Absorbing light waves Color

The simplest filter is colored glass, which absorbs a broad portion of the spectrum and transmits other portions. Table 18-1 showed the relation between absorbed and transmitted colors. For finer control, interference filters are constructed to pass radiation in the region of interest and reflect other wavelengths (Figure 20-10). These devices derive their performance from constructive or destructive interference of light waves within the filter. 

Pigment particles, often molecules, determine the color of a substance by absorbing certain light waves and reflecting others. 

In order to fully illustrate the nature of complementary colors, consider the following. If white light is passed through a medium which absorbs all the blue light (wave-... 

Substances that are intrinsically fluorescent can often be excited with long-wave-length UV light. They absorb the radiation and then emit, usually in the visible region of the spectrum, so that they appear as bright luminous zones, which can frequently be differentiated by color. They, thus, set themselves apart from the multitude of substances that only exhibit absorption. This detection possibility is characterized by high specificity (Sec. 2.3). 

Transition metal atoms form polyatomic ions that result in colored species. These polyatomic ions exhibit bonding in d orbitals. Specific wavelengths of light are absorbed by these d orbital bonds, and the remaining reflected waves are colors in the visible spectrum. 

Experiments have also demonstrated the influence not only on adsorption but on dissolution processes too (19). Considerable differences can be observed if the wave lengths of the irradiated light are absorbable. A colored substance will show the highest effect if the irradiation is done with complementary light. If light the same color as the substance is used, the result will be the same as in darkness. Every substance, then, has its own chemistry in darkness and in light. If the substance is... 

Gelbstoff. A complex mixture of natural compounds dissolved in seawater, characterized by light absorbance that increases with decreasing wavelength, giving a yellow color to the water and causing a blue fluorescence when irradiated with long-wave ultraviolet radiation. 

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