In this review article, we provide an overview of recent research activities in the study of plasmonic optical properties of metal nanostructures with emphasis on understanding the relation between surface plasmon absorption and structure. Both experimental results and theoretical calculations have indicated that the plasmonic absorption strongly depends on the detailed structure of the nanomaterials. Examples discussed include spherical nanoparticles, nanorods, nanowires, hollow nanospheres, aggregates, and nanocages. Plasmon–phonon coupling measured from dynamic studies as a function of particle size, shape, and aggregation state is also reviewed. The fascinating optical properties of metal nanostructures find important applications in a number of technological areas including surface plasmon resonance, surface-enhanced Raman scattering, and photothermal imaging and therapy. Their novel optical properties and emerging applications are illustrated using specific examples from recent literature. The case of hollow nanosphere structures is highlighted to illustrate their unique features and advantages for some of these applications.

Plasmonic Optical Properties and Applications of Metal Nanostructures

Microemulsion-based synthesis is found to be a versatile route to synthesize a variety of nanomaterials. The manipulation of various components involved in the formation of a microemulsion enables one to synthesize nanomaterials with varied size and shape. In this tutorial review several aspects of microemulsion based synthesis of nanocrystalline materials have been discussed which would be of interest to a cross-section of researchers working on colloids, physical chemistry, nanoscience and materials chemistry. The review focuses on the recent developments in the above area with current understanding on the various factors that control the structure and dynamics of microemulsions which can be effectively used to manipulate the size and shape of nanocrystalline materials.

Microemulsion-based synthesis of nanocrystalline materials

This paper provides a brief overview of recent research activities concerning metal nanomaterials, including their synthesis, structure, surface plasmon absorption, surface enhanced Raman scattering (SERS), electron dynamics, emerging applications, and the historical context by which to view these subjects. We emphasize coinage metals, particularly silver and gold. Silver and gold nanostructures exhibit fascinating optical properties due to their strong optical absorption in the visible as a result of the collective oscillation of conduction band electrons, known as the surface plasmon. This is the origin of many interesting physical phenomena and related applications such as surface plasmon resonance (SPR) and SERS useful in chemical and biomedical detection and analysis. SERS offers high sensitivity and molecular specificity that are attractive for sensing and imaging applications. Electron dynamics in metal nanostructures have been studied using ultrafast laser techniques to gain fundamental insight in...

Novel Optical Properties and Emerging Applications of Metal Nanostructures

Nanoparticles probably constitute the largest class of nanomaterials. Nanoparticles of several inorganic materials have been prepared by employing a variety of synthetic strategies. Besides synthesizing nanoparticles, there has been considerable effort to selectively prepare nanoparticles of different shapes. In view of the great interest in inorganic nanoparticles evinced in the last few years, we have prepared this perspective on the present status of the synthesis of inorganic nanoparticles. This article includes a brief discussion of methods followed by reports on the synthesis of nanoparticles of various classes of inorganic materials such as metals, alloys, oxides chalcogenides and pnictides. A brief section on core-shell nanoparticles is also included.

Recent progress in the synthesis of inorganic nanoparticles

Preparation of starch-based nanoparticles through high-pressure homogenization and miniemulsion cross-linking: Influence of various process parameters on particle size and stability

By lowering the reaction temperature during metal ion reduction in a reverse micelle system, gold nanoparticle size can be subtly tuned from 6.6 to 2.2 nm in diameter. Under these reaction conditions, the water-to-surfactant ratio (W value) also plays an important role in controlling the particle size, enabling a wide range of products obtainable via a simple, quick, reproducible synthesis. Particle sizes were measured by HRTEM, and size trends were supported by UV-vis spectroscopy.

Fine-tuning size of gold nanoparticles by cooling during reverse micelle synthesis.

Gold and platinum nanoparticles were prepared using a reverse micelle technique, creating products with several particle sizes. The stabilized metal nanoparticles can be deposited over long-range distances forming ordered arrays using supercritical carbon dioxide to remove the colloid solvent. The use of supercritical carbon dioxide creates uniformly deposited particle layers and can be removed without disturbing the precipitated particles. We also show that these nanoparticles can be deposited efficiently in nanometer trenches, which is not possible using conventional particle deposition by liquid evaporation.

Deposition of Ordered Arrays of Gold and Platinum Nanoparticles with an Adjustable Particle Size and Interparticle Spacing Using Supercritical CO2

Silver sulfide and cadmium sulfide nanoparticles of controllable sizes are synthesized using a water-in-hexane microemulsion method and stabilized by dodecanethiol. The stabilized metal sulfide nan...

Depositing ordered arrays of metal sulfide nanoparticles in nanostructures using supercritical fluid carbon dioxide.

CHAPTER 11 – Digestive Ripening, or “Nanomachining,” to Achieve Nanocrystal Size Control

Multiplexed printing and sensors for biological applications. Sensors can be made with high sensitivity and by high throughput methods. Multiple capture molecules can be applied to the same or different sensor elements such as cantilevers. The sensor element can be a microcantilever. Direct write lithography from nanoscopic tips can be used to make the sensor. Proteins and hydrogels can be printed. Specific binding can be detected.

Alexander B. Smetana

Papers

Fine-tuning size of gold nanoparticles by cooling during reverse micelle synthesis.

Deposition of Ordered Arrays of Gold and Platinum Nanoparticles with an Adjustable Particle Size and Interparticle Spacing Using Supercritical CO2

Depositing ordered arrays of metal sulfide nanoparticles in nanostructures using supercritical fluid carbon dioxide.

CHAPTER 11 – Digestive Ripening, or “Nanomachining,” to Achieve Nanocrystal Size Control

Sensors and biosensors