Transmission IR spectra

Repeated attempts to obtain the band at 1030 cm 1 in spectra of the respective solids of various compositions did not furnish the desired result. Nevertheless, the band was observed in IR transmission spectra of gaseous components that separated from molten K2NbF7 and were collected in a standard gas phase cell with Csl windows appropriate for IR measurements. Fig. 85 presents the structure of the band and exact wave numbers of its components. Storage of the gas in the cell for several days resulted in a yellow deposit on the windows due to oxidation and subsequent separation of iodine. Analysis of available reported data [364 - 367] enables to assign the band observed at -1030 cm 1 to vibrations of OF radicals. It should be emphasized that a single mode was observed for OF in the argon matrix while in the case of nitrogen, two modes were indicated [367]. 

Fig. 3 Single beam IR transmission spectra of a single-crystal of orthorhombic Sg at two polarizations (hiu parallel to crystal c axis, l 2u+ 3u perpendicular to c) showing the strong absorption of the IR active vibrations V4 and Vg (resolution 2 cm ), after [105]. Sample thickness 450 pm...

Figure 6. FT-IR transmission spectra of 1- to 11- monolayer LB films of C12AzoC5-Ba deposited on ZnSe plates. 

Figure 25. VCD and IR transmission spectra of azidomethemoglobin A, 4.77 mil (in tetra-mer) in pH 6.0 phosphate buffer. Sample path length 0.0S8 mm, resolution 10 cm, time constant 3 s. (Reproduced with the permission of Reidel from ref. 115a.)...

However, the use of IR spectra is limited for the analysis of food because sample preparation is more complicated in comparison with NIR. Dehydration, homogenization, dissolution or dispersion of samples is necessary. In addition, to make an IR transmission spectra of liquid samples, it is necessary to use a cuvette with very narrow path length of 0.001 - 0.1 mm because the absoiptivities are very high, which causes a sample loading... 

IR transmission spectra (T) of the thin polycrystalline specimens or powders were measured using IR microscope of the Fourier-spectrometer at room temperature in the spectral range of 600 5,000 cm-1. Optical absorption spectra were calculated as -ln(T). Figure 11.11 demonstrates normalized absorption spectra of fulleranes C60Hx with x = 36, 42, 48 and 60 together with the well known spectrum of fullerit... 

Figure 2. IR transmission spectra of a) very thin mica 1 pm) and b) mica cleaved to a thickness 70 pm) comparable to that reported in ref. 8.

The IR transmission spectra (Fig. 3) of the fullerene precipitated from the solution saturated with air show four predominant absorption peaks at 526.7, 576.2, 1182.7 and 1429.7 cm 1 that could be attributed to the IR active vibration modes (Flu) of the C o molecule with high symmetry (//,). The IR spectra of 1,2 dichlorobenzene and isopropyl alcohol are also presented on Fig. 3 for comparison. The appearance of the IR bands with the peaks at 746.2, 1034.4, 1126.1, 1249.6 and 1454.2 cm 1 confirmed the presence of 1,2 dichlorobenzene in the fullerene (see spectra 1 and 2, Fig. 3). At the same time no visible bands corresponding to the isopropyl alcohol were observed in the IR transmission spectra (see spectra 2 and 3, Fig. 3). There is a peak at 1537 cm"1 that is still difficult for interpretation. In fact, precipitation leads to the introduction of mainly solvent molecules but not the molecules of precipitator in the structure of fullerene. 

Fig. 2.16. Examples of the IR transmission spectra for a-Si H samples deposited at different growth conditions. The deposition power is indicated A and C refer to deposition on the anode and cathode (Lucovsky ei at. 1979).

Infrared spectroscopy. The IR transmission spectra of PBTMSS films (original thickness 3500 A) in the range 900 to 1200 cm after passivation by various methods are shown in Figure 6. The difference spectra between the initial and etched (for 1 and 10 min.) films corrected for changes in film thickness are also plotted in Figure 6. 

Figure 19. IR transmission spectra for newborn rat stratum corneum at various temperatures A, 25°C B, 125°C C, 250°C. Data from Ref. 18.

The FT-IR transmission spectra of the individual blend components PHB and PLA and of a PHB/PLA (50 50wt%) blend film are shown in Figure 9.21a and b, respectively. In Figure 9.21a, only a limited number of absorption bands are detectable which are specific for the individual blend components PHB and PLA. For FT-IR imaging, primarily the nonoverlapped left and right wings of the intense... 

