Visual spectrum

In any optical evaluation of commercial sugars, the spectrophotomet-ric data in the visual spectrum are the primary ones, since all other results... 

Resonant absorption-A specific type of conjugate dipole absorption associated with two auxochromes separated by a conjugated chain of carbon atoms characterized by absorption in the visual spectrum. The resonance is due to the low velocity of charge transport along the molecule. As a result, the effective wavelength of the molecule is equal to that of the incident photons. The absorption is... 

There are a variety of interaction modes between photons and chemicals. They can generally be grouped as involving destruction, ionization and excitation. They can also be sorted with respect to whether they impact a single atom, a ligand or the entire molecule. The mechanism of interest in vision involves the quantum-mechanical excitation of the entire molecule by photons with a wavelength within the visual spectrum. 

One of the major paradoxes of the current time is that no investigator has isolated and measured the visual spectrums of the chromophores of vision in the laboratory. The above figure illustrates why. The chromophores of vision only exhibit their unique spectral characteristics when in the liquid crystalline state. Furthermore, in the absence of an appropriate de-excitation mechanism, the molecules are excited rapidly (bleach) due to ambient laboratory light and remain in the excited state indefinitely. To achieve a steady-state condition allowing repetitive spectral absorption measurements, a de-excitation mechanism must be provided. 

The molecules constituting the Rhodonines are extremely sensitive, as are all molecules sensitive to excitation by light of less than 1-2 electron-volts energy, corresponding to the visual spectrum. Furthermore, these molecules will only exhibit the appropriate spectra when in the conditions described above. In the process of transitioning to in-vitro laboratory conditions, experimenters have inevitably destroyed the necessary conditions for observing the resonant visual spectra associated with these chromophores. The scenario is generally as follows ... 

This is the mechanism proposed in the model for the transduction of visual spectrum photons by the eye. It has led to a very accurate equation for the perceived spectral response of all eyes in the animal world, including the ultraviolet sensitivity of many animals. This is particularly true for the well-documented sensitivity of (many) insects. 

From here on, our emphasis will not fall on retinol itself but on its derivatives. This is because although retinol derives from a well-known natural dye, carotene retinol and the retinenes are not dyes themselves. While they exhibit a minor absorption at 500 nm in the visual spectrum when in dilute solution, this absorption feature is not used in the visual system. Normally, it cannot be measured in-vivo because of the much greater absorption coefficients related to the molecules when in the liquid crystalline state. 

The polymethines can be considerably shorter and still achieve significant absorption in the visual spectrum, typically 3 or 4 conjugated double bonds. 

Note as the discussion proceeds, the near total independence of the functional absorption spectra of the Rhodonines, based on their resonant absorption cross section, from the nature of the ionone ring and whether the chromogen was Vitamin Al, A2 or A3. While the dipole-molecular absorption of the Rhodonines in the visual spectrum may reflect a small change relative to the parent chromogen, the enhancement related to resonant-molecular absorption does not. 

Duijnen, P.Th. van, Greene S.N. and Richards N.G.J., Time dependent density functional the-ory/discrete reaction field spectra of open-shell systems the visual spectrum of [Felu (PyPepSjz ] in aqueous solution. J.Chem.Phys. (2007) 127 045105. 

In the earliest days of motion pictures, color film had not yet been invented. Some films were colorized by hand, but that soon proved impractical. Color film first came out in the mid-1930s. It used three layers of colored film to reproduce the visual spectrum. Because color film was expensive and required precise control of lighting, black and white film remained the standard until the mid-1950s. Color and black-and-white were both used until the late 1960s, when color became the standard. This was partly because many films were sold for television broadcast after appearing in theaters, and black-and-white films were much harder to sell for television. 

Other tests are specified in the USP for specific types of plastic based on the specific hazards that they pose to their contained pharmaceutical preparations. For instance, certain types of PET bottles have a tendency to leach colorant into the liquid preparations. For this reason, a specific test protocol is defined that allows for the spectrophotometric analysis (visual spectrum) of the extraction solution relative to the blank solution. When this analysis is performed at the wavelength of maximum absorption of the plastic, it can be reasonably inferred that any significant difference between the test solution and the blank can be attributed to leaching of the colorant. ... 

Designing an imager for automotive applications necessitates balancing various factors. A high geometrical resolution (e.g., 4kx4k) can only be achieved by squeezing pixel pitch and in sequence the fill factor and sensitivity. The need for deep submicron CMOS processes shifts the maximum of the spectral response towards the blue end of the visual spectrum with small quantum efficiency. 

The human visual system is, due to its physical and physiological properties (as mentioned earlier), most of the time superior to visual-spectrum camera systems. The human eye is very sensitive to colour differences, especially when these colours are observed in a controlled environment (typically a lighting cabinet with a neutral, homogeneous backgrotmd). The srrrallest colorrr differences the hitman eye can see depend very much on the colour itself. Colour differences can be defined in terms of hue, chromaticness (or chromaticity) and lightness. 

This same full-scan and SRM approach used for ACs is also done for amino acids. Basic amino acids such as citrulline and arginine are characterized by loss of 102 Da and ammonia or other basic amino side chain. Selective reaction monitoring (SRM) is used rather than full scan and is based on NL of 119 for citrulline (102 -I-17, where 17 is ammonia) and NL of 161 for arginine (102 -i- 59, where 59 is the amino side chain). These SRMs are often grouped together in the visual spectrum as shown in Figure 13.12. Note that citrulline can also be acquired in an NL 102 scan since source-induced dissociate may cause the ammonia to be lost and hence detection of m/z 215 (MH+ minus 17) versus m/z 232. Details of this fragmentation are described elsewhere. 

Stanlight 770 can be combined with UV absorbers to optimize a polymer s UV light stabilization properties. It has no effect on the polymer s color, as there is no absorption in the visual spectrum. 

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