Monday, June 09, 2008

When Regular Atoms Become Superatoms

Atoms act really weird if only a few of them are grouped together. Gold and other (typically metal) atoms begin to form highly symmetrical structures depending on the number of atoms clustering together. These clusters take on the characteristics of the single atoms of a completely different element, transforming into what scientists have dubbed "superatoms".

What makes regular atoms become superatoms is their ability to transform physical properties and imitate those of other elements at extremely small scales. What we can observe with the naked eye, the size, shape and color of a certain material, changes as the number of atoms is reduced, starting at around a few million. For example, silicon is normally rigid and breakable, but group a small number of silicon atoms together and they become malleable, almost supple. Quantum dots, a type of semi-conducting particle, displays light across a spectrum of colors, depending on their size.

Superatom behavior is even more perplexing at smaller scales. Take 20 gold atoms and they will aggregate into a solid pyramid. Remove a couple, and 16 atoms will display a cage-like structure. Groups of tin atoms behave like conductors or semiconductors, depending on the addition or removal of just a few atoms.

Scientists have recently created several new supersatoms and determined their structures. The goal is to use the superatoms of elements such as gold and carbon to develop completely new materials. These custom-made materials would have all sorts of useful properties that we can't obtain from natural materials. Scientists are currently working on a superatom material capable of storing solid hydrogen at room temperature, in hopes of solving the difficult and expensive problem of transporting and storing hydrogen, needed for the development of hydrogen fuel cells.

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