Your new post is loading...
The wave nature of light expresses itself in the propagation all over space, showing an intrinsic limitation to be localized beyond the so-called diffraction limit which is of the order of half the wavelength of the photons propagating. However when interacting with matter, light often gets reflected, diffracted, scattered or absorbed depending on the interactions and excitations induced in the material. In particular, at visible wavelengths, between 450 nm and 800 nm, metals interact with electromagnetic waves producing a variety of optical effects. The conduction electrons that constitute the metal can oscillate rigidly at certain optical frequencies that depend on the electron density. Furthermore, when metals are physically bounded by surfaces and interfaces as it is usually the case in nanoparticles and nanostructures, the oscillations of the electron charge density at the surfaces show resonant localized modes so-called surface plasmons. The excitation of these surface plamons by light produces a localization and enhancement of the visible light at the surface of the metal at distances of a few nanometers, well below the diffraction limit, thus acting metallic nanostructures as resonant emitters or receptors of light. This is the reason why metallic nanostructures are often referred to as optical nanoantennas.
