Nanomaterials for Nanoscience and Nanotechnology part 10 pps

... with the size of the particle and the highest image inten- sity is approximately at a distance d =(R ± L) from the center of the particle. For very large particles, the particle contrast evolves ... < 1, the brightness of a particle increases with the size of the particle and the image intensity has a maximum at the center of the particle. If R/L > 1, the parti- cle intensity slow...

Ngày tải lên: 12/08/2014, 02:23

... metal nanoparticles: a) cubocta- hedron, formed by a fcc crystal truncated at (100 ) and (111) atomic planes; b) icosahedron and c) deca- hedron. b) and c) are known as Multiply-Twinned-Particles ... information about the particle size and exter- nal form is concentrated. No details of the internal atomic arrangements are con- tained in the small-angle intensity distribution (see [3,4...

Ngày tải lên: 12/08/2014, 02:23

... levels, bands are formed. An energy gap between the con- duction band and the valence band would be formed, which is a key factor in deter- Nanomaterials for Nanoscience and Nanotechnology 5 Part ... Poncharal, Z.L. Wang, D. Ugarte and W.A. de Heer, Science, 1999, 283, 1513. Nanomaterials for Nanoscience and Nanotechnology 11 1.1.9 Carbon fullerences and nanotubes...

Ngày tải lên: 12/08/2014, 02:23

... order in small particles. In the fol- lowing sections we describe the basic process and the special features of EXAFS experiments on nanoparticles, and illustrate these with a particular example. 2.4.2 ... between absorbing and neighbor atoms, and f(k) represents the total photoelectron phase-shift and depends on both photoabsorber and scattering atoms. A(k) is the backscattering...

Ngày tải lên: 12/08/2014, 02:23

... with a truncated octahedral shape and oriented along [ 110] , and (b) with a octahedral shape and oriented along [ 110] and [001]. The inset in (a) is a model of the particle shape. Figure 3-9. HRTEM ... higher surface energy. Facets tend to form on the particle surface to increase the portion of the low index planes. Therefore, for particles smaller than 10- 20 nm, the surface is...

Ngày tải lên: 12/08/2014, 02:23

... can be emitted from the valence band. The difference between Figures 3-23b and 3-23c is the emission of photon in the former and the Auger electron in the latter, and the two processes are complimentary. 62 ... material. Here, E f is the Fermi level, E b the binding energy, and C.B., V.B. and V.L. are the conduction-band minimum, valance- band maximum, and vacuum level, respective...

Ngày tải lên: 12/08/2014, 02:23

... overlapping discs. The numeral 2 stands for two- beam interference, 3 for three-beam interference, 4 for four-beam interference, and the letter D indi- cates detector positions for dark-field lattice imag- ing. The ... These instruments have a vacuum better than 10 10 torr throughout the whole microscope system and have elaborate auxiliary chambers for preparing, testing, an...

Ngày tải lên: 12/08/2014, 02:23

... of Nanoparticles 103 Figure 4-16. Intensity and radius data from particles in HAADF and SE images of silver nanoparticles plotted as (intensity) 1/3 against particle radius R. The HAADF and SE ... structure, and composition of metal parti- cles is of primary importance in understanding the synthesis-structure-activity rela- tionships and is essential for a qualitative and quan...

Ngày tải lên: 12/08/2014, 02:23

... indi- vidual nanoparticles 141]. This type of information is extremely important for under- standing the role of nanoparticles during catalytic reactions. Electron energy-loss images, formed by selecting ... pioneering work of MacDonald and Waldrop [122]. The driving force for developing high spatial resolution SAM is related to the characterization of nanoparticles and other nano- st...

Ngày tải lên: 12/08/2014, 02:23

... nanocrystals and emphasize how the struc- tures and the properties are characterized using the techniques presented in the book. Nanomaterials for Nanoscience and Nanotechnology 9 Figure 1-3. A small particle ... Z.L. Wang, D. Ugarte and W.A. de Heer, Science, 1999, 283, 1513. Nanomaterials for Nanoscience and Nanotechnology 11 3.2 High-resolution TEM lattice imaging...

Ngày tải lên: 04/06/2014, 15:19