kubelka-munk reflectance to absorbance
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Abstract. 4). Synthesis of Antifungal Agents from Xanthene and Thiazine Dyes and Analysis of Their Effects. Figure 17.14 shows the KM and absorption coefficient spectrums of maltose. All the geometric peculiarities of the inhomogeneous sample are condensed into a single parameter, the scattering coefficient s. The diffuse reflectance 4 ¶ is given as: 4 ¶1 E G O F ¨ G O 2 E G O p where k is the absorption coefficient of the sample ( G Asterisk ( * ) -- Example: "elect*" retrieves documents containing "electron," "electronic," and "electricity", Question mark (?) A relation between the Kubelka‐Munk function F(R) and the absorbance of dyed fibers is proposed. Kubelka-Munk theory has several limitations (Judd and Wyszecki, 1963) as a result of numerous simplified assumptions made in the theory, such as: The scattering and absorption coefficients are assumed to be the same throughout the thickness of colourant layer. Please confirm that JavaScript is enabled in your browser. Conversely, the relationship between the concentration of glucose powder and the naturalized logarithm of the inverse relative diffuse reflectivity was nonlinear (Fig. x ScienceDirect ® is a registered trademark of Elsevier B.V. ScienceDirect ® is a registered trademark of Elsevier B.V. On the Kubelka–Munk absorption coefficient. 17.19) for the sample covered by three sheets of paper because of the large decrease in the SNR and the influence of multiple reflections from the sheets. A new specular reflectance technique has been recently demonstrated for measuring k for aerosol particles resuspended on coarse (5-μm pores) and fine (0.4-μm pores) nucleopore filters in a broad spectral range from ∼300 nm to 2.5 μm (Martins et al., 2009). This is the basis of the method developed in the USA for assessing the hiding power of paints, which was standardized as ASTM D2805 and in Germany as DIN 53162. It can be specified for individual particles, but in remote sensing, a single value is assumed for the entire volcanic ash column (Krotkov et al., 1999a,b). However, as FTIR has become more common, the diffuse reflection method has become widely used. Similarly, for thin films, the light may not have a chance to scatter, which makes a significant difference in the results. However, due to the difficulty in measuring the absolute reflectance Râ, in practice, the comparative reflectance râ with respect to a standard powder such as KBr or KCl, of which K is near zero (0) in the actual measurement range. Copyright © 2020 Elsevier B.V. or its licensors or contributors. account. These more complex calculations also deal with absolute concentrations of pigments rather than the relative proportions predicted by the earlier computations. O Here, we discuss the measurement of solids, particularly powder samples, by the diffuse reflection method. The Kubelka-Munk functions is given by: F (R) = (1–R)²/2R = k/s = Ac/s. The K-M equation is applicable to monochromatic light only. 17.15a). Mn The incident light is assumed to be perfectly diffused. ‘Colour on demand’ will be the challenge and the paint formulator will have to use colour measurement tools intelligently. Relationship between the powdered glucose concentration and (a) the calculated score using the KM spectrum and multivariable analysis, and (b) the naturalized logarithm of the inverse relative diffuse reflectivity. The absorption spectrum is shown as a dashed line for comparison. all light reflected for S→0 (no scattering) R∞→0, i.e. The measured diffuse reflectance of the mixture is then inverted using the Kubelka–Munk theory to estimate the bulk absorption coefficient of the ash. As noted above, the most important optical characteristic related to ash composition is the refractive index, m(λ), which is specified as a complex number (m = n − ik) expressing refraction (scattering) as a real component, n, and absorption by an imaginary component, k. The refractive index is determined by ash composition and is wavelength dependent. Login to access OSA Member Subscription. Click here to learn more. 17.15b). These simultaneous equations can be rewritten as the linear matrix equation: The absolute of the concentration cannot be calculated, because [I] is the ratio of the absorption and scattering coefficients.
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