Studies of atoms in which one electron is excited to a state of are principal quantum number n are described. Such atoms possess unusual physical characteristics. This opens up new opportunities for the control and manipulation of atomic wavefunctions and for testing classical-quantum correspondence. Rydberg atoms are strongly perturbed by the presence of a nearby metal surface. Image charge effects lead to formation of hybridized states similar to Start states that can be oriented towards, parallel to, or away from the surface.
Ionization can occur through tunneling of the excited electron into vacant levels in the metal.