ATR-FTIR

Adsorption phenomena from solutions onto sohd surfaces have been one of the important subjects in colloid and surface chemistry. Sophisticated application of adsorption has been demonstrated recently in the formation of self-assembhng monolayers and multilayers on various substrates [4,7], However, only a limited number of researchers have been devoted to the study of adsorption in binary hquid systems. The adsorption isotherm and colloidal stabihty measmement have been the main tools for these studies. The molecular level of characterization is needed to elucidate the phenomenon. We have employed the combination of smface forces measmement and Fomier transform infrared spectroscopy in attenuated total reflection (FTIR-ATR) to study the preferential (selective) adsorption of alcohol (methanol, ethanol, and propanol) onto glass surfaces from their binary mixtures with cyclohexane. Om studies have demonstrated the cluster formation of alcohol adsorbed on the surfaces and the long-range attraction associated with such adsorption. We may call these clusters macroclusters, because the thickness of the adsorbed alcohol layer is about 15 mn, which is quite large compared to the size of the alcohol. The following describes the results for the ethanol-cycohexane mixtures [10],... 

FIG. 4 FTIR-ATR spectra of ethanol on a silicon oxide surface in ethanol-cyclohexane binary liquids at various ethanol concentrations 0.0, 0.1, 0.3, 0.5, 1.0, and 2.0 mol%. 

Figure 9 (a) FTIR ATR image of silicone oil distribution in PA/PTFE blend. Top left ... 

Figure 13 FTIR ATR image of the polymer laminate (top left IR spectrum of COPA layer bottom left IR spectrum of EVA layer). The amide I absorption of COPA (top right) and the ester absorption of EVA (bottom right) were integrated (high intensities represented in bright color). An Intermediate region of ca. 5 pm (dimension bar) is assumed to be the LLDPE-MAH layer. Image area 50 pm x 50 pm.

Figure 57 FTIR-ATR spectrum acquired from the outer surface of the outer layer of catheter sample 1, Area A.

Figure 61 FTIR-ATR spectrum recorded from the outside surface of the inside layer of catheter sample 2, Area C.

Leppinen (1990) used FTIR-ATR techniques to study the adsorption of ethyl xanthate on pyrite, pyrrhotite and chalcopyrite. The FTIR spectra of the reaction products on pyrite, pyrrhotite and chalcopyrite after treatment with 1x10 mol/L KEX solution at pH = 5 is presented in Fig. 1.7. He found that the FTIR signals... 

In an early study, Mauritz et al. investigated anion—cation interactions within Nation sulfonate membranes versus degree of hydration using FTIR/ ATR and solid state NMR (SSNMR) spectroscopies. An understanding of the dynamic ionic—hydrate molecular structures within and between the sulfonate clusters is essential for a fundamental understanding of the action of these membranes in ion transport. This information can be directly related to the equilibrium water swelling that, in turn, influences molecular migration. 

Zhao and Brittain [280-282] reported the LCSIP of styrene on planar silicon wafers using surface modifications of 2-(4-(ll-triethoxysilylundecyl)phenyl-2-methoxy-propane or 2-(4-trichlorosilylphenyl)-2-methoxy-d3-propane respectively. Growth of PS brushes from these SAMs has been successfully achieved factors that influence PS thickness included solvent polarity, additives and TiC concentration. Sequential polymerization by monomer addition to the same silicate substrate bearing the Hving polymer chains resulted in thicker PS films. FTIR-ATR studies using a deuterated initiator indicated that the initiator efficiency is low, and the... 

An infrared spectrum is a plot of percent radiation absorbed versus the frequency of the incident radiation given in wavenumbers (cm ) or in wave length ( xm). A variation of this method, diffuse reflectance spectroscopy, is used for samples with poor transmittance, e.g. cubic hematite crystals. Increased resolution and sensitivity as well as more rapid collection of data is provided by Fourier-transform-IR (FTIR), which averages a large number of spectra. Another IR technique makes use of attenuated total reflectance FTIR (ATR-FTIR) often using a cylindrical internal reflectance cell (CIR) (e.g. Tejedor-Tejedor Anderson, 1986). ATR enables wet systems and adsorbing species to be studied in situ. 

