of total stability. The CAE serves as an indicator of stability when substantial charge transfer occurs affecting states... 

Andres R P, Averback R S, Brown W L, Brus L E, Goddard W A III, Kaldor A, Louie S G, Moscovits M, Peercy P S, Riley S J, Siegel R W, Spaepen F and Wang Y Research opportunity on clusters and cluster-assembled materials—a department of energy, council on materials science panel report J. Mater. Res. 4 704... 

The Pd clusters have been produced by a recently developed high-frequency laser evaporation source, ionized, then guided by ion optics through differentially pumped vacuum chambers and size-selected by a quadrupole mass spectrometer [16-18]. The monodispersed clusters have been deposited with low kinetic energy (0.1-2 eV) onto a MgO thin film surface. The clusters-assembled materials obtained in this way exhibit peculiar activity and selectivity in the polymerization of acetylene to form benzene and aliphatic hydrocarbons [30]. 

Our experiments provide several novel aspects to the scenario of sp chains production and assembling. In cluster-assembled films polyynes and polycumulenes can survive in a sp" carbon matrix at room temperature if oxygen is absent moreover, they can survive a landing process where the kinetic energy per atom is of several fraction of eV [22]. 

Here we present some results concerning the role that ion irradiation has in 1. modifying cluster assembled carbon thin films obtained by low energy cluster beam deposition (LECBD) and containing a cabynoid component and 2. producing carbynoid-like materials after irradiation of solid frozen benzene and of asphaltite, a natural bitumen. 

The field of clusters and fullerenes represents areas of modern science where the properties are determined by the reduced coordination. This will modify the functional properties when clusters are used in disperse forms or as units in cluster assembled materials. Examples of applications can be catalysts, sensor materials, units in nanophase/nanocrystalline materials with improved mechanical, electrical, magnetic or optical properties, of cluster based materials for sun protection, solar energy conversion, as an alternative to quantum dots produced with traditional techniques, fabrication of mesoscopic systems etc. The hope is to tune the properties with cluster size, making cluster based materials with characteristics more advanced than those of conventional materials. Production of these types of cluster and exploration of their properties of free as well as deposited clusters are a challenging task of basic and applied science which will be covered in the following sections of this article. 

Odd-even electron numbers and energy level statistics in cluster assemblies... 

S.G., Moscovits, M., Peercy, P.S., Riley, S.J., Siegel, R.W., Wang, Y Research opportunities on clusters and cluster-assembled materials. In A Department of Energy, Council on Materials Science Panel Report. J. Mater. Res. 4, 704-736 (1989)... 

The body of experimental data for clusters assembled from a molecule of HF or HCl with one or more Ar atoms presents a challenge and a testing ground for theoretical predictions. The vibrations of these weakly bound floppy clusters are difficult to determine by analytical methods because of large-amplitude motions, anharmonic motions, multiple minima, and high number of dimensions. Two sets of QMC calculations for the Ar HF n = 1-4) system have been reported recently one by Lewerenz ° and the other by Niyaz et al. Both are successful in predicting energies, structures, and hydrofluoric acid frequency shifts for these species. 

---