Gold sols, particle size

Creighton J.A., Blatchford C.B., Albrecht M.C., Plasma resonance enhancement of Raman-scattering by pyridine adsorbed on silver or gold sol particles of size comparable to the excitation wavelength, J. Chem. Soc. Faraday Trans. 1979 2 790-798. 

AP particles are of colloidal size and can be observed under an electron microscope. Figures 10, 11, and 12 show electron micrographs of AP from the solutions. X-ray diffraction work has indicated that this material (the hexagonal platelets) is gibbsite (8, 30). Also shown on the micrographs are gold sol particles (small, dark spheres and tetrahedrons). 

Bright red sol, particle size about 1-6 10 cm. Highly sensitive to electrolytes. Concentrated solutions p to 0.12% gold) may be obtained by dialysis. 

Roark D, Yphantis DA (1969) Ann New York Acad Sci 164 245 Rinde H (1928) The Distribuhon of the Sizes of Particles in Gold Sols Prepared According to the Nuclear Method. PhD Thesis, University of Uppsala, Uppsala, Sweden Harding SE (1988) Gums and Stabilisers for the Food Industry 4 15 http //www.wyatt.com/... 

After supporting these sols on activated carbon, however, the obtained particle size depends on the capability of the protective agent to maintain the particle dimension. The obtained three catalysts, having different characteristics, are summarized in Table 3. As it is shown, mean size of gold nanoparticle obtained by TEM measurement did not always match with X-ray powder diffraction (XRPD) data. This result is not surprising as TEM measurements represent particle sizes, whereas from X-ray diffraction (XRD) it is possible to obtain crystallite dimensions that do not necessarily coincide with the size of... 

As reported in the literature by Heard et al. [156], the colour of the gold sol depended strongly on the size of the particles. The blue sol corresponded to 20-30 nm elongated agglomerated particles whereas pink sols corresponded to <20 nm particle size. 

A review of preparative methods for metal sols (colloidal metal particles) suspended in solution is given. The problems involved with the preparation and stabilization of non-aqueous metal colloidal particles are noted. A new method is described for preparing non-aqueous metal sols based on the clustering of solvated metal atoms (from metal vaporization) in cold organic solvents. Gold-acetone colloidal solutions are discussed in detail, especially their preparation, control of particle size (2-9 nm), electrophoresis measurements, electron microscopy, GC-MS, resistivity, and related studies. Particle stabilization involves both electrostatic and steric mechanisms and these are discussed in comparison with aqueous systems. 

The shapes of the absorption band cease to be independent of size for particles smaller than about 26 A, which suggests that the bulk dielectric function is inapplicable. Indeed, the broadening and lowering of the absorption peak can be explained by invoking a reduced mean free path for conduction electrons (Section 12.1). Thus, the major features of surface modes in small metallic particles are exhibited by this experimental system of nearly spherical particles well isolated from one another. But when calculations and measurements with no arbitrary normalization are compared, some disagreement remains. Measurements of Doremus on the 100-A aqueous gold sol, which agree with those of Turkevich et al., are compared with his calculations in Fig. 12.18 the two sets of calculations are for optical constants obtained... 

Rinde, H., The Distribution of the Sizes of Particles in Gold Sols, Disserta-... 

---