Deposition procedure

Fig. 7. Susceptibility of the pristine sample (+) and of the K-doped sample (closed circle). The open circle points correspond to the susceptibility of the K-imercalated powder before the film deposition procedure [35].

The deposition procedure described earlier allows one to obtain protein films chemically bound to the activated surface of spherical glass particles. Subsequent compression of preformed protein monolayer with these particles permitted to coverage of the particle area that initially has not come in contact with the monolayer, as schematically shown in Figure 14. Even if such a procedure does not initially result in deposition of strictly one monolayer, this fact does not seem to be critical, because only the monolayer chemically attached to the surface remains after washing. 

From the results of the urease activity test summarized in Figure 15, it is clear that the deposition procedure preserved to a certain extent the enzyme catalytic activity. Heating the sample before testing decreased the enzyme in the film by about 30% but did not eliminate it completely. The results of the activity test of two samples are summarized in Table 1 together with reference values for a spontaneous reaction without enzyme. It is necessary to underline that enzymatic activity on spherical supports was higher than the respective value in flat films, which could indicate that apparent catalytic efficiency was improved due to an increased area-to-volume ratio. 

Tolstoy, V. P. 1997. The peroxide route of the successive ionic layer deposition procedure for synthesizing nanolayers of metal oxides, hydroxides and peroxides. Thin Solid Films 307 10-13. 

The hetero Y-type layers were prepared by an alternating deposition of compound C180AZ0SN and arachidic add ( surface pressure = 25 mNm1 for C180AZ0SN and 30 mNm 1 for arachidic add, and subphase was 10 M aq. cadmium chloride solution). For the preparation of the Z-type layers, the monolayers of C180AZ0SN were deposited only during withdrawing substrates. The Y-type layers were prepared by the ordinary deposition procedure. 

The feasibility of the fabrication of comb like fluorocarbonpolymer LB films has been shown. These films can be deposited onto different kinds of substrates as y-type layers by the usual LB technique. In this case the deposition procedure is much simpler than the one for polyimide LB films, but the temperature, chemical and mechanical stability, and dielectricproperties of the fluorocarbonpolymers are not inferior to those of polyimides. The fluorocarbons are more hydrophobic than ordinary hydrocarbons, hence shorter hydrophobic chains can be used and thinner monolayers can be prepared (the PFHA-AA LB monolayer thickness investigated was 16.5 x l(L8cm). 

In what follows we delineate details of an actual (6) deposition procedure for producing, for example, Ni-Cu multilayers as a practical example. As with previous methods, artificially layered deposits may be obtained from a single chemical solution... 

In particular cases, autocatalytic processes take place involving mainly active surface species or sites generated by the deposition procedure. As a conse-... 

The study in Ref. 74 followed essentially the same deposition procedure as before, but on Cr-plated steel (compared with steel in the previous studies see Sec. 9.2.1 for an explanation of the effect of Cr plating based on the poor electro-catalytic activity of Cr) and with a CuCliKCN etch at 90°C (the reason for this specific etch was not explained). These modifications led to improved PEC response, which was further improved using As-doped CdS, deposited by adding AsCE to the deposition bath. 

The main differences in the deposition procedure between the study in Ref. 80 and the previous study are the somewhat lower temperature, the (almost certainly) lower pH (while not given the previous deposition, using ammonia, was probably carried out at a minimum pH of 10), and the lack of ammonia in this study. 

Deposition Procedures. A schematic of a typical growth sequence is shown in Figure 6. After baking the system (step a), the system temperature is adjusted for growth and the substrate is brought into contact with the melt in the first bin (step b). In normal LPE practice, supersaturation of the liquid solution is achieved by temperature adjustment. The initial temperature can be set above, at, or below the liquidus value. If meltback is desired, a small increase in temperature above saturation is fixed first. The subsequent rate of etching decreases with time as the composition locally adjusts towards the equilibrium value. 

Screen-printed electrodes used for the PB modification were home produced. A detailed description of the electrodes used and of the procedure adopted for PB modification is found in Procedure 17 (in CD accompanying this book). The most important thing to note about this procedure is that it does not involve any electrochemical step and, for this reason, it has been designed as chemical deposition . This procedure is also very easy to perform and could be adapted to mass production of modified electrodes (see Procedure 17 in CD accompanying this book). The suitability of the proposed deposition procedure was carefully evaluated with different electrochemical techniques and its application in real samples has been summarised and discussed here. 

