Surface plasmon resonance oscillating electric field

Figure 20-22a shows essentials of one common surface plasmon resonance measurement Monochromatic light whose electric field oscillates in the plane of the page is directed into a prism whose bottom face is coated with a thin layer (—50 nm) of gold. The bottom surface of the gold is coated with a chemical layer (—2-20 nm) that selectively binds an analyte of inter-... 

For centuries, metal nanoparticles have never ceased to attract scientists and artists from many diverse cultures. In this section we briefly introduce a phenomenon of metal nanoparticles that still inspires scientists localized surface plasmon resonance (LSPR) (Hutter and Fendler, 2004). Metal nanoparticles show nonlinear electronic transport (single-electron transport of Coulomb blockade) and nonlinear/ultrafast optical response due to the SPR. Conduction electrons (—) and ionic cores (-F) in a metal form a plasma state. When external electric fields (i.e., electromagnetic waves, electron beams etc.) are applied to a metal, electrons move so as to screen perturbed charge distribution, move beyond the neutral states, return to the neutral states, and so on. This collective motion of electrons is called a plasma oscillation. SPR is a collective excitation mode of the plasma localized near the surface. Electrons confined in a nanoparticle conform the LSPR mode. The resonance frequency of the surface plasmon is different... 

The fascinating phenomenon of surface plasmon resonance (SPR) occurs when an electromagnetic wave interacts with the conduction electrons of a metal (6). The periodic electric field of the electromagnetic wave causes a collective oscillation of the conductance electrons at a resonant frequency relative to the lattice of positive ions. Light is absorbed or scattered at this resonant frequency. The process of... 

Raman enhancement can take place by either increasing the electric field ( ) experienced by the molecule (electromagnetic enhancement) or by changing the molecular polarizability of the adsorbate (chemical enhancement). The electromagnetic enhancement mechanism is explained by a phenomenon known as surface plasmon resonance. Surface plasmons are oscillations of conduction band electrons at a metal surface. At the surface... 

Figure 13.1 Description of the plasmon resonance, (a) Schematic of the coherent oscillations of the surface conduction band electrons induced by the oscillating electric field (reproduced with permission from Ref...

The source of radiation, in the classical electromagnetic theory, is an accelerated charge. For time-harmonic fields, electrical current serves as the source. There is a considerable amount of literature on the radiation properties of apertures and antennas at radio and microwave frequencies. At these frequencies, the penetration of the fields into a metal is small. Thus, it is frequently quite acceptable to model these structures by assuming the metals are PECs. At optical frequencies, a significant portion of the incident energy can be dissipated in the metal. In addition, typical metals exhibit surface plasmon resonances at optical frequencies. Associated with a surface plasmon is an oscillating charge distribution on the surface of the structure, localized within the skin depth of the metal. 

As is specified in work [17], the system of conductivity electrons in a nanocrystal is similar to the resonator. Thereof electromagnetic field in a crystal can give rise to collective electronic excitations [17], which refer to as surface plasmons as they are caused by charges on a nanocrystal surface in dielectric [16]. At a>v dielectric permeability e (oj) according to the formula (5) is negative. It means that conductivity electrons in a nanocrystal oscillate out of phase with electric oscillations of an external field [16]. 

Nanobiosensors Noble-metal nanoparticles have a strong ultraviolet UV-vis absorption band that is not observed in the spectra of the bulk metals [113-115]. If the incident photon has a frequency that is close to the frequency that characterizes the collective oscillations of conduction electrons (plasmons) at the surface, resonant absorption can occur. The enhanced local electric fields near the surface of nanoparticles, which are dependent on the size and morphology of the nanoparticles, result in strong surface-sensitive contributions to UV-vis spectra. In Ref. [114], the authors review studies of this phenomenon of localized... 

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