Gray-colored materials synthesized by calcining the precursor powders, which were produced in a microemulsion, are identified to be rutile structured SnO2 nanorods 20-45nm in diameter and several micrometers in length by x-ray diffraction, transmission with electron microscopy, and high-resolution transmission microscopy. Conspicuous far-infrared (FIR) absorption spectrum platform peaks with widths of up to 61.6 and 119 cm21 are observed, and are explained as the overlap of the surface modes of cylindrical and spheroid particles. Good agreement is achieved between FIR platform peaks and calculated results.

The thermal stability of helical multiwalled cylindrical gold nanowires is studied using molecular-dynamics simulations. From our simulation, the melting temperature of gold nanowires is lower than the bulk value, but higher than that of gold nanoclusters. It is interesting to find that the interior melting temperature in ultrathin nanowires is lower than that of the surface melting. The melting starts from the interior atoms, while the surface melting occurs at relatively higher temperature. This unique thermodynamic behavior is closely related to the interior structures. We propose that the surface melting represents the overall melting in ultrathin metallic nanowires.

The structures of free-standing zirconium nanowires 0.6-2.8nm in diameter are systematically studied by using genetic algorithm simulations with a tight-binding many-body potential. Several multishell growth sequences with cylindrical structures are obtained. These multishell structures are composed of coaxial atomic shells with the three- and four-strand helical, centered pentagonal and hexagonal, and parallel double-chaincore curved surface epitaxy. Under the same growth sequence, the numbers of atomic strands in inner and outer shells show even-odd coupling and usually differ by 5. The size and structure dependence of angular correlation functions and vibrational properties of zirconium nanowires are also discussed.

Conductance resonance of a metal-insulator-metal junction with an embedded metal cluster, which has different size and structure, is studied by the generalized Breit-Wigner formula in a tight-binding approximation. We find that a certain metal cluster possesses a specific peak pattern in the conductance data, that is, the conductance resonance peaks depend on the size and structure of metal clusters and the resonant broadening G is related to the tunnel barrier parameters. This arrangement can induce a high-quality tunneling structure with very narrow resonance peaks. Therefore, both the size effect and structure effect of the metal clusters can be predicted by observing conductance resonance of tunneling structure of embedding metal clusters in metal-insulator-metal junction. It is also possible to develop some new microelectronic devices with this structure.

Empirical tight binding model potentials have been used in molecular dynamics simulations of local order and defects in liquid and glass under high and normal pressures. Results are reported for some solidlike cluster and for structural properties of liquid and glass. Not only are Frank-Kasper polyhedra and Bernal hole polyhedra detected, but also a variety of defective icosahedra. A dramatic split of the second peak of g(r) is associated with the glass transition. The split of the second peak is caused by the fluidity of the liquid phase in glass. The nearest distance is shortened, and the nearest-neighbor coordination number increases under high pressure. High pressure favors glass formation. The microstructure of glass is very similar to medium range order icosahedra structure.

The geometrical and electronic structures of the germanium clusters with up to 25 atoms are studied by using density-functional theory with the generalized gradient approximation. The Gen clusters follow a prolate growth pattern with n>13. For medium-sized clusters, we find two kinds of competing structures, stacked layered structures and compact structures. The stacked layered structures with capped tetrahedron Ge9 cluster are more stable than compact structures and other stacked structures. The size dependence of cluster binding energies, highest-occupied and lowest-unoccupied molecular orbital gap, and ionization potentials are discussed and compared with experiments.

Raman scattering spectra are used to investigate LiF cluster-based nanophase films. The experiments confirm the existence of multi-order-like Raman scattering and surface phonon modes. Good agreement is achieved between the observed spectral lines and the calculated results if the Raman scattering lines are attributed to an appropriate linear combination of primary modes and surface optical modes. The fine structure observed in the case of the smaller cluster has reflected the intensity of the cluster-substrate interaction, which may result in the splitting of Raman peaks.

The structural and magnetic properties of Co182mCum (0<m<18) clusters are investigated with a genetic algorithm and a spd-band model Hamiltonian in the unrestricted Hartree-Fock approximation, respectively. In general, Cu atoms tend to occupy the surface, while Co atoms prefer to the interior of the clusters. Layered structures appear in some clusters with given stoichiometric compositions. The introduction of Cu atoms leads to a large increase of the magnetic moment of Co-rich circumstance and nearly zero magnetism of the Cu-rich ambient. The interaction between Cu and Co atoms induces nonzero magnetic moment for Cu atoms. The total magnetic moments tend to decrease with the increase of Cu atoms. However, some particular large magnetic moment are found to be closely related to the structures. The environments of Cu and Co atoms have a dominant effect on the magnetism of the cluster.

8-keV neutral argon atoms arc used to bombard pure polycrystaUine copper for production of ion clusters which are analyzed by a high-precision mass spectrometer. The odd-even alternations in the secondary emission of copper-ion clusters together with various kinds of hetcroisotopic cluster ions are observed. For the first time the experiments have shown that the isotopic effect plays an important role in the formation of polyatomic cluster ions by sputtering.