نتایج جستجو برای: metal cluster
تعداد نتایج: 395377 فیلتر نتایج به سال:
Many dwarf galaxies have disproportionately rich globular cluster (GC) systems for their luminosities. Moreover, the GCs tend to be preferentially associated with the most metal-poor stellar populations in their parent galaxies, making them attractive tracers of the halos of dwarf (and larger) galaxies. In this contribution, I briefly discuss some constraints on cluster disruption obtained from...
Interaction between catalytic metals and carbon atoms on formation process of SWNTs are studied by the home-made multi-body potentials base on density functional theory calculations of small metal-carbon binary clusters. The Co cluster has a partially crystal structure where metal atoms are regularly allocated and embedded in the hexagonal carbon network. On the other hand, carbon atoms cover t...
The influence of electronic shell effects on the barriers and channels pertaining to metal-cluster fission is studied using a shell correction method in connection with an asymmetric two-center-oscillator model potential. This approach has the advantage that the ensuing shape parametrization allows for an independent variation of the deformations of parent and daughter clusters. Results for bot...
A novel 3D hexadecanuclear heteropolyoxozincate organic framework, IFMC-200, has been successfully synthesized based on a late transition metal-oxygen cluster. IFMC-200 not only represents the first example of (3,4,24)-connected framework but also contains the first 24-connected single metal cluster in a crystal structure. It exhibits superior thermal stability, good water-stability, and even i...
Perhaps the most noteworthy of recent findings in extragalactic globular cluster (GC) research are the multimodal GC metallicity distributions seen in massive early–type galaxies. We explore the origin of these distinct GC populations, the implications for galaxy formation and evolution, and identify several new properties of GC systems. First, when we separate the metal–rich and metal–poor sub...
Size selected metal oxide, sulfide and oxynitride clusters, soft-landed onto highly ordered pyrolytic graphite (HOPG) at room temperature, have been studied in this work. Based on their size and chemical compositions, the deposited clusters have exhibited various surface structures as illustrated by in situ Scanning Tunnelling Microscope (STM) and ex situ Atomic Force Microscope (AFM). In contr...
Halide clusters have not been used as catalysts. Hexanuclear molecular halide clusters of niobium, tantalum, molybdenum, and tungsten possessing an octahedral metal framework are chosen as catalyst precursors. The prepared clusters have no metal–metal multiple bonds or coordinatively unsaturated sites and therefore required activation. In a hydrogen or helium stream, the clusters are treated at...
The possibility of obtaining metal cluster (M3O(+), M = Li, Na, K) supported pristine, B-doped and BN-doped graphene nanoflakes (GR, BGR and BNGR, respectively) has been investigated by carrying out density functional theory (DFT) based calculations. Thermochemical analysis reveals the good stability of M3O(+)@GR/BGR/BNGR moieties. The dynamic stability of M3O(+)@GR/BGR/BNGR moieties is confirm...
Motivated by the use of electrodes modified at the nanoscale by supported metal species, we studied computationally how the reactivity changes in such a composite system compared to the reactivity of the individual systems, metal clusters and metal surfaces. Specifically, we examined hydrogen adsorption on and hydrogen spillover from Au- and Cu-supported Pt(3) and Pd(3) clusters, using a method...
We present spectroscopy of two clusters in the dwarf irregular galaxy NGC 6822. From these we deduce an age for Cluster VII of 11 −3 Gyr and [Fe/H] = −1.95±0.15 dex. Cluster VII appears to be an analog of the metal-poor galactic globular clusters. Cluster VI is found to be much younger and more metal rich, with an age of approximately 2 Gyr. Its derived metallicity, [Fe/H] ≈ −1.0 dex, is compar...
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