Glucose induced in-situ reduction of chloroaurate ions entrapped in a fatty amine film: formation of gold nanoparticle-lipid composites

The formation of gold nanoparticle-lipid composite films by glucose-induced reduction of chloroaurate ions entrapped in thermally evaporated fatty amine films is described. Simple immersion of films of the salt of octadecylamine and chloroaurate ions (formed by immersion of thermally evaporated fatty amine films in chloroauric acid solution) in glucose solution leads to the facile in-situ reduction of the metal ions to form gold nanoparticles in the fatty amine matrix. The formation of gold nanoparticles is readily detected by the appearance of a violet color in the film and thus forms the basis of a possible new, gold nanoparticle-based colorimetric sensor for glucose. The formation of the fatty amine salt of chloroauric acid and the subsequent reduction of the metal ions by glucose has been followed by quartz crystal microgravimetry, Fourier transform infrared spectroscopy, X-ray photoemission spectroscopy and transmission electron microscopy measurements

Photoelectron spectroscopy study of surface oxidation of SnTe PbTe and PbSnTe

X-ray photoelectron spectroscopic measurements of the oxidation of SnTe, PbTe and Pb0.5Sn0.5Te surfaces in oxygen and air at different temperatures are reported. SnTe heated in oxygen atmosphere for a short duration showed rapid formation of SnO2. However, a sample heated in air for 2h. in the temperature interval 220-650° C showed the formation and gradual increase of TeO2 on the surface. On oxidation, the PbTe surface had a composition of PbO2, TeO2 and Te. The oxidation of Pb0.5Sn0.5Te is a superimposed oxidation behaviour of the two binary compounds PbTe and SnTe. In the Pb0.5Sn0.5Te system Sn is oxidised most quickly and tellurium behaves like the PbTe system. The experimental results are explained on the basis of heats of formation of the oxides of Sn, Pb and Te

Phase transfer of aqueous CdS nanoparticles by coordination with octadecanethiol molecules present in nonpolar organic solvents

The transfer of CdS nanoparticles of dimensions 60 Å synthesized in an aqueous environment into petroleum ether (pet ether) by coordination of the nanoparticles with octadecanethiol (ODT) molecules present in the organic phase is described. The phase transfer of the CdS nanoparticles into pet ether occurs extremely rapidly during vigorous stirring of the biphasic mixture (CdS-in-water/ODT-in-pet ether). Hydrophobization of the CdS nanoparticles due to surface coordination of ODT facilitates the phase transfer process. The hydrophobized CdS nanoparticles may be precipitated and redispersed in different nonpolar organic solvents without an apparent distortion in the particle size distribution. Close-packed CdS nanoparticle thin films were formed by immersion of suitable substrates in the organic solutions and evaporation of the organic component. The CdS nanoparticles have been characterized at different stages of the synthesis procedure using UV-vis spectroscopy, Fourier transform infrared (FTIR) spectroscopy, X-ray diffraction, thermogravimetry, X-ray photoemission spectroscopy (XPS), and contact angle measurements

Sequential electrostatic assembly of amine-derivatized gold and carboxylic acid-derivatized silver colloidal particles on glass substrates

The formation of alternating layers of positively charged gold and negatively charged silver colloidal particles on glass substrates via electrostatic interaction is described. The charging of the gold and silver colloidal particles is accomplished by self-assembly of 4-aminothiophenol (4-ATP) and 4-carboxythiophenol (4-CTP) monolayers on the colloidal particles respectively and subsequent ionization of the functional groups at appropriate pH values of the colloidal solution. Glass substrates, which are negatively charged at pH > 3, are immersed first in the positively charged amine-derivatized gold solution leading to the formation of a monolayer of the gold particles and charge reversal of the glass surface. Thereafter, the gold particle covered glass surface is immersed in the negatively charged carboxylic acid-derivatized colloidal silver solution and the silver particles electrostatically self-assembled on the glass surface. This process may be continued to yield multilayer structures of the colloidal particles. The kinetics of electrostatic self-assembly of the colloidal particles on glass, the formation of the multilayer films, and their thermal stability have been followed with UV-vis spectroscopy, X-ray diffraction, ellipsometry, and X-ray photoemission spectroscopy measurements

X-ray Photoelectron Spectroscopic Study of Surface Oxidation of Nickel Selenide

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X-ray photoemission investigation of electron beam reduction of lead<SUP>2+</SUP> in lead arachidate Langmuir-Blodgett films

This article does not have an abstract

Synthesis and characterization of dodecanethiol-capped cadmium sulfide nanoparticles in a winsor II microemulsion of diethyl ether/AOT/water

This article does not have an abstract

Mechanism of high-temperature oxidation of tin selenide

High-temperature oxidation of SnSe in the temperature interval 25 to 650° C has been studied by X-ray photoelectron spectroscopy, X-ray diffraction and thermal analysis techniques. Exposure to dry oxygen (760 torr pressure) at up to 200° C leads to the formation of SnO2 on the surface. The high-temperature bulk oxidation between 250 and 650° C goes through distinct steps of formation of intermediate tin oxoselenides, presumably SnOSe or SnSeO2 and its subsequent conversion to SnO2