Using FTIR Spectroscopy

Composition and structure Synthesis Specific surface area/m Reference 

HS-AIF3 post fluorinated (F2) alkoxide route (microwave activation) 330 48 

Fluorides often present surface impurities as residuals from synthesis. Their identification can elucidate the reaction mechanisms in particular, it has been demonstrated by IR spectroscopy that aluminium hydroxy fluorides having the HTB structure contain coordinated or protonated ammonia. Curiously, their synthesis involves a nitrate A1(N03)3,9H20 precursor and ammonia is absent as a reagent. Therefore we have deduced that precursor decomposition implies nitrate reduction to ammonia by isopropanol during the reaction, thus explaining the presence of both ammonia inside the material and acetone 

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Most rubbers used in adhesives are not resistant to oxidation. Because the degree of unsaturation present in the polymer backbone of natural rubber, styrene-butadiene rubber, nitrile rubber and polychloroprene rubber, they can easily react with oxygen. Butyl rubber, however, possesses small degree of unsaturation and is quite resistant to oxidation. The effects of oxidation in rubber base adhesives after some years of service life can be assessed using FTIR spectroscopy. The ratio of the intensities of the absorption bands at 1740 cm" (carbonyl group) and at 2900 cm" (carbon-hydrogen bonds) significantly increases when the elastomer has been oxidized [50]. 

Pennington, N. et al., Red and white wine varietal authenticity using FTIR spectroscopy and chemometrics, in Abstracts of Papers, 229th ACS National Meeting American Chemical Society, San Diego, CA, 2005. 

Irudayaraj, J., Xu, F., and Tewari, J. (2003). Rapid determination of invert cane sugar adulteration in honey using FTIR spectroscopy and multivariate analysis. /. Food Sci. 68, 2040-2045. 

Biocompatibility. The analysis of polymer implants has been employed using FTIR spectroscopy to elucidate the long-term biocompatibility and quality control of biomedical materials. This method of surface analysis allows the determination of the specific molecular composition and structures most appropriate for long-term compatibility in humans. 

The NH4-Beta-300 (Zeolyst International, number denote Si02/Al203 molar ratio) was transformed to corresponding proton form using a step calcination procedure at 500 °C. H-Beta-300 was partially modified with Fe by repeated ion-exchange method (Fe(III)nitrate). The surface areas as well as acidities (Bronsted and Lewis acid sites) of Fe-Beta (iron content - 0.1 wt %) were determined by nitrogen adsorption and pyridine desorption at 250, 350 and 450 °C using FTIR spectroscopy [6]. 

Regan F., MacCraith B.D., Walsh J.E., O Dwyer K., Vos J.G., Meaney M., Novel teflon-coated optical fibres for TCE determination using FTIR spectroscopy, Vib. Spec., 1997 14 239-246. 

Carlson, R. C. Hayden, A. F. Telfair, W. B., Remote observations of effluents from small building smokestacks using FTIR spectroscopy, Appl. Opt. 1988, 27, 4952 4959... 

The conclusions apply to the information before subtracting the spectra at the no adsorption condition. The upshot of all these considerations is that one has to be careful when using FTIR spectroscopy to see that the information is indeed surface information. One of the most encouraging ways of doing this is to look at the frequency of a peak as a function of electrode potential. If the information is truly coming from adsorbed substances, there will usually be a slight variation of the peak with potential. However, this is only confirmatory, and not a necessary characteristic of the information. 

Information on the mechanism of the reduction of CO2 can be made with great ease when using FTIR spectroscopy. 

Determination of Surface Coverage of an Adsorbate on Silica Using FTIR Spectroscopy 159... 

Natarajan and Davidson and Goundcr. Yeung and Jasse subsequently used FTIR spectroscopy to restudy orientation effects in PTFE/ and found behavior generally in accord with the results we reported earlier but they were able to improve the resolution of the 780 cm band into a doublet. They commented on the differences in orientation function obtained for various XL bands,... 

Other laboratories have used FTIR spectroscopy to determine the kinetics of reactions on different polymer supports39 and to enumerate factors regulating site interactions in different types of supports (see Chapter 7, p. 219).40 A major weak point of the procedure is the need for IR diagnostic functions or changes in hybridization to be involved in the transformation to be investigated. For phenylacetylene oligomers, however, the TMS and terminal acetylene absorptions are ideal. 

Authors have often used FTIR spectroscopy to estimate the quantity of residual amide after irradiation, and sometimes the quantity of carboxylic acids (v = 1720-30 cm4). Musikas selected specific titration in nonaqueous medium to determine the concentration of amide, amine, and carboxylic acids (189). 

An interesting technique recently published uses FTIR spectroscopy to detect anions [149]. Thin films of tetraalkylated ferrocenium salts were evaporated onto ATR crystals. Exposure to anion-containing solutions caused incorporation of the anions, and they could then be detected via their IR absorbances. Limits of detection for 10-min analyses varied from 10 6 to 10 s M for a variety of anions however, this technique cannot be used to detect anions that do not have IR absorbances, such as halides. 

Romeo, M., Wood, B. R., Quinn, M. A. and McNaughton, D. (2003) The removal of blood components from cervical smears implications for cancer diagnosis using FTIR spectroscopy. Vib. Spectrosc. 72, 69-76. 

Cohen et al. [49] studied temperature-induced order-disorder phase transitions in LB monolayers on Cd arachidate deposited on silver and aluminum substrates using FTIR spectroscopy. Similarly to the multilayer films, monolayers undergo reversible disordering at temperatures above 60°C and become irreversibly disordered if heated above the bulk melting point. 

Reaction between LB films of Cd arachidate and ground state atomic oxygen, 0(3P), was investigated at various temperatures using FTIR spectroscopy [55,56]. Intensity of the CH2 stretching infrared band was monitored in a transmission mode and was found to decrease in the course of the reaction due to disappearance of the CH2 groups. 

Upon air drying of aminosilane modified silica, samples often get a bright yellow colour. This was also observed upon drying of aqueous APTS solutions. Naviroj et al.12 intended to use FTIR spectroscopy to study the aminosilane structure in aqueous solution at various pH. For spectroscopic analysis, hydrolyzed APTS was casted onto an AgBr plate, dried and analyzed. The spectrum showed varying features according to the drying atmosphere. The spectra did therefore not reflect the solute conformation, but the structure of the dried material. 

Mariey, L., Signolle, J.P., Amiel, C., and Travert, J., Discrimination, classification, identification of microorganisms using FTIR spectroscopy and chemometrics, Vibra. Spectrosc., 26, 151-159, 2001. 

The reaction mechanism on a vanadia-titania catalyst has been re-investigated using FTIR spectroscopy [114], although the conclusions were not markedly different from earlier proposals. The interaction of methylpyrazine with the catalyst surface involves a consecutive transformation of co-ordinatively bound methylpyrazine into oxygenated surface compounds, namely an aldehyde-like complex and an asymmetric carboxylate. The main reaction product, amidopyrazine, is formed through the interaction of the surface oxy-intermediates with adsorbed ammonia species. 

In a complementary structural study of stress-specific stabilization using FTIR spectroscopy, Prestrelski et al. [9] found that the recovery of activity after rehydration correlated directly with the ability of the additives to preserve the native structure of the enzymes in the dried state. Full activity recovery and maintenance of essentially aqueous structure in dried samples were only noted when a combination of PEG and sugar was employed. Based on these results, Prestrelski et al. [9] have proposed a model of the conformational events during lyophiliza-tion and rehydration, which is shown in Figure 8. Briefly, this model proposes that... 

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