Fight Reflectance

Grayness of a fabric swatch is not directly proportional to its content of black pigment (or artificial soil). A basic formula relating reflectance to the pigment content or concentration can be applied to the evaluation of detergency test swatches (64, 125-127). In simple form, an adaptation of the Kubelka-Munk equation, it states that the quantity (1 R) /2R (where R is the fraction of fight reflected... 

Two-dimensional PBG crystals can be thought of as a two-dimensional array of atoms in a transparent medium, and opal is an example of a three-dimensional PBG crystal. The fight reflected by an opal gives a measure of the photonic band gap of the gemstone. Many insects also use photonic crystal structures for the production of vivid colours, and a study of insect colours, especially of iridescent butterfly wings, has led to advances in understanding structures similar to those in PBG materials. 

The color of a polymer sample is an observer s interpretation of the reflectance spectrum of the sample. While what we eall "color" is dependent on the observer, color is a critical property of polymers in commercial appUcations. Color is affected by the gloss or surface on a sample. Both the fraction of the fight reflected and the angle of reflection of that light are dependent on the surface roughttess of the sample. These two factors, in turn, affect how an observer perceives color. 

Metallized glass n. Glass spheres, flaks, or fibers that have been coated with silver or aluminum and, as fillers, provide increased electrical conductivity and fight-reflecting pigmentation. 

Consider a ceramic specimen in the form of a plate that has front and back surfaces. For research purposes, a reflectance measurement would be made from a specimen in which the amount of fight reflected from the back surface, and lost from transmission through the specimen, is negligible compared to light scattered from the interior and the front surface. In other words, the specimen would appear infinitely thick to fight that penetrates the surface. With such a semiinfinite specimen, the total reflection coefficient (from the combined diffuse and specular components) is designated as. ... 

Another common use of spectrophotometers is to measure reflectance. The operation of the system for these measurements is very similar to that of the transmittance, except that the beam paths are modified so the fight that reaches the detector is the light reflected by the sample. There are two main modalities of reflectance measurements, the diffuse reflectance, where fight reflected by the sample in all directions is collected (paper-fike reflection) and specular reflectance, where only the fight that is reflected by the sample at an angle identical to that of the angle of incidence is collected (mirror-like reflectance). 

To finally detect the fight after its interaction with the sample to be evaluated for its spectral absorptivity or reflectivity, optoelectric devices are employed. They transform fight signals into electric signals. Two different main types are in use. 

In a typical experiment, linearly polarized pulsed laser fight of frequency co strikes the electrode snrface at an angle 9 from the snrface normal. The harmonic light of frequency 2co generated at or near the angle of specnlar reflection is analyzed... 

If the reflected fight intensity of a clean plate (7g) is combined with the reflected value (or the spectrum) of the TLC spot (J) as... 

The reflected fight intensity of the plain plate 7g can easily be taken at a surface area free of any other compounds. In this equation, m indicates the mass of the... 

The trend of discovering the analytical field of environmental analysis of surfactants by LC-MS is described in detail in Chapters 2.6-2.13 and also reflected by the method collection in Chapter 3.1 (Table 3.1.1), which gives an overview on analytical determinations of surfactants in aqueous matrices. Most methods have focused on high volume surfactants and their metabolites, such as the alkylphenol ethoxylates (APEO, Chapter 2.6), linear alkylbenzene sulfonates (LAS, Chapter 2.10) and alcohol ethoxylates (AE, Chapter 2.9). Surfactants with lower consumption rates such as the cationics (Chapter 2.12) and esterquats (Chapter 2.13) or the fluorinated surfactants perfluoro alkane sulfonates (PFAS) and perfluoro alkane carboxylates (PFAC) used in fire fighting foams (Chapter 2.11) are also covered in this book, but have received less attention. 

The plot in figure 10.8 clearly shows that silicate melts may exert marked fractionation on REE acidic melts with relatively greater free oxygen activity display the highest mean activity coefficients in fight REE (TREE). LREE are thus less soluble in these melts than heavy REE (HREE). The opposite is observed in basic melts, which have the highest mean activity coefficients at the HREE level. In other words, REE relative concentrations in silicate melts simply reflect their relative solubilities, as we saw for crystal structures. 

For our purpose of discussing thermoluminescence, the main problem is whether the observation that the strong, narrow bands in an overwhelming majority of cases are due to pseudoquadrupolar transitions can be explained by their molar extinction coefficient s being particularly high in the mixed oxides, or whether additional effects operate in favour of hypersensitive luminescence. If we neglect reflection of fight from the sample. 

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