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Luminescence of Crystals, Molecules, and Solutions by Ferd Williams download in pdf, ePub, iPad

In the first stable zinc sulfide phosphor was described. Of course, the atoms of every material are vibrating at room temperature already, but this vibration is just sufficient to produce temperature radiation in the far infrared region of the spectrum. Although bioluminescent systems have not yet found practical applications, they are interesting because of their high luminescence efficiency. The electroluminescence sometimes observed at the electrodes during electrolysis is caused by the recombination of ions therefore, this is a sort of chemiluminescence.

Their main shortcoming is their relatively poor stability in light, because of which they are used mostly when durability is not required. It produced a brilliant white light by the discharge of high voltage through carbon dioxide at low pressure.

In some of them, activators must first be introduced into the crystal. Similar observations have been made with numerous organic and inorganic substances. Thermoluminescence Thermoluminescence means not temperature radiation but enhancement of the light emission of materials already excited electronically by the application of heat. Luminescence and incandescence As mentioned above, luminescence is characterized by electrons undergoing transitions from excited quantum states. In all of these cases, positive and negative electric charges are produced by the mechanical separation of surfaces and during the crystallization process.

In the gas phase these

This is the explanation for the fact that only a relatively small number of compounds are able to exhibit efficient luminescence. For high efficiency, only a trace of the activator may be inserted into the host crystal, and its distribution must be as regular as possible. The situation is far more complicated in the case of inorganic phosphors. Thus, many luminescent centres will be produced, and strong activation will result. When they approach the Earth, they are concentrated by its geomagnetic field near the poles.

Zinc sulfide and cadmium sulfide phosphors are especially efficient in electroluminescence. In the gas phase these interactions are smaller than they are in the condensed phase of a liquid or a solid material.

Zinc sulfide and cadmium sulfide phosphors