  A metal film supports the continuum of propagating surface plasmon waves. The
interaction of these waves with a dipole (nanoparticle) positioned some
distance from the surface of the film can produce well defined localized
plasmon modes whose frequency nonetheless resides inside the continuum. This
leads to the resonant enhancement of scattering of surface plasmons off the
dipole. The maximum of scattering is found to occur when the distance from the
dipole to the surface of the film is equal to one half of the film thickness.
The possibility of controllable plasmon scattering could be advantageous for
the field of nanoplasmonics.