A TEA CO2 laser (Lumonics 103-2) was used to stimulate the reaction. In order to determine the configuration and the electronic state of the surface adsorbed species, IR transmission spectra (NICOLET FT-IR 5DX) and X-ray photoelectron spectra (XPS HP 5950A) were observed. The binding energy of the emission peak in XPS was calibrated assuming that the Au 4f 7/2 of the evaporated Au film on the sample to be 84.0 eV. 

We probed the forward and reverse transformations of the molecular to the t) phase in different regions of P-T space (Fig. 8) We used IR transmission spectra as diagnostics of the degree of transformation to the nonmolecular phase. The absence of IR bands corresponding to vibrons and lattice modes of the molecular phase was used as a criterion. Since both the molecular and nonmolecular phases are transparent in the mid-IR, the amount of the phase present is simply proportional to the amplitude of the corresponding IR peaks. This is unlike the situation with Raman spectra, which are attenuated by absorption of the t] phase. We... 

Because saturated ethylene-propylene copolymers are not crosslinked in this process, it is concluded that the crosslinking reaction is definitely related to the double bonds in the diene monomer imits. However, the double bonds of the EPDM copolymers are not consumed in the crosslinking process, only decreased to some extent. The IR transmission spectra of the thin sections (20 xm) of EPDM containing ENB units has absorption peaks at 1688 and 808 cm l (assigned to C C double bonds) both before and after crosslinking (Fig. 7). Solid state MAS NMR spectra do not give spectra sufficiently resolved to interpret the reaction mechanism. 

Far-IR transmission spectra were recorded of Structure I [ethylene oxide (EtO) hydrate] and Structure 11 [cyclopropane, trimethylene oxide (TMO), 1,3-dioxolane, tetrahydrofuran (THE), and cyclobutanone hydrates] hydrates. The slight water lattice stretching due to the large size of cyclobutanone was indicated by the most... 

Figure 11. FT-IR transmission spectra demonstrating the phase inhomogeneity of BN films deposited at 17bs = 60 V. The IR beam with a diameter of about 1 mm was moved in 1 mm steps radially from the outer region towards the center of the substrate (spectra a-g). Within the lateral resolution limit of the method a sharp transition from noncubic (outer part) to cubic BN (inner part) is found.

The catalyst (RhCla/Cab-O-Sil 5) was pressed into a self-supporting pellet and was treated successively in an infrared cell (attached to a BOMEM MB 102 spectrometer) with CO (p = 1 bar, T= 75-80 °C), CH3I (p = 5 mbar, T = 32-80 C) and CH3OH (p = 10 mbar, T = 35-120 C) in the presence of CH3I (p = 5 mbar) and CO (p = 30 mbar). FT-IR transmission spectra (4 cm resolution, 512 scans) were recorded for each stage with the above components in the gas phase and under high vacuum (p = 5-10 bar). 

Figures 3.58a,fo show the p- and -polarized IR transmission spectra (y>i = 45°) of 0.5-pm Si02 films deposited by the radio-frequency (RF) cosputtering method, with 6-15-nm Ge microcrystals embedded in Si wafers at different values of the filUng factor / [317]. As / increases, the intensity of the vlo band at 1240 cm decreases significantly and the band FWHM increases (Fig. 3.58c),...

Figure 3.58. Dependence of experimental (a-c) and simulated (of, e) IR transmission spectra ( 1 = 45°) of Ge-Si02 composite film on Si wafer on filling factor f of Ge microcrystals (6-15 nm size). Obtained with (a) p- and (b) s-polarized incident light (c) result of substraction. Spectra in (b) and (c) correspond to adsorption at itq aad > lo. respectively. Reprinted, by permission, from M. Fujii, M. Wada, S. Hayashi, and K. Yamamoto, Phys. Rev B 46, 15930 (1992), pp. 15932, (Fig. 2) and 15933, (Fig. 6). Copyright 1992 American Physical Society.

Recording IR transmission spectra of ultrathin layers on the surface of transparent materials is perhaps the simplest IR spectroscopy technique. If the layer is located on the surface of a plane-parallel plate that is transparent in the IR region, it is sufficient to place it into an IR spectrometer at the focal point in the sample compartment and to measure the spectrum of the tfansmitted radiation in the usual manner. 

Figure 5.17. IR transmission spectra of a-Si H film (l)iDefore and (2) after 3 s and (3) 10 s annealing by CO2 laser (X = 10.6 xm, p = 100 W cm" ). Reprinted, by permission, from H. Gleskova, V. V. Ilchenko, V. A. Skryshevsky, and V. I. Strikha, Czech J. Phys. 43,169 (1993). Copyright 1993 Czech Journal of Physics.

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