FTIR and Raman spectroscopies

FTIR and Raman spectroscopies can in principle provide infomiation about surface functionality on fibers and composites. In both techniques, however, the sampling depth is considerable, which means that if there is any chemical functionality in the interior of the fiber or composite, then the information is ambiguous. Nev- 

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Analysis of Surface Molecular Composition. Information about the molecular composition of the surface or interface may also be of interest. A variety of methods for elucidating the nature of the molecules that exist on a surface or within an interface exist. Techniques based on vibrational spectroscopy of molecules are the most common and include the electron-based method of high resolution electron energy loss spectroscopy (hreels), and the optical methods of ftir and Raman spectroscopy. These tools are tremendously powerful methods of analysis because not only does a molecule possess vibrational modes which are signatures of that molecule, but the energies of molecular vibrations are extremely sensitive to the chemical environment in which a molecule is found. Thus, these methods direcdy provide information about the chemistry of the surface or interface through the vibrations of molecules contained on the surface or within the interface. 

In this chapter, three methods for measuring the frequencies of the vibrations of chemical bonds between atoms in solids are discussed. Two of them, Fourier Transform Infrared Spectroscopy, FTIR, and Raman Spectroscopy, use infrared (IR) radiation as the probe. The third, High-Resolution Electron Enetgy-Loss Spectroscopy, HREELS, uses electron impact. The fourth technique. Nuclear Magnetic Resonance, NMR, is physically unrelated to the other three, involving transitions between different spin states of the atomic nucleus instead of bond vibrational states, but is included here because it provides somewhat similar information on the local bonding arrangement around an atom. 

The molecular structure of Li-, Na-, and K-silicates in 0.2 to 3 mole SiOj/L aqueous solutions has been investigated by FTIR and Raman spectroscopy to help exploring their solidification process. These silicates were found to be only partially dissociated and their average molecular weight (AMW) varies with the type of the alkaline ion, the alkaline/silicon ratio, and the concentration. It is demonstrated that these differences are associated with differences in the Qn connectivity ratios of [Si04] tetrahedra and in the dominating siloxane ring structures which can be identified by their vibrational spectra. 

J. Cornel, C. Lindenberg and M. Mazzotti, Quantitative application of in situ ATR-FTIR and Raman spectroscopy in crystallization processes, Ind. Eng. Chem. Res., 47, 4870 882 (2008). 

In 2007, in a very exhaustive paper, Paradies and coworkers carried out a comprehensive structural characterization of the colorless and yellow forms of Af-hydroxyphthalimide (NHPI) by means of single-crystal X-ray diffraction, FTIR and Raman spectroscopies and scanning electron microscopy. In the yellow form, the Af-hydroxyl group is significantly out of the plane (1.19°), but the Af-hydroxyl group in the colorless form is only 0.06° out of the plane. The irreversible conversion of the colorless crystalhne form to the yellow crystalhne form is more like a dynamic isomerism than a polymorphic transformation. 

In another study, samples for polymorphic analysis were processed using gentle grinding after mixing [17]. Here, a combination of FTIR and Raman spectroscopy with multivariate analysis was utilized to quantify Form-II in mixtures with Form-I. Multivariate analysis using the PLS... 

Spectroscopic methods, such as FT-infrared (FTIR) and Raman spectroscopy detect changes in molecular vibrational characteristics in noncrystalline solid and supercooled liquid states. Various nuclear magnetic resonance (NMR) techniques and electron spin resonance (ESR) spectroscopy, however, are more commonly used, detecting transition-related changes in molecular rotation and diffusion (Champion et al. 2000). These methods have been used for studies of the amorphous state of a number of sugars in dehydrated and freeze-concentrated systems (Roudaut et al. 2004). 

Wharton. C.W. (1996) FTIR and Raman Spectroscopy in the Study of Proteins and other Biological Molecules, in Proteins Labfax (Price, N.C., Ed.). BIOS, Oxford. 

The secondary structure of proteins may also be assessed using vibrational spectroscopy, fourier transform infrared spectroscopy (FTIR), and Raman spectroscopy both provide information on the secondary structure of proteins. The bulk of the literature using vibrational spectroscopy to study protein structure has involved the use of FTIR. Water produces vibrational bands that interfere with the bands associated with proteins. For this reason, most of the FTIR literature focuses on the use of this technique to assess structure in the solid state or in the presence of non-aqueous environments. Recently, differential FTIR has been used in which a water background is subtracted from the FTIR spectrum. This workaround is limited to solutions containing relatively high protein concentrations. 

The precursor gels were characterized by TGA and the calcined catalysts by FTIR and Raman spectroscopy, XRD, SEM and surface area determination. 

Schraml-Marth et al. [89] studied the two types of chromia by means of diffuse reflectance FTIR and Raman spectroscopy. Amorphous chromia has a higher density of labile oxygen sites than that of crystalline chromia in the temperature range 423-473 K and is accordingly more active. 

In this chapter common methods to evaluate chemical properties and phase composition of bioceramic coatings will be briefly described that are available in many laboratories including X-ray diffraction (XRD), vibrational spectroscopy techniques such as infrared (FTIR) and Raman spectroscopy and nuclear magnetic resonance spectroscopy (NMR). These methods provide a host of information on bulk phase composition, degree of crystallinity and crystallite size. Some special techniques including cathodoluminescence serve to reveal intrinsic coating properties that cannot be assessed by conventional analytical techniques, for example to distinguish between amorphous calcium phosphate (ACP) and crystalline calcium phosphates. 

