Complementary colour

This is the familiar absorption process illustrated by the appearance of an aqueous solution of copper sulphate as blue due to the absorption of the complementary colour, red, by the solution. 

Complementary colours 660 Completeness of deposition 507 Completeness of precipitation 418 Complexation 51... 

The spectrum in Figure 9.4 shows that only light within the range 200-300 nm is absorbed. It follows, therefore, that if light of these wavelengths is absorbed, then such light cannot also be available to be seen , i.e. to enter the eye. In fact, we only see the remainder of the light - that which is not absorbed. We say that the colour observed by the eye is the complementary colour to that absorbed. 

The frequency of the light absorbed to effect the photo-excitation is in the red and near-infrared parts of the visible region, so the complementary colour seen is blue. This explains why sapphire is blue. It is again a charge-transfer excitation, but not of the mixed-valence type. The optical band formed is intense, so a strong colour is seen even though the concentrations of iron and titanium are minuscule. 

The colour actually seen is in fact the complementary colour since light is absorbed, so, for example, a blue colour is seen if the material absorbs red light. 

Think back to the split d orbitals. Electrons in the lower energy d orbitals can absorb energy and move to the higher energy d orbitals. If the energy absorbed in these so-called d-d transitions is in the visible part of the electromagnetic spectrum, the colour of the transition metal compound will be the complementary colour of the absorbed colour. So the colour we see will be white light minus the colour absorbed. 

Colorimetry can be used to determine the concentration of coloured substances in solution. A colorimeter essentially consists of a light source, a coloured filter, a light detector and a recorder. The filter chosen is the complementary colour to the solution as this will result in the maximum absorbance. The light passes through the filter and then through the coloured solution. The difference in absorbance between the coloured solution and water is detected and noted as an absorbance value. Colorimetry uses the relationship between the intensity of the colour of the solution and the concentration. 

The staleness of reward reported by self-absorbed people makes one think of habituation or fatigue. Any neuronal process, if repeated frequently during a short period of time, wilt lose vigour. For instance, if one stares at a solid colour for any period of time the visual pigment that subtends that colour will be depleted so that if one then stares at a neutral screen one will see the complementary colour. Data about the generality of this phenomenon in psychophysiology have been summarized by Solomon (1980), who proposed an increasing recruitment... 

After absorption of the blue-green colour from white light (carotene absorbs light of wavelength up to about 500 nm), the complementary colour (red-yellow) remains to be reflected and perceived by our eyes. P-Carotene, therefore, appears intensely orange coloured as the name implies, it is found in high concentrations in carrots. 

When a flashing Talisman is referred to in the Z2, it is generally a flat object of virgin paper, coloured the colour of the planetary force to be called on, and with drawings of sigils and seals of said planet, in the complementary colour. One can use disks of metal of the nature of the planet but this is rather expensive. 

UV-vislble spectra, registered by Miyamoto et al. Li], show that hydration shifts the main transitions from the UV region to longer wavelengths and the specimen shows the complementary colour which is yellow. It means in other words that the yellow colour is caused by hydration and not by tbe oxidation state of vanadium ions. 

Colour of light absorbed Approximate wavelength ranges / nm Corresponding wavenumbers (approximate values) / cm Colour of light transmitted, i.e. complementary colour of the absorbed light... 

In a colour wheel representation, complementary colours are in opposite sectors... 

If the 71 bonded electrons are linked to a conjugated system (alternate double and single carbon-carbon bonds), the absorption will shift to a lower frequency, and the substance may be coloured. The colour observed will be the complementary colour of that absorbed. 

If the refractive index of the substrate is greater than that of the film then a phase change will be introduced both at the air-film interface and at the film-substrate interface. In this case, the reflected colour seen at normal incidence when viewed in white light will be the complementary colour to that just described. These are listed in Section S4.ll in the column labelled colour transmitted . 

This colour is the complementary colour to that reflected. It is the same as that shown in transmission by a thin transparent plate of an anisotropic crystal viewed in white light between parallel polars. In addition, these colours are seen in reflection when a thin transparent film on a substrate with a greater refractive index is viewed in white light. 

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