Editorial for Biointerphases in focus: Surface plasmon resonance-plasmonics

Optical characterization of ultrathin films and interfaces using surface plasmon polariton or surface plasmon resonance (SPR) excitation in “free-electron-like” metals of gold and silver was pioneered by two research groups from Germany in the late 1960s.1,2 They showed that the SPR phenomenon could be excited optically by the method of attenuated total reflection (ATR) either via a very thin air gap-“the Otto configuration”-or by a route where the thin metal film was deposited directly on the base of a glass prism-“the Kretschmann configuration.” Both methods were extensively used to study fundamental optical properties of thin metal films and inorganic/organic coatings deposited on top of the metal film surface. In the following years the SPR-ATR approach became very popular for studies of monomolecular assemblies of Langmuir-Blodgett films on metals3 and later for the determination of molecular orientation4 in such assemblies as well as for measurement of refractive index changes occurring during phase transitions in liquid crystals.5