Verify the effectiveness of the PB deposition procedure onto the SPEs by cycling the modified electrodes from —0.05 to 0.3V. Figure. 17.1 shows the voltammograms of the classic PB-modified SPE obtained in phosphate buffer solution+0.1 mol 1 1 KC1. The typical two pairs of redox waves showing the oxidation as well as the reduction of PB are present. 

Both these parameters could be used in order to evaluate the deposition of PB and for statistical evaluation of the reproducibility of the deposition procedure. 

Several other sample preparation methods were developed to simplify the solution-deposition procedures. For example, Cooks and coworkers studied adduct ion formation (cationization) of several organic compounds when the organic was burnished (rubbed) onto a metal foil, mixed with a metal salt and then burnished onto a metal foil, or just mixed with metal powders or salts and pressed into pellets. Not only did the SIMS spectra show dramatic differences is the efficiency of adduct ion formation for different metals, but the sample preparation methods had an equally dramatic effect on the SIMS spectra [18]. 

Although several metal-containing heterocyclic compounds (such as porphyrins, phthalocyanines, naphthenates) are present in oil fractions most of the bench-scale research has been based on relatively rapid Ni, V, or Ni/V deposition procedures in which experimental FCC formulations have been artificially metal contaminated with solutions of Ni and/or V naphthenate dissolved in benzene (or toluene) (24). Metal levels in these novel FCC are usually above 0.5% that is well above the concentration that today exist on equilibrium FCC, see Figure 1. High metal concentration facilitate the study and characterization of Ni and V effects by modern characterization techniques such as X-ray photoelectron spectroscopy (XPS), Laser Raman spectroscopy (LRS), X-ray diffraction (XRD), electron microscopy, secondary ion mass spectrometry (SIMS), and 51V nuclear magnetic resonance (NMR). 

A problem with monofunctional reactions, e.g., cracking, alkylation, etc. is that they have a tendency to quickly deactivate because of coke deposition. This problem is usually not of concern with bifunctional reactions, e.g., those that employ a metal function in addition to the acid sites. However, we avoided the use of metal function because of the possible unknown modifications that could be introduced to a given sample by the metal deposition procedure. This is especially important when dealing with samples like VPI-5. Thus, to minimize the rate of deactivation, the alkylation experiments were conducted at 463 K. This low temperature introduces another problem, namely, the adsorption of reactants and products. At the experimental conditions employed here, the catalyst bed becomes saturated at time of 10 minutes or less (depending on sample). From this point onward, deactivation is clearly observable via the decrease in conversion with time. The data reported here were obtained at 11-13 minutes on-line. Since meta-diisopropylbenzene proceeds through several reaction pathways that lead to a number of products, it is most appropriate to compare the catalytic data at the constant level of conversion. Here we report selectivities at approximately 25 % conversion. For each catalyst, the results near 25 % conversion were repeated three times to ensure reproducibility. 

The deposition procedure is illustrated schematically in Scheme 13.3. It relies upon the difference in solubility between the reduced (uncharged) and oxidized (positively charged) forms of the polymer in dichloromethane solutions containing a tetraalkylammonium salt, such as tetraethylammon-ium tetrafluoroborate (TEAT). Upon the application of a potential step to 0.7 V (SCE), PVF0 is oxidized to PVF+, which deposits upon the... 

In the course of impregnation, the support is contacted with a solution of TMC, and the excess solution is then evaporated. The weakness of the interaction in this deposition procedure usually leads after activation to metal particles with sizes larger than 4—5 nm. 

One of the most salient advantages of thermal vacuum evaporation is that it enables fabrication of multilayer devices in which the thickness of each layer can be controled easily, in contrast to spin coating (see below). In addition, 2-dimensional combinatorial arrays of OLEDs, in which two parameters (e.g., the thickness or composition of two of the layers) may be varied systematically across the array, can be relatively easily fabricated in a single deposition procedure.50,12 This combinatorial fabrication greatly enhances the efficiency of systematic device fabrication aimed at optimizing the various parameters. 

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