Two-Layer Film

It is convenient to manage some processes of chemical technology (like liquid-phase extraction, as well as nitration and sulfonation of liquid hydrocarbons) in double hydrodynamic films. 

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One important constitnent of cell membranes is a class of molecules— the phosphohpids— that spontaneously form two-layer films in a... 

Very interesting behavior of incorporating anions can be observed when a multicomponent electrolyte is used for oxide formation. Here, anion antagonism or synergism can be observed, depending on the types of anions used. The antagonism of hydroxyl ions and acid anions has been observed in a number of cases. Konno et a/.181 have observed, in experiments on anodic alumina deterioration and hydration, that small amounts of phosphates and chromates inhibit oxide hydration by forming monolayer or two-layer films of adsorbed anions at the oxide surface. Abd-Rabbo et al.162 have observed preferential incorporation of phosphate anions from a mixture of phosphates and chromates. 

It was not until recently that Chen and Goodman probed the influence of the oxide support material on the intrinsic properties at the metal surface. By covering a titania support with one or two flat atomic layers of gold they eliminated, direct adsorbate-support interactions as well as particle size and shape effects. Their results definitively showed that the electronic properties at the metal surface changed due to charge transfer between the support and the metal. Furthermore, their comparison of one- and two-layer films highlighted the dependence of these effects on the thickness of the metal slab. 

Production of a two-layer film made out of copper phthalocyanine and a perylene tetracarboxylic derivative. A power conversion efficiency of about 1% has been achieved. 

Figure 4,5 Diagram of reflections from a two-layer film.

These SnS films (in one study, propylene glycol was used instead of acetone to dissolve the SnCli), coated with CD Cu S, were shown to possess spectral characteristics favorable for various solar control purposes [106,107]. Depending on the thicknesses of the two layers, films with varying absorption and reflection could be obtained that might be suitable for solar collectors or for window glazing. 

Example 13.4. The result of a typical X-ray measurement is shown in Fig. 13.10 for a galactocerebroside [605], The plot on the left side shows the normalized reflected X-ray beam intensity versus the incident angle a for two different film pressures. The pressure-area isotherm is shown in the inset, together with the points of measurement a and b. On the right side are the extracted electron density profiles normal to the film surface taken at the same film pressures. At 0 A we find the monolayer surface (top of the alkyl chains), a depth of -40 A corresponds to pure water. In between is the film. The measurement is so sensitive that we even find two different electron densities within the monolayer. This is illustrated by the dashed boxes denoted by film 1 and film 2 (shown for curve b only) which represents the simplified electron density distribution in the so-called two-box model. A box is defined as a part in the film of a certain thickness where the electron density is constant. In the two-box model the film is divided into two layers. Film 1 represents the hydrocarbon tails, film 2 corresponds to the mean electron density of the head groups. 

By our technology two-layer film is obtained, the lower semitransparent layer is inert to the etchant, dissolving the upper layer. 

The bicatalyst electrocatalytic reduction and oxidation of nitrite by Fe(ll) and Cu(ll) complexes constitutes another interesting achievement [13]. A two-layer film of iron(II) complex and Cu(II) complex adsorbed on a glassy carbon electrode was used to oxidize N02 to N03 through the iron(II/III) complex redox couple and to reduce nitrite to nitrous oxide through the copper(II/I) redox couple [13]. 

D. Abruna, P. Denisevich, M. Umana, T. J. Meyer, and R. W. Murray, Rectifying interfaces using two-layer films of electrochemically polymerized vinylpyridine and vinylbipyridine complexes of ruthenium and iron on electrodes, J.Am.Chem.Soc., 103 1 (1981). 

Further experiments on two layer films clearly show a sharp anomaly in the heat capacity behavior, suggesting that the SmBhex-SmA transition is not well described by the theory of defect-mediated... 

Free-standing liquid crystal films are unique model systems because they combine the properties of controlled size and a high uniformity in the SmA ordering [14]. In practice, utilizing appropriate liquid crystal materials, uniform films of two to a few thousand molecular layers in thickness can be easily prepared [3]. Since these films are substrate-free and stable down to only two layers in thickness, they provide an important and unique physical system to investigate the evolution from three dimensional (thick films) to two dimensional (two-layer films) behavior, the nature of two dimensional phenomena and the effect of free surfaces as well as reduced dimensionality. 

Figure 14.9 Effects of altering the speed of the moving mirror on the PA spectrum. Sample a two-layer film consisting of soft poly (vinyl chloride) (base) and poly (vinyl fluoride) (surface). Speed of the moving mirror in centimeter per second (a) 1.28, (b) 0.64, (c) 0.32, and (d) 0.16.

Blooming (archaic) A British term for depositing a thin film by vacuum evaporation. Example Double blooming means depositing a two-layer film. 

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