Colloid silver

Yu N-T, Nie S and Lipscomb L 1990 Surface-enhanced hyper-Raman spectrosocpy with a picosecond laser. New vibrational information for non-centrosymmetric carbocyanine molecules adsorbed on colloidal silver J. Raman Spectrosc. 21 797-802... 

Rearrangement of the diazo ketone, with loss of nitrogen, in the presence of suitable reagents and a catalyst (colloidal silver, silver oxide, or silver nitrate in the presence of ammonia solution). An acid is formed In the presence of water, an amide results when ammonia or an amine is used, and an ester is produced in the presence of an alcohol ... 

Collimation Collimators (+)-CoUinusin S. collinus Tb 365 Colloidal particles Colloidal silica Colloidal silver Colloidal state Colloidal sulfur Colloid mills Colloids... 

The elements are obtainable in a state of very high purity but some of their physical properties are nonetheless variable because of their dependence on mechanical history. Their colours (Cu reddish, Ag white and Au yellow) and sheen are so characteristic that the names of the metals are used to describe them. Gold can also be obtained in red, blue and violet colloidal forms by the addition of vtirious reducing agents to very dilute aqueous solutions of gold(III) chloride. A remarkably stable example is the Purple of Cassius , obtained by using SnCla as reductant, which not only provides a sensitive test for Au but is also used to colour glass and ceramics. Colloidal silver and copper are also obtainable but are less stable. 

Silber-rhodanid, n. silver thiocyanate, -solbe, /. Pharm.) colloid silver ointment, -salpeter, m. silver nitrate, -salz, n. silver salt, -sau, /. silver ingot, -scfaaum, m. silver in thin leaves, or an imitation of it. -scheidtmg, /. separation of silver silver refining, -schein,... 

Silver chloranilate cannot be used in the determination because it produces colloidal silver chloride. 

They do not occur in homogeneous solution, as two radicals encountering each other dimerize or disproportionate. However, the formation of by short-lived radicals can be catalysed by colloidal metals The most detailed investigation has been carried out with colloidal silver Figure 1 shows the mechanism in a... 

Silver/Colloidal Silver (Ag+). Silver has a slow inhibiting effect on bacterial and algicidal growth. It is a very expensive treatment and certainly not cost effective. If the silver or colloidal silver is not stabilized, it is not compatible with quats and polyquats. It will react with the chlorides of the quats. 

SERS can be used to characterise ng and pg amounts of solutes on colloidal silver-treated HPTLC plates using... 

Colloidal dispersion 1.0 nm-1.0 pm Particles not resolved by ordinary microscope but visible by electron microscopy pass through filter paper but not semipermeable membranes generally slow diffusion Colloidal silver sols, surfactant micelles in an aqueous phase, aqueous latices and pseudolatices... 

Nagata Y, Watanabe Y, Lujita S, Dohmaru T, Taniguchi S (1992) Lormation of colloidal silver in water by ultrasonic irradiation. J Chem Soc Chem Commun 1620-1622... 

Yonezawa Y, Sato T, Kuroda S, Kuge KJ (1991) Photochemical formation of colloidal silver peptizing action of acetone ketyl radical. J Chem Soc Faraday Trans 87 1905-1910... 

Lynne K, Maritza G, Arnim H (1996) Bimetallic colloids Silver and Mercury. J Phys Chem 100(27) 11203-11206... 

Violence of reaction depends on concentration of acid and scale and proportion of reactants. The following observations were made with additions to 2-3 drops of ca. 90% acid. Nickel powder, becomes violent mercury, colloidal silver and thallium powder readily cause explosions zinc powder causes a violent explosion immediately. Iron powder is ineffective alone, but a trace of manganese dioxide promotes deflagration. Barium peroxide, copper(I) oxide, impure chromium trioxide, iridium dioxide, lead dioxide, manganese dioxide and vanadium pentoxide all cause violent decomposition, sometimes accelerating to explosion. Lead(II) oxide, lead(II),(IV) oxide and sodium peroxide all cause an immediate violent explosion. 

Hildebrandt P., Stockburger M., Surface-enhanced resonance Raman-spectroscopy of rhodamine-6G adsorbed on colloidal silver, J. Phys. Chem. 1984 88 5935-5944. 

K. Kneipp, A. Jorio, H. Kneipp, S.D.M. Brown, K. Shafer, J. Motz, R. Saito, G. Dresselhaus, and M.S. Dresslhaus, Polarization effects in surface-enhanced resonant Raman scattering of single-wall carbon nanotubes on colloidal silver clusters. Phys. Rev. B 63, 081401.1-081401.4 (2001). 

The purple colour is caused by colloidal silver, formed in a similar manner to the image on a black-and-white photograph after For this reason, an SSCE should be remade fairly frequently. (We in Chapter 10.)... 

Duff, D.G. et al., The microstructure of colloidal silver evidence for a polytetrahedral growth sequence, J. Chem. Soc. Chem. Commun., 1264, 1987. 

Since we could not prepare a stable solution of the ester, we attempted its preparation in the styrene solution to be polymerised. Silver perchlorate was dissolved in this and the reaction was started by the crushing of a phial containing 1-phenylethyl bromide (under our conditions styrene was not polymerised by the silver perchlorate alone). The solutions became cloudy because of the formation of colloidal silver bromide, but no colour formation could be observed until the end of the polymerisation then the solutions became yellow, very like the reaction mixtures in which perchloric acid had been used as catalyst. The ester was found to be as effective a catalyst as anhydrous perchloric acid. Equal concentrations of the ester and the acid produced very similar polymerisations as shown in the Figure. The accelerating parts of the curves obtained with the ester as catalyst are readily explained by the fact that the reaction between silver perchlorate and 1-phenylethyl bromide is not instantaneous and therefore a steady increase in catalyst concentration characterises the first part of the polymerisation. 

Henglein A, Tausch-Treml R (1981) Optical absorption and catalytic activity of subcolloidal and colloidal silver in aqueous solution a pulse radiolysis study. J Colloid Interface Sci 80 84-93... 

Silver paint A conductive material comprising colloidal silver suspended in a polymeric base, which is liquid when applied to form an electrical contact, but then sets rapidly to form a hard and highly conductive contact. The material is commonly applied with a brush, hence the term paint . 

Figure 1 shows experimental reaction curves obtained in the absence of added catalyst and in the presence of various colloidal catalysts. The reaction has a pronounced induction period in the absence of added catalyst, and the curve shows the typical shape expected for an auto-catalytic reaction. Addition of colloidal silver, gold, palladium, and silver sulfide markedly decrease the magnitude of the induction period. 

In the oxidation of hydroxylamine by silver salts and mercurous salts, the nature of the reaction product apparently depends upon the extent to which catalysis participates in the total reaction. This is illustrated by some results obtained with mercurous nitrate as oxidizing agent. The reaction is strongly catalyzed by colloidal silver, and is likewise catalyzed by mercury. The reaction of 0.005 M mercurous nitrate with 0.04 M hydroxylamine at pH 4.85 proceeds rapidly without induction period. The mercury formed collects at the bottom of the vessel in the form of globules when no protective colloid is present, so the surface available for catalysis is small. Under these conditions the yield is largely nitrous oxide. Addition of colloidal silver accelerates the reaction and increases the yield of nitrogen. Some data are given in Table III. 

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