A quantum-mechanical linear-response formalism is further developed to deal with the energy-level shifts of excited states of atoms near an arbitrary flat interface. We establish physical interpretations for different components of these energy-level shifts, and as examples treat atoms in free space, near a perfect conductor, near a metal, and near a dielectric waveguide. The effects of surface excitations such as surface plasmons and waveguide modes are considered in detail; we point out certain striking differences in the effects of these particular excitations.

• Received 28 March 1985

DOI:https://doi.org/10.1103/PhysRevA.32.2030