An experimental and theoretical study of bismuth-doped aluminum clusters in the gas phase has revealed two particularly stable clusters, namely, Al(3)Bi and Al(5)Bi. We show that their electronic structure can be understood in terms of the aromatic and "Jellium" models, respectively. Negative ion photodetachment spectra provide a fingerprint of the electronic states in Al(n)Bi(-) (n = 1-5) anions, while theoretical investigations reveal the nature of the electronic orbitals involved. Together, the findings reveal that the all-metal Al(3)Bi cluster with 14 valence electrons is a cyclic, planar structure with a calculated large ionization potential of 7.08 eV, a low electron affinity of 1.41 eV, and a large gap of 1.69 eV between the highest occupied and lowest unoccupied molecular orbitals (HOMO-LUMO gap). The Al(3)Bi cluster has molecular orbitals reminiscent of aromatic systems and is a neutral cluster with no need for counterion or ligand support. A slightly larger cluster, Al(5)Bi, has 20 valence electrons and is another highly stable compact structure with a calculated large ionization potential of 6.51 eV and a large HOMO-LUMO gap of 1.15 eV. This cluster's stability is rooted in a Jellium electronic shell closing. The formation of stable species using aromatic bonding allows us to extend the idea of cluster-assembled materials built out of stable clusters with Jellium shell closings (superatoms) to include ones involving aromatic building blocks.

Titanium carbide nanoparticles were synthesized by flowing methane through a plasma generated from an arc discharge between two titanium electrodes. Different methane concentrations were employed in studies made to investigate the effects of carbon concentration on particle morphology. Transmission electron microscopy and X-ray diffraction were used to investigate the synthesized TiC nanopowders, whereupon it was found that nanocrystalline TiC nanoparticles prefer a cubic morphology at low concentrations of methane and a cuboctahedron morphology at high concentration of methane. The change in particle morphology is attributed to carbon affecting the relative growth rates of the {111} and {100} facets on a TiC seed crystal.

Experimental photoelectron and computational results show diniobium-carbon (Nb(2)C(n)) clusters to coexist in multiple structural isomers: three-dimensional geometries, planar rings, and linear chains. Three-dimensional clusters having up to five carbons are formed preferentially with Nb-Nb bonding, whereas only Nb-C bonding is observed experimentally at six carbons. Clusters consisting of an odd number of atoms are also observed with linear geometries. The larger binary clusters (n > or = 7) display properties similar to those of pure carbon clusters. We provide evidence for niobium substitution of carbon atoms.

The electronic structure and stability of neutral and negatively charged Bi x In y (x ) 1-4, y ) 1-6) clusters are investigated through anionic photoelectron spectroscopy employing magnetic bottle and photoelectron velocity map imaging experiments. Experimental and theoretical adiabatic and vertical detachment energies of the anionic species containing up to 4 Bi and 4 In atoms are deduced from first principles calculations. Among the Bi x In y series, many clusters are found to exhibit special stability in the mass spectra, exhibit a large gap between the highest occupied and lowest unoccupied molecular orbitals (HOMO-LUMO gap), and a large formation energy. This stability is rationalized by different mechanisms. Bi 2 Inis classified as a gas phase Zintl species despite only having three atoms, making it the smallest possible case. Bi 3 In 2 -, with 12 valence electrons and a closo structure in agreement with Wade's rule, is similar to Bi 3 Ga 2 -, a gas phase Zintl analogue of Sn 5 2-. Bi 4 Inand Bi 4 In 2 are both found to follow Wade's rule, indicating gas phase Zintl clusters. BiIn 3 is a cyclic planar molecule similar to BiGa 3 and BiAl 3 , all-metal aromatic systems, and BiIn 5 is a 20 electron closed shell Jellium species. Additionally, an even-odd oscillation of the HOMO-LUMO gaps, formation energies, and adiabatic electron affinities are found correlating with the open-shell/closedshell nature of the clusters.