Metallic nanoparticles resonance

One possible explanation for this enhanced energy transfer could be related to the nature of polymer excitons and the fact that the Si02 Au nanoparticles can exhibit greatly enhanced local field intensities. Since metal nanoparticle resonances have excitation lifetimes of only a few picoseconds, the donor-... 

Klar T ef a/1998 Surface-plasmon resonances in single metallic nanoparticles Phys. Rev. Lett. 80 4249... 

Near-Field Optical Imaging of Localized Plasmon Resonances in Metal Nanoparticles... 

Figure 8. Illustration of the interaction visible light and the confined electron gas of a metal nanoparticle, resulting in a plasmon resonance.

When the size of metals is comparable or smaller than the electron mean free path, for example in metal nanoparticles, then the motion of electrons becomes limited by the size of the nanoparticle and interactions are expected to be mostly with the surface. This gives rise to surface plasmon resonance effects, in which the optical properties are determined by the collective oscillation of conduction electrons resulting from the interaction with light. Plasmonic metal nanoparticles and nanostructures are known to absorb light strongly, but they typically are not or only weakly luminescent [22-24]. 

A clear, commonly accepted terminology to describe few-atom subnanoscale metals exhibiting quantized energy levels is lacking. The lack of a coherent terminology leads to confusion and may hamper development. In this chapter, we restrict the term metal cluster to describe few-atom metals with discrete energy levels, and use metal nanoparticle, for particles that have surface plasmon resonance effects (approximate size range between 1 and 100 nm). 

Van Duyne RP, Haes AJ, Zou S, Schatz GC (2004) A Nanoscale Optical Biosensor The Long Range Distance Dependence of the Localized Surface Plasmon Resonance of Noble Metal Nanoparticles. J Phys Chem B 108 109-116... 

Metal nanoparticles have been intensively studied due to their potential for both fundamental and applied research. They give a possibility to examine the material properties in transient conditions between the bulk material and separated atoms. Some phenomena, such as surface plasmon resonance transitions, electron-electron or electron-phonon scattering have special character in metal nanoparticles. 

Similar to zero-dimensional metal nanoparticles, most of the work on one-dimensional metal nanostructures focuses almost exclusively on gold nanorods. The high interest in anisometric gold nanoclusters arises from their unique optical and electronic properties that can be easily tuned through small changes in size, structure (e.g., the position, width, and intensity of the absorption band due to the longitudinal surface plasmon resonance is strongly influenced by the shell as well as the aspect ratio of the nanorods), shape (e.g., needle, round capped cylinder, or dog bone), and the inter-particle distance [157]. 

Electro-optic effects induced by doping liquid crystals with one-dimensional metal nanoparticles were not only investigated in standard electro-optic test cells, but also in costume-made cells consisting of a thin layer of liquid crystal either deposited onto a thin film of alumina with embedded GNRs [443], or using rubbed polyimide alignment layers modified with solution-cast GNR [444]. In both cases, surface plasmon resonance frequencies of the GNR integrated into these liquid crystal cells could be electrically controlled. 

Quantum size effects famous examples are the color shift upon size reduction of semiconductor nanoparticles like CdSe [14-16], and the surface plasmon resonance of metallic nanoparticles like gold [17, 18]. 

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