3. Surface plasmon resonance imaging (SPRI)

3.1 Surface plasmon resonance

Surface plasmons are electromagnetic waves localized in the vicinity of an interface between two materials. These propagating waves are evanescent in both materials, i.e. their amplitudes decrease exponentially with distance from the surface. Compliance with Maxwell's conditions governing their existence implies that these materials must necessarily have opposite dielectric constants. This means that, in the visible range, the systems practically implemented are located on an interface between a dielectric and a metal. In fact, this wave is linked to a phenomenon of collective oscillation of the free electrons of the metal at the interface, the latter behaving in a manner analogous to a plasma, hence the name "plasmons" associated with this phenomenon....