Sivakesava, S., Irudayaraj, J., and DebRoy, C. (2004). Differentiation of microorganisms by FTIR-ATR and NIR spectroscopy. Trans. ASAE 47,951-957. 

Lastly, Polystyrene (PS) brushes on silicate substrates were grafted via carbocationic polymerization from self-assembled monolayer (SAM) initiators as reported by Brittain et al The carbocationic initiators, 2-(4-(ll-triethoxysilylundecyl))phenyl-2-methoxypropane and 2-(4-trichlorosilyl-phenyl)-2-methoxy-d3-propane, and their corresponding SAMs were prepared on various substrates. The monolayers were characterized by FTIR-ATR, contact angles, and X-ray reflectometry. The growth of the PS brushes from... 

Fig. 22. FTIR-ATR spectra on silicon taken after deposition of one, three, and six monolayers C195]...

TOF. see Time-of-flight Trans-Blot membranes, electroblotting and elution, 185-190, 193-197 trans fatty acid determination by FTIR-ATR, 505-511... 

Thus, a poly isobutylene coating on silver halide optical fiber was used for environmental analysis of chlorinated hydrocarbons in water in an instrument designed for operation in seawater 500 m under the surface (Fig. 9.27). The enrichment membrane concept can be used for FTIR-ATR analysis of liquid and gaseous samples alike. 

Optical methods are based on fluorescence probe-labeled aptamers (fluorescence intensity, fluorescence anisotropy), or label-free aptamers can be used for detection of analyte using SPR or Fourier transform infrared attenuated total reflection (FTIR-ATR). 

Another label-free optical detection method—FTIR-ATR—has been applied for detection of thrombin by means of DNA aptamers [73], The antithrombin DNA aptamer previously developed by Tasset et al. [17] was immobilized covalently onto Si surface using UV irradiation method. As a quantitative measure, the area of N-H and CH2 bands was used. This method allowed to detect thrombin with a sensitivity around 10 nmol/L. The specificity of binding of protein to aptamer was also investigated using DNA with no binding site for thrombin. It has been noted that for effective binding study by FTIR-ATR method, the concentration of protein should be kept lower than 100 nmol/L. 

Forensic/security analysis 874 Forest-spring encephalitis e265 Free radicals 418 Fructose 256 Fruits e280 FTIR-ATR 819, 821 Fuel cell catalysts 915 materials 932 Fullerenes 56-57, 68 Fusarium sp e303... 

Solomon, D., Lehmann, J., Kinyangi, J., Liang, B., and Schafer, T. (2005a). Carbon K-edge NEXAFS and FTIR-ATR spectroscopic investigation of organic carbon speciation in soils. Soil Sci. Soc. Am. I. 69,107-119. 

Figure 12.1 FTIR ATR spectrum of (A) anhydrous crystalline glucose and (B) hydrated amorphous glucose.

A typical set-up for a FTIR ATR experiment is described in Figure 1. A Brewster angle rotating Ge polarizer is place in the IR beam, in front of the C face of an ATR crystal, which can be made of Si, Ge, or ZnSe. A separate background spectra are recorded for the s- and p-polarization, and the crystal is used as a substrate either for LB or SA monolayer samples. 

We have used FTIR-ATR extensively to study SA monolayers (e.g., 1), and multilayers of alkyltrichlorosilanes (11, 39,40). Figure 8a presents the bulk (CC14 solution) IR spectrum of 1, while Figures 8b, and 8c, present the grazing angle and ATR spectra of a monolayer of 1 on aluminized silicon, and silicon ATR prism, respectively. 

Figure 3.6 FTIR-ATR spectra of (a) uncrosslinked 50/50 (w/w) CSM/XNBR blend, (b) self-crosslinked 50/50 (w/w) CSM/XNBR blend, (c) (b-a) difference spectrum...

---