Infrared reflection absorption spectroscopic studies

Szanyi J, Kuhn W K and Goodman D W 1994 CO oxidation on palladium 2. A combined kinetic-infrared reflection absorption spectroscopic study of Pd(IOO) J. Phys. Chem. 98 2978... 

Hoshi N, Bae IT, Scherson DA. 2000. In situ infrared reflection absorption spectroscopic studies of coadsorption of CO with underpotential-deposited lead on Pt(lll) in an aqueous acidic solution. J Phys Chem B 104 6049-6052. 

Beck et al. [250] conducted infrared reflection absorption spectroscopic studies on anodic over-oxidation of polypyrrole in the presence of nucleophiles such as II2O, OH", CH3OH, CHjO", Br" and CN". The formation of carbonyl groups occurred at the three-position and hydroxyl groups at the four-position via a di-cation intermediate in aqueous medium, but a bromine substitution at the four-position in the presence of Br nucleophile. Multi-methoxylation, similar to that reported in anodic oxidation of aromatics [256], occurred when the experiment was conducted in methanolic solution with 0.5 M KF as supporting electrolyte according to the following equations... 

X. Bin, Electrochemical and polarization modulation Fourier transform infrared reflection absorption spectroscopic studies of phospholipids bilayers on a Au(lll) electrode surface . PhD thesis, University of Guelph, 2005. 

Westermark, G. and Persson, 1. (1998) Chemisorption of tertiary phosphines on coinage and platinum group metal powders. An infrared reflectance absorption spectroscopic, enhanced Raman spectroscopic and surface coverage study. Colloids and Surfaces A -Physicochemical and Engineering Aspects, 144, 149-166. 

In addition to the indirect experimental evidence coming from work function measurements, information about water orientation at metal surfaces is beginning to emerge from recent applications of a number of in situ vibrational spectroscopic techniques. Infrared reflection-absorption spectroscopy, surface-enhanced Raman scattering, and second harmonic generation have been used to investigate the structure of water at different metal surfaces, but the pictures emerging from all these studies are not always consistent, partially because of surface modification and chemical adsorption, which complicate the analysis. 

Strategies for the development of novel catalytic materials and the design of highly active catalysts for DLFC applications largely depend on a detailed understanding of the reaction mechanism and, in particular, of the rate-limiting step(s) during the electrooxidation under continuous reaction conditions. The most commonly used technique in the electrochemical studies of fuel cell reaction mechanisms has been voltammetry, chronoamperometry (chronopotentiometry), in situ spectroscopic techniques, e.g., electrochemically modulated infrared spectroscopy (EMIRS) and infrared reflection-absorption spectroscopy (IRRAS), differential electrochemical mass spectroscopy (DEMS) and ex-situ techniques, e.g.. X-ray photoelectron spectroscopy (XPS) [92]. 

There is a number of vibrational spectroscopic techniques not directly applicable to the study of real catalysts but which are used with model surfaces, such as single crystals. These include reflection-absorption infrared spectroscopy (RAIRS or IRAS) high-resolution electron energy loss spectroscopy (HREELS, EELS) infrared ellipsometric spectroscopy. 

The use of infrared spectroscopy in the Earth and environmental sciences has been widespread for decades however, until development of the attenuated total reflectance (ATR) technique, the primary use was ex situ material characterization (Chen and Gardella, 1998 Tejedor-Tejedor et al., 1998 Degenhardt and McQuillan, 1999 Peak et al., 1999 Wijnja and Schulthess, 1999 Aral and Sparks, 2001 Kirwan et al., 2003). For the study of environmental systems, the strength of the ATR-Fourier transform infrared (FTIR) technique lies in its intrinsic surface sensitivity. Spectra are collected only from absorptions of an evanescent wave with a maximum penetration depth of several micrometers from the internal reflection element into the solution phase (Harrick, 1967). This short optical path length allows one to overcome any absorption due to an aqueous phase associated with the sample while maintaining a high sensitivity to species at the mineral-water interface (McQuillan, 2001). Therefore, ATR—FTIR represents a technique capable of performing in situ spectroscopic studies in real time. 

