Visible spectra standard value

The use of these formulas involves subdividing the visible spectrum into L (at least 16) intervals. The subscript n labels these wavelength intervals. / characterizes the intensity of illumination in interval n, while Rn is the average reflection factor for this interval. The quantities xn, yn, and zn are found in tables (contained in standards) for typical illumination conditions and for an observer with normal vision. If two colored samples are of the same color, their X, Y, and Z values are equal pairwise. If two objects have the same color under a given illumination, this... 

Tristimulus values Three values (XYZ) calculated using a spectrum in the visible range, standard illumirrate values, and weighting factors associated with the CIE color space system. 

It is known that the optical absorption which is the major drawback of the classical plastic materials such as PMMA, is dominated by the higher harmonics of the carbon-hydrogen stretching vibrations. The value of polymers from 2,2-dichlorovinyl chloroformates derivatives has to do with their lower optical absorption as compared to standard plastics in the visible and near-infrared regions of the spectrum (0.6 to 1.5 J.m). Some new 1,2-dichlorovinyl carbonates prepared by standard procedures in 90-95 % yield for that purpose are gathered in table 3-19 (Ref. 169). 

The chromatographic smdy must be complemented spectroscopically, with UV-visible spectroscopy being the most commonly used because of its availability and simplicity. The UV-visible absorption spectrum of a pure pigment is usually recorded in various solvents, and the values obtained for the absorption maxima and fine structure are compared with those listed in the bibliography, and if possible, with the spectmm of a pure standard recorded under the same conditions. In practice, it is normal to find differences of a few nanometers with respect to the Aj values in the literature, because basically of instmment-related factors. Table 6.12 details the absorption maxima in different solvents for the carotenoid pigments commonly found in foods of plant and animal origin. 

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