Abstract

It is well known that surface plasmons (SP’s) can propagate for approximately 500 μm in the visible region if there are identical dielectric materials on both sides of a thin metallic film. Owing to their long ranges and the localized nature of the electric-field distributions, the long-range surface plasmons (LRSP’s) may become a very powerful tool for investigating metallic surface conditions and especially for investigating the properties of molecules in the vicinity of metals. The presence of a metallic surface dramatically changes the decay properties of an excited molecule, depending on the distance between the molecule and the surface. As a result, the Raman signal radiated from molecules is mostly converted to the excitation of SP’s when the distance is smaller than the emission wavelength but larger than the atomic length. In recent years it has been suggested that the Raman signal can be further enhanced through coupling to LRSP’s guided by a symmetrically bounded metallic slab.

© 1993 Optical Society of America