Ellipsometric data

Figura 3 Common structure assumed for ellipsometric data analysis and are the...

The two predominant features in Figure 3.24 are attributable to the 4f orbitals of the Pt electrode. The two peaks were deconvoluted as shown into a main peak and a smaller satellite peak. At potentials > 0.7 V vs. SCE, a peak at 77.1 eV was observed which was attributed to PtO. On the basis of these results, those of Kim et ai (1971), and the coulometric and ellipsometric data discussed above, Augustynski and Balsenc (1979) proposed that the signal attributed to the Pt 4f orbitals shifted via formation of PtO was only observed after the formation of the phase oxide, since it is only after this place exchange that the chemical environment of the Pt atoms is modified... 

The combination of the electrochemical and ellipsometric data has led to the conclusion that Au oxides are composed of two layers the inner film a and the outer... 

Fig. 12. 53. Experimental coverage-potential relation for n-valeraldehyde on platinum as a function of electrode potential. Two things should be noted First, adsorption-potential plots are roughly parabolic. Second, there is medium-good agreement between two entirely different methods, one based on the interpretation of ellipsometric data and the other on FTIR measurements. (Reprinted from J. O M. Bockris and K. T. Jeng, J. Electroanal-chem. 330 553, copyright 1992, with permission from Elsevier Science.)...

Ellipsometry. Layer thickness of GPS, PS, FPS and FSI on the flat silica wafers was evaluated at k = 633 nm and an angle of incidence of 70° with a SENTECH SE-402 microfocus null ellipsometer (lateral resolution is defined by the beam spot of about 20 pm). The measurements were performed for each sample after each step of modification to use the data of the previous step as a reference for the simulation of ellipsometric data. Initially, the thickness of the native SiC>2 layer (usually 1.4 0.2nm) is calculated at refractive indices n = 3.858 — iO.Ol8 and n = 1.4598... 

The experimental aim is to derive from ellipsometric data the tensor e ... 

An optical three-layer model has proved superior to a one-layer model for the interpretation of the ellipsometric data. The refractive indices of the film and surface layers are determined and it is found that the index for the surface is higher than that for the film core. A Lorenz-Lorentz type treatment of NBF reveals that there are approximately seven water molecules per molecule of surfactants in both NaDoS and NaDoBS films. The optical data obtained by the three-layer model for NBF from NaDoS indicate that the thickness of the aqueous core is zero while that of the adsorption monolayers of surfactant molecules with refractive index 1.365 is 1.8 nm, i.e. the thickness of NBF is 3.6 nm. 

Ellipsometric data are usually interpreted in terms of one equivalent homogeneous film with a refractive index n and an ellipsometric thickness d . This homogeneous layer is defined as a layer that gives the same reflected intensity and phase shift as the actual polymer layer with a z-dependent concentration. The parameters n " and can be extracted from the experimental data using the Drude equations (sec. 1.7.10b) usually, a numerical iteration is required. 

Fig. 21 Profiles of a surface-attached weak polyacid brush as obtained from FT analysis of ellipsometric data at different pH. The pH is given in the figure. Analysis of the same ellipsometric data by Fresnel modeling. Best fits to complementary error functions at different pH given in the figure. For more details see text...

Fig. 22 Swollen thickness of a polymethacrylic acid brush attached to a planar lanthanum oxide surface as a function of the pH of the solution. The thickness is determined by FT analysis (closed symbols) and by Fresnel modeling (open symbols) of ellipsometric data. For details see text...

Standard Si wafers (n-Si (100), 0 5 cm, resistance 0.5 Q cm, surface roughness 3 nm) were used for preparation of hybrid structures. Cleaned Si wafers were immersed for 4 min into 1% APTES (3-aminopropy 1-triethoxy silane) solution in toluene at 60°C. According to ellipsometric data, the thickness of APTES layer was 10 nm. The hybrid samples were prepared by deposition of DNA and Ag nanoparticles from solution on Si substrates with modified surface. Ag nanoparticles (0 5 nm) were covered by polyvynilpropylene (PVP). 

Figure 2. (a) Ellipsometric data for multilayer composites of 1-1-1-. .. grown on a planar Si wafer, (b) Ellipsometric data for ZrP-2 multilayer films deposited with (circles) and without (squares) ad d electrolyte. The average thicknesses are 38 and 7 A, respectively. 

A under these conditions. The equivalent thickness of the top and interfacial layers as a function of ion bombardment energy are also shown in Fig. 41, bottom. The results of XPS measurements agree fairly well with the ellipsometric data. Surface films are all too common in electrochemical engineering, especially in corrosion. 

NiFe)S0jj 6H20 by xray diffraction. The two types of measurement can be compared by using published density and refractive index. We believe that the discrepancy between the two may be an error in the ellipsometry due to the serious roughening of the surface. In our experience atmospheric corrosion almost always leads to sufficient roughening to affect ellipsometric data. This roughening must be taken into account in any model of the corrosion process. 

A model of flocculent and dripless adsorptive layers also is good agreed with the experimental ellipsometric data on kinetics of adsorption of different upon nature and length polymieric chains and also on number and distribution in them of the functional groups [19-23], It is follows from these references that the kinetic curves of adsorption of the polymeric chains Ifom the diluted solutions consist of two sections the first is starting - quick and short with the characteristic time by 10 s order and the second one (final) - slow and long with the characteristic time... 

Although the optical properties of the adsorbed layer by evaluation of the ellipsometric data obtained are quite interesting for its characterization, for inter-facial science the information about the amount adsorbed at an interface is especially important. In the calculation of this quantity, however, the problem appears to be of a proper proportionality between the layer properties provided by ellipsometry and the adsorbed amount. Recently, it was shown that for ultrathin adsorbed layers of conventional soluble surfactants ellipsometry is insufficient and additional experimental methods are required (245,250). Relatively thick layers are also often not homogeneous in the bulk (substrate) normal to the interface. In this case the refractive index and the thickness of the layer calculated from the experimental values of 8 A and 8 A represent mean optical quantities. If, additionally, the relractive index n is a linear function of the solute concentration in the layer ... 

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