Sb clusters

Plate 15. Thermal conversion of Sb4 clusters on Si(lOO). (a) Sb clusters deposited on Si(OOl) surface at room temperature show three distinct types of precursors as well as the final-state clusters of two dimers, (b) After annealing at 410 K for 20 minutes, almost all precursors are converted to the final-state clusters. See Mo (1992) for details. Original images courtesy of Y. W. Mo. 

The reaction of the Os-Sb cluster Os3(//,-H)(//,-SbPh2)(/Z3, 72-C6H4)(CO)9 with nitrile solvent results in loss of CO and solvent substitution to yield Os3(//-I I)(SbPh2)(//2> 2-C6l C)(CO)y(CN( Bu). Photolysis of this complex results in CO loss on the Os center having four CO ligands. The product has an rjA benzene in which all three Os centers are involved. Structural data are provided for the complexes [99]. 

Fig. 1.9. Energetic impact of antimony clusters onto a graphite target, (a) 2,480 x 2,480 STM image of an HOPG substrate after deposition of Sb4+ clusters with 230 eV kinetic energy at room temperature. Stable nanodot (hillock) formation is observed, (b) 47 x 47 STM image of the impact location of an Sb4+ cluster with 150 eV collision energy, (c) 71 X 71A STM image of the impact of an Sbs cluster with 410 eV collision energy [58,87,90]...

Nb6Cl12]2 +, a typical halide cluster containing a metal from the left of the d-block, a mixed Co-Sb cluster, Sb4[Co(CO)3]4. 

The resonances exhibit interesting variations as a function of atomic number, the origin of which is unexplained. As can be seen in fig. 12.14, their intensity relative to the rest of the spectrum fluctuates strongly, with the giant resonance actually disappearing from view for n = 8, 12, 16, etc atoms in the cluster. This behaviour seems in some way to be related to the fact that Sb clusters tend to be made up from smaller groups of four atoms stuck together. 

Fig. 12.14. The quasiatomic giant resonances in Sb clusters of different sizes. Note the marked dependence of the amplitude of the giant resonance on the number of atoms in the cluster (after C. Brechignac et al. [696]).

Figure 10.1 The mass spectrum of antimony (Sb) clusters formed by electron impact ionization of the cluster beam several centimeters from the nozzle. Both singly and doubly charged cluster ions are observed. Taken with permission from Brechignac et al. (1995).

A study was made of the migration of spherical Sb clusters which had been deposited onto graphite surfaces. Good agreement with computer simulations was found, and this fact was used to deduce the diffusivity of clusters, which contained about 2300 Sb atoms, on the substrate. The results were described by ... 

On the other hand, when a physisorbed Sba transforms to a chemisorbed Sba or dissociates into dimers, the diffusion barriers of these Sb species on HOPG are expected to increase significantiy from that of physisorbed Sba. We believe that the crystalline 2-D and 1-D structures are nucleated from these chemisorbed Sb species, and these nucleation events occur when the chemisorbed Sb clusters meet on a graphite terrace, not necessarily at defects. This offers a channel competing with 3-D island growth. Which channel is dominant depends on the kinetic parameters of these processes and deposition conditions. 

Most elements thermally vaporize as atoms but some, such as Sb, C, and Se, have a portion of their vapor as clusters of atoms. For these materials, special vaporization sources, called baffle sources, can be used to ensure that the depositing vapor is in the form of atoms by causing the material to be vaporized from multiple hot surfaces before it leaves the source. 

Typical borane clusters incorporating As or Sb atoms are c/oso-l,2-BioHioCHAs and closo-... 

A fascinating variety of discrete (or occasionally polymeric) polynuclear halogeno complexes of As, Sb and Bi have recently been characterized. A detailed discussion would be inappropriate here, but structural motifs include face-shared and edge-shared distorted (MXe) octahedral units fused into cubane-like and other related clusters or cluster fragments. Examples (see also preceding paragraph) are ... 

The detailed coordination geometry about As, Sb or Bi in these clusters varies substantially, and is of considerable signilicancc in describing the nature of the bonding in these species. 

With Sb even larger clusters can be obtained. For example reaction of Co(OAc)2-4H20 and... 

In addition to the heteronuclear clusters considered in the preceding paragraphs. As, Sb and Bi also form homonuclear clusters. We have already seen that alkaline earth phosphides M3P14 contain the [Pv] cluster isoelectronic and isostructural with P4S3, and the analogous clusters [Asy] " and [Sbv] have also been synthesized. Thus, when As was heated with metallic Ba at 800° C, black lustrous prisms of BasAs were obtained, isotypic with Ba3Pi4 these contained the [Asv] anion with dimensions as shown in Fig. 13.25(a).Again,... 

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