X deposition

Foresti ML, Milan S, LogUo F, Innocent M, Pezzatini G, Cattarin S (2005) Ternary CdSj Sei.x deposited on Ag(lll) by ECALE Synthesis and characterization. Langmuir 21 6900-6907... 

The actual deposition process can be visualised as taking place in the manner shown in Figure 4.1. Here it is supposed that, on the upward stroke, hydrophilic interaction is responsible for adhesion and that, on the downward stroke, hydrophobic interaction is responsible for adhesion. The deposition ratio is defined as the ratio of the area of film deposited to the change in area at the air/water interface corresponding to this deposition. If the deposition is very near unity, it is assumed that perfect deposition has taken place. If the deposition ratio is near unity for both upward and downward strokes, the material is said to be deposited in the Y mode. If this ratio is near unity on the up stroke and near zero on the down stroke, the deposition is said to be in the Z mode and the converse situation is said to lead to deposition in the X mode. A simplistic interpretation of Z and X deposition would lead one to suppose that such deposition would lead to a non-centrosymmetric structure. In some cases this is indeed true but, in many cases, there appears to be some kind of rearrangement after deposition so that apparent X or Z deposition leads to a structure similar to that which one would achieve with Y deposition and a structure of regular bilayers is produced. 

Other deposition modes were observed as well, namely X-deposition, when the film transfer occurs only at downstrokes [39], and Z-deposition, when the film transfer occurs only at upstrokes [6]. X- or Z-mode deposition occurs more commonly in the films consisting of amphiphilic molecules where either the head group is only weakly polar (such as ester) or the terminal group of the hydrophobic tail is not a methyl. 

Table X. Deposit Mass and Relative Build-Up Rates for the Decker Samples at a Furnace Temperatrue of 1500 5°C (Deposition Zone Gas...

M. Chmielowska, A. Kopia, C. Leroux, S. Saitzek, J. Kusinski, J.R. Gavarri, Structural and catalytic properties of thin films of CuOx-Ce02-x deposited by laser ablation, Funct. Nanomater. Optoelectronics Other Appl. 99-100 (2004) 235. 

Ou et al. [179] reported on the successful fabrication of X-deposited multilayer films using the Langmuir-Schaefer deposition technique [187]. They used a polysiloxane copolymer containing both a mesogenic and an NLO side chain (30). 

Madey and co-workers followed the reduction of titanium with XPS during the deposition of metal overlayers on TiOi [87]. This shows the reduction of surface TiOj molecules on adsorption of reactive metals. Film growth is readily monitored by the disappearance of the XPS signal from the underlying surface [88, 89]. This approach can be applied to polymer surfaces [90] and to determine the thickness of polymer layers on metals [91]. Because it is often used for chemical analysis, the method is sometimes referred to as electron spectroscopy for chemical analysis (ESCA). Since x-rays are very penetrating, a grazing incidence angle is often used to emphasize the contribution from the surface atoms. 

Figure Bl.19.32. AFM image of Blue Seript II plasmid (400 mu x 400 mu) in propanol, taken with super tip , prepared by earbon deposition on nomral tip in SEM, followed by ion milling. (Taken from [152], figure 1.)...

Figure Bl.22.1. Reflection-absorption IR spectra (RAIRS) from palladium flat surfaces in the presence of a 1 X 10 Torr 1 1 NO CO mixture at 200 K. Data are shown here for tluee different surfaces, namely, for Pd (100) (bottom) and Pd(l 11) (middle) single crystals and for palladium particles (about 500 A m diameter) deposited on a 100 A diick Si02 film grown on top of a Mo(l 10) single crystal. These experiments illustrate how RAIRS titration experiments can be used for the identification of specific surface sites in supported catalysts. On Pd(lOO) CO and NO each adsorbs on twofold sites, as indicated by their stretching bands at about 1970 and 1670 cm, respectively. On Pd(l 11), on the other hand, the main IR peaks are seen around 1745 for NO (on-top adsorption) and about 1915 for CO (tlueefold coordination). Using those two spectra as references, the data from the supported Pd system can be analysed to obtain estimates of the relative fractions of (100) and (111) planes exposed in the metal particles [26].

Success of depositing compounds where an 18-carbon chain was attached to one end of an azobenzene group and various different hydrophilic groups attached to the other end has been reported in X and Z mode [52] and piezo-and pyroelectric effects were demonstrated. 

Figure C2.10.5. Magnitude of the Fourier transfonn of tire /c-weighted absorjDtion fine stmcture k (/c) measured at tire Cu K edge for tire underiDotential deposition of Cu/Au(l 11) from 0.1 M KCIO +IO M HCIO +S x 10 M Cu (010 )2+10 M potassium salt of sulfate, chloride, bromide and a mixture of sulfate and chloride, for polarization of tire x-rays parallel to tire sample surface ( ) or parallel to tire surface nonnal (E (from [81]).

Tidsweii i M, Lucas C A, Markovic N M and Ross P N 1995 Surface structure determination using anomaious x-ray scattering Underpotentiai deposition of copper on Pt(111) Phys. Rev. B 51 10 205-8... 

Li J and Abruna FI D 1997 Coadsorption of sulphate/bisulphate anions with Fig cations during Fig underpotential deposition on Au (111) An In situ x-ray diffraction study J. Phys. Chem. B 101 244-52... 

Page 1170 (Figure 28 5) is adapted from crystallographic coordinates deposited with the Protein Data Bank PDB ID IDDN White A Ding X Vanderspek J C Murphy J R Ringe D Structure of the Metal Ion Activated Diphtheria Toxin Re pressor/Tox Operator Complex Nature 394 p 502 (1998)... 

The experiment we have just described is not very satisfactory from a practical point of view, since it is very difficult to deposit a thin layer of solution between two bulk portions of solvent without some mixing. An experimentally more convenient method consists of layering equal volumes of solvent and solution so that a sharp boundary exists between them at x = 0, with c = Cq for... 

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