Gold nanorods: Synthesis, characterization and applications

TL;DR: Some of the recent progress in the manufacture and use of gold nanoparticles, with particular emphasis on gold nanorods are described, and the spectroscopic and photochemical applications of gold nanospheres and nanorod are described.

TL;DR: Nanomaterials are highly effective for developing sensitive and selective nanosensors due to their unique properties.

TL;DR: It is proposed that the growth of these nanostructures can stem from a decrease in the reaction rate as temperature increases due to an enhanced copolymer hydrophobicity, which gives rise to a structure of interacting micelles formed from the fluid via a percolation transition (known as "soft gel") at elevated temperatures.

Abstract: Over the past several years, a high degree of control over morphology has been achieved in the chemical synthesis of nanoparticles by manipulating the growth kinetics of various crystal phases. An important step towards more complex structures is the introduction of branching by switching between two crystal structures within one nanocrystal. It is now possible to produce semiconductor structures in a wide variety of shapes with tunable chemical composition. Hyperbranched CdTe nanoparticles are illustrative of structures that can be prepared with very complex 3D shapes–varying from delicate spider-net like networks to very compact urchin-like particles. Such particles have already been used in organic–inorganic blend materials for solar cells. The creation of active devices from inorganic nanocrystals often requires their assembly in well-defined geometries and orientations at specific locations on surfaces. Moreover, the arrangement of different types of nanocrystals in unique hybrid structures is also essential. The creation of hybrid metal– semiconductor nanostructures is an important next step towards such self-assembled functional structures. Recently, the Banin group has achieved some success in growing metal tips on tetrapods and on one or both tips of rod-shaped CdSe and CdS particles. These researchers have demonstrated the possibility of using the metal tips as direct electrical contact points and as assembling and reaction centers. There is also considerable interplay between the optical and electronic behavior of the components of such hybrid materials, potentially leading to enhanced or new properties. Here, we report the synthesis of a novel metal–semiconductor hybrid based on hyperbranched CdTe particles. These particles are considerably larger and more complex than the previously reported CdSe and CdS hybrid particles. Gold particles have been grown selectively onto the tips of preformed semiconductor substrates at room temperature in air. The gold-tipped hyperbranched particles not only provide intriguing insight into the level of control of inorganic hybrid nanomaterials, but may also enable the creation of blends with organic molecules for the eventual fabrication of novel electronic and optical materials. We propose a chemical reaction pathway supported by detailed spatially resolved elemental analysis and control experiments. Hyperbranched CdTe particles have been synthesized in trioctylphosphine oxide (TOPO) by the reaction of trioctylphosphine telluride (TOP=Te) with Cd-phosphonic acid (PA) complexes under an argon atmosphere. The metal tips have been added to the hyperbranched particles in a second step at room temperature (in open air) by mixing with a gold growth solution containing HAuCl4, dodecylamine (DDA), and didodecyldiamineammonium bromide (DDAB) in toluene; the tips of the hyperbranched particles act as nucleation centers for the growth of gold. The volume ratio between the gold growth solution and the CdTe hyperbranched particles controls the amount of gold deposited on the substrates. Our choice of solvent is essential for the success of the reaction. We have analyzed the growth of gold onto the hyperbranched CdTe particles by transmission electron microscopy (TEM) before and after the addition of the gold growth solution (Fig. 1). Figure 1a shows an image of the original hyperC O M M U N IC A TI O N

TL;DR: In this paper, a Potpourri of Particles is used to describe surface modes in small Particles and the Angular Dependence of Scattering is shown to be a function of the size of the particles.

TL;DR: Light scattering by small particles as mentioned in this paper, Light scattering by Small Particle Scattering (LPS), Light scattering with small particles (LSC), Light Scattering by Small Parts (LSP),

TL;DR: In this paper, the authors describe recent progress in the theory of nanoparticle optical properties, particularly methods for solving Maxwell's equations for light scattering from particles of arbitrary shape in a complex environment.