Blog Post Image: Long Predicted Atomic Collapse State Observed in Graphene

Nonrelativistic electrons orbiting a subcritical nucleus exhibit the traditional circular Bohr orbit of atomic physics. But when the charge on a nucleus exceeds the critical value, Zc, the semiclassical electron trajectory is predicted to spiral in toward the nucleus, then spiral away, a novel electronic state known as “atomic collapse.” Artificial nuclei composed of three or more calcium dimers on graphene exhibit this behavior as graphene’s electrons move in the supercritical Coulomb potential. (Image courtesy of Michael Crommie.)