Trilobite Molecules

While this may look like the ancient trilobite, it is actually an ultra-long-range two-atom rubidium molecule.

Researchers have recently predicted the existence of a giant two-atom rubidium molecule with an electron cloud resembling a trilobite, the ancient, hard-shelled creature which lived in the Earth's seas over 300 million years ago. The peaks in the figure represent the probability of finding an outer (valence) rubidium electron at different points in space. If successfully produced in subsequent experiments, the trilobite molecule would have many remarkable properties in addition to the shape of its electron cloud. For example, it would be huge for something consisting of just two atoms: the researchers calculate that the cores of the Rb atoms would be separated from anywhere between 500-50,000 Angstroms, where 1 Angstrom is roughly the size of a typical atom.

Picture courtesy of the University of Colorado and JILA.
Text courtesy of the American Institute of Physics.