Band assignment

The skeleton vibrations. C3NSX, CjNSXj. C NSXY, or C NSXj (where X or Y is the monoatomic substituent or the atom of the substituent which is bonded to the ring for polyatomic substituents), have been classified into suites, numbered I to X. A suite is a set of absorption bands or diffusion lines assigned, to a first approximation, to a same mode of vibration for the different molecules. Suites I to VIII concern bands assigned to A symmetry vibrations, while suites IX and X describe bands assigned to A" symmetry vibrations. For each of these suites, the analysis of the various published works gives the limits of the observed frequencies (Table 1-29). 

The infrared and Raman spectra of many alkyl and arylthiazoles have been recorded. Band assignment and more fundamental work has been undertaken on a small number of derivatives. Several papers have been dedicated to the interpretation of infrared spectra (128-134, 860), but they are not always in agreement with each other. However, the work of Chouteau (99, 135) is noteworthy. The infrared spectrum of thiazole consists of 18 normal vibrations as well as harmonic and combination bands. 

Thiazole shows a first absorption band assigned to a type... 

Band assignment Vibration frequency [cm- ] Tunneling splitting [cm ] ... 

When a plasma polymerized acetylene film on a steel substrate was reacted with the squalene-containing model rubber compound at 155°C for 15 min, a new band assigned to zinc stearate appeared near 1539 cm in the RAIR spectra... 

In 1951, Witkop et al. interpreted the infrared spectra of quinol-2-and -4-ones to favor the oxo formulation. Since then, many investigators, especially Mason, have reported that potential a- and y-hydroxy compounds show infrared absorption bands in the vN—H (3500-3360 cm ) and vC—O (1780-1550 cm ) regions of the spectrum and, hence, exist predominantly in the oxo form references to this work appear in Table I. A study of the bands which occur in the NH-stretching region of the infrared spectra of a series of substituted pyrid-2-ones and quinol-2-ones also supported an oxo formulation for these compounds. Detailed band assignments have been published for pyrid-2- and -4-one. Mason has reported that solutions of j8-hydroxy compounds in chloroform or carbon tetrachloride show... 

Bands Assigned to in-Phase out-of-Plane CH Bending AIodes... 

Table 27. IR absorption spectrum and band assignment of Nb02F43 (D4h) in the compound K.2NaNb02F4 (F - occurs in tran -position relative to the oxygen ion). Reproduced from [195], K. Dehnike, G. Pausewang, W. Rudorff, Z. Anorg. Allg. Chem. 366 (1969) 64, Copyright 1969, with permission of Wiley-VCH.

The complex structure of the various solutions was investigated by Raman and IR absorption spectroscopy. Containers made of sapphire and KRS-5 were used for Raman and IR spectra measurements, respectively. Vibration spectra analysis was performed based on the band assignment [171, 187] presented in Table 45. 

Table 45. Vibration spectra band assignment of hydrofluoric solutions containing niobium (after Keller [171] and Surandra et al. [187]).

Table 47. Vibration spectra bands assignment of hydrofluoric solutions containing tantalum.

The infra-red measurements were of two types, normal-film measurements with the sample sandwiched between KBr plates, and tilted-film experiments with the sample sandwiched between 45° prisms of KBr, in each case with layers of Nujol to provide optical matching. Whereas the 1616 cm 1 Raman line occurs in a region well clear of other lines so that it was satisfactory to measure peak intensities, the infra-red spectrum of PET shows many overlapping bands. Accurate assessment of absorption intensities therefore requires the computer separation of the spectrum into a set of overlapping peaks (shown to be Lorentzian in profile) and a linear background. The procedures adopted and the band assignments are discussed in detail by Hutchinson et al. 6). 

TABLE 7.8 FTIR Absorption Band Assignment of Resole Resins... 

The HS2 radical was detected by its infrared absorption spectrum and the S2 molecule by luminescence spectroscopy. In addition, infrared bands assigned to dimers of disulfane molecules were observed at higher H2S2 concentrations. The HS2- radicals may further be split into hydrogen atoms and S2 molecules during the photolysis since the concentration of HS2- first increases and then decreases while that of S2 steadily increases. No evidence for the thiosulfoxide H2S=S was found, and the probably formed HS- radicals are assumed to be unable to leave their cage in the matrix and either recombine to H2S2 or form H2+S2 [69]. 

Figure 5. IR spectra of s.o. samples after various treatments. Section a after adsorption of NH3 (1 mbar) at RT Zr02 (curve 1), ZV0.58(a)pH4 (curve 2), ZV1.21(a)pH4 (curve 3). Section b ZV0.58(a)pH4 sample after adsorption of NO+O2 at 623 K (curve 1), after subsequent adsorption of NH3 (1 mbar) at RT (curve 2) and after subsequent heating at 623 K (curve 3). Bands assigned to bridged bidentate nitrates ( ) and to chelating nitrates ( ). Section c the same treatments as in section b on s.o. 1.21(a)pH4.

A typical OES spectrum taken from CH4-N2 plasma used in a-C(N) H film deposition is shown in Figure 13 [63]. This figure also shows band assignment of the... 

Table 52.1. Band Assignments and Their Vibration modes.

The photochemical formation and the analysis of the absorption and magnetic circular dichro-ism spectra of the anion radical of zinc phthalocyanine were carried out. A complete assignment of the optical spectrum of the anion radical was proposed.834 Similarly, spectroelectrochemical cells have been used to record absorption and magnetic circular dichroism spectra of zinc phthalocyanines and a band assignment scheme proposed.835... 

B. Raman Optical Activity Band Assignments for Folded Proteins. 60... 

Further evidence for these a-helix ROA band assignments in the extended amide III region comes from the ROA spectrum of poly-L-alanine dissolved in a mixture of chloroform (70%) and dichloracetic acid (30%), known to promote a-helix formation (Fasman, 1987), which shows strong positive ROA bands at 1305 and 1341 cm-1 (unpublished results), and of the cv-helix forming alanine-rich peptide AK21 (sequence Ac-AAKAAAAKAAAAKAAAAKAGY-NHg) in aqueous solution which shows strong positive ROA bands at 1309 and 1344 cm-1 (Blanch et al., 2000). 

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