  Using a recently obtained (general) formula for the interaction energy
between an excited and a ground-state atom (Sherkunov Y 2007 Phys. Rev. A 75
012705), we consider the interaction energy between two such atoms near the
interface between two media. We demonstrate that under the circumstances of the
resonant coupling of the excited atom to the surface polariton mode of a
vacuum-medium system the nonretarded atom*-atom interaction energy can be
enhanced by (several) orders of magnitude in comparison with the van der Waals
interaction energy of the two isolated atoms.
