科研之友
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摘要
An experimental and theoretical study of bismuth-doped aluminum clusters in the gas phase has revealed two particularly stable clusters, namely, Al3Bi and Al5Bi. We show that their electronic structure can be understood in terms of the aromatic and "Jelliurn" models, respectively. Negative ion photodetachment spectra provide a fingerprint of the electronic states in AlnBi- (n = 1-5) anions, while theoretical investigations reveal the nature of the electronic orbitals involved. To-ether, the findings reveal that the all-metal Al3Bi 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 Al3Bi 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, Al5Bi, 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.
- 出版日期2008-12-25
