Nanoparticles structure

Nanoparticle structure, 263, 512-516 Nanoparticle thermodynamics, 509-511 Nucleation and growth model for CO oxidation, 163... 

G. Fiandaca, E. Vitrano, and A. Cupane, Ferricytochrome c encapsulated in silica nanoparticles structural stability and functional properties. Biopolymers 74, 55—59 (2004). 

With the ability to obtain information about the concentrations of various types of metal surface sites in complex metal nanocluster catalysts, HRTEM provides new opportunities to include nanoparticle structure and dynamics into fundamental descriptions of the catalyst properties. This chapter is a survey of recent HRTEM investigations that illustrate the possibilities for characterization of catalysts in the functioning state. This chapter is not intended to be a comprehensive review of the applications of TEM to characterize catalysts in reactive atmospheres such reviews are available elsewhere (e.g., 1,8,9 )). Rather, the aim here is to demonstrate the future potential of the technique used in combination with surface science techniques, density functional theory (DFT), other characterization techniques, and catalyst testing. 

A last notable example is represented by a templated self-assembly of metallic nanoparticles by using DNA as a scaffold. This leads to the formation of extended, close-packed, ligand-stabilized metal nanoparticle structures, including long chains of nanoparticles [158]. 

Chemically Directed Self-Assembly of Nanoparticle Structures on Surfaces... 

In general, there are two approaches to assemble nanostructured materials, namely, physical assembly and chemical assembly. Physical assembly techniques are based on the assembly of nonfunctionalized nanoparticles on surfaces by physical forces, which include convective or capillary assembly,3,4 spin coating,5 and sedimentation.6 The physical assembly of nanoparticles generally results in relatively simple, closely packed two- or three-dimensional particle arrays. In addition, the physically assembled nanoparticle structures lack long term stability because they were deposited at relatively low surface pressures.7... 

In this review, we describe the recent developments of chemically directed self-assembly of nanoparticle structures on surfaces. The first part focuses on the chemical interactions used to direct the assembly of nanoparticles on surfaces. The second part highlights a few major top-down patterning techniques employed in combination with chemical nanoparticle assembly in manufacturing two- or three-dimensional nanoparticle structures. The combination of top-down and bottom-up techniques is essential in the fabrication of nanoparticle structures of various kinds to accommodate the need for device applications. 

Keywords Nanoparticles, structure, EPR, doping metal ions, Titanium dioxide, photoelectrochemistry... 

Multicomponent and complex nanoparticle structures have been designed. For instance, Pt22V35Fe43 ternary alloy nanoparticles have been synthesized by... 

Fig. 2. Diagram of nanoparticle structure (core-shell morphology)...

PVP is rarely successful at producing anisotropic gold nanoparticle structures that can be explained by the selective binding growth model, unless Ag is also present. Indeed, for the gold nanooctahedra and nanodecahedra above, PVP was present but did... 

Figure 19.6 Experimental geometries for distance dependent control of fluorescence enhancement on top of silver nanoparhcles (structure I) and underneath silver nanoparticles (structure II), respectively. Re vinted from reference 48 with permission of the SPIE.

The optical and spectroscopic data of the local nanoparticle structures investigated showed that SERS is a local and time-dependent phenomenon, because (1) only few particles are Raman active particles, (2) strongest enhancements in SERS are obtained from particle agglomerates, (3) typically the Raman radiation is emitted from irregular stmctures like the necks between two or more particles agglomerated, (4) a time-dependent behavior characterized by intensity fluctuations was observed. 

It is evident that the properties of nanoparticle structures depend not only on the individual particle size, particle shape, or the degree of size dispersion but also on their spatial distribution and the degree of aggregation or film formation. Therefore, before investigating the optical and electronic properties of nanoparticles, it is important to gain knowledge of how to control the particle size, particle density, and spatial distribution. 

For investigating nanoparticle structures by means of a Raman microscope, it is necessary to increase the spatial resolution and depth of sharpness of the Raman signal. 

Instead of SNOM, in many cases, particularly if the sample is to be screened for Raman active spots and their spatial distance is more than half of the wavelength of the laser, it is also confocal Raman microscopy that delivers enough morphological and spectral information on both nanoparticle structure and SERS activity, respectively. Thus, confocal Raman microscopy is interesting for a wide variety of applications in biology, medicine, and technological materials research. 

The preparation regime and experimental experience was transferred to the generation of gold nanoparticles onto ITO and glassy carbon substrates. It was shown that various nanoparticle structures with particle sizes from 10 to 500 nm could be prepared [37]. 

To demonstrate the versatility of this approach, we created binding patterns of different size and allowed different nanoparticles to form superstructures (Fig. 15.7c). Again a fraction of nanoparticles was inactive, and the thermal drift caused a slight distortion of the red structure. However, even the scale bar could be trustfully assembled. The expansion of this approach towards multicomponent structures is straightforward since there exist couplers with orthogonal affinities that can be linked to the transfer DNA. Whereas the assembly of planar nanoparticle structures of arbitrary design can easily be assembled this way, an expansion into the third dimension appears challenging but achievable. 

Preparation and Nanoparticle Structure of Epitaxial Thin Film Model Catalysts... 

Magg N, Giorgi J, Frank M, Immaraprom B, Schroeder T, Baumer M, et al. (2004). Alumina-supported vanadium nanoparticles structural characterization and CO adsorption properties. 

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