Although gold is the subject of one of the most ancient themes of investigation in science, its renaissance now leads to an exponentially increasing number of publications, especially in the context of emerging nanoscience and nanotechnology with nanoparticles and self-assembled monolayers (SAMs). We will limit the present review to gold nanoparticles (AuNPs), also called gold colloids. AuNPs are the most stable metal nanoparticles, and they present fascinating aspects such as their assembly of multiple types involving materials science, the behavior of the individual particles, size-related electronic, magnetic and optical properties (quantum size effect), and their applications to catalysis and biology. Their promises are in these fields as well as in the bottom-up approach of nanotechnology, and they will be key materials and building block in the 21st century. Whereas the extraction of gold started in the 5th millennium B.C. near Varna (Bulgaria) and reached 10 tons per year in Egypt around 1200-1300 B.C. when the marvelous statue of Touthankamon was constructed, it is probable that “soluble” gold appeared around the 5th or 4th century B.C. in Egypt and China. In antiquity, materials were used in an ecological sense for both aesthetic and curative purposes. Colloidal gold was used to make ruby glass 293 Chem. Rev. 2004, 104, 293−346

Gold nanoparticles: assembly, supramolecular chemistry, quantum-size-related properties, and applications toward biology, catalysis, and nanotechnology.

The interest in nanoscale materials stems from the fact that new properties are acquired at this length scale and, equally important, that these properties * To whom correspondence should be addressed. Phone, 404-8940292; fax, 404-894-0294; e-mail, mostafa.el-sayed@ chemistry.gatech.edu. † Case Western Reserve UniversitysMillis 2258. ‡ Phone, 216-368-5918; fax, 216-368-3006; e-mail, burda@case.edu. § Georgia Institute of Technology. 1025 Chem. Rev. 2005, 105, 1025−1102

Chemistry and properties of nanocrystals of different shapes.

This review focuses on the synthesis, protection, functionalization, and application of magnetic nanoparticles, as well as the magnetic properties of nanostructured systems. Substantial progress in the size and shape control of magnetic nanoparticles has been made by developing methods such as co-precipitation, thermal decomposition and/or reduction, micelle synthesis, and hydrothermal synthesis. A major challenge still is protection against corrosion, and therefore suitable protection strategies will be emphasized, for example, surfactant/polymer coating, silica coating and carbon coating of magnetic nanoparticles or embedding them in a matrix/support. Properly protected magnetic nanoparticles can be used as building blocks for the fabrication of various functional systems, and their application in catalysis and biotechnology will be briefly reviewed. Finally, some future trends and perspectives in these research areas will be outlined.

Magnetic nanoparticles: Synthesis, protection, functionalization, and application

Nanocrystals are fundamental to modern science and technology. Mastery over the shape of a nanocrystal enables control of its properties and enhancement of its usefulness for a given application. Our aim is to present a comprehensive review of current research activities that center on the shape-controlled synthesis of metal nanocrystals. We begin with a brief introduction to nucleation and growth within the context of metal nanocrystal synthesis, followed by a discussion of the possible shapes that a metal nanocrystal might take under different conditions. We then focus on a variety of experimental parameters that have been explored to manipulate the nucleation and growth of metal nanocrystals in solution-phase syntheses in an effort to generate specific shapes. We then elaborate on these approaches by selecting examples in which there is already reasonable understanding for the observed shape control or at least the protocols have proven to be reproducible and controllable. Finally, we highlight a number of applications that have been enabled and/or enhanced by the shape-controlled synthesis of metal nanocrystals. We conclude this article with personal perspectives on the directions toward which future research in this field might take.

Shape‐Controlled Synthesis of Metal Nanocrystals: Simple Chemistry Meets Complex Physics?

