"...The 16-atom gold cage is about 5.5 angstroms in diameter. The spheres were created by vaporizing gold with a laser in a vacuum...15 or fewer atoms formed a planar array; 19 or more atoms formed a solid..."
FDS

I think atomic art is usualy done using tuneling microscope. why they used laser?

Because the buckygold was formed when the vaporised gold condensed while floating free in midair (ok mid-vacuum).

A scanning tunneling microscope can be used to move atoms around on a surface, it's not very good for building balls.
It also suffers from a speed problem, since it works atom by atom, where the condensation of vaporised gold happens to a lot of atoms at the same time.

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This should be good...

why?

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"What you think you thought you saw you did not see." Agent J, MiB - Manhatten Bureau

Well, how might one get an atom inside a cage whose 'bars' are closer together {presumably) than the atom's diameter?

A probable, but uncertain, quantum leap.

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The "stuffed" fullerenes (a fullerene with an atom or more inside the cage) are called Endohedral fullerenes (Wikipedia article). They are generally produced by trapping the caged atom inside, before the cage is completed (during synthesis of the fullerene), but they have also been made by chemically opening the cage (breaking some of the bonds), inserting the atom inside, and reclosing the cage.

The interest, at least in the carbon systems, is to change the properties of the fullerene.

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Likewise the gold cage:Hope they choose a silver atom, at some point.

I was wondering when we'd be heading down Argentine way.

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A natural heuristic!