This chapter covers the applications of Fourier transform infrared (FTIR) and Raman spectroscopy to the characterization of water-soluble polymers. The structural analysis of poly(oxyethylene), poly ethylene glycol), poly methacrylic acid), and poly acrylic acid), and the interactions of selected polymers with solvents and surfactants are presented. Structural features of these compounds in the crystalline and melt states are compared with their structural features upon dissolution in aqueous solvents. Special emphasis is given to the recent studies of the interactions between water-soluble polymers or copolymers and solvents or surfactants. New experimental approaches and the sensitivities of both FTIR and Raman spectroscopy to monitor such interactions are presented. 

The theory of IR (or FTIR) and Raman spectroscopy has been reviewed in several monographs (i-3) and various general references on Raman spectroscopy (3-6). The objective of this review is to survey the spectroscopic results obtained for various water-soluble polymers and to evaluate recent experimental techniques. In particular, this chapter will focus on the studies of selected water-soluble polymers and copolymers and their interactions with solvents and surfactants. 

It is worth noting the emergence of several online or in-line composition measurement techniques such as ATR-FTIR and Raman spectroscopy as well as the application of GC and NMR in an online manner [133]. 

SSNMR spectroscopy. However, FTIR and Raman spectroscopy, thermal microscopy, variable-temperature x-ray diffractometry (VTXRD), and DSC may also be used to identify polymorphs. Solvates may be similarly characterized by the techniques mentioned above. In addition, the stoichiometric number of the solvent molecules in the crystal lattice of solvates may be determined by thermogravimetric analysis (TGA), gas chromatography, or, in the case of a hydrate, by Karl Fiseher titrimetry [37]. 

A novel approach to the study of the hydroxylation and dehydroxylation of fumed and precipitated silicas is given in the study by Bumeau et al. (Chapter 10), which was based on FTIR and Raman spectroscopy techniques. 

Fourier transform infrared spectroscopy (FTIR) and Raman spectroscopy have also been used for analyses of complexes. Upon complexation of the guest, shifts or changes in the spectrum occur. There are interferences in the spectra from the CD, and some of the changes are very subtle, requiring careful interpretation of... 

The example cited in this chapter clearly establish that physical analysis techniques, such as GPC, FTIR and Raman spectroscopy, NMR, DSC, thermogravimetric analysis (TGA), and DMTA, are broadly applicable in adhesive research, product development, manufacturing, and quality control or assurance programs. Unfortunately, space constraints have prevented detailed discussions of array of techniques that further enhance the utility of all the physical analysis techniques that were introduced here. Discussion of these can be found in many of the references cited in this chapter. 

The outline of this chapter is as follows. The spectroscopic techniques that can be used for surface of interface characterization of adhesively bonded materials are listed in Table 1. The most popular techniques are then discussed briefly in terms of the type of information they provide and where they can be applied. Their limitations are also described briefly. Since just a handful of techniques are used on a regular basis, notably XPS, AES, SIMS, FTIR, and Raman spectroscopy, only these techniques will be discussed in detail. Recent and ongoing instrumental developments are described and specific applications of each of these techniques are presented and discussed. Finally, a bibliography containing many references to textbooks and important artieles is given. 

Applications of solid state NMR along with FTIR and Raman spectroscopy and X-ray crystallography to study the structural changes in the proton transport cycle of the light-driven pump, bacteriorhodopsin, have been reviewed by Laniy. " ... 

The thermal stability and structural variation of the PANI-NT films produced on Si windows during a treatment at 80 °C for three months were studied by FTIR and Raman spectroscopies [442]. The morphology of the films was preserved during the degradation, but the molecular structure had been changed. The results indicate that the spectral changes correspond to deprotonation, oxidation, and chemical cross-linking reactions. The films of... 

In comparison with bulk polymerization, for the free radical reaction of VK in the presence CNTs, PVK was reacted directly with MWNTs at 70 °C in DCB with azo-bis-izobutyronitrile (AIBN) as the radical initiator [199]. After purification, deep-grey products, which can be dissolved in common solvents such as chloroform and 1,2-dichlorobenzene (DCB), were obtained. It was confirmed that PVK was grafted onto the surface of CNTs by FTIR and Raman spectroscopy, CPS, TGA, TEM, and UV-VIS spectra [199]. 

N.S. Sariciftci, M. Bartonek, H. Kuzmany, H. Neugebauer, and A. Neckel, Analysis of various doping mechanisms in polyanihne by optical, FTIR and Raman spectroscopy, Synth. Mer., 29, 193-202 (1989). 

FTIR and Raman spectroscopy are frequently used to characterize polymorphs. Both the molecular conformation and the crystal packing may lead to differences in the FTIR spectra of polymorphs the differences are more pronounced for compounds capable of hydrogen bonding. Characteristic shifts in C=0, N-H, and O-H stretching frequencies often lead to unequivocal polymorphic identification. Differences in fine structure and in the positions and intensities of IR bands enabled seven crystalline forms of the steroid prasterone 3 to be distinguished."" The presence of characteristic absorption bands due to included solvent molecules allows ready distinction between polymorphs and pseudopolymorphs. 

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