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Mono- and multiparticulate nanostructured silica films were prepared by the Langmuir–Blodgett (LB) technique both from hydrophilic and hydrophobic Stober silica nanospheres of 92 and 107 nm diameters. The effective refractive index and the film thickness were determined from the transmission spectra (300–1200 nm) by evaluating interference peaks and parameter fitting. The spectra were notably different depending on particle sizes, number of layers transferred, and particle hydrophobicity. The monolayers showed expressed antireflection properties. From the film thickness values obtained for multiparticulate LB films we came to the conclusion that the particles arrange themselves in a close-packed array during the preparation of LB films.

The influence of calcium and zinc ions on the corrosion inhibition effect of 1‐hydroxyethane‐1,1‐diphosphonic acid (HEDP) on carbon steel has been investigated by electrochemical techniques, X‐ray photoelectron spectroscopy, and atomic force microscopy. Addition of calcium or zinc ions greatly increased the inhibition efficiency of HEDP in a synergistic manner. The highest inhibition effect was obtained for molar ratios of Ca/HEDP = 0.5 and Zn/HEDP = 3 for . The corrosion inhibition mechanism in the presence of these additives proved to be different from that with HEDP alone and was related to the formation of different complex species between HEDP and cation additives. The frequency response of the studied system was described by a transfer function containing two relaxation time constants corresponding to the charge‐transfer process and the porous oxide layer. Higher zinc and phosphorous content in the inhibitor layer and a continuous change in the O‒Fe and HO‒Fe ratio were achieved by increasing zinc concentration in the solution (in the range Zn/HEDP = 0.5–3) as supported by XPS measurements. Changes in the chemical structure were established in the oxide‐hydroxide layer developed spontaneously on the steel surface. The synergistic effect of inhibitor compounds appeared also in surface morphology, leading to the development of smooth, i.e., dense, protective layers as revealed by atomic force microscopy. © 1999 The Electrochemical Society. All rights reserved.

A possible sink for divalent lead in the environment is clays such as montmorillonite that have cation exchange capacities. To assess the reaction, a calcium–montmorillonite was mixed with lead perchlorate solutions of varying concentrations and at various pH's. The recovered solids were studied by a variety of techniques (X-ray photoelectron and infrared spectroscopy, scanning electron microscopy, and atomic force microscopy) to determine what, if any, alterations occurred. The ion exchange of lead for calcium reduced the hydrated water in the clay, and evidence for proton–lead ion exchange at the edges of the sheets was observed. Evidence for a second, unexpected, reaction was also observed. Small spots (0.2 to 1 μm) of lead enrichment were observed on the surface of clay particles. They were also observed on clays recovered from the sediment of a Hungarian lake. The results show that lead ions are adsorbed onto montmorillonite by two processes: cation exchange and nano- and microparticle production. Cation exchange leads to the even distribution of the ions, while the production of spots causes the enrichment of lead ions. The production of these particles is not expected from the thermodynamic properties of the solution and cannot be observed in the absence of clay.