Spectrophotometric curves

Spectrophotometry. The instrument generally used for this basic type of measurement is the spectrophotometer. The data obtained, usually pictured in the form of a spectrophotometric curve, indicate the ability of the sample to transmit or reflect light of the various wave lengths. Various instruments are available which can be used to determine more or less complete spectrophotometric curves. 

The important thing about such a spectrophotometric curve is that it describes a physical property of the material that is fundamentally related to its color. If, then, the color-determining component can be extracted from the product under test, a... 

Abridged Spectrophotometry. It is not always necessary to obtain complete spectrophotometric curves in order to measure physical characteristics related to color. The procedure can often be considerably simplified by some abridged form of spectrophotometry. Measurements may be made only at critical wave lengths or wave-length bands, as has been done to determine chlorophyll degradation (1, 8). In such instances the real problem that faces the investigator is to establish the critical wave lengths. 

Data obtained from reflectance spectrophotometric curves shown in Figure 5)... 

When Munsell devised his color space, he did so on the basis of minimum observable color perception steps. But the problem with the Munsell System was one of reproducibility, which the CIE Standard Observer cured. In formulating a color match, one wants to be able to predict the correct concentration of colorants required, whose scattering and absorption properties are known, i.e.- the lightness, so as to match the sample submitted, starting with their spectrophotometric curves. In practice, this is not so simple, since two colors must have identical spectrophotometric curves to be exactly equal. It turns out that the human eye will identify the two colors to be equal if their spectrophotometric reflectances are reasonably close. Two colors may appear to be equal under Daylight illumination, but quite different under incandescent lamp illumination. These colors are known zus "metamers" and the phenomenon "metamerism". 

Procedure a)0.4g sample of rocket chge was treated in a fared 100 ml beaker with 50 ml of hot benzene and the mixt allowed to stand on a hot bath for 10 mins with frequent stir ring b)The beaker was removed, cooled to 10-12° and, by means of a filtering stick, the supernatant soln of a material, later identified as TNAns, was removed c)The residual material, later found to be HNDPhA, was washed 3 times with 5 ml of cold benzene (10°) and dried to const wt. The increase in wt of the beaker was considered as the amt of HNPhA d)After evaporating the benzene from soln (b) the residue was identified as TNAns by its mp (65-67°) and its equivalent wt of 13.5 was detnd by reduction with titanous sulfate e)The residue in beaker of proced (c) was identified as HNDPhA by its mp (242°) and its equiv wt of 12.6 f)The TNAns was confirmed, as such, by the mp of a mixt of the unknown material and pure TNAns (mixed mp), and the similarity of spectrophotometric curves and... 

It is important to appreciate that particular values for the wavelength exponent, n, and the attenuation index, a, at some one wave length will characterize the entire transmittancy curve in the visible spectrum of the sugar solution. When a sugar liquor is treated with a solid adsorbent, the changes in the spectrophotometric curves in the visible spectrum are adequately defined by changes in the values of n and a (see Table I). This procedure promises to be an effective tool, both in research and in applications.31... 

Overlapping spectrophotometric curves—The multidye system contained dyes whose spectrophotometric curves overlapped, hindering simple analysis. A 16-point computer program, in... 

Figure 6-1 Spectrophotometric Curves of Colored Objects. Source From Hunter Associates Lab., Inc.

Fig. 4 Progress curves of 4NPX hydrolysis catalyzed by SXA. Reactions contained 100 mM succinate-NaOH, pH 5.3 at 25°C. [4NP] was determined spectrophotometrically. Curves were generated from the KINSIM calculations, assuming rapid equilibrium binding, with the indicated [enzyme] and [4NPX] and the following as inputs E+S <=> (A m =0.7l6 0.032 mM) E S=>E+P+Q (Aca =32.1 0.5 s ) ...

Figure 8. Spectrophotometric curves of a yellow absorption pigment coated on a red interference pigment at -15/15, -15/60 and by transmission.

Filter spectrophotometer A spectrophotometer that uses filters of fixed, narrow band-pass transmissions of discrete wavelengths spaced across the spectrum, to measure the transmittance or reflectance of materials at these discrete wavelengths. The resulting special data arranged in order constitute an abridged spectrophotometric curve. Thus, the series of filters replaces the dispersion monochromator used in a continuous spectrophotometer. Willard HH,... 

The state of uniform application of a paint film which, when dry, exhibits identical spectrophotometric curves over a perfect white of 100% reflectance and a perfect black of 0% reflectance. In the Kulblka-Munk equations, spectrophotometric hiding is defined as R o at all wavelengths. Koleske JV (ed) (1995) Paint and coating testing manual. American Society for Testing and Materials, West Conshohocken, PA. 

The state of a uniform paint film in which the spectrophotometric curves measured over white and black areas are not identical addition of more paint is required to... 

Spectrophotometric n. Adjective referring to spectrophotometry. The word spectral is frequently used in place of the longer spectrophotometric , but they are not necessarily synonymous. Spectral is the adjective referring to spectrum and is the more general term, hence a spectrophotometric curve is also a spectral curve. 

Spectrophotometric curve n. A curve measured on a spectrophotometer hence a graph of relative reflectance or transmittance (or absorption) as the ordinate, plotted versus wavelength or frequency as the abscissa. The most common curves in the visible region use wavelength units of nanometers, with the short wavelength units at the left of the scale. 

To solve these complicated complex equilibria some graphical and numerical analysis of spectrophotometric curves Extinction =... 

Goniospectrophotometer n An instrument used to measure a spectrophotometric curve at various angles of incidence and reflectance. The angles of incidence and reflectance may be changed. On goniochromatic samples, the results obtained are dependent on the... 

Hiding, Spectrophotometric, Incomplete n The state of a uniform paint film in which the spectrophotometric curves measured over white and black areas are not identical addition of more paint is required to achieve complete spectrophotometric hiding or identity of reflectance curves of the film over white and black substrates. Films wliich appear visually to be at complete hiding are not necessarily at complete spectrophotometric hiding. 

FIGURE 13 Spectrophotometric curves of a set of subtractive primary filters and their mixtures, superimposed in various combinations. [From Billmeyer, F. W, Jr., and Saltzmann, M. (1981). Principles of Color Technology, 2nd ed. Copyright 1981 John Wiley Sons, Inc. Reprinted by permission of John Wiley Sons, Inc.]... 

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