Nanoscale optical property

Keywords a -Conjugation Barcode Biosensor Doping Electron beam Hybridization Hydrothermal Light-emitting polymer Nanoscale optical property Nanostructure Optoelectronics... 

There is great interest in the electrical and optical properties of materials confined within small particles known as nanoparticles. These are materials made up of clusters (of atoms or molecules) that are small enough to have material properties very different from the bulk. Most of the atoms or molecules are near the surface and have different environments from those in the interior—indeed, the properties vary with the nanoparticle s actual size. These are key players in what is hoped to be the nanoscience revolution. There is still very active work to learn how to make nanoscale particles of defined size and composition, to measure their properties, and to understand how their special properties depend on particle size. One vision of this revolution includes the possibility of making tiny machines that can imitate many of the processes we see in single-cell organisms, that possess much of the information content of biological systems, and that have the ability to form tiny computer components and enable the design of much faster computers. However, like truisms of the past, nanoparticles are such an unknown area of chemical materials that predictions of their possible uses will evolve and expand rapidly in the future. 

The fundamental physical properties of nanowire materials can be improved even more to surpass their bulk counterpart using precisely engineered NW heterostructures. It has been recently demonstrated that Si/Ge/Si core/shell nanowires exhibit electron mobility surpassing that of state-of-the-art technology.46 Group III-V nitride core/shell NWs of multiple layers of epitaxial structures with atomically sharp interfaces have also been demonstrated with well-controlled and tunable optical and electronic properties.47,48 Together, the studies demonstrate that semiconductor nanowires represent one of the best-defined nanoscale building block classes, with well-controlled chemical composition, physical size, and superior electronic/optical properties, and therefore, that they are ideally suited for assembly of more complex functional systems. 

Ion traps have been used in a number of studies of optical properties of microdroplet lasers14,15 and the ion trap itself can be used as a useful mass spectrometer for fundamental studies of trapped particles and micrometer to nanoscale aerosols16. 

We have overviewed some strategies for the surface-mediated fabrication of metal and alloy nanoscale wires and particles in mesoporous space, and their structural characterization and catalytic performances. Extension of the present approaches for metal/alloy nanowires may lead to the realization of the prospechve tailored design of super active, selective and stable catalysts applicable in industrial processes. The organometallic clusters and nanowires offer exciting and prospechve opportunities for the creahon of new catalysts for industry. Various metal/ alloy nanowires and nanoparhcles in the anisotropic arrangement in porous supports would help in understanding the unexpected electronic and optic properties due to the quantum effect, which are relevant to the rational design of advanced electronic and optic devices. 

The major trends in ferroelectric photonic and electronic devices are based on development of materials with nanoscale features. Piezoelectric, electrooptic, nonlinear optical properties of fe are largely determined by the arrangement of ferroelectric domains. A promising way is a modification of these basic properties by means of tailoring nanodomain and refractive index superlattices. 

Conventional SERS substrates typically have disordered nanoscale features, such as that found in electrochemically roughened Au or Ag surfaces.170 SERS substrates can also be rationally designed by lithography, by self-assembly, or a combination of the two. Both supramolecular and nanoscale self-assembly methods can be used to fabricate two-dimensional Au nanoparticle arrays with tunable optical properties.33 171172 For example, macrocyclic surfactants based on resorcinarenes (a subclass... 

It has been proposed recently that phase separation of GalnN into In-rich and Ga-rich phases has profound consequences on the optical properties and on the lasing properties of GalnN/GaN/AlGaN quantum well heterostructures [1,2]. The nanoscale compositional fluctuations resulting from phase separation are believed to lead not only to exciton localisation [2] but even to a quantum-dot-like behaviour [3], A more detailed discussion of the microscopic aspects of phase separation is given elsewhere in this volume. 

Prashant KJ, Huang X, El-Sayed IH, El-Sayed MA. Noble metals on the nanoscale Optical and photothermal properties and some applications in imaging, sensing, biology and medicine. Acc Chem Res 2008 in press. 

The study of nanosized particles has its origin in colloid chemistry, which dates back to 1857 when Michael Faraday (1791-1867) set out to systematically investigate the optical properties of thin hhns of gold. Faraday prepared a suspension of ultra-small metaUic gold particles in water by chemically reducing an aqueous solution of gold chloride with phosphorus (Faraday, 1857). To this day, nanoscale metal particles are stiU produced by chemical reduction in aqueous solutions. 

UV Raman studies of ferroelectricity in strain-free non-stoichiometric and nominally stoichiometric SrTiOs films, in combination with dielectric, ferroelectric, nonlinear optical and nanoscale piezoelectric property measurements highlighted the sensitive role of stoichiometry when exploring strain and epitaxy-induced electronic phenomena in oxide films, heterostmctures, and interfaces. 

In addition, subjects such as molecular photochemistry and photophysics and optical properties from the molecular to the nanoscale are closely related. Accordingly, a brief selection of lead-in references in these areas is provided. The organization and selection are strongly influenced by the interests of the author. Where possible review articles are cited rather than primary literature. At present the best consistent medium for review articles on inorganic photochemistry is Coordination Chemistry Reviews. 

Profound changes may occur in the electronic properties of materials as their characteristic length scale is reduced to the nanoscale. These changes affect the optical properties, mechanical response, adsorption behavior, and catalytic properties of the material. 

The fascinating optical properties of metal nanoparticles have caught the attention of many researchers from the pioneering and almost parallel works of G. Mie and J.C. Maxwell-Garnett at the beginning of the twentieth century. These original properties, like many other phenomena specifically appearing in matter divided to the nanoscale, are linked with confinement effects, since quasi-free conduction 461... 

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