Combinations of elemental atoms have electronic signatures that mimic other elements
‘Superatoms’ Mimic Elements: Research Reveals New Perspective of Periodic Table
Penn State researchers said they have shown that certain combinations of elemental atoms have electronic signatures that mimic the electronic signatures of other elements. The team’s leader A. Welford Castleman Jr., a science professor in the departments of chemistry and physics said, “the findings could lead to much cheaper materials for widespread applications such as new sources of energy, methods of pollution abatement, and catalysts on which industrial nations depend heavily for chemical processing.”
The team used photoelectron imaging spectroscopy to examine similarities between a nickel atom and a titanium-monoxide molecule. Left: Graphical displays of energy peaks were similar between a nickel atom and a titanium-monoxide molecule. Right: Bright spots in the images, which correspond to the energy of the electrons emitted during their removal from the atoms’ outer shells, appeared to be similar between a nickel atom (right, top) and a titanium-monoxide molecule (right, bottom). Credit: Castleman lab, Penn State.
The researchers are said to have also shown that the atoms that have been identified so far in these mimicry events can be predicted simply by looking at the periodic table. The team used advanced experimentation and theory to quantify these new and unexpected findings. “We’re getting a whole new perspective of the periodic table,” said Castleman. The team’s findings will be published in the 28 December 2009 early on-line issue of the journal Proceedings of the National Academy of Sciences.
Castleman said the molecules titanium monoxide, zirconium monoxide, and tungsten carbide are superatoms of nickel, palladium, and platinum, respectively. Superatoms are clusters of atoms that exhibit some property of elemental atoms. Former work in Castleman’s lab has involved investigating the notion of superatoms. One of his previous experiments is said to have shown that a cluster of 13 aluminum atoms behaves like a single iodine atom. Adding a single electron to this aluminum-atom system results in the cluster behaving like a rare-gas atom. Further, he showed that a cluster of 14 aluminum atoms has a reactivity similar to an alkaline earth atom.
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