Metal nanostructures, electronic properties

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]. 

Both the discovery of new synthesis processes for nanostructured materials and the demonstration of the highly reactive properties of these materials have increased rapidly within recent years. The new synthesis processes have made available nanostructured materials in a wide variety of compositions of metal oxides and metals supported on metal oxides, which have led to recognition of their exceptional chemical, physical, and electronic properties. The objective of this review is to provide recent results on synthesis of nanostructured materials using the novel processes that were developed in these laboratories recently and to contrast them to other important, new methods. Because some of the most important applications of nanostructured materials are as catalysts for chemical processing, several key reports on enhanced catalytic reactivity of nanostructured grains will be discussed along with the pertinent theory responsible for controlling both activity and selectivity of these new catalysts. 

Synthesis of metal nanostructures with tunable properties (optical, magnetic, electronic, catalytic, etc.), in specific physicochemical environments, is today of great importance from a fundamental as well as an applied point of view. Since the physicochemical properties of nanostructures are strongly dependent not only on the size but also on the shape, controlling the architecture of metal nanoparticles... 

Surface plasmons (SPs) are collective electronic excitations near the surfaces of metallic structures. They can usually be described well with classical electromagnetic theory and correspond to electromagnetic fields that are localized and relatively intense near the metallic surfaces [1, 2]. These properties make them potentially useful for a variety of applications in optoelectronics, chemical and biological sensing, and other areas. Metallic nanostructures such as metal nanoparticles and nanostructured thin metal films, particularly those composed of noble metals such as silver or gold, are of special interest because often their SPs can be excited with visible-UV light and are relatively robust. 

OPTICAL AND ELECTRONIC PROPERTIES OF METAL AND SEMICONDUCTOR NANOSTRUCTURES... 

For the comprehension of mechanisms involved in the appearance of novel properties in polymer-emhedded metal nanostructures, their characterization represents the fundamental starting point. The microstructural characterization of nanohllers and nanocomposite materials is performed mainly by transmission electron microscopy (TEM), large-angle X-ray diffraction (XRD), and optical spectroscopy (UV-Vis). These three techniques are very effective in determining particle morphology, crystal structure, composition, and particle size. 

In this chapter we discuss a novel approach to the concept of nanostructuring, which is based on coating metal or semiconductor nanoparticles with silica, so that the final morphology involves a silica sphere of the desired size containing a core placed precisely at its center. Although such concepts have been proposed before, it has only recently been possible to synthesize such coated materials in a reproducible manner. These composite spheres can then be used as the building blocks of the nanostructured material. The interest of these systems is due to the unique optical and electronic properties of nanosized metal and semiconductor particles. 

Statistical analysis of electronic properties of aikanethiols in metal-molecule-metal junction Sensitivity, selectivity and stability of tin oxide nanostructures on large area arrays of microhotplates... 

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