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Bulk gold

Figure C2.17.13. A model calculation of the optical absorjDtion of gold nanocrystals. The fonnalism outlined in the text is used to calculate the absorjDtion cross section of bulk gold (solid curve) and of gold nanoparticles of 3 mn (long dashes), 2 mn (short dashes) and 1 mn (dots) radius. The bulk dielectric properties are obtained from a cubic spline fit to the data of [237]. The small blue shift and substantial broadening which result from the mean free path limitation are... Figure C2.17.13. A model calculation of the optical absorjDtion of gold nanocrystals. The fonnalism outlined in the text is used to calculate the absorjDtion cross section of bulk gold (solid curve) and of gold nanoparticles of 3 mn (long dashes), 2 mn (short dashes) and 1 mn (dots) radius. The bulk dielectric properties are obtained from a cubic spline fit to the data of [237]. The small blue shift and substantial broadening which result from the mean free path limitation are...
Although bulk gold is poorly active as a catalyst, gold NPs attached to a variety of support materials exhibit unique catalytic properties in oxidation. The general features can be summarized as follows. [Pg.68]

Table 1. Isomer shifts (IS) and quadmpole splitting (QS) of Au55(PPh3)i2Cl6 and of bulk gold. Table 1. Isomer shifts (IS) and quadmpole splitting (QS) of Au55(PPh3)i2Cl6 and of bulk gold.
Figure 9 [171] shows the Au 4f emission of the nanoparticles at different steps of the sputtering. The as-cleaned spectrum (curve (a)) is equivalent to the published data of bulk gold. The Au/Si ratio was around 3.3, showing that the gold film was discontinuous. With further ion bombardment, the position of the 4f emission shifted to... [Pg.95]

Figure 2 shows a representative XANES spectrum from a bulk gold sample (a 1 pm gold film) and a representative spectrum of gold reacted with oat biomass. [Pg.404]

The results indicated that the reaction time of 1 h was insufficient for the total reduction of gold. Figure 3 shows the Fourier transformed EXAFS of both a bulk gold(O) sample and nanoparticles produced by the reduction of tetrachloroaurate by oat biomass. [Pg.405]

Figure 2. Representative XANES of gold nanoparticles from an oat sample reacted with tetrachloroaurate for 24 h and a bulk gold sample recorded from a 1 pm gold film. Figure 2. Representative XANES of gold nanoparticles from an oat sample reacted with tetrachloroaurate for 24 h and a bulk gold sample recorded from a 1 pm gold film.
Liu YC, Kin LH, Chiu WH (2004) Size-controlled synthesis of gold nanoparticles from bulk gold substrates by sonoelectrochemical methods. J Phys Chem B 108 19237-19240... [Pg.129]

The elusive nature of binary gold carbonyls - known only from earlier matrix-isolation studies and from CO adsorbed on surfaces of bulk gold - has prompted quantum-chemical studies of the hypothetical species Au(CO) with n = 1, 2, 3. Two independent investigations (on the HF and ab initio level, MP2, CCSD(T)) have consistently... [Pg.297]

Another study compared the bulk gold electrode to Nafion coated gold electrodes using RRDE in 0.5 M H2S04. There were no significant differences observed in the reaction pathway or kinetics of ORR on the electrodes.213... [Pg.356]

Figure 10.21 Heats of adsorption for CO on (A) 0.5 ML Au/Ti02, (B) 0.25 ML Au/Ti02, and (C) 0.125 ML Au/Ti02. For comparison, the heat of adsorption of CO on bulk gold at the zero coverage limit is 10.9 kcal/mol. (Reprinted from Meier, D.C. and Goodman, D.W., J. Am. Chem. Soc., 126, 1892-1899, 2004. Copyright 2004. With permission from American Chemical Society.)... Figure 10.21 Heats of adsorption for CO on (A) 0.5 ML Au/Ti02, (B) 0.25 ML Au/Ti02, and (C) 0.125 ML Au/Ti02. For comparison, the heat of adsorption of CO on bulk gold at the zero coverage limit is 10.9 kcal/mol. (Reprinted from Meier, D.C. and Goodman, D.W., J. Am. Chem. Soc., 126, 1892-1899, 2004. Copyright 2004. With permission from American Chemical Society.)...
Synthesis of novel materials with desired and tunable physical and chemical properties continues to draw wide interest. Nanomaterials with a variety of shapes and sizes have been synthesized as they offer numerous possibilities to study size and shape-dependent variations of electronic, optical, and chemical properties. Nanomaterials of a particular element show drastic differences in physical and chemical properties when compared with the bulk state. For example, bulk gold, a metal that is insoluble in water can be made dispersible when it is in the nanoparticle form. There are drastic changes in the optical properties as well. Bulk gold appears yellow in color, but when it is in the nanoparticle form with an average core diameter of 16 nm, it appears wine red. Likewise, the chemistry of gold, such as catalysis, also shows a drastic change when the constituent units are in the nanometer range. [Pg.334]

To determine the phase properties of the calcined bimetallic nanoparticles, a detailed x-ray diffraction (XRD) study was carried out. The XRD data of AuPt/C showed that the diffraction patterns for the carbon-supported nanoparticles show a series of broad Bragg peaks, a picture typical for materials of limited structural coherence. Nevertheless, the peaks are defined well enough to allow a definitive phase identification and structural characterization. The diffraction patterns of Au/C and Pt/C could be unambiguously indexed into an fcc-type cubic lattice occurring with bulk gold and platinum. We estimated the corresponding lattice parameters by carefully determining... [Pg.294]


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See also in sourсe #XX -- [ Pg.21 , Pg.391 ]




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Color of bulk gold

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