Core/Shell Nanoparticles: Classes, Properties, Synthesis Mechanisms, Characterization, and Applications

PROBLEM TO BE SOLVED: To provide a monodisperse air suspended particle classifier which permits the production of monodisperse standard particles having a particle size of 0.1 to 1.0 μm. SOLUTION: Non-charged particles distributed so as to contain particles having a desired particle size are guided to a chamber 11. A photo ionizer 16 capable of adjusting soft X-ray output is attached to the chamber 11 and charges the particles in the chamber 11. Therein, the level of the soft X-ray output is adjusted so as to become single charge by a controller 17. Subsequently, the charged particles are guided to a differential electric mobility analyzer 21 and are classified and, thereby, the monodisperse particles can be obtained. COPYRIGHT: (C)2005,JPO&NCIPI

Monodisperse air suspended particle classifier

In semiconductor manufacturing processes, surface contamination is a very important issue because it decreases the product yield of the LSI. In this study, a new method to remove fine airborne particles and gaseous contaminants in the wafer stocker using a UV/photoelectron method has been investigated. Two kinds of wafer stockers are used for investigating the efficiency of the UV/photoelectron method for controlling (1) particulate and gaseous contaminants under atmospheric conditions and (2) particulate contaminants under low pressure conditions.

Control of fine particulate and gaseous contaminants by UV/photoelectron method

Improvement of semiconductor integration requires the contamination control of finer particle in semiconductor manufacturing processes. In particular, the control of particle contamination in semiconductor material gases is important for enhancing the production yield. A flow-cell type optical particle counter based on light scattering method was developed for real-time measurement of particles in semiconductor material gases. In this paper, the flow-cell type particle counter was inserted in gas supply lines of semiconductor manufacturing processes. This enabled direct and in-line measurement of particles in the semiconductor material gases for the first time. The measurements showed that the concentration of particles in semiconductor material gases depended on the material and condition of gas cylinders and gas filters. The particle concentration was also affected by the operation of gas supply systems. It was suggested that there was a considerable amount of particulate contaminant generation in the semiconductor gases. The measured results for inert gases were significantly different from those of the semiconductor gases. Consequently, the importance of the direct and in-line measurement was confirmed.

Detection of Particles in Semiconductor Material Gases Using Light Scattering Method

Tb-doped Y 2 SiO 5 phosphor particles were prepared directly by a continuous droplet-to-particle preparation process using an ultrasonic spray generator. The photoluminescence characteristics of as-prepared and calcined particles were investigated. The particles of Y 2 SiO 5 prepared below 1100°C had poor crystallinity because of the short residence time of the particles inside the hot wall reactor, while the particles of Y 2 SiO 5 prepared at 1200°C had sharp crystallinity. The crystal structure of Y 2 SiO 5 particles was changed from the X1 to X2 type after calcining above 1400°C. Both prepared and calcined particles had spherical morphology, submicron size, and narrow size distribution. Agglomeration of particles did not occur even after calcining at 1200°C. The prepared Y 2 SiO 5 :Tb particles absorbed excitation energy in the range from 220 to 325 nm, and the maximum excitation wavelength was near 240 nm. The main emission peak was 538 nm. The optimum brightness was obtained at the doping concentration of 4 atom %. The activation of terbium occurred directly even at short reaction times inside the hot wall reactor. The brightness of as-prepared particles increased with increasing temperature because of good activation and crystallization in high temperatures. The PL intensity of as-prepared particles at 1200°C was 96% in comparison with maximum intensity of calcined particles.

Luminescence Characteristics of Y2SiO5: Tb Phosphor Particles Directly Prepared by the Spray Pyrolysis Method.

https://www.jstage.jst.go.jp/article/sptj1978/39/9/39_9_670/_pdf

Kikuo Okuyama

Papers

Monodisperse air suspended particle classifier

Control of fine particulate and gaseous contaminants by UV/photoelectron method

Detection of Particles in Semiconductor Material Gases Using Light Scattering Method

Luminescence Characteristics of Y2SiO5: Tb Phosphor Particles Directly Prepared by the Spray Pyrolysis Method.

Preparation of Nano-particles by Aerosol Process