Metallic colloidal transmission electron

So far, we have prepared and tested many kinds of colloids, mainly in nonaqueous suspensions with combinations of metals or alloys as a dispersed phase and organic liquids as the dispersion media, without the use of any dispersing agents these are listed in Table 9.4.1. We next give some examples of transmission electron micrographs of nanoparticles produced by an aerosol method. A sample for TEM measurement was obtained by dropping colloidal suspension onto a Cu mesh coated with an evaporated carbon film of 10 nm thickness. Many colloids were so unstable... 

The colloidal metals prepared in the manner described above were characterized by transmission electron microscopy. The solutions, as prepared, were diluted to a concentration adequate to allow for the formation of a film of aluminoxane on a sample grid of sufficient thinness for adequate imaging of the metal particles. 

Transmission electron microscopy (TEM) measurements on Ag hydrosols were obtained by using a Philips EM 201 instrument with an electron beam emitted at 80 kV, after placing a drop of colloidal sample on a carbon-Cu grid. Large magnifications (up to 46,000) were adopted in order to investigate the metal aggregates at the level of nanoparticles. 

AuNPs in Liquid-State Environment Solute pure and monolayer-coated ( capped ) AuNPs are central targets in colloid and surface science also with a historical dimension [258-262]. Facile chemical syntheses introduced by Schmid et al. [260] and by Brust et al. [263] have boosted AuNP and other metal nanoparticle science towards characterization of the physical properties and use of these nanoscale metallic entities by multifarious techniques and in a variety of environments. Physical properties in focus have been the surface plasmon optical extinction band [264—269], scanning and transmission electron microscopy properties, and electrochemical properties of surface-immobilized coated AuNPs [173, 268-276], To this can be added a variety of AuNP crosslinked molecular and biomolecular... 

Hence, finite size effects on the optical response of metal nanoparticles are very difficult to take into account in an accurate manner. Moreover, in most experiments carried out on thin nanocomposite films or colloidal solutions the particle size distribution is not mono-dispersed but more or less broad, that can be usually determined by analysis of transmission electronic microscopy images. It should be underlined that the relevant quantity for smdying size effects in the optical response of such media can definitely not be the mean cluster radius , although it is often used in the literature [28-33], since the contribution of one nanoparticle to the optical response of the whole medium is proportional to its volume, i.e. to (cf. Eq. 7). The relevant quantity, that we call the optical mean radius , would then rather be the third-order momentum of the size distribution, = / ... 

As for all catalysts, well-characterized samples are necessary to be able to relate the catalytic performance to physico-chemical properties. Transmission electron microscopy (TEM) and X-ray absorption spectroscopy (XAFS) were used in this study to characterize the stabilized metal colloid. The necessity of such extensive characterization of particle size has been outlined by Harada et al. [6,7] showing that the formation of aggregates may be overlooked and misinterpreted as large metal particles when using TEM alone. The actual availability of the polymer stabilized surface has been probed by hydrogen/oxygen titration adopted from the description of Bernard et al. [8]. 

Average particle sizes were determined with TEM. For that purpose a drop of the colloidal solution was placed on a carbon covered copper grid (Balzers) and analyzed with a high resolution transmission electron microscope (model JEOL 200 CX). Particle size distributions were determined by optical inspection of the photographs. From this data, metal areas of the catalysts were estimated assuming spherical particle shape and a rhodium surface density of 1.66 10 mol Rh/m [10]. As a reference material for characterization and testing, a commercial rhodium on carbon catalyst (5w% Rh, Aldrich) was used. 

Metal colloids in an aqueous solution are ideal markers for cell surfaces and intracellular components for microscopic observation (light and fluorescence microscopy, transmission and scanning electron microscopy) and for studying molecular organization and cell function It also has numerous medical uses as a drug and as a test for various diseases For more specific information about the interfacial behaviour... 

In this chapter we report some results for several nonionic polymers and cationic polyelectrolytes and their ability to stabilize platinum colloids. Both steric and electrostatic stabilization of the metal colloids can be combined by the use of polyelectrolytes (5). The materials have been examined by transmission electron microscopy (TEM) in order to determine the average particle size, size distribution and particle pe. The catalytic activity of these polymer-protected platinum nanoparticles has been tested by the hydrogenation of cyclohexene, d cyclooctene, and 1-hexene. 

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