Diffuse-reflection spectra, compared with

These paramagnetic, air-stable complexes could equally well be formulated as Os " arylnitrenes. Both crystal-field and charge-transfer bands have been observed in the diffuse reflectance spectrum of [OSF5] . Calculation of the spin-orbit coupling constant and crystal-field parameters indicated that the degree of covalency is high for a fluorocomplex, and comparable with that found for quadrivalent [MFg] species of the first transition series. ... 

The diffuse reflection spectrum of powdered a-cinnamic acid 1 reflects its solid-state absorption spectrum, which extends into the visible, in contrast to the solution spectrum (Fig. 2.1.2) [20]. It also indicates the wavelength range in the irradiations (365 and 405 nm) and helps in the judgment of light penetration when compared with the absorptivity in methanol (the molecules under (010) of the single crystal are inclined by 32°). 

Since the insolubility of the solid polymer precluded any ultraviolet studies in solution, attempts were made to obtain a diffuse reflectance spectrum of the solid. Meaningful data could not be obtained. Again, however, the liquid polymer could be compared with authentic polystyrene. Figure 4 shows the ultraviolet spectra of the two materials. Although the resolution is poor for the liquid polymer, its spectrum generally agrees with that of polystyrene. 

The UV-visible diffuse reflectance spectrum of N-doped HO2 (anatase), which was prepared by the sol-gel method, is compared with that of bare T1O2 (anatase) in Fig. 6.14. The two spectra essentially differ for the broad absorption in the... 

Figure 17-12 compares the conventional IR absorption spectrum for carbazole obtained by means of a KBr pellet with the diffuse-reflectance spectrum of a. 5 o... 

Another study reported that to obtain carbon-doped 1102, oxidation at 350°C for more than 50 h was recommended without any annealing in O2 atmosphere [159]. The substituted carbon atoms were confirmed by the Cls spectrum of XPS at 282 eV, which was due to the Ti-C bond (281.9 eV). Ti2p peaks in its XPS spectrum were not different from those of pure Ti02. It was also reported that carbon-doped Ti02 with high photocatalytic activity can be obtained from TiC by oxidation at 350°C for 8 h [160] in this case the amount of substituted carbon was about 0.7 mass%. This material was gray-white in color and its diffuse reflectance spectrum showed a red shift of 36 nm compared with pure anatase-type 1102. Its photoactivity under visible light irradiation was confirmed by the decomposition of trichloroacetone. 

In Figure 14.7, the PA spectrum of a coal sample is compared with its diffuse-reflection spectrum. The qualities of the two spectra are similar, but the PA spectrum in (a) was obtained from the coal sample directly, whereas pulverization of the coal to an appropriate particle size followed by dilution in KBr powder was necessary in order to measure the diffuse-reflection spectrum shown in (b). The PA spectmm of the coal sample was measured also by the micro-sampling technique [1], and it was observed that slightly but clearly different spectra were obtained from small pieces taken from various parts, indicating that coal is not a uniform material. 

Diffuse Reflection. Using a set of flat and elliptical mirrors, this device can measure a sufficient amount of light diffused by a sample dispersed in KBr powder (Fig. 10.20). By comparing the diffused reflection obtained with neat KBr, a result resembling the transmission spectrum is obtained. Kubelka-Munk s correction can be used to improve the spectrum. 

Spectra A and B in Figure 1 can be compared to the aqueous phase spectrum taken on the same sample by CIR spectroscopy (spectrum C, Figure 1). The solution-phase spectrum has narrower bands in this region than were obtained with either of the solid-phase methods. Band widths at half-maximum are 72 and 89 cm for the 1635 and 1390 cm bands, respectively widths of 190-215 and 160 cm were obtained similarly from the KBr pellet and diffuse-reflectance bands. In addition, both major bands in spectrum C appear as doublets. The carboxylate asymmetric stretch at 1590 cm in the dry samples appears at 1635 and 1565 cm in the aqueous phase. The symmetric stretch is shifted from 1415 cm in the dry samples to 1395 and 1370 cm in the aqueous phase. In addition, two weaker bands which appear at 1103 and 937 cm. ... 

The subject of investigation is the planar structure comprising of oxidized Cu granules (5.5 nm in diameter) manufactured by laser electrodispergation. The spectra of coherent transmission, diffuse transmission and reflection were measured for these specimens. Experimental data were compared with those spectrum calculated with regard to some parameters of the planar structure and the size-dependence of Cu optical constants. 

Figure 17 presents another example a Li surface was in contact with a thin layer of 1-3 dioxolane (DN), was sealed with a KBr window (see Figure 2), and measured periodically by FTIR spectroscopy (internal reflectance mode). The DN IR peaks (spectrum a) disappeared upon storage, and the spectra are characterized by typical ROLi peaks (spectrum b). Upon storage, air diffuses to the Li surface and CO2 reacts with the ROLi to form ROCOzLi, and ROCOzLi and trace water react also to form LizCOs (spectrum 17d), ROCOzLi peaks around 1630 cm 1300 cm , and 822 cm and Li peaks at 2500 cm and 879 cm (compare with the reference spectra in Figure 15). 

Most commonly used is the recording of UVA IS spectra, which are compared with spectral libraries. However, more informative is the recording of a FTIR- or Raman-spectrum in situ. These relatively recent developments to measure diffuse reflectance can now be carried out routinely. The in situ employment of MS after TLC detection is described in detail elsewhere (see Chapter 9, Thin Layer Chromatography Coupled with Mass Spectrometry), as well as the employment of radioactively labelled substances (see Chapter 12, Thin-Layer Radiochromatography). 

In Figure 12.8, the diffuse-reflection spectmm of coal is compared with its absorbance spectrum obtained from a transmission measurement using a KBr disk. For black materials like coal and toner used for printing, it is generally difficult to obtain high-quality infrared spectra by the transmission method, but sampling for the diffuse-reflection method is easier and spectra of higher quality can often be measured by this method. 

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