INDEX spectra

In addition to the numeric data (color, solubility, refraction index, spectra, etc.), these factual databases also include a bibliographic section with references or sources and a section with information for the identification of a compound (e.g., name, CAS Registry Number, molecular weight). 

Compilations of Reference Spectra There are several compilations of reference mass spectra available of which the oldest is the American Petroleum Institute (Ref 82) collection of spectra obtained mostiy on the older type instruments. Recent collections index spectra variously, eg, under reference number (Ref 19). molecular weight (Refs 12 19), molecular formula (Ref 19), fragment ion values (Ref 19), and base peak (Refs 12 19). A quarterly journal, Archives of Mass Spectral Data ... 

Fig. 7.62. Refractive index spectra of iron for different potentials. (Reprinted with permission from V. Jovancicevic, R. C. Kainthla, Z.

Johnson, L. F., and Jankowski, W. C. (1972). Carbon-13 NMR Spectra, a Collection of Assigned, Coded, and Indexed Spectra. New York Wiley. 

Johnson LRF, Jankowski WC (1972) Carbon-13 NMR spectra. A collection of assigned, coded and indexed spectra. WUey, New York... 

Figure 11 shows the complex index spectra of the three polymers of interest polymethylmethacrylate (PMMA), polyvinyl nitrate (PVN), and nitrocellulose (NC). These were obtained as described above from sets of IR reflection data obtained every 5° from 25 to 80° at both s and p polarization for each material. The spectra for PMMA agree substantially with those found in the literature [98]. 

Analysis of the infrared spectra requires accounting for thin film interference effects, which, upon shock compression, change the composite reflectivity. To analyze the thin film interference effects, the infrared complex refractive index spectra for ambient samples of PVN, and the inert polymethylmethacrylate (PMMA), were determined as described in the section above. The only modification to the description above is the inclusion here of the dispersive rarefaction wave that releases the pressure [102]. 

A Kramers—Kronig analysis allows one to separate the absorption index and refractive index spectra. Different algorithms for this analysis are available. 

Figure 7(a) shows the absorption and refractive index spectra for MAB/PMMA samples before and after the photochromic reaction. The dye concentration is 0.20 mol/l. The conversion of the photochromic reaction is assumed to be a unity, which is supported by the following facts. We could not observe the Jt-Jt transition band of the trans isomer in the irradiated sample, and the... 

Figure 6. (a) Absorption spectra and refractive index spectra of... 

FG540/PMMA. For absorption spectra, the thin line is for an unirradiated sample and the bold line is for an irradiated sample. For refractive index spectra, circles represent refractive indices measured by an / -line method for an unirradiated sample (o) and irradiated sample( ). Lines represent continuous spectra of refractive indices obtained by Kramers-Kronig transformation, (b) Spectra of refractive index changes. Circles represent refractive index changes measured by an m-line method and the line represents refractive index changes obtained from Krameis-Kronig transformation by using a difference absorption spectrum ftom 200 nm to 2 jum. 

Figure 8(a) shows absorption spectra and refractive index spectra for P(MMA-co-GMA-PNCA) before and after the photochromic reaction. The dye concentration is approximately 2.4 mol/l assuming that the density of this polymer is 1.0 g/cm. The actual concentration could be higher. Refractive indices were measured at wavelengths where they showed normal dispersion. Therefore, we simplified eq. (3) to the form which does not depend on (oi as shown below. 

Figure 9 Specular reflection FT-IR and application of Kramers-Kronig algorithm (A) schematic showing external (front-surface, specular) mid-infrared reflection measurement from an optically thick sample (B) specular reflectance spectrum recorded from a 0.6-mm thick polymer molding (C and D) refractive index and absorption index spectra derived by applying Kramers-Kronig algorithm to the recorded specular reflection spectrum (B), respectively.

Johnson, L. E, andW. C. Jankowski, Carbon-13 NMR Spectra A Collection of Assigned Coded and Indexed Spectra, 25 MHz, WUey-Interscience, New York, 1972. 

Figure 1.4. (a) Refractive index and (b) absorption index spectra of poly(methyl methacrylate). 

Figure 13.3. Refractive index and absorption index spectra calculated from the spectra shown in Figure 13.2.

Figure 16.17 Absorption-index spectra of a polycarbonate resin, (a) Resin before light-resistance test and (b) resin after light-resistance test. (See text for details spectra have been offset for clarity.)...

Figure 3.10a, b shows ATR-FUV spectra in the 140-260 nm region for formamide (FA), N-methylformamlde (NMF), N-methylacetamide (NMA), NJ l-dimethylformamide (NdMF), and N,N-dimethylacetamide (NdMA) in the liquid phase and their absorption index spectra obtained by the Kramers-Kronig transformation, respectively [9]. All FUV spectra show a peak due to amide group in the 180-200 nm region. The peak maximum varies in the order of FA (6.88 eV), NMA (6.81 eV), NMF (6.67 eV), NdMA (6.44 eV), and NdMF (6.44 eV) with the intensity being lowered as the number of methyl groups on the N atom increases. 

Marketed databases offer the advantage of being operational as soon as they are installed on a computer. They contain tens of thousands of mass spectra—a considerable number even if nature produces several millions of molecules The indexed spectra obviously correspond to molecules such as pesticides, environmental pollutants, toxins, and drugs that interest the largest number of analysts. Chemists who work in these and other relevant fields are more likely to find spectra of their molecules of interest in marketed databases. 

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