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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

A Prelude to a Third Dimension of the Periodic Table: Superatoms of Aluminum Iodide Clusters

Jones, Naiche Owen 01 January 2006 (has links)
Calculations have been carried out to investigate the stability and electronic structure of aluminum iodide clusters using first principles gradient-corrected density functional theory. Analysis of A113Ix-, A114Ix-, and A17I- clusters reveals that their stability is governed by the geometrically unperturbed A113-, A1142+, and A17+ units, respectively, that are demonstrated to constitute the compact cores of the clusters upon significant iodine content. The compact, icosahedral A113, icosahedral-like A1 14, and capped square bi-pyramid A17 superatom structures of the stable aluminum cores have an analogous electronic configuration to that of halogen, alkaline-earth, and alkaline atoms, respectively. Novel chemistry is demonstrated in superatoms, arising from two primary sources. Firstly, the calculations demonstrate the preference to break molecular I2 bonds in favor of iodine atoms individually adsorbing onto the aluminum sites of the central aluminum core surface. Secondly, the calculation show that observations of alternating stability trends dependent on the number of iodine ligands are connected to the formation and quenching of active sites. The significance of the induced active centers on aluminum iodide clusters upon association to alkenes is addressed, demonstrating a method towards predicting the location and extent of binding hydrocarbons. The novel chemistry of superatoms allows for a host of possible applications that integrate their unique properties in original ways and some key examples are described. Superatoms are the analogs to atoms and subsequently, just as the periodic table of elements lists atoms that can assemble into molecules and lattice structures, there exists the fathomable possibility to incorporate superatoms into extended structures such that they maintain their unique properties and result in a new class of materials. Initiation of such cluster-materials insinuates that cluster-mediated periodic table may be a proper extension to allow for a simple means for conveying fundamental information about clusters.
2

Electronic Structure and Stability of Ligated Superatoms and Bimetallic Clusters

Blades, William H 01 January 2016 (has links)
Quantum confinement in small metal clusters leads to a bunching of states into electronic shells reminiscent of shells in atoms. The addition of ligands can tune the valence electron count and electron distribution in metal clusters. A combined experimental and theoretical study of the reactivity of methanol with AlnIm− clusters reveals that ligands can enhance the stability of clusters. In some cases the electronegative ligand may perturb the charge density of the metallic core generating active sites that can lead to the etching of the cluster. Also, an investigation is conducted to understand how the bonding scheme of a magnetic dopant evolves as the electronic structure of the host material is varied. By considering VCun+, VAgn+, and VAun+ clusters, we find that the electronic and atomic structure of the cluster plays a major role in determining how an impurity will couple to its surroundings.

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