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About this book The book reviews the properties of surface plasmons that depict electromagnetic surface waves or surface plasma polaritons. Show all. Surface plasmons on smooth surfaces Pages Raether, Professor Dr.
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Surface plasmons on surfaces of small roughness Pages Raether, Professor Dr. Surfaces of enhanced roughness Pages Raether, Professor Dr. Surface plasmons on gratings Pages Raether, Professor Dr.
Conclusions Pages Raether, Professor Dr. Show next xx. Read this book on SpringerLink. Recommended for you. PAGE 1. Surface plasmon resonance SPR is the resonant oscillation of conduction electrons at the interface between negative and positive permittivity material stimulated by incident light. SPR is the basis of many standard tools for measuring adsorption of material onto planar metal typically gold or silver surfaces or onto the surface of metal nanoparticles. It is the fundamental principle behind many color-based biosensor applications, different lab-on-a-chip sensors and diatom photosynthesis.
Since the wave is on the boundary of the conductor and the external medium air, water or vacuum for example , these oscillations are very sensitive to any change of this boundary, such as the adsorption of molecules to the conducting surface.
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To describe the existence and properties of surface plasmon polaritons, one can choose from various models quantum theory, Drude model , etc. The simplest way to approach the problem is to treat each material as a homogeneous continuum, described by a frequency-dependent relative permittivity between the external medium and the surface.
This quantity, hereafter referred to as the materials' " dielectric function ", is the complex permittivity. In order for the terms that describe the electronic surface plasmon to exist, the real part of the dielectric constant of the conductor must be negative and its magnitude must be greater than that of the dielectric. They exhibit enhanced near-field amplitude at the resonance wavelength.
Surface plasmon polariton - Wikiwand
Light intensity enhancement is a very important aspect of LSPRs and localization means the LSPR has very high spatial resolution subwavelength , limited only by the size of nanoparticles. Because of the enhanced field amplitude, effects that depend on the amplitude such as magneto-optical effect are also enhanced by LSPRs. In order to excite surface plasmons in a resonant manner, one can use electron bombardment or incident light beam visible and infrared are typical. The incoming beam has to match its momentum to that of the plasmon.
S-polarized light polarization occurs perpendicular to the plane of incidence cannot excite electronic surface plasmons. Electronic and magnetic surface plasmons obey the following dispersion relation :. Typical metals that support surface plasmons are silver and gold, but metals such as copper, titanium or chromium have also been used. When using light to excite SP waves, there are two configurations which are well known.
In the Otto setup, the light illuminates the wall of a glass block, typically a prism, and is totally internally reflected. A thin metal film for example gold is positioned close enough to the prism wall so that an evanescent wave can interact with the plasma waves on the surface and hence excite the plasmons. In the Kretschmann configuration , the metal film is evaporated onto the glass block. The light again illuminates the glass block, and an evanescent wave penetrates through the metal film.
The plasmons are excited at the outer side of the film. This configuration is used in most practical applications.
ECE 695S - Nanophotonics - Electrical and Computer Engineering - Purdue University
When the surface plasmon wave interacts with a local particle or irregularity, such as a rough surface , part of the energy can be re-emitted as light. This emitted light can be detected behind the metal film from various directions. Surface plasmons have been used to enhance the surface sensitivity of several spectroscopic measurements including fluorescence , Raman scattering , and second harmonic generation.
However, in their simplest form, SPR reflectivity measurements can be used to detect molecular adsorption, such as polymers, DNA or proteins, etc. Technically, it is common to measure the angle of minimum reflection angle of maximum absorption. This angle changes in the order of 0. See also the Examples.
In other cases the changes in the absorption wavelength is followed.
The same principle is exploited in the recently developed competitive platform based on loss-less dielectric multilayers DBR , supporting surface electromagnetic waves with sharper resonances Bloch surface waves. If the surface is patterned with different biopolymers, using adequate optics and imaging sensors i. This method provides a high contrast of the images based on the adsorbed amount of molecules, somewhat similar to Brewster angle microscopy this latter is most commonly used together with a Langmuir—Blodgett trough.
For nanoparticles, localized surface plasmon oscillations can give rise to the intense colors of suspensions or sols containing the nanoparticles. Nanoparticles or nanowires of noble metals exhibit strong absorption bands in the ultraviolet - visible light regime that are not present in the bulk metal. This extraordinary absorption increase has been exploited to increase light absorption in photovoltaic cells by depositing metal nanoparticles on the cell surface.
Related complementary techniques include plasmon waveguide resonance, QCM , extraordinary optical transmission , and dual polarization interferometry. Unlike many other immunoassays, such as ELISA , an SPR immunoassay is label free in that a label molecule is not required for detection of the analyte.
Besides binding kinetics, MP-SPR can also provide information on structural changes in terms of layer true thickness and refractive index. MP-SPR has been applied successfully in measurements of lipid targeting and rupture,  CVD-deposited single monolayer of graphene 3.
The most common data interpretation is based on the Fresnel formulas , which treat the formed thin films as infinite, continuous dielectric layers. This interpretation may result in multiple possible refractive index and thickness values.
However, usually only one solution is within the reasonable data range. In Multi-Parametric Surface Plasmon Resonance , two SPR curves are acquired by scanning a range of angles at two different wavelengths, which results in a unique solution for both thickness and refractive index.