Infrared spectroscopic studies of macromolecules became increasingly powerful with the development of Fourier transform techniques [44, 47, 48, 59-67]. (See Chap. 1 for a description of an FTIR spectrometer.) FTIR measurements can be used to probe changes in the bonding or interactions of individual amino acid side chains in proteins. Bacteriorhodopsin provides an illustration. When bacterio-rhodopsin is illuminated, its protonated retinylidine Schiff base chromophore isomerizes and then transfers a proton to a group in the protein. FTIR measurements showed the formation of an absorption band at 1,763 cm in addition to a set of absorption changes attributable to the chromophore [63, 68]. In bacteriorhodopsin that was enriched in [4- C]-aspartic acid the band appeared at 1,720 cm and an additional shift to 1,712 cm was obtained when the sovent was replaced by D2O. These observations indicated that the band reflected C=0 stretching of a protonated aspartic acid, leading to identification of a particular aspartic acid residue as the H" acceptor for deprotonation of the chromophore. 

Wu YG, Hui L, Li X, Zhang YZ, Zhang WC (2007) Degradation of aniline in weihe riverbed sediments under denitrification conditions. J Environ Sci Health, Part A Tox Hazard Subst Environ Eng 42(4) 413-419. doi org/10.1080/10934520601187302 Yadav S, Tyagi DK, Yadav OP (2011) EquiUbrium and kinetics studies on adsorption of aniline blue from aqueous solution onto rice husk carbon. Int J Chem Res 2(3) 59-64 Yang J, Tsai FP (2001) Development of a solid-phase microextraction/reflection-absorption infrared spectroscopic method for the detection of chlorinated aromatic amines in aqueous solutions. Anal Sci 17 751-756... 

Almost every modem spectroscopic approach can be used to study matter at high pressures. Early experiments include NMR [ ], ESR [ ] vibrational infrared [33] and Raman [ ] electronic absorption, reflection and emission [23, 24 and 25, 70] x-ray absorption [Tf] and scattering [72], Mossbauer [73] and gems analysis of products recovered from high-pressure photochemical reactions [74]. The literature contains too many studies to do justice to these fields by describing particular examples in detail, and only some general mles, appropriate to many situations, are given. 

The attenuated total reflection (ATR) Fourier transform infrared spectroscopic (FT-fR) studies of Gendreu, Jakobsen, and others79 have the potential for direct determination of conformational changes during the adsorption process due to shifts in the infrared absorption bands. Sakurai et al. 80,81), have used ATR-FT1R, as well as CD, to probe conformational changes upon adsorption. 

Several spectroscopic and nonspectroscopic techniques may be used to study the bonding nature of the adsorbate to the surface [2a, 4]. In the first case we want to emphasize the importance of diffuse reflectance techniques for absorption and emission studies in the ultraviolet (UV), Visible (Vis), and near infrared (NIR) spectral ranges. X-ray photoelectron spectroscopy, and Fourier transform infrared spectroscopy. In the second group, we refer the heat adsorption and the isotherm adsorption techniques, among others. 

An example of direct examination is Ae examination of the polymer film by infrared or ultra-violet spectroscopy or of Aicker sections of polymer by attenuated total reflectance (ATR) infrared spectroscopy. Such techniques have severe limitations in that, because the additive is in effect heavily diluted with polymer, detection limits are usually well above the low concentration of additive present and Ais method is only applicable if the additive has distinct sharp absorption bands in regions where the polymer itself shows little or no absorption. In-situ spectroscopic techniques are not likely to be of value, then, in the analysis of samples of unknown composition. If known amounts of additive can be incorporated into additive-free polymer, however, these techniques are likely to be extremely useful in Ae study of solvent extraction procedures, and the study of additive ageing processes (ie. the effects of heat, light, sterilization, radiation, etc.), since the rate of disappearance of or decay can be measured directly by the decrease in absorbance of Ae sample at a suitable wave-lengA. 

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